CN115257703A - Offset control method and offset control system for distributed drive vehicle - Google Patents
Offset control method and offset control system for distributed drive vehicle Download PDFInfo
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- CN115257703A CN115257703A CN202210965753.0A CN202210965753A CN115257703A CN 115257703 A CN115257703 A CN 115257703A CN 202210965753 A CN202210965753 A CN 202210965753A CN 115257703 A CN115257703 A CN 115257703A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
- B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
- B60W40/105—Speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
- B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
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Abstract
The invention relates to an offset control method and an offset control system for a distributed drive vehicle. The offset control method includes: acquiring the offset of the distributed driving vehicle in real time; judging whether offset correction is needed or not according to the offset; calculating an offset correction torque of the distributed drive vehicle in real time based on the offset amount when it is determined that the offset correction is required; and distributing the offset correction torque to the plurality of wheels in real time to compensate for the offset amount. The offset control method and the offset control system of the invention can improve the straight-line running performance of the vehicle.
Description
Technical Field
The invention relates to the technical field of vehicles. In particular, the invention relates to an offset control method and an offset control system for a distributed drive vehicle.
Background
During the running of the vehicle, a lateral force acting from the center of the wheel in the wheel-axle direction of the vehicle may be generated due to road surface conditions, crosswind, curve running, the vehicle itself factors, and the like. Since the wheel is an elastic body, when the lateral force does not reach the maximum frictional force between the wheel and the ground, the lateral force deforms the tire and deflects the wheel, thereby causing the wheel direction to deviate from the predetermined running direction. This phenomenon is called a shift of the vehicle. There are many factors that may cause vehicle misalignment, such as axle asymmetry of the left and right wheels, tire anomalies, four-wheel alignment anomalies, non-uniform loading, tire wear, suspension component deformation, road surface inclination, crosswinds, and the like.
The distributed drive vehicle refers to a vehicle having a plurality of wheels that can be driven and controlled independently of each other. For distributed drive vehicles, the vehicle is prone to drift due to wheel speed imbalances because the individual drive wheels are in a fully decoupled and independent state. Currently, the offset phenomenon for distributed drive vehicles can generally only be corrected by four-wheel positioning. Four-wheel alignment refers to adjusting and correcting the angular orientation of each wheel individually while the vehicle is stationary. However, vehicle offset often cannot be addressed by simply performing four-wheel alignment. Offset correction based on four-wheel alignment can only be performed when the vehicle is stationary, and when the vehicle deviates from a predetermined trajectory during traveling, the vehicle is generally unable to recognize such a phenomenon in real time and perform active correction. This reduces the straight-driving performance of the vehicle. Therefore, it is required to improve the straight-line running performance of the distributed drive vehicle.
Disclosure of Invention
Therefore, an object of the present invention is to provide an offset control method and an offset control system capable of improving the straight-line running performance of a distributed drive vehicle.
The above technical problem is solved by an offset control method for a distributed drive vehicle according to the present invention. The distributed drive vehicle includes a plurality of wheels that can be driven and controlled individually. The offset control method comprises the following steps: acquiring the offset of the distributed driving vehicle in real time; judging whether offset correction is needed or not according to the offset; calculating offset correction torque of the distributed drive vehicle in real time based on the offset amount when it is determined that the offset correction is required; and distributing the offset correction torque to the plurality of wheels in real time to compensate for the offset amount. This offset control method is intended to compensate for the offset amount of the vehicle by applying an additional offset correction torque to the vehicle. The offset correction torque here may be generated by a drive actuator of each wheel. That is, the drive actuators of the respective wheels additionally generate an offset correction torque for the offset amount in addition to the normal driving force for driving the vehicle to travel, and the applied offset correction torque at least partially cancels the offset amount, so that the vehicle offset can be corrected in real time during the travel of the vehicle. This can significantly improve the straight-running performance of the vehicle.
According to a preferred embodiment of the present invention, obtaining the offset of the distributed-drive vehicle in real time may include obtaining at least one characteristic parameter of the offset to characterize the offset, and the at least one characteristic parameter may include one or more of a yaw-rate deviation, a heading-angle deviation, and a lateral-displacement deviation. Preferably, all of the above three characteristic parameters may be obtained to jointly characterize the offset. The offset state of the vehicle can be described relatively accurately by the above-mentioned characteristic parameters.
