TWI421178B - An intelligent differential control method for in-wheel hub motors and apparatus thereof - Google Patents

Description

Differential speed control method and device for intelligent multi-wheel independent power wheel

The present invention relates to a differential control method and apparatus for a multi-independent power wheel vehicle, and more particularly to a differential control method and apparatus capable of intelligently updating a differential speed intelligently.

With the increasing requirements of environmental protection, energy saving and quietness, electric vehicles are more valued by the industry than traditional gasoline and diesel vehicles. In order to improve transmission efficiency, more and more electric vehicles use In-wheel hub motors. In-wheel motor refers to the integration of motor power and tires, eliminating the need for drive shafts, transmissions, differential gears or other drive components. In this way, the energy loss caused by the transmission can be avoided.

Although the in-wheel motor (or power wheel) has the above advantages, since the power and speed output between the power wheels are independent, the vehicle needs to be equipped with a central control system to meet various traveling states of the vehicle (for example, The differential relationship at the time of rotation). The electronic differential system is capable of speed matching for multiple independent power-driven vehicles. It develops an adapted algorithm based on the size of the vehicle (including important parameters such as track and wheelbase) to obtain a differential relationship that satisfies kinematics. In addition, if the configuration setting of the drive wheel is changed (for example, the predecessor setting and the rear drive setting), the applicability problem of the control algorithm will also be caused. Therefore, the "electronic differential controller" has the disadvantage of being insufficient in general use compared with the "traditional mechanical differential mechanism" and lacks practical convenience.

In order to improve the electronic differential system with insufficient differential accuracy, many technologies have been developed in the industry. For example, the mainland application No. 201021151 patent and the Taiwan publication No. I307319 patent.

The differential device disclosed by the former determines the left (right) wheel differential control signal output by comparing the left (right) differential signal of the steering wheel with the pedal acceleration signal through the left (right) wheel comparison circuit module. This kind of analog signal driving the differential speed of the analog wheel, if there is a lack of rigorous cross-simulation and comparison with the vehicle dynamics, the effect on vehicle stability control is limited.

The latter uses the sensor to detect the current vehicle driving dynamics and driving control requirements, and the transmission signal is sent to the electronic control unit. The electronic control unit calculates and determines the rotation speed of each wheel of the carrier to match the driving control requirement, and controls the rotation dynamics of each wheel by the power driving unit according to the rotation speed control signal control, so that the vehicle drives the action according to the driving action requirement, and the bending can be reduced. When the steering wheel controls the load, it can also effectively reduce the maximum tumbling angle generated by the vehicle during cornering, and can effectively suppress the body roll angle after entering the curve and ending the cornering, and greatly reduce the tumbling angle. The possibility of vehicle overturning when cornering.

Although the above-mentioned electronic differential system has been proposed in the industry, in addition to the shortcomings of insufficient differential accuracy, it takes a long time to develop an adaptive algorithm according to the size of the vehicle. It is a short period of two months and a long period of several years.

Based on the above problems of the prior art, the present invention provides a differential control method for a smart multi-wheel independent power wheel and a control device thereof. The differential control method and the control device can dynamically and intelligently update the differential law according to the actual driving state of the vehicle to quickly adjust the differential law suitable for the vehicle.

According to an embodiment, the differential control method of the intelligent multi-wheel independent power wheel is adapted to receive a user command to drive a plurality of power wheel operations, the control method comprising: capturing user commands and driving parameters, and driving parameter corresponding power Wheel; determining whether the power wheel is operating in the smart mode according to the user command and the driving parameter; if yes, executing the differential update procedure; and if not, driving the power wheel according to the user command and the differential law.

According to an embodiment, the step of determining whether the power wheel is in the smart mode according to the user instruction and the driving parameter comprises: determining whether the steering angle signal commanded by the user is greater than a steering angle threshold; and if the steering angle signal is greater than a steering angle threshold, Then, it is determined whether the total torque is less than the torque threshold according to the driving parameter; and if the total torque is less than the torque threshold, it is determined that the power wheel is operated in the smart mode.

According to an embodiment, the step of determining whether the total combined torque is less than the torque threshold according to the driving parameter comprises: obtaining a single wheel torque according to the driving voltage, the driving current and the rotating speed of the driving parameter, and the single wheel torque corresponding to the power wheel; adding a single wheel Torque obtains the combined torque; and determines if the combined torque is less than the torque threshold.

