Claims:We Claim:
1. A method of operation of a balancing system (200) for balancing a vehicle (100), the method comprising the steps of:
receiving information from a plurality of sensors (230, 240, 250), including a steering angle sensor (250), corresponding to dynamic conditions of the vehicle (100) by the balancing-control unit (235);
calculating a balancing steering angle (As) based on information received for the plurality of sensors (230, 240, 250) by the balancing-control unit (235);
actuating an actuator unit (205) towards achieving the balancing steering angle (As) by performing steering angle control to maneuver a steering system (120) of the vehicle (100);
comparing the balancing steering angle (As) with an actual steering angle (As’) of the steering system (120);
identifying an updated vehicle running condition based on difference between the actual steering angle (As’) and the balancing steering angle (As);
updating the balancing steering angle (As) based on the updated vehicle running condition and accordingly driving the actuator unit (205) to maneuer the steering system (120).
2. The method of operation of the balancing system (200) as claimed in claim 1, wherein the actuating of the actuator unit (205) being done by applying an actuator angle and an actuator torque, towards achieving the balancing steering angle (As), to maneuver the steering system (120) of the vehicle (100).
3. The method of operation of the balancing system (200) as claimed in claim 1, wherein the steering system (120) comprises a steering shaft (212) rotatably journaled about a frame assembly (105), and the actuating of the actuator unit (205) performs rotation of the steering shaft (212) by one of a direct engagement or through a torque enhancer unit (210).
4. The method of operation of the balancing system (200) as claimed in claim 1, further comprising estimating a mean (Mean [As’ (t-n: t)]) of the actual steering angle (As’) over a pre-determined time (t-n: t) to identify a change in actual steering angle (As’) with reference to the balancing steering angle (As).
5. The method of operation of the balancing system (200) as claimed in claim 4, wherein the mean of the actual steering angle (As’) over a pre-determined time (t-n: t) being compared with a balancing steering angle (As) for a difference therebetween (Mean [As’(t-n: t)] – As (t)).
6. The method of operation of the balancing system (200) as claimed in claim 5, wherein the identifying of the updated vehicle running condition includes identifying a time differential (Diff (As’(t) - As (t))) between the actual steering angle (As’) and the balancing steering angle (As), wherein the updated vehicle running condition being identified as a steady maneuvering condition when the differential (Diff (As’(t) - As (t))), the mean (Mean [As’(t-n: t)] – As (t)) both being less than a corresponding threshold (Ath, Adth).
7. The method of operation of the balancing system (200) as claimed in claim 5, wherein the identifying of the updated vehicle running condition includes identifying a differential (Diff (As’(t) - As (t))) between the actual steering angle (As’) and the balancing steering angle (As), wherein the updated vehicle running condition being identified as a transient maneuvering condition when at least one of the differential (Diff (As’(t) - As (t))), the mean (Mean [As’(t-n: t)] – As (t)) both being greater than a corresponding threshold (Ath, Adth).
8. The method of operation of the balancing system (200) as claimed in claim 1, wherein the updating the balancing steering angle (As) for a next instance being (As (t+1)), wherein the updated balancing steering angle (As (t+1)) being same as the balancing steering angle (As (t+1)), estimated earlier, when the updated vehicle running condition being a steady maneuvering condition.
9. The method of operation of the balancing system (200) as claimed in claim 1, wherein updating the balancing steering angle (As) for a next instance being (As (t+1)), wherein the updated balancing steering angle (As (t+1)) being a integration of the balancing steering angle (As (t+1)) estimated earlier and a differential (Diff (As’(t) - As (t))) between the balancing steering angle (As’) and the balancing steering angle (As), when the updated vehicle running condition being a transient maneuvering condition.
10. The method of operation of the balancing system (200) as claimed in claim 9, wherein the differential (Diff (As’(t) - As (t))) between the balancing steering angle (As’) and the balancing steering angle (As) being multiplied with a gain factor (G1), wherein the gain factor (G1) being a value between 0 and 1.
11. The method of operation of the balancing system (200) as claimed in claim 1, wherein driving the actuator unit (205) being done by one of a current-controlled or a voltage-controlled operation.
12. A method of current control for operation of a balancing system (200) for balancing a vehicle (100), the method comprising the steps of:
receiving information from a plurality of sensors (230, 240, 250,), including a steering angle sensor (250), corresponding to dynamic conditions of the vehicle (100) by the balancing-control unit (235);
calculating a balancing steering angle (As) continuously based on information received for the plurality of sensors (230, 240, 250,) by the balancing-control unit (235);
actuating an actuator unit (205) towards achieving the balancing steering angle (As) to maneuver a steering system (120) of the vehicle (100);
comparing the balancing steering angle (As) with an actual steering angle (As’);
calculating a difference between the actual steering angle (As’) and the balancing steering angle (As);
identifying an updated vehicle running condition based on difference between the actual steering angle (As’) and the balancing steering angle (As);
updating the balancing steering angle (As) based on the updated vehicle running condition and accordingly driving the actuator unit (205) to maneuver the steering system (120) by applying a controlling current (I’).
13. The method of current control for operation of the balancing system (200) as claimed in claim 12, wherein comparing the balancing steering angle (As) with an actual steering angle (As’) being done by identifying an error value (|As’- As|).
14. The method of current control for operation of the balancing system (200) as claimed in claim 13, wherein the error value (|As’- As|) being compared with an upper threshold value (Eth_U), and the balancing-control unit (235) performs an immediate correction when the error value being greater than the upper threshold value (|As’- As| > Eth_U) by applying a controlling current (I’).
15. The method of current control for operation of the balancing system (200) as claimed in claim 14, wherein the controlling current (I’) being one of an addition and an integration of an estimated current (I), based on the balancing steering angle (As), and a balancing current (I1) (I’ = ± (I+I1).
16. The method of current control for operation of the balancing system (200) as claimed in claim 15, wherein the error value (|As’- As|) being compared with a lower threshold value (Eth_L) when the error value (|As’- As|) being less than the upper threshold value (Eth_U), and the balancing-control unit (235) performs an correction when the error value being greater than the lower threshold value (|As’- As| > Eth_L) by applying a controlling current (I’).
