DESC:TECHNICAL FIELD OF THE INVENTION
[0001] The present disclosure generally relates to battery modelling systems for unmanned aerial vehicles (UAVs).
BACKGROUND OF THE INVENTION
[0002] Typically, battery powered unmanned aerial vehicles (UAVs) are programmed to return to their launch location, i.e., home location, (or any other pre-known location), as a fail-safe mechanism, based on prefixed threshold values of the remaining power/voltage in a battery. This threshold value is normally towards the battery’s lower operable end, as setting the threshold value higher will result in reduced efficiency of a flight. This method of setting the threshold value relies on an assumption that remaining battery power/voltage is enough for the UAV to travel the distance to home location and land safely. However, this assumption is a very weak parameter and always creates less confidence in flights because if the assumption fails, the UAV will crash.
[0003] One conventional example discloses a data processing device, drone, and control device, method, and processing program therefore. The above example discloses a subject matter related to controlling a UAV according to a battery level. In this, the UAV masters its own battery level (a remaining battery level), and records in a flight log a battery level consumed by performing each flight action while flying. A flight distance from its own position to a landing (returning) place and a battery level required for flying over this distance are calculated in a flying process. The calculated battery level is compared with the remaining battery level of the UAV, to judge whether to remind returning. The device first calculates a flight distance, according to an airframe position at any time point, a highest attitude attained during a current flight, and a landing place of the drone, and then acquires the battery level of the drone. Further, an estimated battery consumption is calculated when the drone flies over the flight distance, and decide, on the basis of the estimated battery consumption and the battery level of the drone, whether the drone is capable of flying over the flight distance and return.
[0004] Another example discloses a method and device for controlling return flight of unmanned aerial vehicles. The subject matter related to this example includes detecting the running state of each device through the output data state of the sensor of each device on the unmanned aerial vehicle or the output data state of the relevant device of each device on the unmanned aerial vehicle; or detecting the battery power consumption state of the unmanned aerial vehicle; and controlling the unmanned aerial vehicle to return according to the running state of each device of the unmanned aerial vehicle or the battery power consumption state of the unmanned aerial vehicle.
[0005] Another example discloses a safety system for operation of an Unmanned Aerial Vehicle (UAV). The subject matter related to this example includes selecting an unmanned aerial vehicle (UAV) command on a controller, the controller comprising a first processor with addressable memory; presenting a first activator and a second activator on a display of the controller for the selected UAV command, wherein the second activator is a slider; and sending the UAV command to a UAV if the first activator and the second activator are selected, the UAV comprising a second processor with addressable memory.
[0006] Therefore, there is a need for a system for UAV to control return to launch of the UAV and a method thereof, in addition to providing other technical advantages.
OBJECTIVE OF THE INVENTION
[0007] The main objective of the present invention is to control unmanned aerial vehicles (UAV’s) by providing a fail-safe return mechanism. In particular, the performance of a battery in actual flights, a linear battery model (parameters) is constructed and further the distance to be travelled from the UAV’s present location to its intended location of landing is tracked at frequent periodic intervals for enabling a fail-safe return to launch (or home location) to the UAV.
SUMMARY OF THE INVENTION
[0008] An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below.
[0009] Accordingly, in one aspect of the present a system for controlling an unmanned aerial vehicle (UAV) is disclosed. The system includes a battery module configured to generate a relation of a filtered voltage of a battery associated with the unmanned aerial vehicle (UAV) and maximum flight time of the UAV based at least on a linear mapping model function to determine at least a remaining flight time and intended landing voltage. The system includes a positioning module configured to determine at least the location coordinates of the UAV and a length of trajectory to a home location associated with the UAV at regular intervals. Further, the system includes a speed detection module configured to determine flight speed and a plurality of flight speed parameters. The system further includes a processing unit operatively coupled to the battery module, the positioning module, and the speed detection module. The processing unit is configured to at least divide the length of trajectory to the home location based on the flight speed, determine a time of returning to the home location, and determine whether the time of returning to the home location is equal to the remaining flight time to trigger a propulsion unit of the UAV to return to the home location.
[0010] Accordingly, in one aspect of the present invention a method performed by the system to control an unmanned aerial vehicle (UAV) is disclosed. The method includes sensing voltage of a battery associated with the unmanned aerial vehicle (UAV). The method includes filtering the sensed voltage of the battery using battery filter constant to obtain a filtered voltage. Further, the method includes generating a relation of the filtered voltage of the battery associated with the unmanned aerial vehicle (UAV) and maximum flight time of the UAV based at least on a linear mapping model function to determine at least a remaining flight time and intended landing voltage. The method further includes determining at least the location coordinates of the UAV and a length of trajectory to a home location associated with the UAV at regular intervals. The method includes determining flight speed and a plurality of flight speed parameters and partitioning the length of trajectory based on the flight speed. The method includes determining a time of returning to the home location. The method includes triggering the UAV to return to home location based on determining whether the time of returning to the home location is equal to the remaining flight time.
[0011] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0012] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and modules.