According to an embodiment, the differential update procedure includes: determining whether the rotational speed of the drive parameter is lower than a rotational speed threshold; and if so, updating the differential law according to a steering angle signal and a rotational speed commanded by the user.

According to an embodiment, the differential control device of the intelligent multi-wheel independent power wheel is adapted to receive a user command to drive the power wheel to operate. The control device includes a sensor, a motor driver, and a differential controller. The sensor is used to sense user instructions. The motor driver is used to drive the power wheel to operate and output operating parameters corresponding to the power wheel. The differential controller has a differential law and determines whether the power wheel is operating in a smart mode based on user commands and operating parameters. If the power wheel is operating in the smart mode, the differential controller performs a differential update procedure. If the power wheel is not in the smart mode, the differential controller controls the motor driver to drive the power wheel according to the user command and the differential law.

By the differential control method and the differential control device, it is possible to determine whether the vehicle is in the smart mode (low-speed inertia cruise mode) when the vehicle of the multiple independent power wheels is running, and if so, perform a differential update procedure to apply the inertial cruise mode. Next, the differential relationship between the wheels is dynamically updated in the differential law to obtain the differential law that best fits the vehicle, which can be applied to all types of independent power wheels, and effectively shortens the development of the differential law. Verification time.

The features and implementations of the present invention are described in detail below with reference to the preferred embodiments.

First, please refer to "Figure 1". Fig. 1 is a block diagram showing the circuit of an embodiment of the differential control device 10 according to the present invention. The differential control device 10 is adapted to receive a user command 90 to drive the power wheels 92a, 92b, 92c, 92d to operate. Each of the power wheels 92a, 92b, 92c, 92d has an in-wheel motor 94a, 94b, 94c, 94d, respectively. When the in-wheel motors 94a, 94b, 94c, 94d are in operation, the power wheels 92a, 92b, 92c, 92d are rotated. As can be seen from the figure, the differential control device 10 can control the four power wheels 92a, 92b, 92c, 92d to operate, but not limited thereto, the control device 10 can also control two, six or eight The power wheels 92a, 92b, 92c, 92d operate. The power wheels 92a, 92b, 92c, 92d are in this embodiment an electric power wheel.

The aforementioned user command 90 refers to the user's driving intention. The user command 90 can be, but is not limited to, acceleration (or acceleration signal, acceleration intent, throttle opening), deceleration (or brake signal, deceleration intent), and steering (or steering angle signal, steering intent).

As can be seen from the figures, the differential control device 10 includes a sensor 12, a motor driver 16, and a differential controller 14. The sensor 12 is configured to sense the user command 90 and output a corresponding signal. The sensor 12 can include a steering angle sensor, an acceleration sensor, and a deceleration sensor. The steering angle sensor is configured to receive the steering intention of the user command 90 and output a steering angle signal. The acceleration sensor is configured to receive the acceleration intention of the user command 90 (or the opening of the accelerator pedal) and output an acceleration signal. The deceleration sensor is configured to receive the deceleration of the user command 90 (opening degree of the brake pedal) and output a deceleration signal.

The motor driver 16 is used to drive the power wheels 92a, 92b, 92c, 92d to operate and output operating parameters corresponding to the power wheels 92a, 92b, 92c, 92d. The operating parameters may be, but are not limited to, a driving voltage V, a driving current I, and a rotational speed ω (or may be referred to as a wheel rotational speed). The rotational speed may be obtained from the Back Electro-Magnetic Field (EMF) of the motor driver 16. When the motors 94a, 94b, 94c, 94d are driven, a counter electromotive force is obtained on the motor driver 16. This back electromotive force can be detected and output in pulse mode. The physical quantity corresponding to this pulse may be the angular speed (rotary speed) of the motors 94a, 94b, 94c, 94d. Therefore, the motor driver 16 can instantaneously output the drive current I, the drive voltage V, and the rotational speed ω while the drive power wheels 92a, 92b, 92c, 92d are operating.

The above-described rotational speed ω is measured by the counter electromotive force. In addition, some of the motors 94a, 94b, 94c, and 94d also have built-in Hall effect sensors. At this time, the motor driver 16 can measure the rotational speed ω of the power wheels 92a, 92b, 92c, 92d via the Hall effect sensor. The rotational speed ω is herein referred to as rotation per minute (rpm), but is not limited thereto.

