Method for elastic power control of four-wheel independent electric drive robot chassis driver

Abstract

The application discloses a kind of four-wheel independent electric drive robot chassis driver's elastic power control method, including four-wheel independent electric drive robot receiving remote controller issuing marching instruction;Desired current of four-way drive unit is respectively set according to marching instruction requirement;The junction temperature of power device is calculated in real time through junction-shell thermal network model, output to temperature closed-loop fuzzy controller, and temperature closed-loop control parameter is adaptively adjusted, and the current limit value of each drive unit is dynamically output;Current setting strategy is formulated in combination with finite state machine principle, and the actual current limit value of each drive unit is corrected;The running current of chassis driver is changed by current closed-loop control, and then the power output state of chassis driver is optimized.The application can guarantee the thermal safety of four-wheel independent electric drive chassis driver, and realize the elastic control effect of four-wheel independent electric drive chassis driver power.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of direct current motor driver control, and particularly relates to an elastic power control method for a four-wheel independent electric drive robot chassis driver. BACKGROUND

[0002] With the development of society and the progress of science and technology, wheeled robots have become an indispensable part of people's production and life. Wheeled robots are light in weight and fast in speed, and four-wheel independent electric drive robots can achieve precise control of four groups of drive motors, have high transmission efficiency, convenient drive control, flexible maneuvering and other advantages, and have been widely applied to many fields such as industrial manufacturing, agricultural production and automobile driving.

[0003] Four-wheel independent electric drive robots are usually required to carry a large amount of load and have strong climbing and obstacle crossing ability, that is, the robot needs to have excellent instantaneous overload capacity, and the driver should also have a high power density level, so the four-wheel independent electric drive robot chassis driver often has a high risk of over-temperature failure. In order to improve the operation reliability of the four-wheel independent electric drive robot, it is urgent to improve the internal temperature state of the chassis driver and optimize the power regulation.

[0004] In view of such problems, at present, there are related patents that propose power optimization schemes from the perspective of the operation thermal safety of the motor and its driver. Chinese patent CN109591615A proposes an overload output method for electric vehicle drivers, which calculates a reasonable torque current maximum limit value through a temperature closed-loop controller, thereby improving the load capacity and output power upper limit of the electric vehicle. Chinese patent CN206743154U realizes closed-loop vector control based on precise current and magnetic field position detection, and has the advantages of high overload efficiency and stable power.

[0005] In the existing patents, the research objects are all single motor drivers, which are not applicable to the power elastic control of four-wheel independent electric drive robots. The reason is that the four-wheel independent electric drive robot chassis includes four independent drive units. In order to complete different driving conditions of the robot, the operating currents and power output capabilities of the drive units are related and restricted to each other, and the power output and overload capacity of each drive unit are maximized under the condition of ensuring the thermal safety of the chassis driver, so the existing power control ideas cannot realize the cooperative control between different drive units of the entire driver. SUMMARY

[0006] The application aims to provide an elastic power control method for a four-wheel independent electric drive robot chassis driver, which solves the problem of cooperative elastic control of the output power of each drive unit of the four-wheel independent electric drive robot chassis driver under different operating conditions.

[0007] The technical solution of the application is as follows: an elastic power control method for a four-wheel independent electric drive robot chassis driver, the four-wheel independent electric drive robot chassis driver comprising four groups of independent drive units in front and back of the chassis, and the specific control steps are as follows:

[0008] Step 1: the chassis driver obtains the travel control command sent by the remote controller and sets the expected current of the four groups of drive units in front and back of the four-wheel independent electric drive robot chassis driver respectively, so as to switch the travel mode of the robot and proceed to step 2.

[0009] Step 2: according to the junction-shell thermal network model and the loss model of the power device, the output junction temperature of the power device is calculated, and the real-time junction temperature is transmitted to the temperature closed-loop fuzzy controller to set the limit value of the reference current of the chassis driver, and proceed to step 3.

[0010] Step 3: combining the control command of the four-wheel independent electric drive robot and the current travel state, the chassis driver current setting strategy based on the principle of finite state machine is designed, the four groups of drive units of the chassis driver are related to each other and restricted to each other, the current expected current or actual current limit value of each group is compared with the current limit value output by the temperature closed-loop, the running current limit of the driver is dynamically set to ensure the thermal safety of the chassis driver, and the running current of the four-way drive unit is controlled in a current closed loop according to the running current reference value obtained after the setting, and the power output state of the driver is actively adjusted.

[0011] Compared with the prior art, the application has the following advantages:

[0012] (1) Not only the power control of the chassis driver of the four-wheel independent electric drive robot in a single state is performed, but also the cooperative elastic control between the four groups of drive units of the chassis driver under different operating conditions is considered, the power output capability of the chassis driver is comprehensively optimized, the driver operating temperature margin is significantly improved, and the driver operating safety is effectively ensured.

[0013] (2) The fuzzy control algorithm is introduced on the basis of the traditional temperature closed loop, the dependence of the controller on the mathematical model can be eliminated in the face of different control systems, and the anti-interference ability and dynamic response speed of the system are greatly improved. DETAILED DESCRIPTION

[0014] Figure 1 It is a principle diagram of the elastic power control method for the four-wheel independent electric drive robot chassis driver.

[0015] Figure 2 It is a schematic diagram of the four-wheel independent electric drive robot chassis driver.

[0016] Figure 3 It is a schematic diagram of the junction-shell thermal network model of the power device.

[0017] Figure 4 Temperature closed-loop fuzzy controller schematic diagram.