[0013] FIG. 1 illustrates a simplified block diagram representation of an unmanned aerial vehicle (UAV), in accordance with an embodiment of the present disclosure; and
[0014] FIG. 2 is a flowchart depicting a method performed by a system of the UAV for enabling the UAV to return to the home location, in accordance with an embodiment of the present disclosure.
[0015] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present disclosure. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
[0017] The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
[0018] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. References in the specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[0019] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
[0020] Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged communications system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.
[0021] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present disclosure. It will be apparent, however, to one skilled in the art that the present disclosure may be practiced without these details. One skilled in the art will recognize that embodiments of the present disclosure, some of which are described below, may be incorporated into a number of systems. However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the presently disclosure and are meant to avoid obscuring of the presently disclosure.
[0022] In an embodiment, the present disclosure discloses a battery modelling system for unmanned aerial vehicles (UAVs) and method thereof, which are configured to monitor the performance of a battery in actual flights. The system and method are configured to generate a linear battery model/parameter(s), which relates different stages of battery power/voltage to the maximum time the UAV can still safely fly from that point in time. Additionally, the distance to be travelled from the UAV’s present location to its intended location of landing is tracked at frequent periodic intervals. By using the linear battery model/parameter and the distance, and further accommodating intended flight speeds during the travel to home location, a user may be able to know an exact battery state (i.e., charge/voltage of the battery) when the right to launch (RTL) fail-safe needs to be triggered.
[0023] Various embodiments of the present disclosure are further described with reference to FIG. 1 and FIG. 2.
[0024] FIG. 1 illustrates a simplified block diagram representation of an unmanned aerial vehicle (UAV) (100), in accordance with an embodiment of the present disclosure. Although the UAV (100) is depicted to include one or a few components, modules, or devices arranged in a particular arrangement in the present disclosure, it should not be taken to limit the scope of the present disclosure. In an exemplary embodiment, the UAV (100) may be flights, drones, aircrafts, and other aerial vehicles without human pilot. The UAV (100) includes a system (102) for triggering return to launch (RTL) based on monitoring voltage parameter of a battery (116) associated with the UAV (100).
[0025] In general, the system (102) corresponds to a battery modelling system for unmanned aerial vehicles (UAVs). The system (102) includes a derivation module (104), a battery module (106), a sensing module (108), a positioning module (110), a speed detection module (112), and a processing unit (114). The system (102) is configured to manage operations of the UAV (100) to enable a user to know an exact battery state (i.e., charge/voltage of the battery (116)) and trigger the RTL for the UAV (100).
[0026] The derivation module (104) is configured to perform a plurality of test flights of the UAV with pre-defined battery related parameters and derive battery model parameters. In an embodiment, the pre-defined battery related parameters include, but are not limited to, a targeted battery type (chemistry), state of charge (SoC), state of health, and a battery cycle. Typically, the battery model parameters are the real indicators of the performance of the battery type and can be derived by performing multiple test flights (in their targeted mode of operations) of the UAV (100) with the targeted battery type (chemistry), state of charge, state of health, and the battery cycle. Thus, the derived battery model parameters may include, but are not limited to,
A. voltage dip (V_dip) during high load condition (take-off time),
B. maximum voltage (V_max) when the battery is fully charged,
C. minimum safe voltage (V_minSafe) of the battery below which the discharge-time curve severely skews aways from linearity (operation below this point is not safe),
D. average maximum flight time (Max_fltTime) from multiple flights (in the targeted mode of an operation of the UAV) from a fully charged battery to minimum safe voltage of the battery,
E. battery sensor filter constant time average (Vbat_timeAvg) to reduce the sensing of battery state to a same level,
F. user buffer period (Time_buff),
G. intended voltage at the time of landing (V_landVolt),
H. state of charge (SOC),
I. state of health (SOH),
J. battery cycle (one-charge-discharge is one cycle), and
K. battery temperature.
[0027] The battery module (106) may be configured to cooperate with the derivation module (104). The battery module (106) receives the derived battery model parameters. The battery module (106) is further configured to generate a relation of a filtered voltage of the battery (116) associated with the UAV (100) and maximum flight time of the UAV (100) based at least on a linear mapping model function to determine at least a remaining flight time and intended landing voltage. In particular, the battery module (106) may be further configured to take the average maximum flight time defined in the derived model parameters and linearly map the average maximum flight time with the range of voltage from maximum voltage, when the battery is fully charged to minimum safe voltage and after accommodating for the voltage dip during take-off. In an embodiment, the battery module (106) may be configured to provide a linear battery model function, which relates to a charge/voltage state of the battery to the maximum time remaining for which the UAV can still fly. In one embodiment, the battery model function uses settable derived battery model parameters. In another embodiment, the battery module (106) may be configured to generate the linear mapping model function between the filtered voltage (v_filtered) and maximum flight time (Max_fltTime) to arrive at the flight time remaining (flt_time) to land at intended landing voltage (V_landVolt). The intended landing voltage is computed using the following equation:
flt_time = (Max_fltTime/(V_max-V_dip-V-minSafe))*(v_filtered-V_landVolt) …… (Eq. 1)