17. The method of current control for operation of the balancing system (200) as claimed in claim 16, wherein a controlling current (I’) being a difference between an estimated current (I), based on the balancing steering angle (As), and a balancing current (I1).
18. The method of current control for operation of the balancing system (200) as claimed in claim 15 or claim 17, wherein the balancing current (I1) having a sign (+, -), for directional control of the steering system (120), being dependent on rider intention identified from the comparison of the balancing steering angle (As) with the actual steering angle (As’).
19. The method of current control for operation of the balancing system (200) as claimed in claim 14, wherein when the error value (|As’- As|) being less than an upper threshold value (Eth_U) and a lower threshold value (Eth_L) then a controlling current (I’) being same an estimated current (I) of the balancing steering angle (As).
20. A method of operation of a balancing system (500) for balancing a vehicle (100), the method comprising the steps of:
receiving information from a plurality of sensors (540, 550, 560, 565), including a steering angle sensor (550) and a steering torque sensor (560), corresponding to dynamic conditions of the vehicle (100) by a balancing-control unit (535);
calculating a balancing steering angle (As) and a balancing steering torque (T) based on information received for the plurality of sensors (540, 550, 560, 565) by the balancing-control unit (535);
actuating an actuator unit (205) towards achieving the balancing steering angle (As) and the balancing steering torque (T) to maneuver a steering system (120) of the vehicle (100);
comparing the balancing steering angle (As) with an actual steering angle (As’) and the balancing steering torque (T) with an actual steering torque (T’);
identifying an updated vehicle running condition based on difference between the actual steering angle (As’) and the balancing steering angle (As), and difference between the actual steering torque (T’) and the balancing steering torque (T); and
updating the balancing steering angle (As) and the balancing steering torque (T) based on the updated vehicle running condition and accordingly driving the actuator unit (205) to maneuver the steering system (120).
21. The method of operation of the balancing system (500) as claimed in claim 20, wherein a difference between the balancing steering torque (T) and the actual steering torque (T’) being estimated to calculate an error value (|T’- T|), wherein the error value (|T’- T|) being compared with a threshold value (Tth).
22. The method of operation of the balancing system (500) as claimed in claim 22, further comprising identifying a rider input when the error value (|T’- T|) being greater than the threshold value (Tth) thereby enabling the balancing-control unit (535) to perform balancing by one of a current-controlled or a voltage-controller operation.
23. The method of operation of the balancing system (500) as claimed in claim 24, wherein the balancing-control unit (535) performing balancing and updating the balancing steering torque (T) and the balancing steering angle (T’).
24. The method of operation of the balancing system (500) as claimed in claim 22, further comprising identifying no rider input when the error value (|T’- T|) being less than the threshold value (Tth) thereby the balancing-control unit (535) performs receiving of information from the plurality of sensors ( 540, 550, 560, 565) for any imminent balancing requirement.
25. A balancing system (200, 500) for a vehicle (100), the balancing system (200, 500) configured to preform balancing the motor vehicle (100), the vehicle (100) comprising:
a frame assembly (105), the frame assembly (105) comprising a head tube (106) disposed in a front portion thereof;
a steering shaft (212), the steering shaft (212) rotatably journaled about the head tube (106);
a plurality of sensors (230, 240, 250, 540, 550, 560, 565) for sensing various dynamic parameters of the vehicle (100), the plurality of sensors (230, 240, 250, 540, 550, 560, 565) comprising a steering angle sensor (250, 550);
an actuator unit (205, 505) configured to control operation of the steering shaft (212);
a balancing support-control unit (235, 535) configured to estimate a balancing steering angle (As) based on inputs received from the plurality of sensors (230, 240, 250, 540, 550, 560, 565) and comparing the balancing steering angle (As) with an actual steering angle (As’) received from the steering angle sensor (250, 550) and thereby triggering the actuator unit (205, 505) to perform steering operation of the steering shaft (212) to balance the vehicle and achieve updated balancing steering angle (As).
26. The balancing system (200, 500) for the vehicle (100) as claimed in claim 25, wherein the plurality of sensors (230, 240, 250, 540, 550, 560, 565) includes an inertia monitoring unit (240, 540), a steering angle sensor (250, 550), a torque sensor (560), a global positioning sensor (230), a speed sensor (565), and wherein the one or more sensor (230, 240) of the plurality of sensors are disposed at a posterior region of the vehicle (100) and substantially in close vicinity of the balancing control unit (235).
, Description:TECHNICAL FIELD
[0001] The present subject matter relates to a saddle type vehicle, which requires balancing, and more particularly to a balancing system for the saddle type vehicle.
BACKGROUND
[0002] Generally, vehicles like four-wheelers or higher order multi-wheeled (more than four) are balanced and do not require any additional balancing except in case of cornering or the like. Moreover, the present day four-wheeled vehicles can perform one autonomous task at a time. For example, these vehicles mostly incorporate autonomous safety-oriented features, such as automatic lane keeping or adaptive cruise control. Some other advanced four-wheeled vehicles can perform two autonomous tasks at a time, for example, steering as well as performing lane-keeping, or auto-braking and adaptive cruise control. Thus, the four-wheeled vehicles are implementing these electric powers assisted systems (EPAS), and electronic stability programs (ESP).
[0003] However, there exists a major gap in terms of autonomy for the two-or three-wheeled vehicles, which are typically saddle-ride type vehicles. Even before considering autonomy, there is a major challenge of balancing the saddle-ride type vehicles. Unlike four-wheeled vehicles, or vehicles with more than four-wheels, the saddle-ride type vehicles are unstable and have the tendency to roll over or capsize towards one lateral side. The vehicles including two-and three-wheeled vehicles are steered by operating a handle bar in order to operate one or more front wheels. The rider has to exert high steering forces in order to maneuver the vehicle. At lower speeds, the inertia of a steering system is higher causing fatigue to the rider to balance the vehicle, let alone performing maneuvering.