[0018] Figure 5 Four-wheel independent electric drive robot chassis driver high elasticity control method based on finite state machine principle current setting strategy flow chart. DETAILED DESCRIPTION

[0019] The application will be described in further detail below with reference to the drawings.

[0020] As shown in Figure 1 , the elastic power control method of the four-wheel independent electric drive robot chassis driver, the specific control steps are as follows:

[0021] Step 1, the chassis driver obtains the travel control command sent by the remote controller and sets the expected current of the four groups of drive units on the front and rear sides of the four-wheel independent electric drive robot chassis driver respectively, so as to switch the travel mode of the robot.

[0022] The schematic diagram of the four-wheel independent electric drive robot chassis driver is shown in Figure 2 , which includes four groups of drive units and a main control board C1. The four groups of drive units can be divided into a front left side first drive unit D1, a front right side second drive unit D2, a rear left side third drive unit D3, and a rear right side fourth drive unit D4 according to position. The first drive unit D1 includes power devices Q1, Q2, Q3, and Q4. The second drive unit D2 includes power devices Q5, Q6, Q7, and Q8. The third drive unit D3 includes power devices Q9, Q10, Q11, and Q12. The fourth drive unit D4 includes power devices Q13, Q14, Q15, and Q16. The control commands sent by the remote controller facing the chassis driver include travel commands, steering commands, throttle commands, and turning commands. The robot obtains start signals and travel directions through travel commands, left turn signals, right turn signals, and in-place steering signals through steering commands, robot travel power through throttle commands, and robot steering amplitude when steering through turning commands. Through the above control commands, the four-wheel independent electric drive robot can stop, travel straight, turn left, turn right, and in-place steering. In addition, to improve the output capacity of the four-wheel independent electric drive robot, the expected reference current value sent by the remote controller to the chassis driver under the operating conditions of the robot generally consists of two parts, including the controlled motor rated current value and the overload current value. The front and rear drive units generate a constraint relationship through steering current differences ΔI1 and ΔI2 when steering, so that at least one controlled motor of the same side drive unit reaches an overload output state.

[0023] Step 2 is entered.

[0024] Step 2, according to the junction-shell thermal network model and the loss model of the power device, the output junction temperature of the power device is calculated, and the real-time junction temperature is transmitted to the temperature closed-loop fuzzy controller to set the limit value of the reference current of the chassis driver.

[0025] Specifically, the loss model of the power device is established by a loss calculation method based on a data manual, and the calculated loss power is taken as an input condition of the junction-shell thermal network model. Taking a MOSFET as an example, in each switching cycle, the total loss of the power MOSFET includes the switching loss and conduction loss of the body itself, the conduction loss and reverse recovery loss of the body diode, and the body loss calculation process is as follows:

[0026]

[0027] In the above formula, P c_MOS is the conduction loss of the power MOSFET, P sw_MOS is the switching loss of the power MOSFET, R DS_on (T j ) is the on-state resistance, which is related to the junction temperature, I Drms is the effective value of the on-state current of the power device, U D is the input voltage value of the power device, i a and i b are the current values at the on and off times of the device, t on and t off are the on and off times of the device, and f sw is the switching frequency of the power device.

[0028] The loss calculation process of the body diode is as follows:

[0029]

[0030] In the above formula, P c_Diode is the conduction loss of the body diode, P rr_Diode is the reverse recovery loss of the body diode, Q rr and u do are the reverse recovery charge of the body diode and the on-state voltage drop of the body diode at zero current, respectively, which can be obtained by querying the data manual of the power device, R d is the on-state resistance of the body diode, I fav and I frms are the average value and effective value of the on-state current of the body diode, respectively.

[0031] The power device junction-shell thermal network model is as follows: Figure 3As shown, the junction-shell thermal network model takes the measured shell temperature as the boundary condition for the power device junction temperature estimation, takes the device power loss as the input condition, and calculates the device junction temperature by iteratively solving the differential equations, wherein respectively represent the shell temperature and junction temperature of the four groups of power devices in the first driving unit D1, respectively represent the shell temperature and junction temperature of the four groups of power devices in the second driving unit D2, respectively represent the shell temperature and junction temperature of the four groups of power devices in the third driving unit D3, respectively represent the shell temperature and junction temperature of the four groups of power devices in the fourth driving unit D4, and the calculation process is as follows:

[0032]

[0033] In the above formula, P is the total loss of the power device, T j is the junction temperature of the power device, T c is the shell temperature of the power device, T1 to T m are the temperatures of each node in the junction-shell network, C i is the thermal capacity of the i-th node, R i is the thermal resistance of the i-th node, wherein i = 1, 2, … m, and m is the total order of the thermal network model.

[0034] After discretization, the above formula becomes:

[0035]

[0036] In the above formula, T j (k) is the power device junction temperature value to be solved at the current time (i.e. at time k), T j (k-1) is the power device junction temperature value at the previous time, P(k) is the device loss at the current time, T m (k) is the node temperature in the junction-shell thermal network, and Δt is the discrete time step.

[0037] Specifically, Figure 4 is the temperature closed-loop fuzzy controller schematic diagram, the temperature closed-loop fuzzy controller is a two-dimensional fuzzy controller, first compares the power device junction temperature with the preset reference temperature, calculates the error e and the error change rate ec of the fuzzy controller input, obtains the corresponding fuzzy quantity E and EC through fuzzy processing, solves the membership degree by using a triangular membership function, then converts the fuzzy quantity into an accurate quantity by the area barycenter method, and outputs the correction amount ΔK p , ΔK i , ΔK d of the fuzzy controller, and the PID controller adjusts the control parameters K p , K i , K dReal-time setting is performed, and the final output power device current limit value is output. The current limit value of each side driving unit is determined by the minimum value of the four groups of power device current limit values of the side, that is:

[0038]

[0039] In the above formula, is the current limit value of the first driving unit, is the current limit value of the second driving unit, is the operating current limit value of the third driving unit, is the current limit value of the fourth driving unit, is the four groups of power device current limit values output by the first driving unit, is the four groups of power device current limit values output by the second driving unit, is the four groups of power device current limit values output by the third driving unit, is the four groups of power device current limit values output by the fourth driving unit.

