Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed

Field of the invention
[0001] The present disclosure relates to the field of automotive steering’s. In particular, the present invention discloses a steer by wire system for a vehicle and an operating method thereof.

Background of the invention
[0002] One of the many components in an automobile is a steering system and the importance of the steering system cannot be overstated. The steering system helps the driver of the vehicle or automobile to keep the vehicle in a steady path and direction and also to take turns whenever needed. The upcoming technology of a Steer-by-Wire system aims to eliminate the physical connection between the steering wheel and the road wheels of a car by using electrically controlled motors to maneuver the wheels. The Steer-by-Wire system has opened up a new era in automotive technology. Steer-by-Wire consists of a steering wheel actuator, the steering rack actuator and software functions. The mechanical connection via an intermediate shaft is completely eliminated.

[0003] The elimination of the mechanical connection between the steering wheel actuator and the steering rack actuator creates freedom for redesigning the vehicle interior as well as realizing new functions and features. Since the Steer-by-wire system don’t have a mechanical linkage between the steering handle and wheels, the “natural steer-feel” that provides the driver with a sense of the road conditions, such as the traction of the vehicle wheels with the road surface, and with some sense of the condition of the components of the steering system is interrupted.

[0004] Prior arts such as US2003230448 AA speak of simulating the steer feel. However, this “simulated steer-feel” takes a process time to sense and process the tie rod force and send the information to the steering handle to provide the actuation. There is an increased latency compared to the conventional power steering due to the “simulated steer feel” which is a drawback for the driver’s comfort and could provide a wrong proprioception for the further course of action on the steering wheel. This necessitates a mechanism to predict the road profile features such as lane curvatures, bumps, potholes beforehand and simulate a steer feel akin to the “natural steer feel” by compensating the torque and thereby reducing latency effect.

Brief description of the accompanying drawings
[0005] An embodiment of the invention is described with reference to the following accompanying drawings:
[0006] Figure 1 depicts a Steer-by-Wire system (100) for a vehicle; and at least
[0007] Figure 2 illustrates method steps (200) to operate the Steer-by-Wire system (100) for a vehicle.

Detailed description of the drawings

[0008] Figure 1 depicts a Steer-by-Wire (SBW) system for a vehicle. The SBW system (100) comprises a steering control unit (SCU (101)) in communication with a plurality of vehicle sensors, a steering rack (20), a steering shaft (10), a rack force module (102) and at least a steer feel unit (103).

[0009] The SCU (101) is a logic circuitry implemented as any or a combination of: one or more microchips or integrated circuits interconnected using a parent board, hardwired logic, software stored by a memory device and executed by a microprocessor, firmware, an application specific integrated circuit (ASIC), and/or a field programmable gate array (FPGA). The SCU (101) is in communication with various components of the SBW system (100) such as the steering rack (20), steer feel unit (103), rack force module (102) and regulates the operation of the aforementioned components. In a SBW system (100) the SCU (101) receives the steering signal from the steering rack (20) and transforms this driver request electronically to the set the desired position of the wheels. The SCU (101) is further in communication with the plurality of vehicle sensors. The plurality of vehicle sensors include but are not limited to a wheel speed sensor, an inertial sensor, an engine management sensor, a steering angle sensor, a pedal position sensor, a yaw rate sensor and at least the image sensor.
[0010] The steering rack (20) is a rack and pinion assembly that converts the circular motion of a steering handle (11) of the steering shaft (10) into linear motion required to turn the wheel of the vehicle. In a SBW system (100) this circular motion of the steering handle (11) is transmitted to the wheels electronically to the steering rack (20) through the SCU (101) instead of a mechanically linked shaft or column.

[0011] An important non-limiting feature of the present disclosure is the rack force module (102). The rack force module (102) with reference to this disclosure can be defined as a logic circuitry or a software programs that respond to and processes logical instructions to get a meaningful result. The rack force module (102) can either be a software embedded in a single chip or a combination of software and hardware. The rack force module (102) is in communication with the SCU (101). The rack force module (102) configured to predict a rack force felt by the steering rack (20) using data received from the plurality of sensors.

[0012] The rack force module (102) is further configured to; acquire image data of the road ahead from at least one image sensor amongst the plurality of sensors; feed the acquired data to an AI model to identify a distinct road feature ahead; predict a rack force acting upon the steering rack (20) for the distinct road feature using instantaneous vehicle operating parameters received form at least one sensor amongst the plurality of sensors, characteristics of the road feature, and pre-determined trained data. The functionality of the rack force module (102) is better explained in accordance with method steps (200).