[0028] The sensing module (108) is operatively coupled with the battery module (104) and the battery (116) for receiving battery related data and linear mapping model function. The sensing module (108) is configured to sense voltage of the battery (116), battery temperature, and control charging voltage and current of the battery (116). In an embodiment, the sensing module (108) may include a battery sensor (see, 108a). The sensor (108a) may be configured to sense the exact battery status of the UAV (102), measure temperature, and further control the charging voltage and current, accordingly.
[0029] The positioning module (110) is configured to determine at least the location coordinates of the UAV and a length of trajectory to a home location associated with the UAV (100) at regular intervals. The home location corresponds to a point (or launch site) from where the UAV takes up (i.e., a take-off point) and lands (i.e., a landing point). In particular, the positioning module (110) may be configured to detect the position of the UAV (100) at a pre-defined periodic interval. At a certain periodic interval, the positioning module (110) may be configured to calculate a trajectory distance between the UAV’s (100) present location and the home location. In an embodiment, the positioning module (110) may include a gyroscope. In an exemplary embodiment, the positioning module (110) may include a Global Localization System (GLS) which may be configured to detect satellite data and other sensor data to detect the position of the UAV (100).
[0030] The speed detection module (112) may be configured to determine flight speed and detect a plurality of flight speed parameters. The detected flight speed parameters may include, but are not limited to, take-off and landing sites, flying height, direction, speed, flight lines, and overlaps.
[0031] Further, the processing unit (114) is configured communicably coupled with the battery module (106), the sensing module (108), the positioning module (110), and the speed detection module (112). The processing unit (114) may be a processor capable of executing the machine executable instructions to perform the functions described herein. In an embodiment, the processing unit (114) may be implemented as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, the processing unit (114) may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), or the like.
[0032] The processing unit (114) may be configured to divide the length of trajectory to the home location based on the flight speed. In particular, the processing unit (114) further calculates the maximum remaining flight time when the voltage is sensed by the sensing module (108). Further, the processing unit (114) calculates the maximum remaining flight time by using the linear mapping between the flight time and the voltage range. Thereafter, the processing unit (114) divides the calculated trajectory distance to home by using the intended flight speed (defined to the UAV (100) through detected flight speed parameters) to arrive at the time required for returning to the home location. Further, the processing unit (114) determines whether the time of returning to the home location is equal to the remaining flight time for triggering a propulsion unit (118) of the UAV (100) to return to the home location. The processing unit (114) calculates the time required to return to the home location by using the following equation.
time_to_home=dist_home/Nav_speed …… (Eq. 2).
[0033] It is to be noted that the processing unit (114) determines whether the time of returning to the home location is equal to the remaining flight time for triggering the UAV to return to the home location upon consideration of a user defined buffer period. The user defined buffer period may include time delay in providing commands using the controller or the like.
[0034] The processing unit (114) transmits a command signal to the propulsion unit (118) of the UAV (100) based on determining the time of returning to the home location is equal to the remaining flight time. In other words, when the remaining flight time becomes equivalent to the time required for returning to the home location, a return to home command is initiated by the processing unit (114). The processing unit (114) further transmits the return to home command (or the command signal) to the propulsion unit (118). The propulsion unit (118) is configured to return the UAV (100) flight to the launch/home site based on the return to home command (or receipt of the command signal).
[0035] FIG. 2 is a flowchart depicting a method (200) performed by the system (102) for enabling the UAV (100) to return to the home location, in accordance with an embodiment of the present disclosure. The method (200) starts at operation (202).
[0036] At (202), a voltage of the battery (116) associated with the unmanned aerial vehicle (UAV) (100) is sensed.
[0037] At (204), the sensed voltage of the battery (116) is filtered using battery filter constant to obtain a filtered voltage.
[0038] At (206), a relation of the filtered voltage of the battery (116) associated with the unmanned aerial vehicle (UAV) (100) and maximum flight time of the UAV (100) is generated based at least on a linear mapping model function to determine at least a remaining flight time and intended landing voltage.
[0039] The location coordinates of the UAV (100) are determined at regular intervals (see, 208). Further, the length of trajectory to the home location associated with the UAV (100) is determined at regular intervals (see, 210). At 212, the flight speed and the flight speed parameters are determined. Thereafter, the length of trajectory based on the flight speed is divided.
[0040] At 214, the time of returning to the home location is calculated. In other words, the time required to travel back to the home location is computed. At 216, whether the time of returning to the home location is equal to the remaining flight time is checked.
[0041] At 218, a command signal is transmitted to the propulsion unit (118) of the UAV (100) based on determining the time of returning to the home location is equal to the remaining flight time. The time of returning to the home location is determined to be equal to the remaining flight time for triggering the UAV to return to home location upon consideration of user defined buffer period. In case the time of returning to the home location is not equal to the remaining flight time, the process repeats from the step (202). Further, the one or more operations performed by the system (102) are explained with references to FIG. 1, therefore they are not reiterated herein for the sake of brevity.