[0040] The influence law of the power device temperature change of the chassis driver on the current limit value is:

[0041] When the actual temperature of the power device of the chassis driver is less than the preset temperature value, the temperature closed-loop fuzzy controller will increase the current limit value;

[0042] When the actual temperature of the chassis driver is greater than the preset temperature value, the temperature closed-loop fuzzy controller will decrease the current limit value;

[0043] When the actual temperature of the chassis driver is equal to the preset temperature value, the temperature closed-loop fuzzy controller will maintain the current limit value at a stable size.

[0044] Go to step 3.

[0045] Step 3, combine the control command of the four-wheel independent electric drive robot and the current running state, design a chassis driver current setting strategy based on the principle of finite state machine, which correlates the four groups of driving units of the chassis driver with each other, compares the current expected current or actual current limit value of each group with the current limit value output by the temperature closed-loop, dynamically sets the operating current limit of the driver, guarantees the thermal safety of the chassis driver, and actively adjusts the power output state of the driver according to the operating current reference value obtained after setting.

[0046] Specifically, the finite state machine is a Mealy type six-tuple mathematical model, which is represented as:

[0047] M=(S,s0,∑,Λ,G,T)

[0048] In the formula, S is a finite state set, S = {s0, s1,..., s n}, s0 is the initial state, the four-wheel independent electric drive robot has the running states of stopping, straight going, left turning, right turning, and turning in place, corresponding to s1, s2, s3, s4, and s5, respectively, so the maximum number of states n = 5, ∑ is the input event, denoted as ∑ = σ i , Λ is the output event set, Λ = {λ1, λ2,..., λ l}, G is the output function set, and T is the state transition function set. Since the four groups of drive units of the chassis drive are independent of each other, the running currents of each drive unit often differ in different running modes, thereby causing differences in the temperature rise states and output potentials of the sides, so the current setting strategy takes the target state of the robot as a prerequisite, takes the size relationship between the current limit value expected at present or the actual current limit value and the current limit value output by the temperature closed loop as the input event, sets the actual current limit value of each group of drive units, and achieves the collaborative control effect of mutual restriction and mutual restriction.

[0049] Further, the current setting strategy based on the principle of finite state machine precisely sets the running current limit value of each drive unit of the drive, actively adjusts the power output state of the chassis drive, Figure 5 FIG. 1 is a flowchart of the current setting strategy based on the principle of finite state machine in the high flexibility control method of the four-wheel independent electric drive robot chassis drive, and the specific implementation process of the current setting strategy based on the principle of finite state machine is as follows:

[0050] 1) When the four-wheel independent electric drive robot switches from any state to the stopping state, at this time, the running reference current values of the four groups of drive units of the chassis drive should be equal and the numerical value should be constant 0.

[0051] 2) When the four-wheel independent electric drive robot switches from any state to the straight going state, at this time, the running reference current values of the four groups of drive units of the chassis drive should be equal, and the remote controller sends equal and same direction expected current values to each drive wheel to realize the moving posture of advancing or retreating. Since the actual difference between the advancing and retreating of the robot is only in the forward rotation and reverse rotation of the motor, for the sake of simplicity of description, only the implementation process of the advancing state strategy is described. The upper remote control sends the following expected current to each drive unit:

[0052]

[0053] First, the expected current value is compared with the reference current limit value output by the temperature closed loop in the four groups of drive units. If it exceeds the minimum value of the temperature closed loop output of each side drive unit, the input event at this time is:

[0054] σ1:

[0055] The current setting strategy corrects the actual current limit values of the four groups of driving units D1, D2, D3, and D4 to the size of the minimum value at the same time, and represents the result by an output event λ1, that is:

[0056] λ1:

[0057] If the minimum value in the temperature closed-loop output current limit value of each side driving unit is not exceeded, the corresponding input event is:

[0058]

[0059] The chassis driver can take the expected current value issued by the remote controller as the actual running current limit of the four groups of driving units. Finally, the chassis driver will run with the set reference current value, and the four-wheel independent electric drive robot can safely enter the straight forward state. Correspondingly, the output event λ2 at this time can be represented as:

[0060] λ2:

[0061] The setting results of the actual current limit values of the four groups of driving units of the chassis driver under the straight condition are taken as the running reference currents respectively, and current closed-loop control is performed. Four duty cycle signals α1, α2, α3, and α4 are output to each driving unit to change the actual running current of the driver and dynamically adjust the power output state of the chassis driver.