BRIEF DESCRIPTION OF DRAWINGS
[0004] The detailed description is described with reference to the accompanying figures, which is related to a two-wheeled saddle ride vehicle being one embodiment of the present invention. However, the present invention is not limited to the depicted embodiment(s). In the figures, the same or similar numbers are used throughout to reference features and components.
[0005] Fig. 1 illustrates a left-side view of an exemplary vehicle, in accordance with an embodiment of the present subject matter.
[0006] Fig. 2 depicts a steering support system supported by a frame assembly of a vehicle, in accordance with an embodiment of the present subject matter.
[0007] Fig. 3 (a) illustrates a flow chart illustrating a method of operation of a balancing system, in accordance with an embodiment of the present subject matter.
[0008] Fig. 3 (b) illustrates a flow chart depicting a method of operation of a balancing system, in accordance with an embodiment of the present subject matter.
[0009] Fig. 4 illustrates a method of controlling the balancing system by a current control (current-controller operation), in accordance with an embodiment of the present subject matter.
[00010] Fig. 5 (a) illustrates a balancing system, in accordance with a second embodiment of the present subject matter.
[00011] Fig. 5 (b) illustrates a method of functioning of a balancing system comprising a balancing-control unit, in accordance with an embodiment of the present invention, in the form of a flowchart.
DETAILED DESCRIPTION
[00012] I In the conventional two-and some three-wheeled vehicles, the rider has to continuously and consciously perform maneuvering operation to achieve balance and to avoid fall. That is because, unlike four-wheelers, the saddle ride vehicles are influenced by external parameters also, such as irregular road surface or change in friction of terrain due to rains or the like. These external parameters may cause the vehicle highly unstable or imbalanced, which generally leads to fall or accidents. It is even more challenging for a novice rider to achieve balance as there is no knowledge of force required or steering angle required for balancing. Unless for an experienced rider, the amount of steering torque and steering angle to be applied cannot be gauged by the novice rider. Even for the experienced rider such continuous and conscious maneuvering creates fatigue especially in traffic conditions. Thus, the rider of the vehicle, finds it difficult to balance the vehicle while operating at low-speeds.
[00013] Certain attempts were made in the art, to assist the rider in steering operation. This may reduce steering fatigue but still has the problem of balancing anxiety and requires steering skill (direction-angle and force/torque). As per one solution, a rear wheel of the vehicle is controlled for providing balancing. This complicates the overall system and moreover, implementation of such a mechanism in a compact saddle rider type vehicle is difficult. Further, in certain other known designs, the handlebar is disconnected from the steering system. This requires special trainings for the riders to adapt to as it is unconventional. The rider would not be receiving any road feedback. Due to lack of feedback, the rider feels a disconnect from the road conditions whereby riding discomfort is created.
[00014] In certain other systems known in the art, in order to achieve balance, a torque on the wheels is modified by providing a positive or negative acceleration. Even though this may provide balance, such a technique is not preferred as it causes a change in acceleration or deceleration of the vehicle, which may result in accidents. Without the intention or knowledge of the driver, the vehicle may be accelerated or decelerated to attain stability whereby the vehicle may run into a vehicle in front or get hit by a vehicle in the behind (during sudden deceleration).
[00015] Moreover, some solutions propose modifying steering ratio between the input shaft and steering shaft, which is not compatible for saddle ride vehicles (two-wheeled or three-wheeled vehicles), and may even create confusion in mind of the rider as the vehicle responds differently at different conditions (steering ratio), which makes the driving unpredictable. Ease of mind during driving is one major challenge in such systems.
[00016] Moreover, certain vehicles tend to switch between positive trail and negative trail during steering assist and to provide balance. For each of trail of the steering system, the user experiences a different driving posture as it may change handle bar position, effective seat height, wheelbase etc. causing serious discomfort while driving.
[00017] Thus, there exists a need for providing a balancing system and a method thereof for a vehicle, which can provide vehicle stability or balance without the need for modification (dynamic) of riding posture and vehicle dynamics. The system should be capable of providing a feedback to the rider without any disconnection of the steering system from the rider input.
[00018] Hence, the present subject matter provides a balancing system and a method thereof, that addresses the aforementioned and other problems of the prior art.
[00019] The method of operation of a balancing system for balancing a vehicle comprises the steps of receiving information from a plurality of sensors of the vehicle. The plurality of sensors primarily includes an angle sensor. The plurality of sensors provides information corresponding to dynamic conditions of the vehicle to a balancing-control unit. A balancing steering angle is calculated based on information received for the plurality of sensors by the balancing-control unit. An actuator unit is connected to a steering system towards achieving the balancing steering angle to maneuver the steering system of the vehicle. This applies the balancing steering angle to achieve balancing and then the balancing steering angle is compared with an actual steering angle applied by the rider. Comparing or identifying a difference between the balancing steering angle enables the balancing-control unit to identify a rider intention. Accordingly, the system identifies an updated vehicle running condition based on difference between the actual steering angle and the steering angle. The system then updates the balancing steering angle based on the updated vehicle running condition and accordingly the actuator unit is driven to maneuver the steering system thereby achieving stability.
[00020] The method and the system provide the balancing steering angle, at the same time acknowledges the rider intention, thereby performing the balancing operation first and then performing the rider intended maneuvering operation.
[00021] In one embodiment, the method of operation of the balancing system comprises of actuating of the actuator unit by applying an actuator angle, which is same as the balancing steering angle, and an actuator torque towards achieving the balancing steering angle to maneuver the steering system of the vehicle. The system considers the inertia of the steering system and accordingly provides the actuator torque for easing the steering operation for the rider.
[00022] In one embodiment, the steering system comprises a steering shaft rotatably journaled about a frame assembly (a head tube of the frame assembly, as per one implementation). The actuating of the actuator unit performs rotation of the steering shaft by one of a direct engagement or through a torque enhancer unit.
[00023] The torque enhancer unit is configured to provide a gear ratio to cater to the steering operation of the steering system.
[00024] In one embodiment, the method further comprises of determining a mean of the actual steering angle over a pre-determined time. The mean of the actual steering angle taken over the pre-determined time eliminates any error value in the actual steering (for example, error values may occur due to unintentional maneuvers or fluctuation due to road surfaces or other parameters). Through the mean value, the balancing-control unit identifies the change in actual steering angle with respect to the balancing steering angle over the pre-determined time period.