ADVANTAGES
[0042] In an advantageous aspect, the present disclosure provides an efficient system to continuously monitor battery state for controlling the UAV to safely return to the home location.
[0043] The various embodiments described above are specific examples of a single broader invention. Any modifications, alterations or the equivalents of the above-mentioned embodiments pertain to the same invention as long as they are not falling beyond the scope of the invention as defined by the appended claims. It will be apparent to a skilled person that the embodiments described above are specific examples of a single broader invention which may have greater scope than any of the singular descriptions taught. There may be many alterations made in the invention without departing from the scope of the invention.
[0044] Figures are merely representational and are not drawn to scale. Certain portions thereof may be exaggerated, while others may be minimized. Figures illustrate various embodiments of the invention that can be understood and appropriately carried out by those of ordinary skill in the art.
[0045] In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment.
,CLAIMS:
1. A system (102) for controlling an unmanned aerial vehicle (UAV) (100), comprising:
a battery module (106) configured to generate a relation of a filtered voltage of a battery (116) associated with the unmanned aerial vehicle (UAV) (100) and maximum flight time of the UAV based at least on a linear mapping model function to determine at least a remaining flight time and intended landing voltage;
a positioning module (110) configured to determine at least the location coordinates of the UAV (100) and a length of trajectory to a home location associated with the UAV (100) at regular intervals;
a speed detection module (112) configured to determine flight speed and a plurality of flight speed parameters; and
a processing unit (114) operatively coupled to the battery module (106), the positioning module (110), and the speed detection module (112), the processing unit configured to at least:
divide the length of trajectory to the home location based on the flight speed,
determine a time of returning to the home location, and
determine whether the time of returning to the home location is equal to the remaining flight time to trigger a propulsion unit (118) of the UAV (100) to return to the home location.