[0062] 3) When the four-wheel independent electric drive robot switches from any state to the left turning state, the running current reference value relationship of the chassis driver at this time is: the running current reference value of the front right second driving unit should be greater than the running current reference value of the front left first driving unit the running current reference value of the rear right fourth driving unit should be greater than the running current reference value of the rear left third driving unit Therefore, the remote controller can issue the following expected current values:

[0063]

[0064] In the above formula, corresponding to the expected reference current values issued by the remote controller to the driving units D4, D3, D2, and D1, respectively, I0 is the first overload current, I1 is the second overload current, ΔI1 is the front side slip current of the four-wheel independent electric drive robot, and ΔI2 is the rear side slip current of the four-wheel independent electric drive robot. The current setting process when the robot turns left is:

[0065] 3-1): When the expected reference current of the driving unit D4, D2 side the current limit value of the drive unit on this side and the expected reference current of the drive unit D3, D1 less than the current limit value of the drive unit This case is represented by input event σ3:

[0066] σ3:

[0067] The current setting strategy will take As the actual current limit value of the drive unit on the D4, D2 side, due to the existence of the slip current constraint relationship between the drive units D3 and D4, D1 and D2, while the operating reference current of the D4, D2 side is being set, the D3, D1 side will also be affected by the restraint effect, and the actual current limit value is respectively minus the rear side slip current ΔI2, the D2 side current limit value minus the front side slip current ΔI1, the setting result of the current setting strategy can be represented by output event λ3:

[0068] λ3: I lim3 = I lim4 - ΔI2, I lim1 = I lim2 - ΔI1

[0069] Mathematical proof shows that at this time the actual current limit values of the four groups of drive units do not exceed the current limit values on the corresponding side, and turn to 3-2).

[0070] 3-2): When the expected reference current of the drive unit D3, D1 greater than the current limit value of the temperature closed loop output on this side and the expected reference current of the drive unit D4, D2 less than the current limit value of the drive unit The corresponding input event σ4:

[0071] σ4:

[0072] The current setting strategy will take as the actual current limit value of the drive unit on the D3, D1 side, in order to meet the chassis differential steering requirement under left turning state, after completing the setting of the actual current limit value of the drive unit on the D3, D1 side, the size of the D4 side actual current limit value after being affected by the D3 side is the D3 side actual current limit value I lim3 plus the rear side slip current ΔI2, the size of the D2 side actual current limit value after being affected by the D1 side is the D1 side actual current limit value I lim1Add the front side slip current ΔI1, which is represented as the output event λ4, namely:

[0073] λ4: I lim4 = I lim3 + ΔI1 lim2 = I lim1 + ΔI2

[0074] Mathematical proof shows that the actual current limit values of the four groups of driving units do not exceed the current limit values of the corresponding sides at this time, turn to 3-3).

[0075] 3-3): When the expected reference current of the driving units D1, D4 side is greater than the temperature closed-loop output current limit value of the corresponding side and the expected reference current of the driving units D2, D3 side is less than the temperature closed-loop output current limit value of the corresponding side The corresponding input event σ5 is:

[0076] σ5:

[0077] The current setting strategy will take as the actual current limit value of the driving units D1, D4 side, and in the left turning state, in order to meet the continuous differential speed travel requirements of the four-wheel independent electric robot, the actual current limit values of the corresponding driving units D2, D3 side are respectively I lim1 + ΔI1, the actual current limit value of the D1 side lim4 The value minus the rear side slip current ΔI2, and it is represented as the output event λ5, namely:

[0078] λ5: I lim2 = I lim1 + ΔI1, I lim3 = I lim4 - ΔI2

[0079] Mathematical proof shows that the actual current limit values of the four groups of driving units do not exceed the current limit values of the corresponding sides at this time, turn to 3-4).

[0080] 3-4): When the expected reference current of the driving units D2, D3 side is greater than the temperature closed-loop output current limit value of the corresponding side and the expected reference current of the driving units D1, D4 side is less than the temperature closed-loop output current limit value of the corresponding side The corresponding input event σ6 is:

[0081] σ6:

[0082] The current setting strategy will take As the actual current limit value of D2, D3 side drive unit, in the left turn state, in order to meet the requirement of four-wheel independent electric drive robot continuous differential travel, the actual current limit value of D1, D4 side drive unit is respectively D2 side actual current limit value I lim2 The actual current limit value of D3 side drive unit I lim3 Value plus the rear side slip current ΔI2, and it is expressed as output event λ6, that is:

[0083] λ6: I lim1 = I lim2 - ΔI1, I lim4 = I lim3 + ΔI2

[0084] Mathematical proof shows that at this time, the actual current limit value of four groups of drive units does not exceed the current limit value of the corresponding side, turn to 3-5).

[0085] 3-5): When the expected reference current of the current side two groups of drive units D1, D2 exceeds the current limit value of the corresponding side And the expected reference current of the rear side D3 side drive unit exceeds the current limit value of the side The expected reference current of D4 side drive unit does not exceed the current limit value of the side , the current setting strategy will As the actual current limit value of D3 side drive unit, accordingly, the actual current limit value of D4 side drive unit is D3 side drive unit actual current limit value plus rear side slip current ΔI2, since the target state is left turn, the running current of D2 side drive unit is higher than that of D1 side, so the chassis drive D2 side drive unit will face more severe temperature state, therefore, the current setting strategy preferentially sets the actual current limit value of the side, and the setting result is the current limit value of D2 side drive unit temperature closed loop output To complete the left turn travel instruction issued by the upper layer remote control, the actual current limit value of D1 side drive unit also needs to be set accordingly, and the setting result is the actual current limit value of D2 side drive unit minus the front side slip current ΔI1, but the size relationship between this result and the current limit value of the side is unknown, and there is still a risk of thermal failure, which needs to be further identified and guaranteed. Reliability of power control method.

