A multi-axis distributed intelligent drive control method for vehicles

Abstract

The present invention provides a multi-axis distributed intelligent drive control method for vehicles, including: Step 1: Obtain the ballast data of each wheel; Step 2: Determine whether the ballast data is less than, greater than, or equal to a preset threshold; if it is less, then determine that the wheel is in a suspended state and mark the wheel as an invalid wheel; if it is greater than or equal to, then determine that the wheel is in a grounded state and mark the wheel as a pending wheel; Step 3: Determine the slip state of the pending wheels; Step 4: If the angular acceleration difference is greater than the preset threshold, then determine that the wheel is in a slip state and mark it as an invalid wheel; Step 5: Do not allocate torque to the invalid wheels and allocate torque to the valid wheels. The present invention effectively solves the problem that torque cannot be transferred and controlled in the case of wheel slip or suspension in multi-axis distributed drive vehicles in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle drive control, and particularly relates to a multi-axis distributed intelligent drive control method for vehicles. Background Art

[0002] Each wheel of a multi-axis distributed drive vehicle has an independent drive motor. The advantages of this drive method are large total drive power, strong overload capacity, and good power performance; it also has high efficiency at low speeds. The multi-axis distributed drive vehicle eliminates the drive shaft, has a more efficient space layout, can reduce the vehicle's center of gravity to meet some special applications, and is a research direction for future special vehicles.

[0003] The difficulty of multi-axis distributed drive lies in how to coordinate and control each wheel. Traditional vehicles have a mechanical differential lock. After locking, if some wheels are suspended, the torque will automatically transfer to other wheels. After some wheels of a multi-axis distributed drive vehicle are suspended or slip, the torque will not automatically transfer. The rotational speed of the suspended wheel will increase abnormally, and the total drive torque will be less than the driver's required torque. Summary of the Invention

[0004] The present invention provides a multi-axis distributed intelligent drive control method for vehicles, which effectively solves the problem that torque cannot be transferred and controlled in a multi-axis distributed drive vehicle when the wheels are slipping or suspended in the prior art.

[0005] The present invention is realized through the following technical solutions:

[0006] A multi-axis distributed intelligent drive control method for vehicles includes:

[0007] Step 1: Obtain the ballast data of each wheel;

[0008] Step 2: Determine whether the ballast data is less than, greater than, or equal to a preset threshold; if it is less, then determine that the wheel is in a suspended state and mark the wheel as an invalid wheel; if it is greater than or equal to, then determine that the wheel is in a grounded state and mark the wheel as a pending wheel;

[0009] Step 3: Determine the slipping state of the pending wheels; include: calculate the actual angular acceleration of the pending wheels and obtain a first angular acceleration value; calculate the theoretical angular acceleration of the pending wheels in the no-load state and obtain a second angular acceleration value;

[0010] Step 4: Subtract the first angular acceleration value from the second angular acceleration value to obtain an angular acceleration difference. If the angular acceleration difference is less than or equal to a preset threshold, then determine that the wheel is in a normal working state and mark it as an effective wheel; if the angular acceleration difference is greater than the preset threshold, then determine that the wheel is in a slipping state and mark it as an invalid wheel;

[0011] Step Five: Do not allocate torque to the invalid wheels, and allocate torque to the valid wheels.

[0012] Further, the ballast data is obtained by the vehicle controller reading the oil-gas suspension.

[0013] Further, the calculation of the actual angular acceleration of the pending wheel includes: obtained by calculating according to the differential of the motor speed. The discrete sampling time is used in the motor microcontroller, and the difference is used instead of calculation. Therefore, the first angular acceleration value is:

[0014] Further, the calculation of the theoretical angular acceleration of the pending wheel in the no-load state includes: converting the moment of inertia of the wheel to the motor shaft. The transmission ratio from the motor to the wheel is i, and the moment of inertia of the motor is I m , then the moment of inertia I w = I m *η*i 2 , and the equivalent total moment of inertia on the motor shaft is I s = I m (1 + η*i 2 ), after the given motor demand drive torque T d is given, combined with the torque loss calibration value T l at different speeds, then the angular acceleration without external load can be calculated

[0015] Further, the method further includes:

[0016] Step Six: Perform free torque distribution on the valid wheels.

[0017] Further, the method further includes:

[0018] Step Six: Perform full-wheel torque distribution on the valid wheels.