[0013] The AI model running inside the rack force module (102) is trained to identify a distinct road feature and its corresponding characteristics. Using these trained AI models, correlations can be established between different types of data to arrive at some logical understanding of the data. A person skilled in the art would be aware of the different types of AI models such as linear regression, naïve bayes classifier, decision trees, support vector machine, neural networks and the like. A person skilled in the art will also appreciate that the AI module may be implemented as a set of software instructions, combination of software and hardware or any combination of the same. For example, a neural networks are incorporated in specialized silicon chips, which incorporate AI technology and are used for machine learning.

[0014] Another important non-limiting feature of the present disclosure is the steer feel unit (103). The steer feel unit (103) comprises a plurality of actuators acting upon the steering handle (11) of the steering shaft (10). These actuators of the steer feel unit (103) operated by the SCU (101). The SCU (101) activates the plurality of actuators of the steer feel unit (103) to transmit the rack force predicted by rack force module (102) on to the steering handle (11). The actuators comprise a plurality of motors acting along various axes of the steering handle (11). The impact of these plurality of motors is designed to create a steer feel based on the predicted rack force that gives sense of the road conditions, such as the traction of the vehicle wheels with the road surface, the condition of the components of the steering system to the driver operating the steering handle (11).

[0015] It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0016] Figure 2 illustrates method steps to operate the Steer-by-Wire (SBW) system for a vehicle. The SBW system (100) and its relevant components have been explained in accordance with figure 1. Method steps 201 comprises acquiring image data of the road ahead from the image sensor amongst the plurality of sensors. The image sensor could be a camera, thermal imaging devices, radar, LIDAR and the like others.

[0017] Method step 202 comprises feeding the acquired image data to the AI model inside the rack force module (102) to identify a distinct road feature ahead. The AI model is trained on image data from the front vehicle camera that used a ML classification algorithm to predict the road profile features through live images generated using plurality of sensors including vehicle front camera and LiDAR. The AI model further identifies a set of characteristics of the identified distinct feature, for example dimension of a pothole, height and gradient of a bump and the like. Hence feature characteristics provides the vector of feature dimensions like diameter, depth, height, length, etc.

[0018] Method step 203 comprises predicting a rack force that would act upon the steering rack (20) for the distinct road feature by means of the rack force module (102) using instantaneous vehicle operating parameters received from at least one sensor amongst the plurality of sensors, characteristics of the road feature and a pre-determined trained data. The plurality of sensors comprise one or more from the group of a wheel speed sensor, an inertial sensor, an engine management sensor, a steering angle sensor, a pedal position sensor, a yaw rate sensor and at least the image sensor. Correspondingly, the instantaneous vehicle operating parameters include but are not limited to at least one or more from the group of vehicle speed, vehicle accelerations, brake Information, engine Torque, steering Value, driver Pedal request, throttle position, yaw rate factor.

[0019] The pre-determined trained data comprises vehicle design characteristics that shape the impact of force felt by steering rack (20) and the wheels. It defines the correlation between instantaneous vehicle operating parameters, characteristics of the road feature and predicted rack force for the particular vehicle. In an exemplary embodiment of the present disclosure the Rack force module (102) predicts this rack force using trained AI model using supervised training mechanism. Table 1.1 below illustrates an example of how rack force is calculated in method step 203. For a particular feature and its characteristics the trained AI model learns to correlate the instantaneous vehicle operating parameters to the predicted rack force.

Classified road feature Characteristics dimensions of the road feature Vehicle speed(kmph) Vehicle deceleration(m/s^2) Vehicle yaw rate (m/s) Predicted rack force (N)
x1 [v11,v12..v1n] 50 5 7 70
.
. .
. .
. .
. .
. .
.
xm [vm1,vm2..vmn] 25 -6 5 110

Table 1.1

[0020] Method step 204 comprises activating the plurality of actuators of the steer feel unit (103) in dependance of the predicted rack force by means of the SCU (101). The activation of the plurality of actuators of the steer feel unit (103) by means of the SCU (101) is done in a manner to transmit the predicted rack force on to the steering handle (11) when the vehicle is negotiating the road feature. The Predicted rack force intensity is stored in a memory buffer of the SCU (101) temporarily. Further a Plausibility check is performed to compare the predicted rack force intensity with a predetermined range. A time delay is also calculated to release the rack force intensity from the memory buffer to the SCU (101) based on the instantaneous vehicle operating parameters. The plurality of actuators are activated by the SCU (101) after the pre-determined time delay to give a real time steer feel to the driver operating the steering handle (11) when the vehicle is negotiating the distinct feature.