The differential controller 14 has a differential law 140 and determines whether the power wheels 92a, 92b, 92c, 92d are operating in a smart mode based on the user command 90 and the operating parameters V, I, ω. If the power wheels 92a, 92b, 92c, 92d are operating in the smart mode, the differential controller 14 performs a differential update procedure. If the power wheels 92a, 92b, 92c, 92d are not operating in the smart mode, the differential controller 14 controls the motor driver 16 to drive the power wheels 92a, 92b, 92c, 92d in accordance with the user command 90 and the differential law 140. The operation of the aforementioned power wheels 92a, 92b, 92c, and 92d in the smart mode means that the differential controller 14 determines that the current operation modes of the power wheels 92a, 92b, 92c, and 92d belong to a state in which differential learning is possible (timing). In the smart mode, each of the power wheels 92a, 92b, 92c, 92d is in a free rolling state, i.e., does not accept or only accept very low driving power. At this time, the relationship between the rotational speeds ω of the power wheels 92a, 92b, 92c, 92d is a natural phenomenon suitable for the current steering angle, so it can be recorded separately in the differential law (or database). Said).

The aforementioned differential law 140 may be a differential law 140 derived and verified according to a steering angle, a wheelbase of a vehicle, a wheelbase, a driving mode (precursor, a rear drive, or a four-wheel drive), or may be verified. a lookup table. This look-up table is typically, but not limited to, querying the speed difference or speed difference between the driven power wheels 92a, 92b, 92c, 92d at the steering angle. The differential law 140 can be built into the differential controller 14, or a memory can be placed beside the differential controller 14, and the differential law 140 can be stored in the memory and accessed by the differential controller 14. .

Regarding how the differential controller 14 determines whether the power wheels 92a, 92b, 92c, 92d are operating in the smart mode, and how to perform the differential update procedure in the smart mode, please refer to "Fig. 2". It is a schematic flowchart of an embodiment of the differential control method according to the present invention.

As can be seen, the differential control method of the intelligent multi-wheel independent power wheels 92a, 92b, 92c, 92d is adapted to receive user command 90 to drive the power wheels 92a, 92b, 92c, 92d to operate. The differential control method includes the following steps: Step S20: capturing user command 90 and driving parameters V, I, ω, driving parameters corresponding to power wheels 92a, 92b, 92c, 92d; step S30: according to user instruction 90 and The drive parameters V, I, ω determine whether the power wheels 92a, 92b, 92c, 92d are operating in the smart mode; step S40: if yes, execute the differential update procedure; and step S50: if not, according to the user command 90 and the difference The speed law 140 drives the power wheels 92a, 92b, 92c, 92d to operate.

As described above, the user command of step S20 may include a steering angle, an accelerator pedal opening, and a brake pedal opening. The driving parameters of step S20 include a driving voltage V, a driving current I, and a rotation speed ω. The corresponding relationship between the drive parameters V, I, ω and the power wheels 92a, 92b, 92c, 92d is that each of the power wheels 92a, 92b, 92c, 92d has a set of drive voltage V, drive current I and rotational speed ω. Thereby, the differential controller 14 can know information such as the vehicle speed of the vehicle and the drive-out torque of each of the power wheels 92a, 92b, 92c, and 92d. For example, the vehicle speed can be averaged from the rotational speeds ω of all of the power wheels 92a, 92b, 92c, 92d, and the torque of each of the power wheels 92a, 92b, 92c, 92d can be calculated by the following formula (1).

Where n is the nth power wheel, T _n is the torque of the nth power wheel, V _n is the driving voltage of the nth power wheel, I _n is the driving current of the nth power wheel, and ω _n is the nth The speed of the power wheel.

In addition, if you want to calculate the total combined torque, you can calculate it by the following formula (2):

Wherein, T _{all is} the total combined torque, n is the number of power wheels, I _i is the driving current corresponding to the i-th power wheel, and V _i is the driving voltage corresponding to the i-th power wheel, and ω _i is The rotational speed of the i-th power wheel.

Regarding step S30: "Whether or not the power wheels 92a, 92b, 92c, 92d are operated in the smart mode based on the user command 90 and the drive parameters V, I, ω", please refer to "Fig. 3". The smart mode here refers to the current driving state of the vehicle is non-driven (no acceleration, deceleration) and the vehicle adopts the undriven driving method according to the current speed of the vehicle according to its inertia and the interaction between the components of the vehicle. The mode of travel. That is to say, the wheel is currently in a state of free rolling according to its inertia (it can be said that the vehicle is in a coasting state). If the vehicle travels in an undriven patrol mode, the speed relationship between the wheels is the optimal differential relationship of the vehicle. At this time, the current steering angle and the speed relationship can be recorded as The differential law 140 is then applied when the vehicle is driven at the steering angle.