[0019] Further, the method of free torque distribution includes: the vehicle controller receives the target total torque, and determines the number of working motors according to the target total torque. The determination of the number of working motors includes: determining the optimal working area of each motor according to the motor efficiency map of each motor, and then calculating the preferentially selected number of motors. If the number of motors corresponding to the valid wheels is less than the preferentially selected number of motors, then only the motors corresponding to the valid wheels can be selected, and then the total required torque is distributed to the selected motors.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The present invention connects the motor controllers of each wheel through a vehicle controller and a CAN bus, thereby constituting an intelligent control system for a multi-axis distributed drive vehicle; programming the vehicle controller to obtain corresponding intelligent control functions, specifically including: by detecting the ballast of each wheel and comparing the detection result with a preset threshold, it can be determined whether the wheel is in a lifted state. If it is lifted, the vehicle controller does not allocate torque to this wheel. In this way, the torque can be effectively and reasonably allocated, and thus the required torque of the driver can be achieved; by further calculating the wheel with ballast, it can be determined whether the wheel is in a slipping state, that is, there is a ballast situation, but its angular acceleration is close to the angular acceleration under the no-load condition. In this way, it can be determined that this situation is a slipping state; the wheel in the slipping state is also marked as an invalid wheel, and the vehicle controller does not allocate torque to it. In this way, the torque can be effectively and reasonably allocated, and thus the required torque of the driver can be achieved; by setting a free allocation mode, it is possible to automatically and effectively allocate torque to the motor with the highest working efficiency under this working condition according to different terrain conditions, thereby saving energy and improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a wheel being suspended when the vehicle climbs a slope;

[0023] Figure 2 Schematic diagram of the modular structure of the intelligent drive system of the present invention;

[0024] Figure 3 Schematic diagram of the flow of the intelligent drive control method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be described in detail below with reference to the drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

[0026] A multi-axis distributed intelligent drive control method for a vehicle includes:

[0027] Step 1: Obtain the ballast data of each wheel; the ballast data is read by the vehicle controller from the oil-gas suspension.

[0028] Step 2: Determine whether the ballast data is less than, greater than or equal to a preset threshold; if it is less, it is determined that the wheel is in a suspended state and the wheel is marked as an invalid wheel; if it is greater than or equal, it is determined that the wheel is in a grounded state and the wheel is marked as a pending wheel;

[0029] Step 3: Determine the slipping state of the to-be-determined wheel; including: calculating the actual angular acceleration of the to-be-determined wheel to obtain a first angular acceleration value; calculating the theoretical angular acceleration of the no-load state of the to-be-determined wheel to obtain a second angular acceleration value; the calculation of the actual angular acceleration of the to-be-determined wheel includes: calculated according to the differential of the motor speed. In the motor microcontroller, discrete sampling time is used and difference is used instead of calculation. Therefore, the first angular acceleration value is: The calculation of the theoretical angular acceleration of the no-load state of the to-be-determined wheel includes: converting the moment of inertia of the wheel to the motor shaft. The transmission ratio from the motor to the wheel is i, and the moment of inertia of the motor is I m , then the moment of inertia I w = I m *η*i 2 , and the equivalent total moment of inertia on the motor shaft is I s = I m (1 + η*i 2 ). Given the required driving torque T d of the motor, combined with the torque loss calibration value T l at different speeds, then the angular acceleration without external load can be calculated

[0030] Step 4: Subtract the first angular acceleration value from the second angular acceleration value to obtain an angular acceleration difference. If the angular acceleration difference is less than or equal to a preset threshold, then judge that the wheel is in a normal working state and mark it as an effective wheel. If the angular acceleration difference is greater than the preset threshold, then judge that the wheel is in a slipping state and mark it as an ineffective wheel;

[0031] Step 5: Do not allocate torque to the ineffective wheel and allocate torque to the effective wheel.

[0032] Step 6: Perform torque free distribution or torque all-wheel distribution on the effective wheels. The method of torque free distribution includes: the vehicle controller receives the target total torque and determines the number of working motors according to the target total torque. The determination of the number of working motors includes: determining the optimal working area of each motor according to the motor efficiency map of each motor, and then calculating the preferentially selected number of motors. If the number of motors corresponding to the effective wheels is less than the preferentially selected number of motors, then only the motors corresponding to the effective wheels can be selected, and then the total required torque is distributed to the selected motors.

[0033] This intelligent system includes: a wheel suspension elimination module, a wheel anti-slip processing module, an ineffective wheel marking module, a drive and brake coordination module, and a fault diagnosis module.

[0034] The wheel suspension elimination module includes: a ballast measurement module and a suspended wheel marking module.