[00025] In one embodiment, the method comprises the step of estimating a difference between the mean and the actual steering angle, and the estimated difference is compared with a balancing steering angle in order to obtain the updated vehicle condition.
[00026] In one embodiment, the updated vehicle condition will be a steady maneuver condition when the difference (difference between the mean and the balancing-steering angle) being less than a threshold angle. Thus, the system identifies that there is no input from the rider side and the vehicle is also in the steady maneuvering condition.
[00027] In one embodiment, the updated vehicle condition will be a transient maneuvering condition when the difference (difference between the mean and the balancing-steering angle) being greater than a threshold angle. In such a condition, the balancing system performs balancing first by modifying the input to the actuator unit and then enables the rider to perform the transient operation.
[00028] In one embodiment, for identifying of the updated vehicle running condition, a mathematical time differential (rate of change) between the actual steering angle and the balancing steering angle is considered. The updated vehicle running condition is identified as a steady maneuvering condition when the differential and the difference (the mean and the balancing-steering angle) both are less than a corresponding threshold. The differential provides a rate of change of the actual steering angle whereby the balancing-control unit performs a proportionate control.
[00029] In one embodiment, the updated vehicle running condition is identified as a transient maneuvering condition when any of the differential (between the actual steering angle and the balancing steering angle), and the difference (the mean and the balancing-steering angle) are greater than a corresponding threshold. In such a condition, the balancing system identifies an abnormality and performs balancing.
[00030] In one embodiment, the updating of balancing steering angle is performed for a next instance. The updated balancing steering angle is kept same as the balancing steering angle, estimated earlier for the next instance, when the updated vehicle running condition is a steady maneuvering condition.
[00031] In one embodiment, updating of the balancing steering angle is done for a next instance. The updated balancing steering angle is a time integration of the balancing steering angle, estimated earlier, and a time differential between the actual steering angle and the balancing steering angle. Such a correction is performed when the updated vehicle running condition is a transient maneuvering condition.
[00032] In one embodiment, the balancing steering angle and the updated balancing steering angle are applied to the actuator unit by one of a current-controlled or a voltage-controlled operation.
[00033] In one embodiment, a method of current control for operation of the balancing system is preferred. The method comprises the steps of receiving information from a plurality of sensors, calculating a balancing steering angle, actuating an actuator unit towards achieving the balancing steering angle, comparing the balancing steering angle with an actual steering angle applied by the rider. Further, calculating a difference between the actual steering angle and the balancing steering angle. Then identifying an updated vehicle running condition based on the above difference. Accordingly, updating the balancing steering angle based on the updated vehicle running condition and driving the actuator unit to maneuver the steering system by applying a controlling current.
[00034] In one embodiment, the balancing system compares the balancing steering angle with an actual steering angle applied by the rider thereby identifying an error value (error value is equal to a difference, as per one implementation).
[00035] In one embodiment, the method of current control for operation of the balancing system, the error value is compared with an upper threshold value. The balancing-control unit performs an immediate correction when the error value is greater than the upper threshold value by applying a controlling current. This also implies that the rider is providing an input, which has to counteracted and then the rider intended maneuvering is performed.
[00036] In one embodiment, a controlling current is obtained by an integration of an estimated current, based on the balancing steering angle, with a balancing current. The balancing current being estimated by the balancing-control unit, which corresponds to the error value.
[00037] In one embodiment, the error value (between the actual steering angle and the balancing steering angle) is compared with a lower threshold value. If the error value is between the upper threshold and a lower threshold, then the balancing-control unit performs a correction by applying a controlling current.
[00038] In one embodiment, the controlling current, when the error value is between the upper threshold and the lower threshold value, is a difference between an estimated current, obtained based on the balancing steering angle, and a balancing current, corresponding to the error value.
[00039] In one embodiment, the balancing current is either positive or negative depending on a rider intention identified from the earlier stage.
[00040] In another embodiment, the method of operation of a balancing system for balancing a vehicle comprises of receiving information from a plurality of sensors. The plurality of sensors primarily including a steering angle sensor and a steering torque sensor. Then calculating a balancing steering angle and a balancing steering torque. Actuating an actuator unit towards achieving the balancing steering angle and the balancing steering torque. Comparing the balancing steering angle and the balancing steering torque with an actual steering angle and an actual steering torque, applied by the rider. An updated vehicle running condition is identified based on difference between the actual steering angle and the balancing steering angle, and difference between the actual steering torque and the balancing steering torque. This helps in identifying a rider intention depending on a deviation between the actual and balancing values. Accordingly, the balancing steering angle and the balancing steering torque, based on the updated vehicle running condition, are updated and accordingly the actuator unit is driven to maneuver the steering system.
[00041] In another embodiment, a difference between the balancing steering torque and the actual steering torque is calculated thereby obtaining an error value. The error value is compared with a threshold value to understand the rider intention.
[00042] The present invention provides improved riding experience to experience as well as to novice riders as critical balancing function is taken care by the balancing system. The riders can comfortably ride in slow moving conditions like heavy traffic etc.
[00043] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00044] The balancing system may be implemented in any two-wheeled vehicle or a three-wheeled vehicle. However, for the purpose of explanation and by no limitation, the balancing system, and corresponding additional advantages and features are described through the following embodiments. Arrows wherever provided on top right corner of the figure represent direction with respect to vehicle. Arrow F represents forward direction, arrow R represents rearward direction, arrow UW represents upward direction and arrow DW represents downward direction.
[00045] Fig. 1 depicts a left side view of an exemplary vehicle 100, in accordance with an embodiment of the present subject matter. The vehicle 100 includes a frame assembly 105 (shown schematically) comprising a head tube 106, and a main frame. In the depicted embodiment, the main frame comprises a main tube 107 extending rearwardly downward from the head tube 106, and one or more rear tubes 110 extending inclinedly rearward from a rear portion of the main tube 107. In the depicted embodiment, the frame member 105 defines a step-through portion 151, which is used by rider to rest his/her feet or to load luggage thereat. In another embodiment, a main tube may be adapted to extend rearward from the head tube 106 and subsequently downward defining a space below the main tube, for supporting a power unit. A first wheel 101 and a second wheel 102 are rotatably supported by a front suspension system 131 and a rear suspension system 134, respectively. In one embodiment, the second wheel 102 may be additionally supported by a swingarm (not shown).