According to another preferred embodiment of the present invention, a real-time yaw rate may be acquired by a yaw rate sensor, and a yaw rate deviation may be acquired by subtracting an initial yaw rate from the real-time yaw rate; the real-time course angle can be obtained by integrating the yaw angular velocity, and the course angle deviation can be obtained by subtracting the initial course angle from the real-time course angle; and the lateral displacement speed can be calculated according to the course angular deviation and the vehicle speed, the lateral displacement speed is integrated to obtain real-time lateral displacement, and the lateral displacement deviation is obtained by subtracting the initial lateral displacement from the real-time lateral displacement.
According to another preferred embodiment of the present invention, in obtaining the offset amount of the distributed-drive vehicle: each of the at least one characteristic parameter may be set to zero when the distributed drive vehicle is stationary or when the distributed drive vehicle is traveling but has a target steering angle that is not zero; and when the distributed drive vehicle is traveling and the target steering angle is zero, the value of the yaw rate at the time when the steering angle of the distributed drive vehicle is initially zero may be set to the initial yaw rate, and the initial heading angle and the initial lateral displacement may be set to zero. When the vehicle is stationary, the vehicle is unlikely to experience an offset phenomenon, and when the vehicle is traveling at a non-zero target steering angle, i.e., the vehicle is actually being steered in a controlled manner, it is desirable that the vehicle move away from a straight line, so offset compensation is not actually required in both cases. In the case where the characteristic parameters are all zero, the offset correction torque is also zero. When the vehicle travels at a zero target steering angle, that is, travels straight, the correction process is continuously performed in real time starting from the initial time at which the vehicle travels straight each time.
According to another preferred embodiment of the present invention, it is determined that an offset correction is required when any one of the at least one characteristic parameter is greater than a corresponding predetermined threshold value. Since the straight-line driving state of the vehicle is characterized by the characteristic parameters, the fact that any one of the characteristic parameters exceeds the threshold value may indicate that the vehicle generates a large offset. Thereby initiating a correction procedure when any one of the characteristic parameters exceeds a threshold value is advantageous for compensating for the offset in time.
According to another preferred embodiment of the present invention, the offset correction torque may be calculated by adding products of each of the at least one characteristic parameter and a corresponding coefficient, which may be obtained by experiment. The resulting feedback control system based on PID (proportional integral derivative) control theory can effectively correct the offset.
According to another preferred embodiment of the invention, the offset correction torque may be distributed to the plurality of wheels according to at least one of: the arrangement and the operating state of the drive actuators of the plurality of wheels and the magnitude of the offset correcting torque. The configuration and operating state of the drive actuators of the plurality of wheels determines which of the drive actuators of the wheels can take on the task of applying the offset correction torque. When the offset correction torque is small, fewer wheels can be used to accomplish the offset compensation task.
The above-mentioned technical problem is also solved by an offset control system for a distributed drive vehicle according to the present invention. A distributed drive vehicle includes a plurality of wheels that can be driven and controlled independently of each other. Wherein the offset control system comprises: an offset acquisition module configured to acquire an offset amount of the distributed drive vehicle in real time; the correction judging module is configured to judge whether offset correction is needed or not according to the offset; a correction calculation module configured to calculate an offset correction torque of the distributed drive vehicle in real time based on the offset amount when it is determined that the offset correction is required; and a torque distribution module configured to distribute the offset correction torque to the plurality of wheels in real time to compensate for the offset.
According to a preferred embodiment of the invention, the offset acquisition module may be configured to acquire at least one characteristic parameter of the offset to characterize the offset, which may include one or more of yaw-rate deviation, heading-angle deviation and lateral displacement deviation.
According to another preferred embodiment of the present invention, the offset obtaining module may include: a yaw-rate sub-module configured to acquire a real-time yaw rate from a yaw-rate sensor and acquire a yaw-rate deviation by subtracting the initial yaw rate from the real-time yaw rate; a course angle sub-module configured to obtain a real-time course angle by integrating the yaw angular velocity and obtain a course angle deviation by subtracting the initial course angle from the real-time course angle; and a lateral displacement submodule configured to calculate a lateral displacement velocity from the heading angle deviation and the vehicle speed, integrate the lateral displacement velocity to obtain a real-time lateral displacement, and obtain a lateral displacement deviation by subtracting the initial lateral displacement from the real-time lateral displacement.