As can be seen from "Fig. 3", step S30 includes: step S32: determining whether the steering angle signal of the user command 90 is greater than a steering angle threshold; step S34: if the steering angle signal is greater than the steering angle threshold, then driving The parameter determines whether the total combined torque is less than the torque threshold; and step S36: if the combined torque is less than the torque threshold, it is determined that the power wheels 92a, 92b, 92c, 92d are operating in the smart mode.

Step S38: If the steering angle signal is not greater than the steering angle threshold, it is determined that the power wheels 92a, 92b, 92c, 92d are not in the smart mode.

The steering angle signal of the user command 90 in step S32 is output by the sensor 12. The steering angle threshold is used to determine whether the steering angle signal is in a steered state. If the steering angle signal is greater than the steering angle threshold, it indicates that the current user command 90 contains the signal to be turned. At this time, the differential controller 14 needs to refer to the differential law 140 to drive the power wheels 92a, 92b, 92c, 92d. The decision angle of the steering angle signal depends on the minimum angle of the differential law 140 (such as the critical angle of the steering angle), and can generally be set to 0.1 degrees or other values. If the steering angle signal is not greater than the steering angle threshold, it is determined that the power wheels 92a, 92b, 92c, 92d are not operating in the smart mode (step S38).

Next, in step S34, when the steering angle signal is greater than the steering angle threshold, it is determined whether the total torque is less than the torque threshold according to the driving parameter. The total combined torque is calculated by the above formula (2). The determination of the total torque is used to determine whether the vehicle is currently in a state that is not driven by the motor driver 16. In order to determine whether the vehicle is in a state not driven by the motor driver 16, it may be known from the total torque, but it is not limited to the drive current or the drive power. That is to say, if the driving current approaches zero (or current threshold), it means that the vehicle is not currently driven by the motor driver 16. Or use the method of determining whether the driving power is less than the power threshold. This torque threshold can be set to a positive value of zero or near zero. For example, the torque threshold can be 50 N-m (Newton meters). The current threshold can be 10 amps. The power threshold can be 500 watts. The factors that determine the torque threshold can be the speed without the acceleration command, the degree of system noise, and so on.

If the total combined torque is not greater than the torque threshold, it is determined that the power wheels 92a, 92b, 92c, 92d are not in the smart mode (step S38)

For the procedure of step S34, please refer to "Figure 4" for reading. As can be seen from the figure, step S34 includes: step S340: obtaining a single wheel torque according to driving voltage, driving current and rotational speed of the driving parameter, the single wheel torque corresponding to the power wheels 92a, 92b, 92c, 92d; step S342: summing The single wheel torque obtains the total combined torque; and step S344: determining whether the combined torque is less than the torque threshold.

Steps S340 and S342 are the development flow of the above formula (2).

It can be seen from step S32 and step S34 that under the condition that the steering angle and the total combined torque are respectively in accordance with steps S32 and S34, the vehicle is in the undriven cruise mode, that is, in the aforementioned smart mode (step S36). ). If the vehicle (power wheel) is in the smart mode, the "execution differential update procedure" of step S40 can be executed.

Please refer to FIG. 5, which is a schematic flowchart of step S40 of an embodiment of the differential control method according to the present invention. It can be seen from the figure that the "difference update procedure" of step S40 includes: step S402: determining whether the rotational speed of the driving parameter is lower than the rotational speed critical value; and step S404: if yes, updating according to the steering angle signal and the rotational speed of the user command 90; Differential law 140; and step S406: If no, the differential update procedure is ended.

In step S402, it is judged whether or not the rotational speed of each of the power wheels 92a, 92b, 92c, 92d is excessive. If the rotation speed is too large, there may be a slip phenomenon between the power wheels 92a, 92b, 92c, and 92d. That is, if each of the power wheels 92a, 92b, 92c, 92d (vehicle) is currently traveling in an undriven cruise state, if the speed is too high, a certain power wheel 92a, 92b, 92c, 92d will be possible. Will produce slip. As a result, the differential relationship between the power wheels 92a, 92b, 92c, and 92d is not a purely natural (or non-manual) differential relationship, but a "difference relationship with slip" and is not suitable for recording. In other words, the differential update procedure of step S40 updates the purely natural (non-manual) differential relationship between the power wheels 92a, 92b, 92c, 92d to the differential law 140, which does not satisfy the differential speed of step S402. The situation will not be suitable for being recorded. The aforementioned speed threshold (or may be referred to as the wheel speed threshold) may be 1000 revolutions per minute (rpm). Next, step S402 can also increase whether the rotational speed of each of the power wheels 92a, 92b, 92c, 92d is too small, and when the rotational speed is too small, it is not suitable for recording the differential relationship between the wheels.