2. The system (102) as claimed in claim 1, wherein the processing unit (114) is configured to transmit a command signal to the propulsion unit (118) of the UAV (100) based on determining the time of returning to the home location is equal to the remaining flight time.

3. The system (102) as claimed in claim 2, wherein the processing unit (114) determines whether the time of returning to the home location is equal to the remaining flight time for triggering the UAV to return to the home location upon consideration of a user defined buffer period.

4. The system (102) as claimed in claim 1, further comprising a derivation module (104) configured to derive battery model parameters indicating the performance of the battery type based at least on a plurality of test flights of the UAV with predefined battery related parameters.

5. The system (102) as claimed in claim 4, wherein the derived battery model parameters comprise at least:
a voltage dip during high load conditions,
maximum voltage when the battery is fully charged,
a minimum safe voltage of the battery,
average maximum flight time,
battery sensor filter constant time average,
user buffer period,
intended voltage at the time of landing,
state of charge (SOC),
state of health (SOH),
battery cycle, and
battery temperature.

6. The system (102) as claimed in claim 5, wherein the battery module (106) is configured to implement the linear mapping model function to determine the remaining flight time and intended landing voltage based at least the derived battery model parameters from the derivation module (104).

7. The system (102) as claimed in claim 1, wherein the detected plurality of flight speed parameters comprise take-off and landing sites, flying height, direction, speed, flight lines, and overlaps.

8. The system (102) as claimed in claim 1, further comprising a sensing module (108) operatively coupled with the battery module (106) and the battery (116) for receiving battery related data and linear mapping model function, the sensing module (108) configured to sense voltage of the battery, battery temperature, and control charging voltage and current of the battery,
wherein the sensed voltage is subjected to filtering using a battery filter constant to obtain the filtered voltage.

9. A method (200) performed by a system (102) to control an unmanned aerial vehicle (UAV) (100), comprising:
sensing (202) voltage of a battery associated with the unmanned aerial vehicle (UAV);
filtering (204) the sensed voltage of the battery using battery filter constant to obtain a filtered voltage;
generating (206) a relation of the filtered voltage of the battery associated with the unmanned aerial vehicle (UAV) and maximum flight time of the UAV based at least on a linear mapping model function to determine at least a remaining flight time and intended landing voltage;
determining (208; 210) at least the location coordinates of the UAV and a length of trajectory to a home location associated with the UAV at regular intervals;
determining (212) flight speed and a plurality of flight speed parameters;
partitioning the length of trajectory based on the flight speed;
determining (214) a time of returning to the home location; and
triggering (216) the UAV to return to home location based on determining whether the time of returning to the home location is equal to the remaining flight time.

10. The method (200) as claimed in claim 9, further comprising:
transmitting (218) a command signal to a propulsion unit (118) of the UAV (100) based on determining the time of returning to the home location is equal to the remaining flight time, wherein the time of returning to the home location is determined to be equal to the remaining flight time for triggering the UAV (100) to return to home location upon consideration of user defined buffer period.