[00046] In accordance with the present embodiment, a power unit 135 is swingably connected to the frame member 105 and is disposed substantially below a seat assembly 155 and rearward to the step-through portion 151. The power unit 135 includes a transmission system (not shown) for transferring power to the second wheel 102. The transmission system may include a continuously variable transmission, an automatic manual transmission, a belt/chain drive. In one embodiment, the power unit 135 is an internal combustion engine. In another embodiment, the power unit 135 is an electric prime mover. In one another implementation, the power unit is fixedly mounted to the frame assembly 105 of the vehicle 100.
[00047] Further, the first wheel 101 is pivotally supported by the frame assembly 105 and a handle bar assembly 150 is functionally connected to the first wheel 101 for maneuvering and steering the vehicle 100. The handle bar assembly 150 may support an instrument cluster, vehicle controls including throttle, clutch, or electrical switches. Further, a seat assembly 155 is supported by the frame assembly 105 and the rider can operate the vehicle 100 in a seated position on the seat assembly 155. Moreover, in the depicted embodiment, the vehicle 100 includes the step-through portion 151 formed between the handle bar assembly 150 and the seat assembly 155.
[00048] The vehicle 100 is provided with plurality of panels 170A, 170B, 170C mounted to the frame assembly 105 and covering the frame assembly 105 and/or parts of the vehicle 100. The plurality of panels includes a front panel 170A and a leg-shield 170B covering a head tube 106 of the frame assembly 105 in forward and rearward direction, respectively. Further, a rear panel assembly 170C is disposed substantially below the seat assembly 155. The rear panel assembly 170C substantially covers a utility box (not shown) disposed below the seat assembly 155 and also, covering at least a portion of the power unit 135. The vehicle 100 is provided with a balancing system 200 (shown in Fig 2 (a)), which is discussed in following description.
[00049] Fig. 2 illustrates a schematic side view of a balancing system 200 supported on a frame assembly 105 of a vehicle 100, in accordance with an embodiment of the present subject matter. The vehicle 100 comprises a steering system 120, which includes a steering shaft 212. The steering shaft 212 is rotatably journaled about the head tube 106 (the frame assembly 105). In one embodiment, the steering shaft 212 comprises a lower end to which a lower bridge 215 is connected to. The lower bridge 215 is configured to support the front suspension system 131. The front suspension system 131 rotatably supports the first wheel 131. The steering shaft 212 is rotatable about a steering axis S-S’. In the depicted embodiment, the vehicle 100 comprises a positive trail, as the steering axis S-S’ extends ahead of a point of contact 190 of the first wheel 101 to road surface. Further, the present invention enables retaining the trail, say a positive trail, and does not require any change in trail during balancing operation of the vehicle.
[00050] The balancing system 200 of the vehicle 100 comprises of an actuator unit 205, which may directly operate the steering system 120. In another embodiment, a torque enhancer unit 210 is functionally connected to the actuator unit 205. In one embodiment, the actuator unit 205 is fixedly mounted to the frame assembly 105. In another embodiment (not shown), an extension member is fixed to the frame assembly 105 and the actuator unit 205 is supported on the extension member. As per an embodiment, the steering axis S-S’ is parallel to the actuator axis A-A’. The torque enhancer unit 210 is configured to provide driving force from the actuator unit to the steering shaft 212. In one implementation, as per the present invention, an existing configuration of head tube 106 is retained in the vehicle, without the need for changing a front portion (say head tube portion) of the frame assembly 105. In another embodiment, the head tube portion is modified to accommodate the actuator unit and allied sub-systems.
[00051] Further, the balancing system 200 of the vehicle 100 comprises a plurality of sensors that provide a dynamic operating conditions related information of the vehicle 100. Furthermore, a balancing-control unit 235 is mounted on the vehicle 100. In one embodiment, a steering angle sensor 250, which forms part of the plurality of sensors is mounted between an actuator unit shaft (not shown) of the actuator unit 205 and the torque enhancer unit 210. The present subject matter is capable of performing the balancing operation by receiving steering angle information of the steering system 120 from the steering angle sensor 250. Thus, the steering angle sensor 250, which is a critical sensor, is either directly or indirectly connected to the steering shaft 212. In case of an indirect connection, the steering angle sensor 250 is connected through an intermediate gear or an intermediate gear assembly of the torque enhancer unit 210 or the like.
[00052] The steering angle sensor 250 is compactly accommodated on the vehicle without disturbing the function of the steering shaft 212, the actuator unit 205 and the handlebar assembly 150. The steering angle sensor 250 is configured to provide data/ information related to steering angle of the steering shaft 212. A top portion of the steering shaft 212 is functionally connected to a handlebar assembly 150 through a connecting means 216. Further, the plurality of sensors includes, and not limited to, a speed sensor (not shown), a global positioning system (GPS) unit 230, an inertia measurement unit (IMU) 240 supported by the frame assembly 105. As per an embodiment, one or more sensor 230, 240 of the plurality of sensors are disposed at the posterior region of the vehicle and substantially in close vicinity of the balancing control unit 235 to enable a compact and secure layout of the vehicle. The plurality of sensors is communicatively coupled to the balancing-control unit 235 in order to provide various dynamic operating conditions of the vehicle 100.
[00053] In the depicted embodiment, a balancing-control unit 235 is supported by the rear tubes 110 of the frame assembly 105. In another embodiment, the balancing-control unit 235 may be disposed at any other portion of the frame assembly 105, subject to layout of the vehicle 100. The balancing-control unit 235 is communicatively coupled to the actuator unit 205 in order to activate/deactivate or control operation of the actuator unit 205. The balancing-control unit 235 is configured to balance the vehicle 100 by controlling the operation of the actuator unit 205 and correspondingly control an angle of the steering shaft 212. The method of operation of the balancing system is explained through the following illustrations.