According to another preferred embodiment of the invention, when the distributed drive vehicle is stationary or when the distributed drive vehicle is traveling but has a target steering angle other than zero, the yaw-rate sub-module may be configured to set the initial yaw-rate to zero, the heading angle sub-module may be configured to set the initial lateral displacement to zero, and the lateral displacement sub-module may be configured to set the initial lateral displacement to zero; and the distributed drive vehicle is traveling and the target steering angle is zero, the yaw-rate sub-module may be configured to set a yaw-rate value at a time when the steering angle of the distributed drive vehicle is initially zero to an initial yaw-rate, the heading-angle sub-module may be configured to set the initial heading angle to zero, and the lateral-displacement sub-module may be configured to set the initial lateral displacement to zero.
According to another preferred embodiment of the present invention, the correction judging module may be configured to judge that the offset correction is required when any one of the at least one characteristic parameter is greater than a corresponding predetermined threshold.
According to another preferred embodiment of the present invention, the correction calculation module may be configured to store a corresponding coefficient of the at least one characteristic parameter obtained through experiments, and calculate the offset correction torque by adding products of each of the at least one characteristic parameter and the corresponding coefficient.
According to another preferred embodiment of the invention, the torque distribution module may be configured to distribute the offset correction torque to the plurality of wheels according to at least one of: the arrangement and the operating state of the drive actuators of the plurality of wheels and the magnitude of the offset correcting torque.
Drawings
The invention is further described below with reference to the accompanying drawings. Identical reference numbers in the figures denote functionally identical elements. Wherein:
FIG. 1 shows a schematic block diagram of an architecture for performing an offset control method according to an exemplary embodiment of the present invention; and
fig. 2 shows a schematic flow diagram of an offset control method according to an exemplary embodiment of the present invention.
Detailed Description
Specific embodiments of an offset control method and an offset control system according to the present invention will be described below with reference to the accompanying drawings. The following detailed description and drawings are included to illustrate the principles of the invention, which is not to be limited to the preferred embodiments described, but is to be defined by the appended claims.
According to an embodiment of the present invention, there is provided an offset control method for a distributed drive vehicle. The distributed drive vehicle includes a plurality of wheels that can be driven and controlled individually. Each wheel may be provided with an independent drive actuator corresponding thereto. These drive actuators are used to provide torque to the respective wheels to drive the wheels into rotation, and may be provided near the respective wheels (wheel side drive) or within the hubs (hub drive). The wheels are distributed on both sides of the vehicle body. Since the wheels can be driven independently of each other, different torques can be applied to the different wheels, thereby actively generating a torque that shifts the vehicle as a whole. Such an offset actively generated by the driving actuator of the wheel may be used to compensate for an undesired offset of the vehicle generated due to various factors (e.g., wheel axle asymmetry, tire abnormality, four-wheel alignment abnormality, non-uniform load, tire wear, deformation of suspension components, inclination of a road surface, crosswind, etc.) during running of the vehicle, thereby correcting a running state of the vehicle. The offset control method according to the embodiment of the invention performs offset correction on the vehicle according to the above-described principle, particularly, offset correction during running of the vehicle.
Exemplary embodiments of an offset control method according to the present invention are described in detail below with reference to the accompanying drawings. Fig. 1 shows an architecture for performing an offset control method according to an exemplary embodiment of the present invention. As shown in fig. 1, a distributed drive vehicle (hereinafter simply referred to as a vehicle) includes an Electronic Control Unit (ECU), a sensing unit, and an execution unit. In the present embodiment, the offset control method is explained by taking a four-wheel vehicle as an example, the vehicle including four wheels constituting two wheel pairs (including left and right front wheels constituting a front wheel pair and left and right rear wheels constituting a rear wheel pair), and accordingly further including an independent drive actuator corresponding to each wheel. These drive actuators constitute an execution unit. It should be understood that the number of wheels and corresponding drive actuators is merely illustrative, and that the vehicle may include other numbers of wheels and drive actuators, such as six wheels and six drive actuators, eight wheels and eight drive actuators, etc., as long as the offset correction torque for compensating the offset of the vehicle can be generated by applying different torques to different wheels.