[0086] After the current setting strategy is set, if the actual current limit value I lim1 Of D1 side drive unit is less than the current limit value of the side temperature closed loop output , which indicates that the four groups of drive units of the chassis drive can run in a safe limit range, this case is represented by input event σ7, and the setting result is represented by output event λ7:

[0087] σ7:

[0088] λ7: I lim1 = I lim2 - ΔI1, I lim4 = I lim3 + ΔI2

[0089] However, if the I lim1 after the preliminary setting of the current setting strategy is greater than the current limit value of the temperature closed loop output of the side , it indicates that the driving unit of the side still has the risk of over-temperature, and therefore the actual current limit value of the side needs to be further set so as not to exceed the current limit value of the temperature closed loop output of the side. The current setting strategy sets the actual current limit value of the driving unit of the side D1 to be the current limit value of the side Under the differential speed constraint condition, the actual current limit value of the driving unit of the side D2 is also set, and the size is the actual current limit value of the driving unit of the side D1 plus the front side slip current ΔI1. It is mathematically proved that the actual current limit value of the side D2 does not exceed the size of the current limit value of the side, and the four groups of driving units of the chassis driver can enter the left turning state under the safe running condition. The corresponding input event is σ8, and the output event is λ8, that is:

[0090] σ8:

[0091] λ8: I lim2 = I lim1 + ΔI1, I lim4 = I lim3 + ΔI2

[0092] Turn to 3-6).

[0093] 3-6): When the expected reference current of the two groups of driving units D1 and D2 of the current side exceeds the current limit value of the corresponding side , and the expected reference current of the driving unit of the rear side D4 exceeds the current limit value of the side , the expected reference current of the driving unit of the side D3 does not exceed the current limit value of the side , the current setting strategy sets as the actual current limit value of the driving unit of the side D4. Correspondingly, the actual current limit value of the driving unit of the side D3 is the actual current limit value of the driving unit of the side D4 minus the rear side slip current ΔI2. In the left turning working condition, the driving unit of the side D2 has a greater risk of over-temperature than the driving unit of the side D1, and therefore the actual current limit value of the side needs to be set. The setting result is the current limit value of the temperature closed loop output of the driving unit of the side D2 Under the constraint of the slip current, the actual current limit value of the corresponding D1 side driving unit also needs to be adjusted, and the adjustment result is the actual current limit value of the D2 side driving unit minus the front side slip current ΔI1. However, the size relationship between the result and the side current limit value is unknown, and there is still a risk of thermal failure, which needs to be further distinguished.

[0094] If the actual current limit value I lim1 of the D1 side driving unit after the current adjustment strategy adjustment is less than the current limit value of the side temperature closed loop output , it indicates that the four groups of driving units of the chassis driver can operate within the safe limit range. This case is represented by input event σ9, and the adjustment result is represented by output event λ9:

[0095] σ9:

[0096] λ9: I lim1 = I lim2 - ΔI1, I lim3 = I lim4 - ΔI2

[0097] If the actual current limit value I lim1 after the preliminary adjustment of the current adjustment strategy is greater than the current limit value of the side temperature closed loop output , it indicates that the driving unit of the side still has the risk of over-temperature, and the current adjustment strategy further adjusts the actual current limit value of the D1 side driving unit to the current limit value of the side Under the constraint of the differential speed, the actual current limit value of the D2 side driving unit is also adjusted, and the size is the actual current limit value of the D1 side driving unit plus the front side slip current ΔI1. It is mathematically proved that the actual current limit value of the D2 side does not exceed the size of the current limit value of the side, and the four groups of driving units of the chassis driver can enter the left turning state under the safe operating condition. The corresponding input event is σ 10 , and the output event is λ 10 , that is:

[0098] σ 10 :

[0099] λ 10 : I lim2 = I lim1 + ΔI1, I lim3 = I lim4 - ΔI2

[0100] Turn to 3-7).

[0101] 3-7):When the rear two groups of driving units D3, D4 expect reference current exceeds the current limit of the corresponding side and the D1 side driving unit expect reference current exceeds the current limit value of the side D2 side driving unit expect reference current does not exceed the current limit value of the side , the current setting strategy will as the actual current limit value of the D1 side driving unit, accordingly, the actual current limit value of the D2 side driving unit is the actual current limit value of the D1 side driving unit plus the front slip current ΔI1, in the left turning condition, the D4 side driving unit has a greater risk of over-temperature than the D3 side, so the actual current limit value of the side needs to be adjusted first, and the adjustment result is the current limit value of the D4 side driving unit temperature closed loop output Under the constraint of slip current, the actual current limit value of the corresponding D3 side driving unit also needs to be adjusted, and the adjustment result is the actual current limit value of the D4 side driving unit minus the rear slip current ΔI2, but the size relationship between this result and the current limit value of the side is unknown, and there is still a risk of thermal failure, which needs to be further distinguished.

[0102] If the actual current limit value I lim3 of the D3 side driving unit is less than the current limit value of the temperature closed loop output of the side , it indicates that the four groups of driving units of the chassis driver can operate within a safe limit, and this condition is represented by input event σ 11 , and the adjustment result is represented by output event λ 11 :

[0103] σ 11 :

[0104] λ 11 : I lim2 = I lim1 + ΔI1, I lim3 = I lim4 - ΔI2

[0105] If I lim3 after preliminary adjustment by the current setting strategy is greater than the current limit value of the temperature closed loop output of the side , it indicates that the driving unit of the side still has the risk of over-temperature, and the current setting strategy further adjusts the actual current limit value of the D3 side driving unit to the current limit value of the side Under the differential constraint condition, the actual current limit value of the D4 side driving unit is also adjusted, and its size is the actual current limit value of the D3 side driving unit plus the rear differential current ΔI2. It is mathematically proved that the actual current limit value of the D4 side does not exceed the size of the current limit value of the side, and the four groups of driving units of the chassis driver can enter the left turning state under the safe operating condition. The corresponding input event is σ 12 , and the output event is λ 12 , that is:

[0106] σ 12 :

[0107] λ 12 : I lim2 =I lim1 +ΔI1, I lim4 =I lim3 +ΔI2

[0108] Turn to 3-8).