[00054] Fig. 3 illustrates a flow chart depicting a method of operation of the balancing system, in accordance with a first embodiment of the present subject matter. As per the first embodiment, the method considers inputs from the plurality of sensors including the steering angle sensor 250. The balancing-control unit 235 receives inputs from the plurality of sensors to obtain information related to dynamic condition of the vehicle 100 (herein reference is made to Figs. 1 & 2 for system level components). For example, a speed v is sensed from speed sensor. In one implementation, the speed v can be obtained from the GPS unit 230. In yet another implementation, the speed v is measured using a Hall sensor or an encoder, which is locally provided in the vehicle 100. A roll rate and a roll angle ? is sensed from the IMU 240. In one implementation, the roll angle is estimated from a roll angular velocity (a roll angle displacement may directly be measured using IMU 240).
[00055] In one embodiment, the balancing-control unit 235 is configured to balance the vehicle 100. Further, the vehicle 100 is provided with low speed/high speed stability, a steering assist (to reduce steering effort for the rider) and other dynamics improvements. At step S305, the balancing-control unit 235 receives the dynamic condition of the vehicle 100. At step S310, a balancing steering angle As is calculated by the balancing system 200 by receiving information related to steering angle from one or more sensor. In one embodiment, the balancing steering angle As is estimated using various parameters of the dynamic condition of the vehicle 100. In one implementation, a look-up table may be provided with various steering angles corresponding to various dynamic running conditions of the vehicle. To achieve the balancing steering angle As, the actuator unit 205 is applied with a current or voltage to perform the steering control operation. In one implementation, the current to be applied is calibrated for various riding and road conditions and stored in the look-up table for the balancing-control unit 235. As shown in step S315, the balancing-control unit 235 is configured to apply the balancing steering angle As to the actuator unit 205. The actuator unit 205 operates towards achieving the balancing steering angle As and accordingly, a steering torque may be applied by the actuator unit 205, at step S320.
[00056] Further, at step S325, an actual steering angle As’ of the steering system 120 is measured using the steering angle sensor 250 and is fed to the balancing-control unit 235. A difference (error value) between the actual steering angle As’ and the balancing steering angle As is analysed by the balancing control unit 235 to determine a rider intention and a riding condition of the vehicle 100, at step S330. A rider intention is determined from a deviation of the actual steering angle from the balancing steering angle. For example, the rider intention to maneuver in a direction away from the balancing steering angle is recorded by the balancing-control unit 235. The balancing-control unit 235 performs balancing operation and operates the steering system 120 in a direction of the rider intention recorded earlier. At step S335, a mean of the actual steering angle As is measured over a pre-determined time duration. Further, a difference between the mean, and the balancing steering angle As’ is calculated by the balancing-control unit 235 i.e. mean [As’ (t-n: t)] – As (t) {for ease, referred to as difference}. Where ‘n’ defines time duration for which the value is measured. The means helps in identifying a quantity of the maneuvering operation that is happening. Similarly, a time differential/differentiation value between actual steering angle As’ and the balancing steering angle As is also measured i.e. diff [As’(t)-As(t)] {for ease, referred to as differential angle}. Since, the differential angle changes in comparison with a previous instance or over a time period, a rate of change of the state of steering system is monitored by the balancing-control unit 235. The difference and the differential are measured to identify a riding condition of the vehicle 100. At step S335, the difference and differential are compared (to check if they are less than) with a threshold angle Ath and a differential threshold angle Adth. The comparison equations are shown below:
Mean [As’ (t-n: t)] – As (t) < Ath ….. (1)
&
Diff [As’(t) – As (t)] < Adth ….. (2)
[00057] Further, based on the comparison, at step S335, if the outcome of the equations (1) & (2) is ‘Yes’, then at step S340, the balancing-control unit 235 identifies that the vehicle is in a steady maneuvering condition. The steady maneuvering condition is identified, as there is minimal to negligible variation on the left side portion of the equations (1) and (2) or the difference and differential is less the corresponding thresholds. If the difference or differential from equations (1) and (2) is more than the threshold, then the balancing-control unit 235 has to take a corrective action. The mean i.e. mean [As’ (t-n: t)] helps in identifying precise actual steering angle value over the defined time period by eliminating any sudden spikes due to temporary fluctuations in the steering system 120. Thus, when the threshold values are not exceeded, the corrected value of the balancing steering angle As (t+1), for the next instance, is same as the earlier balancing steering angle As (t+1) computed earlier to corrective action.
[00058] Further, at step S335, if the output of the equation (1) or (2) is a ‘No’, which is, the difference or the differential has crossed a threshold valves Ath or Adth, then the balancing-control unit 235 identifies the motion of the vehicle 100 as a transient maneuvering condition. Upon detecting the transient maneuvering condition, the balancing-control unit 235 corrects the balancing steering angle, for the next instance, by adding the differential between the actual steering angle and the balancing steering angle to the balancing steering angle, estimated earlier to detection of updated vehicle condition, for the next instance, i.e.
As (t+1) = As (t+1) + diff (As’(t)-As(t))…..(3)
[00059] The balancing steering angle for the next instance is depicted as As(t+1). The balancing steering angle As(t+1) gets updated by adding the differential value between the measured steering angle As’(t) and the balancing steering angle As(t+1) estimated earlier. This difference is added to the balancing steering angle for the next instance. This updated balancing steering angle for next instance is fed to the actuator unit 205, at step S360. The vehicle is balanced by the balancing system 200 by applying required angle and torque to the steering system 120 through the actuator unit 205, at step S365 by applying the balancing steering angle / torque to the actuator at step 360. For example, the balancing-control unit 235 estimates a balancing steering torque T based on inputs received from the plurality of sensors. Then determines a balancing steering torque T and triggers the actuator unit 205 with input corresponding to the balancing steering torque T thereby balancing the vehicle. The handlebar assembly 150 (rider) and the actuator unit 205 are capable of providing input parallelly to the steering shaft 212 to maneuver the vehicle 100. In another scenario, the balancing-control unit 235, initially, operates the handlebar assembly 150 in a direction opposite to the direction of rotation of the rider (rider intention) for balancing the vehicle 100. This scenario occurs when a differential [diff (As’(t)-As(t)] is negative due to higher deviation between the angle values. Once the vehicle 100 balancing is achieved, the balancing system 200 enables the rider to perform the intended maneuver and even assist if required.