Fig. 2 shows a flow chart of an offset control method according to an exemplary embodiment. As shown in fig. 2, the offset control method mainly includes steps S1 to S4. The specific steps of the offset control method are described below with reference to fig. 2.
First, in step S1, the offset amount of the distributed drive vehicle is acquired in real time. In particular, the offset may be characterized by one or more characteristic parameters, and accordingly, at least one characteristic parameter characterizing the offset may be obtained to characterize the offset. In practice, such characteristic parameters may include yaw-rate deviation, heading-angle deviation and lateral-displacement deviation. These characteristic parameters may be directly measured by the sensing unit or derived from data measured by the sensing unit. The sensing unit includes, for example, a yaw rate sensor, a vehicle speed sensor, and the like. In step S1, one or more of the three parameters described above may be obtained to characterize the offset. Preferably, all of the above three characteristic parameters may be obtained to jointly characterize the offset. The offset state of the vehicle can be described relatively accurately by the characteristic parameters described above. Here, the real-time yaw rate may be directly measured by a yaw-rate sensor as shown in fig. 1, and the yaw-rate deviation is a difference obtained by subtracting the initial yaw-rate from the real-time yaw-rate. The heading angle and lateral displacement velocity may then be derived and calculated from the yaw-rate. Specifically, the real-time heading angle may be obtained by integrating the yaw angular velocity, and the heading angular deviation is a difference obtained by subtracting the initial heading angle from the real-time heading angle. Next, a lateral displacement speed (wherein the vehicle speed can be directly measured by a vehicle speed sensor as shown in fig. 1) can be calculated according to the heading angle deviation and the vehicle speed, and a real-time lateral displacement can be obtained by integrating the lateral displacement speed, wherein the lateral displacement deviation is a difference obtained by subtracting the initial lateral displacement from the real-time lateral displacement.
Preferably, each of the above-described characteristic parameters may be set to zero when the vehicle is stationary or when the vehicle is traveling but has a target steering angle that is not zero. When the vehicle is stationary, there is no offset phenomenon of the vehicle, and when the vehicle is traveling at a non-zero target steering angle, i.e., the vehicle is actually steering under control, it is required that the vehicle move off-straight, so offset compensation is not actually required in both cases. When all the characteristic parameters are zero, the offset correction torque is also zero, and offset compensation is not actually performed. When the vehicle is traveling and the target steering angle is zero, the yaw-rate value at the time when the steering angle of the vehicle is initially zero (i.e., the time when the vehicle starts traveling straight) may be set to the initial yaw-rate, and the initial heading angle and the initial lateral displacement may be set to zero. This means that, when the vehicle travels at a target steering angle of zero, i.e., travels straight, the correction process in which the calculations of the heading angle deviation and the lateral displacement deviation are integrated is continuously performed in real time starting from the initial time of each straight travel of the vehicle. Once the vehicle has finished traveling straight and enters a turning process or a stationary state, the above-described accumulation calculation process is also stopped until the calculation is started again from the beginning when the vehicle enters the straight traveling state again.
Alternatively, in other embodiments, other characteristic parameters may be selected to characterize the offset. For example, where a vehicle is equipped with a positioning system such as a GPS, the offset may be characterized by a trajectory and/or position parameter of the vehicle. The characteristic parameters characterizing the offset amount can also be selected as a function of the actual situation, as long as the correction torque for compensating the offset can be derived from the selected characteristic parameters.
In step S2, it is determined whether or not offset correction is necessary based on the offset amount. The judgment process of step S2 is performed in real time. The criterion for the determination may be that when any one of the selected characteristic parameters is greater than a corresponding predetermined threshold, it is determined that offset correction is required. Since the straight-line driving state of the vehicle is commonly characterized by these characteristic parameters, the exceeding of any one of the characteristic parameters by a threshold value may cause a large deviation of the vehicle. Thereby initiating a correction procedure when any one of the characteristic parameters exceeds a threshold value is advantageous for compensating for the offset in time. The predetermined threshold value for each characteristic parameter may be determined empirically and on actual demand and stored beforehand in the electronic control unit.