[0035] Among them, the ballast measurement module is used to actively evaluate the wheel contact with the ground. The ballast measurement can be read through the oil-gas suspension or estimated by installing a displacement sensor. The suspended wheel marking module obtains the ballast of each wheel, filters out the burrs through a certain debouncing algorithm to obtain the true value, and then compares this value with the calibrated threshold. If it is marked as a suspended wheel, it is marked as not suspended, and no torque is allocated to the suspended wheels during torque distribution.

[0036] The wheel anti-skid processing module includes: an angular acceleration calculation module, an abnormal acceleration detection module, and a recovery drive judgment module. When the current wheel is not suspended but still has an abnormal increase in speed, it enters the second-level protection processing.

[0037] Among them, the angular acceleration calculation module is obtained by calculating the differential of the motor speed. In the microcontroller, discrete sampling time is used, and the difference is used instead of calculation. Specifically, it is as follows: the angular acceleration calculation module is obtained by calculating the differential of the motor speed. In the microcontroller, discrete sampling time is used, and the difference is used instead of calculation

[0038] The abnormal acceleration detection module converts the moment of inertia of the wheel to the motor shaft. The transmission ratio from the motor to the wheel is i, and the moment of inertia of the motor is I m , and the moment of inertia of the wheel I w = I m *η*i 2 , and the equivalent total moment of inertia on the motor shaft is I s = I m (1 + η*i 2 ). Given the required driving torque T d of the motor, combined with the calibrated torque loss value T l at different speeds, the angular acceleration without external load can be calculated Set a calibrated quantity C cal , when the actual angular acceleration is close to the idling acceleration, α f -α r < C cal , it can be judged that the wheel has almost no adhesion, and it is marked as slipping.

[0039] The recovery drive judgment module is used to clear the slipping mark so that torque can be redistributed again. After being marked as invalid, the mark is cleared after a delay of 0.1 to 1 second. The invalid wheel marking module makes a comprehensive judgment based on the wheel suspension state and the wheel slipping state to obtain whether each wheel is effectively allowed to drive or invalid and not allowed to drive finally.

[0040] The drive and brake coordination module includes: a free torque distribution mode and a forced all-wheel drive mode.

[0041] Among them, the free torque distribution mode can automatically distribute the torque of some motors, and the other part of the motors follow. According to the required torque of the driver, the optimal working area is found in the motor efficiency map, and the number of motors to be preferentially selected is calculated. If the number of effective motors is less than the number of preferentially selected motors, only the number of effective motors can be selected, and then the total required torque is distributed to the selected drive motors.

[0042] The forced all-wheel drive mode expects all wheels to output power, and the torque distribution skips the ineffective wheels.

[0043] The fault diagnosis module is used for fault debouncing, fault reporting and safety handling.

[0044] Among them, fault debouncing is used to confirm the current fault state, and the up / down counting method is adopted. That is, when the input is "true", the count value increases, and when the input is "false", the count value decreases. When the count value is greater than the set value, it can be confirmed as a fault. The ratio of the increasing speed to the decreasing speed of the count value can be selected from several ratios: 1 / 4, 1 / 3, 1 / 2, 1, 2, 3, 4. It is expected to be able to detect faults more easily, and a ratio greater than 1 is used as the debouncing method.

[0045] Fault reporting is represented by the method of using a natural number fault number corresponding to a fault. A fault includes a DTC and a fault level. The DTC fault code is defined with reference to the J1939 protocol and is a code for people to view, which is convenient for maintenance. The fault level indicates the severity of the fault.

[0046]

[0047] Whether a fault occurs is stored by bits, that is, this bit 0 / 1 indicates non-occurrence / occurrence. Define bitmask, arrpos, bitpos as 32-bit unsigned integer data, code represents the fault number, and actData is a 32-bit unsigned integer array. Determine the position of the bit to be operated:

[0048] arrpos = code >> 5

[0049] bitpos = code & 0x1F

[0050] bitmask = 1 << bitpos

[0051] Write the occurrence of a fault:

[0052] actData[arrpos] |= bitmask

[0053] Write the non-occurrence of a fault:

[0054] actData[arrpos] &= ~bitmask

[0055] The read fault status value is:

[0056] actData[arrpos] & bitmask

[0057] By traversing the fault numbers, it is judged whether the faults corresponding to the fault numbers have occurred, and then the fault level and fault DTC are read to generate a DM1 message. The DM1 message can be used by a diagnostic instrument to view the faults and perform fault troubleshooting according to the maintenance guidance.