[0021] A person skilled in the art will appreciate that while these method steps describes only a series of steps to accomplish the objectives, these methodologies may be implemented with adaptation and modification to the steer by wire system disclosed in accordance with figure 1. This idea to develop a steer by wire system for a vehicle and an operating method thereof could potentially reduce the latency time between the actual road force and steer feel. Using the proposed method and system, we can get the same comfort and proprioception as in conventional Electronic Power Steering.

[0022] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification and adaptation of the steer by wire system for a vehicle and the operating method (200) thereof are envisaged and form a part of this invention. The scope of this invention is limited only by the claims.
, Claims:We Claim:
1. A Steer-by-Wire system (100) for a vehicle, said Steer-by-Wire system (100) comprising a steering control unit (SCU (101)) in communication with a plurality of vehicle sensors, said SCU (101) in communication with a steering rack (20), characterized in that Steer-by-Wire system (100):
A rack force module (102) in communication with the SCU (101), the rack force module (102) configured to predict a rack force felt by the steering rack (20) using data received from plurality of sensors;
a steer feel unit (103) comprising a plurality of actuators acting upon a steering handle (11) of a steering shaft (10), said actuators of the steer feel unit (103) operated by the SCU (101).

2. The Steer-by-Wire system (100) for a vehicle as claimed in claim 1, wherein the rack force module (102) is further configured to;
acquire image data of the road ahead from at least one image sensor amongst the plurality of sensors;
feed the acquired data to an AI model to identify a distinct road feature ahead;
predict a rack force acting upon the steering rack (20) for the distinct road feature using instantaneous vehicle operating parameters received form at least one sensor amongst the plurality of sensors, characteristics of the road feature, and pre-determined trained data.

3. The Steer-by-Wire system (100) for a vehicle as claimed in claim 1, wherein the plurality of sensors comprise one or more from the group of a wheel speed sensor, an inertial sensor, an engine management sensor, a steering angle sensor, a pedal position sensor, a yaw rate sensor and at least the image sensor.

4. The Steer-by-Wire system (100) for a vehicle as claimed in claim 1, wherein the SCU (101) activates the plurality of actuators of the steer feel unit (103) to transmit the predicted rack force on to the steering handle (11).

5. A method (200) of operating a Steer-by-Wire system (100) for a vehicle, said system comprising a steering control unit in communication with a plurality of vehicle sensors, a steering rack (20), a rack force module (102) in communication with the SCU (101) and at least a steer feel unit (103) comprising a plurality of actuators acting upon a steering handle (11) of a steering shaft (10), the method steps comprising:
acquiring image data of the road ahead from an image sensor amongst the plurality of sensors;
feeding the acquired data to an AI model inside the rack force module (102) to identify a distinct road feature ahead;
predicting a rack force that would act upon the steering rack (20) for the distinct road feature by means of the rack force module (102) using instantaneous vehicle operating parameters received from at least one sensor amongst the plurality of sensors, characteristics of the road feature and a pre-determined trained data;
activating the plurality of actuators of the steer feel unit (103) in dependance of the predicted rack force by means of the SCU (101).

6. The method (200) of operating a Steer-by-Wire system (100) for a vehicle as claimed in claim 5, wherein the plurality of sensors comprise one or more from the group of a wheel speed sensor, an inertial sensor, an engine management sensor, a steering angle sensor, a pedal position sensor, a yaw rate sensor and at least the image sensor.

7. The method (200) of operating a Steer-by-Wire system (100) for a vehicle as claimed in claim 5, wherein the plurality of actuators are activated by the SCU (101) after pre-determined time delay.

8. The method (200) of operating a Steer-by-Wire system (100) for a vehicle as claimed in claim 5, wherein activating the plurality of actuators of the steer feel unit (103) by means of the SCU (101), transmits the predicted rack force on to the steering handle (11) when the vehicle is negotiating the road feature.