[00060] In one embodiment, the equation (3) includes a gain factor G1, which is multiplied with the differential [Diff (As’(t) - As (t))] between the balancing steering angle As’ and the balancing steering angle As. The gain factors G1 is being a value between 0 and 1. The gain factor is chosen is chosen based on rate at which the control action has to be taken. For an immediate control, the gain factor is chosen to be maximum.
[00061] In one embodiment, the balancing system 200 is activated at pre-determined conditions of the vehicle 100. For example, when the rider is operating the vehicle 100 at low-speeds (say at a speed less than 5 kilometers per hour, as per one embodiment), the balancing system 200 is activated. In order to balance the vehicle 100 at such low speeds, the rider usually provides a balancing input to the vehicle 100 by operating the handlebar assembly 150 of the steering system. However, the input provided by the rider may not be sufficient, or may not be in the right direction or with the required rate. The balancing system 200 gets actuated and it applies a partial or complete balancing angle and torque to the steering shaft 212. The steering shaft 212 receives input from the handlebar assembly 150 and from the actuator unit 205. In addition to balancing assist, the actuator unit 205 provides a steering/ torque assist towards performing an intended steering maneuver. The balancing-control unit 235 is configured to estimate a torque to be applied using data from one or more sensors of the plurality of the sensors that include the inertia measurement unit 240, a speed sensor (not shown), a global positioning sensor unit 230 etc. The balancing system 200 predominantly uses data from the steering angle sensor 250. Moreover, the balancing system 200 performs a current control operation to provide the required angle and torque.
[00062] Fig. 3 (b) illustrates a flow chart depicting the method of operation of the system, in accordance with an embodiment of the present subject matter. The method of operation of a balancing system 200 for balancing a vehicle 100 is elaborated in the following steps. At step S1301, the balancing control unit 235 receives information from a plurality of sensors 230, 240, 250, including a steering angle sensor 250, which provides information corresponding to dynamic conditions of the vehicle 100. At step S1310, the balancing-control unit 235 calculates a balancing steering angle As based on information received for the plurality of sensors 230, 240, 250 [in the aforementioned step]. Further, at step S31315, the balancing control unit 235 actuates an actuator unit 205 towards achieving the balancing steering angle As by performing steering angle control for maneuvering the steering system 120 of the vehicle 100. At step S31320, the balancing control unit 235 compares the balancing steering angle As with an actual steering angle As’ of the steering system 120. At step S1325, the balancing control unit 235 identifies an updated vehicle running condition based on difference between the actual steering angle As’ and the balancing steering angle As. Then at step S1330, the balancing control unit 235 updates the balancing steering angle As based on the updated vehicle running condition and accordingly driving the actuator unit 205 to maneuver the steering system 120.
[00063] Fig. 4 illustrates a method of controlling the balancing system by a current control (current-controller operation), in accordance with an embodiment of the present subject matter. As per the present embodiment, the method considers inputs from the plurality of sensors including the steering angle sensor 250. The balancing-control unit 235 receives inputs from one or more sensors to obtain information related to dynamic condition of the vehicle. For example, a speed v is sensed from speed sensor. In one implementation, the speed v can be obtained from the GPS unit 230. In yet another implementation, the speed v is measured using a Hall sensor or an encoder, which is locally provided in the vehicle 100. The roll rate and the roll angle ? is sensed from the IMU 240. In one implementation, the roll angle is estimated from a roll angular velocity (a roll angle displacement may directly be measured using IMU 240).
[00064] At step S405, the balancing-control unit 235 receives the dynamic condition of the vehicle 100 as a state parameter. At step S410, a balancing steering angle As is calculated by the balancing system 200. At step S415, the balancing-control unit 235 is configured to control the actuator unit 205 by sending signals (current control signal) corresponding to the balancing steering angle As to the actuator unit 205. At step S420, the actuator unit 205 performs steering operation towards achieving the balancing steering angle As. At step S425, an actual steering angle As’ of the steering system 120 is measured using the steering angle sensor 250 and is fed to the balancing-control unit 235. A difference (error value) between the actual steering angle As’ and the balancing steering angle As is assessed by the balancing control unit 235 to determine a rider intention and a riding condition of the vehicle 100, at step S430.
[00065] From the difference obtained at step S430, at step 435, an error value | As’- As| is compared with an upper threshold value Eth_U. If the error value is greater than the upper threshold value, if [| As’- As| > Eth_U], then the balancing system 200 detects that the rider is providing an input to the steering system 120 in order to maneuver the vehicle 100. Further, the balancing system 200 detects the direction of rotation (rider intention) from the error value and a sign of the error value. For example, if the center position of the steering system is 0 degrees, and if the balancing steering angle As is +5 degrees but the rider has rotated the steering system 120 in opposite direction of same value, then actual steering angle As’ will be -5. Hence, the difference/ error value would be -10 degrees with a negative sign. Whereas, if the balancing steering angle As is +5 degrees but the rider has rotated the steering system 120 is same direction but beyond 5 degrees, say 10 degrees. Then, the difference/error value would be +5 degrees. From the value and sign of the error value, the balancing-control unit 235 identifies the rider intention or the direction of rotation being performed by the rider.
[00066] At step S440, when the error value is greater than the upper threshold, the balancing-control unit 235 provides a controlling current I’, which is, an estimated current I (based on balancing steering angle As) added / integrated with a balancing current I1. The negative or positive value of the balancing current I’ depends on rider intention identified from the earlier stage. Depending on the direction of operation of steering system 120 to be performed balancing control, the balancing current would be applied in positive or negative form [sign (+, -)] to the actuator unit 205, which is an electric motor in one embodiment, for directional control of the steering system 120 at step S445. The balancing is dependent on rider intention identified from the comparison of the balancing steering angle As with the actual steering angle As’. Thus, with the controlling current I’, the vehicle 100 achieves a balanced condition and the balancing-control unit 235 enables the rotation of the steering system 120 as per rider intention and subsequently continues to monitor dynamic state parameter of the vehicle at step S405.