[0109] 3-8): When the expected reference current of the rear two groups of driving units D3, D4 exceeds the current limit value of the corresponding side and the expected reference current of the D2 side driving unit exceeds the current limit value of the side and the expected reference current of the D1 side driving unit does not exceed the current limit value of the side , the current adjustment strategy will the actual current limit value of the D2 side driving unit, accordingly, the actual current limit value of the D1 side driving unit is the actual current limit value of the D2 side driving unit minus the front differential current ΔI1. In the left turning working condition, the D4 side driving unit has a greater risk of over-temperature than the D3 side, so it is necessary to prioritize the adjustment of the actual current limit value of the side. The adjustment result is the current limit value of the temperature closed loop output of the D4 side driving unit Under the constraint of the differential current, the actual current limit value of the corresponding D3 side driving unit also needs to be adjusted, and the adjustment result is the actual current limit value of the D4 side driving unit minus the rear differential current ΔI2. However, the size relationship between this result and the current limit value of the side is unknown, and there is still a risk of thermal failure, which needs to be further distinguished.

[0110] If the actual current limit value I lim3 of the D3 side driving unit after adjustment by the current adjustment strategy is less than the current limit value of the temperature closed loop output of the side , it indicates that the four groups of driving units of the chassis driver can operate within the safe limit range. This condition is represented by the input event σ 13 , and the adjustment result is represented by the output event λ 13 :

[0111] σ 13 :

[0112] λ 13 : I lim1 =I lim2 -ΔI1, I lim3 =I lim4 -ΔI2

[0113] If the I lim3 after the preliminary setting of the current setting strategy is greater than the current limit value of the temperature closed loop output of the side , it indicates that the drive unit of the side still has the risk of over-temperature, and the current setting strategy further sets the actual current limit value of the D3 side drive unit to the current limit value of the side Under the differential constraint condition, the actual current limit value of the D4 side drive unit is also set, and its size is the actual current limit value of the D3 side drive unit plus the rear side slip current ΔI2. It is mathematically proved that the actual current limit value of the D4 side does not exceed the size of the current limit value of the side, and the four groups of drive units of the chassis driver can enter the left turning state under the safe running condition. The corresponding input event is σ 14 , and the output event is λ 14 , that is:

[0114] σ 14 :

[0115] λ 14 : I lim1 =I lim2 -ΔI1, I lim4 =I lim3 +ΔI2

[0116] Turn to 3-9).

[0117] 3-9): When the expected reference currents of the four groups of drive units of the current front and rear sides all exceed the current limit values of the corresponding sides, since the running currents of the right side D2, D4 drive units of the chassis driver are greater than those of the left side D1, D3 drive units in the left turning working condition, the drive units of the right side have higher potential over-temperature risk. Therefore, the current setting strategy will preferentially set the actual current limit values of the right side D2, D4 drive units, and the setting results are the current limit values of the corresponding side drive units output by the temperature closed loop Since the four-wheel independent electric drive robot has a differential condition in the left turning condition, the actual current limit values of the corresponding left drive units D1 and D3 are respectively set to the actual current limit value of the D2 side minus the front side slip current ΔI1 and the actual current limit value of the D4 side minus the rear side slip current ΔI2. However, at this time, the size relationship between the actual current limit values of D1 and D3 after setting and the current limit values output by the temperature closed loop of each side is unknown. In order to eliminate the potential thermal failure risk of the chassis drive and realize the deep excavation of the overload potential, further judgment is needed.

[0118] If the actual current limit value I lim1 of the D1 side drive unit after setting by the current setting strategy is less than the current limit value output by the temperature closed loop of the side , the actual current limit value I lim3 of the D3 side drive unit is greater than the current limit value output by the temperature closed loop of the side . At this time, the four groups of drive units of the chassis drive can enter the left turning state under safe conditions, and the corresponding input event is σ 15 , and the output event is λ 15 , that is:

[0119] σ 15 :

[0120] λ 15 : I lim1 =I lim2 -ΔI1, I lim3 =I lim4 -ΔI2

[0121] If the actual current limit value I lim1 of the D1 side drive unit after setting by the current setting strategy is less than the current limit value output by the temperature closed loop of the side , the actual current limit value I lim3 of the D3 side drive unit is greater than the current limit value output by the temperature closed loop of the side . At this time, the D3 side drive unit still has a potential thermal failure risk, and the current setting strategy further sets the actual current limit value of the side to the current limit value , and the actual current limit value of the D4 side drive unit is restricted to the actual current limit value of the D3 side plus the rear side slip current ΔI2. It is proved by mathematics that at this time, the four groups of drive units of the chassis drive are within the range of the maximum current limit value, and the four-wheel independent electric drive robot can be safely switched to the left turning state, and the corresponding input event is σ 16 , and the output event is λ 16 , that is:

[0122] σ 16 :

[0123] λ 16 : I lim1 =I lim2 -ΔI1, I lim4 =I lim3 +ΔI2

[0124] If the actual current limit value I lim3 of the D3 side driving unit after the current setting strategy is set is less than the current limit value output by the temperature closed loop of the side If the actual current limit value I lim1 of the D1 side driving unit is greater than the current limit value output by the temperature closed loop of the side At this time, the D1 side driving unit still has a potential risk of thermal failure, and the current setting strategy further sets the actual current limit value of the side to the current limit value The actual current limit value of the D2 side driving unit is restricted to the actual current limit value of the D1 side plus the front side slip current ΔI1, and mathematical proof shows that the four groups of driving units of the chassis driver are within the maximum current limit value range, and the four-wheel independent electric drive robot can be safely switched to the left turning state, and the corresponding input event is σ 17 , and the output event is λ 17 , that is:

[0125] σ 17 :

[0126] λ 17 : I lim2 =I lim1 +ΔI1, I lim3 =I lim4 -ΔI2

[0127] If the actual current limit value I lim3 of the D3 side driving unit after the current setting strategy is set is greater than the current limit value output by the temperature closed loop of the side If the actual current limit value I lim1 of the D1 side driving unit is greater than the current limit value output by the temperature closed loop of the side This indicates that the D3 and D1 side driving units after preliminary setting still have a potential risk of thermal failure, and the current setting strategy further sets the actual current limit value of the D3 side driving unit to the current limit value The actual current limit value of the D1 side driving unit is set to the current limit value In the left turn mode, there is a differential current constraint between the chassis driving units, so the actual current limit values of the D4 and D2 side driving units are also constrained and are set as the current limit values of the D3 side temperature closed-loop output plus the rear side differential current ΔI2, the current limit value of the D1 side temperature closed-loop output plus the front side differential current ΔI1, and it is mathematically proven that the running currents of the four groups of driving units of the chassis driver are within the maximum limit current range at this time, and the four-wheel independent electric drive robot can safely enter the left turn state, and the corresponding input event is σ 18 , and the output event is λ 18 , that is:

[0128] σ 18 :

[0129] λ 18 : I lim2 = I lim1 + ΔI1, I lim4 = I lim3 + ΔI2

[0130] Turn to 3-10).

[0131] 3-10): The expected reference currents of the four groups of driving units on the front and rear sides do not exceed the current limit values of the corresponding sides, and the four groups of driving units of the chassis driver will take the expected current values issued by the remote controller as the actual current limit values, and the corresponding input event is σ 19 , and the output event is λ 19 , that is:

[0132] σ 19 :

[0133] λ 19 :

[0134] The setting results of the actual current limit values of the four groups of driving units of the chassis driver under the left turn condition are taken as the running reference currents, respectively, and current closed-loop control is performed, and four duty cycle signals α1, α2, α3, and α4 are output to each driving unit to change the actual running current of the driver and dynamically adjust the power output state of the chassis driver.

[0135] 4) When the four-wheel independent electric drive robot switches from any state to the right turn state, the running current reference value relationship of the chassis driver at this time is: the front right side second driving unit running current reference value should be less than the front left side first driving unit running current reference value the rear right side fourth driving unit running current reference value Should be less than the left third drive unit operation reference current value Therefore, the remote control can issue the following desired current value:

[0136]

[0137] The current setting process when the robot turns right is:

[0138] 4-1): When the expected reference current of drive unit D3, D1 side Greater than the current limit value of the temperature closed loop output on this side And the expected reference current of drive unit D4, D2 Less than the current limit value of the drive unit This case is represented by input event σ 20 :

[0139] σ 20 :

[0140] The current setting strategy will take As the actual current limit value of the D3, D1 side drive unit, there is a slip current constraint relationship between the drive units D3 and D4, D1 and D2 under the right turn condition, so while the D3, D1 side operation reference current is set, the D4, D2 side will also be affected by the restraint effect, and the actual current limit value is The D3 side current limit value minus the rear side slip current ΔI2, the D1 side current limit value minus the front side slip current ΔI1 The setting result of the current setting strategy can be represented by output event λ 20 :

[0141] λ 20 : I lim4 = I lim3 - ΔI2, I lim2 = I lim1 - ΔI1

[0142] Mathematical proof shows that the actual current limit values of the four groups of drive units do not exceed the current limit values on the corresponding side at this time, and turn to 4-2).

[0143] 4-2): When the expected reference current of drive unit D4, D2 side Greater than the current limit value of the temperature closed loop output on this side And the expected reference current of drive unit D3, D1 Less than the current limit value of the drive unit This case is represented by input event σ 21 :

[0144] σ21

[0145] The current setting strategy will take As the actual current limit value of D4, D2 side driving unit, because there is a constraint relationship of differential current between driving units D3 and D4, D1 and D2, when the D4, D2 side operating reference current is set, the D3, D1 side will also be restrained, and the actual current limit value is respectively Add the rear differential current ΔI2, the D2 side current limit value Add the front differential current ΔI1, the setting result of the current setting strategy can be expressed as output event λ 21 :

[0146] λ 21 : I lim3 = I lim4 + ΔI2, I lim1 = I lim2 + ΔI1

[0147] Mathematical proof shows that the actual current limit values of the four groups of driving units do not exceed the current limit values of the corresponding sides at this time, and turn to 4-3).

[0148] 4-3): When the expected reference current of driving units D1, D4 side is greater than the temperature closed loop output current limit value And the expected reference current of driving units D2, D3 side is less than the temperature closed loop output current limit value The corresponding input event σ 22 :

[0149] σ 22 :

[0150] The current setting strategy will take As the actual current limit value of D1, D4 side driving unit, in the right turning state, in order to meet the continuous differential driving requirements of four-wheel independent electric robot, the actual current limit values of corresponding D2, D3 side driving units are respectively lim1 Subtract the front differential current ΔI1, the D4 side actual current limit value I lim4 The value of the rear differential current ΔI2 is added, and it is expressed as output event λ 22 , that is:

[0151] λ 22 : I lim2 = I lim1 - ΔI1, I lim3 = I lim4+ ΔI2

[0152] Mathematical proof shows that the actual current limit values of the four groups of driving units do not exceed the current limit values of the corresponding sides at this time, and turn to 4-4).