When it is determined in step S2 that offset correction is necessary, step S3 is started. In step S3, an offset correction torque is calculated in real time based on the offset amount. The offset correction torque is a torque for compensating for offset motion that the vehicle currently exists so as to enable the vehicle to at least partially recover a predetermined straight-driving state. The control process of compensating the vehicle offset by the offset correction torque is a PID feedback control process. Based on the PID feedback control method, the offset correction torque can be calculated by adding the products of each of the selected characteristic parameters and the corresponding coefficient. The coefficients of the respective characteristic parameters can be obtained by performing experimental tests on the vehicle. The resulting feedback control system can effectively correct the offset.
After the offset correction torque is obtained, the offset correction torque may be distributed to the plurality of wheels in real time to compensate for the offset amount in step S4. The additional torque distributed to each wheel may compensate for the overall offset of the vehicle to the total additional torque generated by the vehicle. The offset correction torque may be distributed to different wheels and need not necessarily be distributed to all wheels. Preferably, the determination of which wheels need to be allocated offset correction torque may be made according to factors such as the arrangement and operating state of the drive actuators of the respective wheels, and the magnitude of the offset correction torque. This is because the configuration and operating state of the drive actuators of the wheels determines which drive actuators of the wheels can take on the task of applying the offset correction torque. Also, when the required offset correction torque is small and a part of all the wheels is sufficient to generate the required offset correction torque, the number of wheels to which the offset correction torque is distributed can be reduced. In general, in order to facilitate control of the running state of the vehicle, the selected wheels are preferably left-right symmetric pairs of wheels.
Taking the four-wheel vehicle in fig. 1 as an example, the left front wheel, the right front wheel, the left rear wheel and the right rear wheel are all provided with independent driving actuators, and the offset correction torque distribution may be generally performed in the following ways.
The first case is that when all the drive actuators of all the wheels are operating normally (the vehicle is in a four-wheel drive configuration) and the required offset correction torque is greater than a certain predetermined threshold (meaning that the required offset correction torque is large and the drive actuators of some of the wheels may have difficulty providing the torque required to complete the correction task), the drive actuators of all the wheels participate in the offset correction and the distribution of the offset correction torque over the individual wheels, in particular the torque of the drive actuators of the wheels on both sides of the same pair, may be adjusted according to geometric parameters, such as the track width.
The second case is when all the drive actuators of all the wheels are operating normally (the vehicle is in a four wheel drive configuration) but the required offset correction torque is less than some predetermined threshold (meaning that the required offset correction torque is small and the drive actuators of some of the wheels are sufficient to provide the torque required to complete the correction task), only some of the drive actuators of some of the wheels may be involved in the offset correction, the distribution of the offset correction torque over these wheels being adjusted according to a geometric parameter, such as the track width. Typically, the wheels that undertake the offset correction task are wheels that constitute the same wheel pair, such as the left and right rear wheels.
A third situation is when the drive actuators of the wheels of a certain wheel pair of the vehicle are in a fault state or when the vehicle is in a non-four wheel drive configuration (e.g. a front wheel drive configuration or a rear wheel drive configuration), the offset correction is performed using only the drive actuators of the currently available wheels and the torque is distributed to the wheels on both sides of the wheel pair according to geometrical parameters, such as the wheel track. For example, when the drive actuators of either of the rear pair of wheels fail (in the case where the vehicle is in a four-wheel drive configuration) or when the vehicle is in a front-wheel drive configuration, offset correction is performed using only the drive actuators of the front pair of wheels, and offset correction torque is distributed to the drive actuators of the left and right front wheels according to geometric parameters. As another example, when the drive actuators of either of the front pair of wheels fail (in the case where the vehicle is in a four-wheel drive configuration) or when the vehicle is in a rear-wheel drive configuration, offset correction is made using only the drive actuators of the rear pair of wheels, and torque is distributed to the drive actuators of the left and right rear wheels according to the geometric parameters.
In addition, there is also a case where the vehicle is stopped in an emergency state when all of the drive actuators in the front wheel pair and the rear wheel pair fail (the vehicle is in a four-wheel drive configuration), and the target torques of the four drive actuators of the front wheel pair and the rear wheel pair are all zero. At this point, the vehicle may alert the driver of the vehicle's fault condition via a display or other indicating device.