[00067] Whereas, if at step S435, if the error value is less than the upper threshold, then at step S450, the error value is compared with a lower threshold Eth_L. If the error value is less than the lower threshold Eth_L, in that case, the controller current I’ is same as the estimated current I. If at step S450, the error value is greater than the lower threshold, then at step S460, the balancing current I’ is achieved by subtracting a balancing current I1 from the estimated current I and corresponding input is provided to the actuator at step S465 followed by continues to monitor dynamic state parameter of the vehicle at step S405. If vehicle is balanced and does not cross upper threshold Eth_U then the balancing-control unit 235 will achieve the balancing steering angle As and then follow the rider instruction with respect to desired direction of rotation. A range between the upper threshold Eth_U and the lower threshold Eth_U is decided based on the rider feel and vehicle tuning. For example, the range can be varied based on speed of operation, terrain or road surface, and vehicle configuration. At step S465, the directional control is performed for balancing and subsequently, the rider intention is performed. The current control operation is performed to achieve, the New balancing steering angle of step S345/step S355 of Fig. 3.
[00068] Fig. 5 (a) illustrates a balancing system 500, in accordance with a second embodiment of the present subject matter. Fig. 5 (b) illustrates a method of functioning of a balancing system 500 comprising a balancing-control unit 535, in accordance with an embodiment of the present invention, in the form of a flowchart 600. At step S605, the balancing-control unit 535 receives data from a GPS unit or vehicle speed sensor 565 and calculates a vehicle speed/velocity V. Similarly, a balancing-control unit 535 receives dynamic data from one or more sensor of the vehicle including a steering angle sensor 550, a torque sensor 560, a roll angle/roll rate sensor 540 like IMU and the speed sensor 545. In one embodiment, a gear ratio related information is used a dynamic data in case of gear box being used a torque converter between a steering system 120 and an actuator unit 505. Based on the critical information form the steering angle sensor and the torque sensor, in conjunction with other sensors, at step 610, the balancing-control unit 535 calculates a balancing steering angle As and step 615, a balancing steering torque T is estimated for balancing the vehicle 100.
[00069] Based on an inertia of the steering system 120 and an inertia experienced by the first wheel 101, a required balancing steering torque is estimated and is applied. In one embodiment, the balancing-control unit 235 receives estimates an inertia from a differential between the actual steering angle and the steering input provided to the actuator unit 205.
[00070] At step S620, the balancing-control unit 535 applies, the estimated balancing steering torque T to the actuator unit 505 corresponding to the balancing steering angle. The actuator unit 505 starts performing the maneuvering of the steering system 120 to the achieve the balancing steering angle As for balancing the vehicle 100. At step S625, the steering system 120 is controlled by the actuator unit 505. The balancing-control unit 535 at steps S630 & S635, measures an actual steering torque T’ an actual steering angle As’ from the data from the steering angle sensor and the torque sensor.
[00071] At step S640, a difference between the balancing steering torque T and the actual steering torque T’ is estimated. At step S655, an error value/the difference between the actual steering torque T’ and the balancing steering torque T is measure and is compared with a threshold value Tth. Similarly, at step S650, an error value/the difference between the actual steering angle As’ and the balancing steering angle As is measured and compared with a threshold value Ath.
[00072] At step S650, if a magnitude (absolute value) of error value in the angle is less than the threshold values Ath, then the vehicle is determined to be in a balanced state, as per step S655. No further, control is required for the current instance. As there is no significant input from the rider to maneuver the vehicle or there is no change in the vehicle specification, riding condition or road friction and the monitoring of the dynamic state of vehicle as per step S605 continues. If there is input from rider to change the direction or riding condition is changed, this change in dynamic state parameter results in the balancing system 500 to recalibrate the balancing steering angle As and the balancing steering torque T at steps S610 and S615. However, the balancing control unit 535 goes back to receiving information from the plurality of sensors 540, 550, 560, 565 for any imminent balancing requirement.
[00073] Simultaneously, at step S665 5, if the magnitude of error value in torque is less than the threshold values Tth, the balancing-control unit 535 concludes that there is input from rider and there is no change in riding condition and road condition. Whereas, at step S665, if the error value is greater than the threshold value Tth, then at step S670, the balancing-control unit 535 detects that there is a rider input with a deviation from the balancing steering torque T. The balancing-control unit 535 recalibrates the balancing steering angle As and the balancing steering torque at steps S610 and S615. Thus, the torque and angle control provide improved balancing control by understanding rider intention. Further, the balancing-control unit 535 performs a current control or a voltage control to operate and control the actuator unit 505 and thereby controlling the steering system 120 for stability. Since, at step S665 or at step S650, once the balancing-control unit 535 identifies the vehicle is not balance, the balancing-control unit receives the dynamic information of the vehicle (thereby updating the vehicle running condition) and accordingly calculating and inputting an updated balancing steering angle As.
[00074] While certain features of the claimed subject matter have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the claimed subject matter.


List of reference signs:
100 vehicle
101 first wheel
102 second wheel
105 frame assembly
106 head tube
107 main tube
110 rear tube(s)
120 steering system
131 front suspension system
134 rear suspension system
150 handlebar assembly
151 step-through portion
155 seat assembly
170A front panel
170B leg shield
170C rear panel assembly
190 point of contact
200 balancing system
205/505 actuator unit
210 torque enhancing unit
212 steering shaft
215 lower bridge
216 connecting tube
230 global positioning unit
235/535 balancing-control unit
240/540 inertia monitoring unit
250/550 steering angle sensor
560 torque sensor
A-A’ actuator axis
As balancing steering angle
As’ actual steering angle
Ath
Adth
S-S’ steering axis
T balancing steering torque
T’ actual steering torque
Tth
v velocity
F roll angle/ roll rate