[0058] Safety handling is used when there is a fault in the ballast measurement module. The wheel active rejection module is unavailable. This module outputs a state where none of the wheels are suspended. At this time, the anti-skid module is still effective. When a serious fault occurs in the motor system, the motor needs to be shut down for protection, and the motor is prohibited and the torque output is stopped.

[0059] This system marks the effective or ineffective state according to the wheel suspension and slipping conditions. If a certain driving wheel is marked as ineffective, the torque output of this wheel is stopped, and the torque of this wheel is distributed to other wheels, so that the actual driving torque is close to the driver's required torque, and it can also protect the wheels from excessive wear due to too fast rotation speed. This system provides a unified total demand torque interface and intelligently distributes torque internally, improving the modular design.

[0060] The present invention connects the motor controllers of each wheel through a vehicle controller and a CAN bus, thereby constituting an intelligent control system for a multi-axis distributed drive vehicle; programming the vehicle controller to obtain corresponding intelligent control functions, specifically including: by performing ballast detection on each wheel and comparing the detection results with a preset threshold value, it can be judged whether the wheel is in a state of leaving the ground. If it leaves the ground, the vehicle controller does not allocate torque to this wheel. In this way, the torque can be effectively and reasonably allocated, and then the driver's required torque can be achieved; by further calculating the wheel with ballast, it can be obtained whether the wheel is in a slipping state, that is, there is a ballast situation, but its angular acceleration is close to the angular acceleration under the no-load condition. In this way, it can be judged that this situation is a slipping state; the wheel in the slipping state is also marked as an invalid wheel, and the vehicle controller does not allocate torque to it. In this way, the torque can be effectively and reasonably allocated, and then the driver's required torque can be achieved; through the setting of the free distribution mode, for different terrain conditions, the torque can be automatically and effectively allocated to the motor with the highest working efficiency under this working condition, thereby saving energy and improving efficiency.

[0061] The above-given embodiments are preferred examples for implementing the present invention. The present invention is not limited to the above embodiments. Any non-essential addition or replacement made by those skilled in the art according to the technical features of the technical solution of the present invention belongs to the protection scope of the present invention.

Claims

1. A multi-axis distributed intelligent drive control method for vehicles, characterized in that Including: Step 1: Obtain the ballast data of each wheel; Step 2: Determine whether the ballast data is less than, greater than, or equal to a preset threshold; If it is less, determine that the wheel is in a suspended state and mark the wheel as an invalid wheel; if it is greater than or equal, determine that the wheel is in a grounded state and mark the wheel as a pending wheel; Step 3: Determine the slipping state of the pending wheel; including: calculating the actual angular acceleration of the pending wheel and obtaining a first angular acceleration value; calculating the theoretical angular acceleration of the pending wheel in the no-load state and obtaining a second angular acceleration value; Step 4: Subtract the first angular acceleration value from the second angular acceleration value to obtain an angular acceleration difference. If the angular acceleration difference is less than or equal to a preset threshold, then determine that the wheel is in a normal working state and mark it as a valid wheel. If the angular acceleration difference is greater than the preset threshold, then determine that the wheel is in a slipping state and mark it as an invalid wheel; Step 5: Do not allocate torque to the invalid wheels and allocate torque to the valid wheels; Step 6: Perform torque free allocation for the valid wheels; the method of torque free allocation includes: the vehicle controller receives the target total torque and determines the number of working motors according to the target total torque. The determination of the number of working motors includes: determining the optimal working area of each motor according to the motor efficiency map of each motor, and then calculating the preferentially selected number of motors. If the number of motors corresponding to the valid wheels is less than the preferentially selected number of motors, then only the motors corresponding to the valid wheels can be selected, and then the total required torque is allocated to the selected motors; Calculating the theoretical angular acceleration of the to-be-determined wheel in the no-load state includes: converting the moment of inertia of the wheel to the motor shaft, and the transmission ratio from the motor to the wheel is , the moment of inertia of the motor is , then the moment of inertia of the wheel , the equivalent total moment of inertia on the motor shaft is , after giving the required driving torque of the motor , combined with the torque loss calibration value at different speeds , then the angular acceleration without external load can be calculated .

2. The vehicle multi-axis distributed intelligent drive control method according to claim 1, characterized in that The ballast data is obtained by the vehicle controller reading the oil-gas suspension.

3. A multi-axis distributed intelligent drive control method for vehicles according to claim 1, characterized in that Calculating the actual angular acceleration of the to-be-determined wheel includes: obtained by calculating based on the differential of the motor speed. In the motor microcontroller, discrete sampling time is used, and difference is used instead of calculation. Therefore, the first angular acceleration value is: .

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