According to an embodiment of the invention, there is also provided an offset control system for a distributed drive vehicle, which may accordingly perform the offset control method according to the invention.
The offset control system mainly comprises an offset acquisition module, a correction judgment module, a correction calculation module and a torque distribution module. These modules may be integrated in an electronic control unit of the vehicle, each for performing the respective steps of the offset control method described above.
The offset acquisition module is used for executing step S1, namely acquiring the offset of the vehicle in real time. In particular, the offset acquisition module may be configured to acquire at least one characteristic parameter of the offset to characterize the offset. As described above, these characteristic parameters may include one or more of yaw-rate bias, heading-angle bias, and lateral-displacement bias. Preferably, the offset obtaining module may include sub-modules for obtaining the respective characteristic parameters, i.e., a yaw rate sub-module, a heading angle sub-module, and a lateral displacement sub-module, respectively. The yaw-rate sub-module may obtain a real-time yaw-rate from the yaw-rate sensor and obtain a yaw-rate bias by subtracting the initial yaw-rate from the real-time yaw-rate. The heading angle sub-module may obtain a real-time heading angle by integrating the yaw angular velocity and obtain a heading angle deviation by subtracting the initial heading angle from the real-time heading angle. The lateral displacement submodule may calculate a lateral displacement speed from the course angle deviation and the vehicle speed, integrate the lateral displacement speed to obtain a real-time lateral displacement, and obtain a lateral displacement deviation by subtracting the initial lateral displacement from the real-time lateral displacement.
Preferably, as previously described, the yaw-rate sub-module may set the initial yaw-rate to zero, the heading-angle sub-module may set the initial lateral displacement to zero, and the lateral-displacement sub-module may set the initial lateral displacement to zero when the vehicle is stationary or when the vehicle is traveling but has a target steering angle that is not zero. When the vehicle is traveling and the target steering angle is zero, the yaw-rate sub-module may set the value of the yaw-rate at the time when the steering angle of the vehicle is initially zero to an initial yaw-rate, the heading-angle sub-module may set the initial heading angle to zero, and the lateral-displacement sub-module may set the initial lateral displacement to zero.
The correction judging module is used for executing the step S2, namely judging whether the offset correction is needed or not according to the offset. Specifically, the correction judgment module may acquire and store predetermined threshold values for the respective characteristic parameters in advance, and when any one of the respective characteristic parameters is greater than the corresponding predetermined threshold value, the correction judgment module judges that the offset correction is required, and sends the judgment result to the correction calculation module.
The correction calculation module is used for executing step S3, namely calculating the offset correction torque of the vehicle in real time based on the offset amount when the offset correction is judged to be needed. The start of the correction calculation module is triggered by a positive judgment result (namely, the offset correction is needed) sent by the correction judgment module. Preferably, the correction calculation module may store respective coefficients obtained through experiments for the respective characteristic parameters described above, and calculate the offset correction torque by adding products of each of the respective characteristic parameters and the respective coefficients.
The torque distribution module is used for executing the step S4, namely after receiving the offset correction torque obtained by the correction calculation module, distributing the offset correction torque to the plurality of wheels in real time to compensate the offset. As described above, the torque distribution module may distribute the offset correction torque to the plurality of wheels according to at least one of: the arrangement and the operating state of the drive actuators of the respective wheels, and the magnitude of the offset correction torque. The specific allocation method, such as the embodiment of the offset control method, is described with respect to step S4, and is not repeated here.
As shown in fig. 1, the raw signal data required for the offset control method and the offset control system are from sensors such as a yaw rate sensor, a vehicle speed sensor, and the like, and the finally allocated torques thereof are applied by the respective drive actuators, and therefore, these sensors and drive actuators can also be regarded as the constituent structure of the offset control system. However, these structures are the original components of the vehicle, and the modules of the offset control system are all the functional modules integrated in the original electronic control unit of the vehicle, so that the offset control system does not need to add additional structural components.
The offset control method and the offset control system according to the present invention can determine the straight-driving state of the vehicle in real time by calculating the offset amount of the vehicle, and actively compensate for such offset by applying an additional correction torque on the wheels as necessary, whereby the posture of the vehicle body can be corrected in real time during the driving of the vehicle. This significantly improves the straight-driving performance of the vehicle. Meanwhile, such an offset control method and an offset control system do not require an additional structural component to perform, and thus are easy to implement.