The speed threshold of step S402 can be obtained experimentally. In general, at lower vehicle speeds, each of the power wheels 92a, 92b, 92c, 92d is less prone to slip. Therefore, the speed threshold can be 10, 20, 30 or 40 kilometers per hour (Km/hr). However, this speed threshold can also vary with the steering angle. For example, if the steering angle is larger, the speed threshold can be set smaller. Conversely, if the steering angle is larger, the speed threshold can be set slightly larger. The reason for this setting is that as the steering angle is larger, the chance of the wheel slipping increases, so that a lower manual speed is required to obtain a non-manual differential relationship with greater confidence.

When the step S402 is met, the steering angle signal and the rotational speed of the user command 90 are updated in the differential law 140 according to step S404. That is, the differential speed rule 140 is updated by the steering angle and the rotational speed relationship of each of the power wheels 92a, 92b, 92c, and 92d corresponding to the steering angle. If the differential law 140 is a relational expression, the relational calculus (such as regression, approach line, etc.) can be re-executed. If the differential law 140 is a look-up table, the differential values of the power wheels 92a, 92b, 92c, 92d corresponding to the steering angle can be directly updated.

When the step S402 is not satisfied, the "end of the differential update procedure" is performed in accordance with step S406. Going back to step S20.

In the smart mode, whether the obtained speed relationship and the steering angle are suitable to be updated in the differential law 140, a further determination rule may be added: Step S408 "determine whether the deceleration signal of the user command 90 is lower than the deceleration threshold. "." This step eliminates the user's ability to step on the brakes. Since the user may step on the brakes, the wheels may slip. At this time, the differential relationship of each wheel may not be suitable for recording, and may not be used as a basis for updating the differential law 140. The aforementioned deceleration threshold may be, but is not limited to, a certain percentage of the pedaling stroke of the brake pedal, such as 10% of the full stroke of the pedal. Of course, the present invention is not limited thereto, and in some cases, the state in which the brake is depressed may be included in the reference of the updated differential law 140.

Furthermore, in order to be able to increase the preferred practice of updating the differential law 140, a decision process can be added. That is to say, a step S403 "determine whether the rotation speed falls within a reasonable range according to the steering angle" is added before step S404. If yes, step S404 "update the differential speed rule 140 according to the steering angle signal and the rotation speed of the user command 90" is executed. If not, step S406 "End of the differential update procedure" is executed.

The reasonable range in this step S403 refers to a reasonable differential relationship between the power wheels 92a, 92b, 92c, 92d. This reasonable differential relationship can be a reasonable speed difference derived from the general differential theory based on parameters such as track and wheelbase. Therefore, if the differential relationship obtained by the differential controller 14 does not fall within the reasonable speed difference, it indicates that there is a problem, and no update will be performed to avoid unpredictable results.

In addition, regarding the timing of "update the differential law 140" in step S404, the following factors may also be considered:

1. If the steering angle of the current user command 90 is the same as the steering angle to be updated, in order to avoid the occurrence of a setback situation, the current steering angle may be determined before the differential speed rule 140 is updated, and the current steering angle is different from the current steering angle. The differential law 140 is updated when the steering angle is reached.

2. To reduce the frequency of updates, a memory can be placed inside or outside the differential controller 14 to store a backup rule (backup of the existing differential law 140). The backup rule is also updated each time the differential rate rule is updated. When there is a new updateable steering angle and its corresponding differential relationship, it is confirmed whether the relationship to be updated is the same as the current differential relationship before the backup rule. If not, the servo is updated to the differential law in use 140. .

3. To reduce the frequency of updates, you can also confirm whether the data to be updated has been updated in the differential law. If it is, it will not be updated to avoid repeating the same data.