Although possible embodiments have been described by way of example in the above description, it should be understood that numerous embodiment variations exist, still by way of combination of all technical features and embodiments that are known and that are obvious to a person skilled in the art. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. From the foregoing description, one of ordinary skill in the art will more particularly provide a technical guide to convert at least one exemplary embodiment, wherein various changes may be made, particularly in matters of function and structure of the components described, without departing from the scope of the following claims.
Claims (10)
1. An offset control method for a distributed drive vehicle including a plurality of wheels capable of driving and controlling independently from each other,
the offset control method includes:
acquiring the offset of the distributed driving vehicle in real time;
judging whether offset correction is needed or not according to the offset;
calculating an offset correction torque of the distributed drive vehicle in real time based on the offset amount when it is determined that the offset correction is required; and
distributing the offset correction torque to the plurality of wheels in real time to compensate for the offset amount.
2. The offset control method according to claim 1,
obtaining the offset of the distributed-drive vehicle in real-time includes obtaining at least one characteristic parameter of the offset to characterize the offset, the at least one characteristic parameter including one or more of yaw-rate bias, heading-rate bias, and lateral-displacement bias.
3. The offset control method according to claim 2,
acquiring a real-time yaw rate by a yaw rate sensor, and acquiring the yaw rate deviation by subtracting an initial yaw rate from the real-time yaw rate;
acquiring a real-time course angle by integrating the yaw angular velocity, and acquiring a course angle deviation by subtracting an initial course angle from the real-time course angle; and is provided with
Calculating a lateral displacement speed according to the course angular deviation and the vehicle speed, integrating the lateral displacement speed to obtain a real-time lateral displacement, and obtaining the lateral displacement deviation by subtracting an initial lateral displacement from the real-time lateral displacement.
4. The offset control method according to claim 3,
in acquiring the offset amount of the distributed drive vehicle:
setting each of the at least one characteristic parameter to zero when the distributed drive vehicle is stationary or when the distributed drive vehicle is traveling but has a target steering angle that is not zero; and is
When the distributed drive vehicle is traveling and the target steering angle is zero, setting the value of the yaw rate at the time when the steering angle of the distributed drive vehicle is initially zero to the initial yaw rate, and setting the initial heading angle and the initial lateral displacement to zero.
5. The offset control method according to claim 2,
when any one of the at least one characteristic parameter is larger than a corresponding predetermined threshold value, judging that offset correction is needed.
6. The offset control method according to claim 2,
the offset correction torque is calculated by adding products of each of the at least one characteristic parameter and a corresponding coefficient, which is obtained by experiment.
7. The offset control method according to any one of claims 1 to 6,
distributing the offset correction torque to the plurality of wheels according to at least one of: the arrangement and the operating state of the drive actuators of the plurality of wheels, and the magnitude of the offset correcting torque.
8. An offset control system for a distributed drive vehicle including a plurality of wheels capable of driving and controlling independently of each other,
the offset control system includes:
an offset acquisition module configured to acquire an offset amount of the distributed drive vehicle in real time;
the correction judging module is configured to judge whether offset correction is needed or not according to the offset;
a correction calculation module configured to calculate an offset correction torque of the distributed drive vehicle in real time based on the offset amount when it is determined that the offset correction is required; and
a torque distribution module configured to distribute the offset correction torque to the plurality of wheels in real time to compensate for the offset.
9. The offset control system of claim 8,
the offset acquisition module is configured to acquire at least one characteristic parameter of the offset to characterize the offset, the at least one characteristic parameter including one or more of yaw rate deviation, heading angle deviation, and lateral displacement deviation.
10. Offset control system according to claim 8 or 9,
the torque distribution module is configured to distribute the offset correction torque to the plurality of wheels according to at least one of: the arrangement and the operating state of the drive actuators of the plurality of wheels, and the magnitude of the offset correcting torque.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117416213A (en) * | 2023-11-20 | 2024-01-19 | 燕山大学 | Dual-mode coupling driving type automobile feedback braking failure composite control system and method |
| CN117416213B (en) * | 2023-11-20 | 2024-06-18 | 燕山大学 | Dual-mode coupling driving type automobile feedback braking failure composite control system and method |
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