In step S50, "the driving of the power wheels 92a, 92b, 92c, 92d according to the user command 90 and the differential law 140" means that the wheels are acquired on the differential law 140 according to the steering angle signal in the user command 90. The differential relationship is followed by driving the power wheels 92a, 92b, 92c, 92d. For example, if the current steering angle is 5 degrees, the differential relationship between the power wheels 92a, 92b, 92c, and 92d corresponding to the steering angle of 5 degrees is referred to the differential law 140 (if it is a look-up table), and reference is made to The acceleration signal or the deceleration signal forms a driving signal for each wheel, and thereafter, the differential controller 14 supplies the driving signal to the motor driver 16 to drive the power wheels 92a, 92b, 92c, 92d to rotate.

With the above-described differential control method and device for the intelligent multi-wheel independent power wheels 92a, 92b, 92c, 92d, the designer can first design a vehicle with multiple independent power wheels 92a, 92b, 92c, 92d. A more general and extensive differential rule 140 is built in the differential controller 14, and then the vehicle is continuously driven by the tester to each of the steering angles in a smart mode (a learning mode or a non-manual differential relationship). Mode), at this time, the differential control method and device automatically and dynamically update the differential law 140 to obtain a differential law 140 that fully complies with the vehicle. In this way, the design and verification time can be quickly shortened and a more accurate differential relationship can be obtained. At the same time, the differential law 140 completed by the present invention is a differential law 140 that is fully customized for the various conditions of the vehicle. This customized differential law 140 will be more accurate than the differential law configured for the same vehicle in the prior art. Secondly, after the vehicle is shipped, the differential update program can be selectively turned on or off to meet different needs.

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The patent protection scope of the invention is subject to the definition of the scope of the patent application attached to the specification.

10. . . Differential control device

12. . . Sensor

14. . . Differential controller

140. . . Differential law

16. . . Motor driver

90. . . User instruction

92a, 92b, 92c, 92d. . . Power wheel

94a, 94b, 94c, 94d. . . In-wheel motor

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram showing the circuit of an embodiment of a differential control device in accordance with the present invention.

Fig. 2 is a flow chart showing an embodiment of a differential control method according to the present invention.

Figure 3 is a flow chart showing the step S30 of an embodiment of the differential control method according to the present invention.

Figure 4 is a flow chart showing the step S34 of an embodiment of the differential control method according to the present invention.

Figure 5 is a flow chart showing the step S40 of an embodiment of the differential control method according to the present invention.

Claims (24)

A differential control method for a smart multi-wheel independent power wheel is adapted to receive a user command to drive a plurality of power wheel operations, the differential control method comprising: capturing the user command and a plurality of driving parameters, the driving The parameter is corresponding to the power wheels; determining whether the power wheels are operating in a smart mode according to the user command and the driving parameters; if yes, performing a differential update procedure; and if not, according to the user command And a differential law drives the power wheels to operate. The method of claim 1, wherein the step of determining whether the power wheels are in the smart mode according to the user command and the driving parameters comprises: determining whether the steering signal of the user command is And greater than a steering angle threshold; if the steering angle signal is greater than the steering angle threshold, determining whether a total combined torque is less than a torque threshold according to the driving parameters; and if the total torque is less than the torque threshold, It is decided that the power wheels are operated in the smart mode. The differential control method of claim 2, wherein the step of determining whether the power wheels are operated in the smart mode according to the user command and the driving parameters further comprises: if the steering angle signal is not greater than the steering angle threshold The value determines that the power wheels are not operating in the smart mode. The method of claim 2, wherein the step of determining whether the power wheels are operated in the smart mode according to the user command and the driving parameters further comprises: if the total torque is not less than the torque threshold Then, it is determined that the power wheels are not in the smart mode. The differential control method of claim 2, wherein the step of determining whether the total combined torque is less than the torque threshold according to the driving parameters comprises: a plurality of driving voltages, a plurality of driving currents, and a plurality of driving parameters according to the driving parameters The plurality of single-wheel torques are obtained for each of the single-wheel torques, and the plurality of power wheels are matched; the total torque is obtained by summing the single-wheel torques; and whether the combined torque is less than the torque threshold. The differential control method of claim 2, wherein the torque threshold is 50 Newton meters (N-m). The differential control method of claim 2, wherein the steering angle threshold is 0.1 degrees. The differential control method of claim 1, wherein the differential update program comprises: determining whether the plurality of rotational speeds of the driving parameters are lower than a rotational speed threshold; if yes, steering the angular signal according to one of the user commands And the rotation speeds, updating the differential law; and if not, ending the differential update procedure. The differential control method of claim 8, wherein the rotational speed threshold is 100 rpm (rotation per minute). The differential control method of claim 8, wherein before the step of determining whether the plurality of rotational speeds of the driving parameters are lower than the rotational speed threshold, determining whether the deceleration signal of the user command is lower than a deceleration a threshold value; if yes, performing the step of determining whether the rotational speeds of the drive parameters are lower than the rotational speed threshold; and if not, ending the differential update procedure. The differential control method of claim 10, wherein the deceleration threshold is ten percent of a pedal stroke. The differential control method of claim 8, wherein the step of updating the differential law comprises: determining, according to the steering angle, whether the rotational speeds fall within a reasonable range; if so, the steering angle and the rotational speeds Updating to the differential law; and if not, ending the step of the differential update procedure. The differential control method of claim 1, wherein the user command includes a wheel steering angle, an opening of an accelerator pedal, and an opening of a brake pedal. The method of claim 1, wherein the step of determining whether the power wheels are in the smart mode according to the user command and the driving parameters comprises: determining whether the steering signal of the user command is And greater than a steering angle threshold; if the steering angle signal is greater than the steering angle threshold, determining whether a driving current is less than a current threshold according to the driving parameters; and determining that the driving current is less than the current threshold These power wheels are operated in this smart mode. The differential control method of claim 14, wherein the current threshold is 10 amps. The method of claim 1, wherein the step of determining whether the power wheels are in the smart mode according to the user command and the driving parameters comprises: determining whether the steering signal of the user command is And greater than a steering angle threshold; if the steering angle signal is greater than the steering angle threshold, determining whether a driving power is less than a power threshold according to the driving parameters; and determining that the driving power is less than the power threshold These power wheels are operated in this smart mode. The differential control method of claim 16, wherein the power threshold is 50 watts. A differential multi-wheel independent power wheel differential control device is adapted to receive a user command to drive a plurality of power wheel operations, the differential control device comprising: a plurality of sensors for sensing the user command; a motor driver for driving the power wheels to operate and outputting a plurality of operating parameters corresponding to the power wheels; and a differential controller having a differential law, the differential controller is based on the user command and The operating parameters to determine whether the power wheels are operating in one In the smart mode, if the power wheels are operated in the smart mode, the differential controller performs a differential update process, and if the power wheels are not in the smart mode, the differential controller is based on the user command And the differential law controls the motor driver to drive the power wheels; wherein the differential update program includes: determining whether the plurality of rotational speeds of the drive parameters are lower than a rotational speed threshold; and if so, according to the user One of the commands turns the angle signal and the speeds to update the differential law. The differential control device of claim 18, wherein the sensors comprise a steering angle sensor for receiving the user command and outputting a steering angle signal, the differential controller Obtaining a total combined torque according to the operating parameters, wherein the differential controller determines that the power wheels are operated in the smart mode when the steering angle signal is greater than a steering angle threshold and the total torque is less than a torque threshold . The differential control device of claim 19, wherein the operating parameters comprise a plurality of driving voltages, a plurality of driving currents, and a plurality of rotational speeds, the total combined torque being in accordance with the following relationship: Wherein, T _{all is} the total combined torque, n is the number of the power wheels, I _i is the driving current corresponding to the i-th power wheel, and V _i is the driving voltage corresponding to the i-th power wheel, ω _i is the rotational speed corresponding to the i-th power wheel. The differential control device of claim 18, wherein the sensors comprise: a steering angle sensor for receiving the user command and outputting a steering angle signal; and an acceleration sensor for receiving The user instructs and outputs an acceleration signal; and a deceleration sensor for receiving the user command and outputting a deceleration signal. The differential control device of claim 21, wherein the differential controller is based on the steering angle signal, the acceleration signal, the deceleration signal, and the differential law when the power wheels are not operating in the smart mode The motor drive is controlled to drive the power wheels. The differential control device of claim 18, wherein before the step of determining whether the plurality of rotational speeds of the driving parameters are lower than the rotational speed threshold, determining whether the deceleration signal of the user command is lower than a deceleration The threshold value; and if not, the difference update procedure is ended. The differential control device of claim 18, wherein the step of updating the differential law comprises: determining, according to the steering angle signal, whether the rotational speeds fall within a reasonable range; and if so, the steering angle signal and the These speeds are updated to the differential law.