[0153] 4-4): When the expected reference current of the driving units D2 and D3 is greater than the temperature closed-loop output current limit value of the corresponding side and the expected reference current of the driving units D1 and D4 is less than the temperature closed-loop output current limit value of the corresponding side corresponding input event σ 23 :

[0154] σ 23 :

[0155] The current setting strategy will take as the actual current limit value of the driving units on the D2 and D3 sides. In the right turning state, in order to meet the continuous differential speed travel requirements of the four-wheel independent electric robot, the actual current limit values of the corresponding D1 and D4 side driving units are respectively the actual current limit value I lim2 of the D2 side plus the front side slip current ΔI1 and the actual current limit value I lim3 of the D3 side minus the rear side slip current ΔI2, and it is expressed as an output event λ 23 , that is:

[0156] λ 23 : I lim1 = I lim2 + ΔI1, I lim4 = I lim3 - ΔI2

[0157] Mathematical proof shows that the actual current limit values of the four groups of driving units do not exceed the current limit values of the corresponding sides at this time, and turn to 4-5).

[0158] 4-5): When the expected reference current of the current side two groups of driving units D1 and D2 exceeds the current limit value of the corresponding side and the expected reference current of the rear D3 side driving unit exceeds the current limit value of the side and the expected reference current of the D4 side driving unit does not exceed the current limit value of the side , the current setting strategy will As the actual current limit value of the D3 side driving unit, the actual current limit value of the D4 side driving unit is the actual current limit value of the D3 side driving unit minus the rear side slip current ΔI2. Since the target state is right turning, the operating current of the D1 side driving unit is higher than that of the D2 side, so the chassis driver D1 side driving unit will face a more severe temperature state, and therefore the current setting strategy preferentially sets the actual current limit value of this side, and the setting result is the current limit value of the D1 side driving unit temperature closed loop output To complete the right turning instruction issued by the upper layer remote control, the actual current limit value of the corresponding D2 side driving unit also needs to be set, and the setting result is the actual current limit value of the D1 side driving unit minus the front side slip current ΔI1, but the size relationship between this result and the current limit value of this side is unknown, and there is still a risk of thermal failure, and the reliability of the power control method needs to be further identified and guaranteed.

[0159] After being set by the current setting strategy, if the actual current limit value I lim2 of the D2 side driving unit is less than the current limit value of the temperature closed loop output of this side, it indicates that the four groups of driving units of the chassis driver can operate within a safe limit range, and this condition is represented by input event σ 24 , and the setting result is represented by output event λ 24 :

[0160] σ24:

[0161] λ 24 : I lim2 = I lim1 - ΔI1, I lim4 = I lim3 - ΔI2

[0162] However, if I lim2 after preliminary setting by the current setting strategy is greater than the current limit value of the temperature closed loop output of this side, it indicates that the driving unit of this side still has the risk of over-temperature, and therefore the actual current limit value of this side needs to be further set so as not to exceed the current limit value of the temperature closed loop output of this side. The current setting strategy sets the actual current limit value of the D2 side driving unit to the current limit value of this side Under the differential constraint condition, the actual current limit value of the D1 side driving unit is also set, and its size is the actual current limit value of the D2 side driving unit plus the front side slip current ΔI1. It is mathematically proved that the actual current limit value of the D1 side does not exceed the size of the current limit value of this side, and the four groups of driving units of the chassis driver can enter the right turning state under safe operating conditions, and the corresponding input event is σ 25The output event is λ 25 ,Right now:

[0163] σ 25 :

[0164] λ 25 : I lim1 =I lim2 +ΔI1, I lim4 =I lim3 +ΔI2

[0165] Proceed to 4-6).

[0166] 4-6): The expected reference current of the two sets of drive units D1 and D2 on the current side exceeds the current limit of the corresponding side. Furthermore, the desired reference current of the rear D4-side drive unit exceeds the current limit value on that side. The D3-side drive unit expects the reference current to not exceed the current limit value on that side. At that time, the current setting strategy will As the actual current limit value for the D4-side drive unit, the corresponding actual current limit value for the D3-side drive unit is the actual current limit value for the D4-side drive unit plus the rear slip current ΔI2. Under right-turn conditions, the D1-side drive unit has a greater risk of over-temperature compared to the D2-side unit; therefore, the actual current limit value for this side needs to be tuned. The tuning result is the current limit value of the temperature closed-loop output of the D1-side drive unit. Under the constraint of slip current, the actual current limit value of the corresponding D2 side drive unit also needs to be set accordingly. The setting result is the actual current limit value of the D1 side drive unit minus the front slip current ΔI1. However, the relationship between this result and the current limit value of this side is unknown, and there is still a risk of thermal failure, which needs to be further determined.

[0167] If the actual current limit value I of the drive unit on the D2 side is set by the current setting strategy... lim2 Less than the current limit value of the closed-loop output on this side of the temperature. This indicates that all four drive units of the chassis drive system are operating within safe limits. This situation is represented by the input event σ. 26 This indicates that the tuning result is represented by the output event λ. 26 express:

[0168] σ 26 :

[0169] λ 26 : I lim2 =I lim1 -ΔI1, I lim3 =I lim4 +ΔI2

[0170] If the current setting strategy is initially set I lim2 is greater than the current limit value of the temperature closed loop output of the side , it means that the drive unit of the side still has the risk of over-temperature, and the current setting strategy further sets the actual current limit value of the D2 side drive unit to the current limit value of the side Under the differential constraint condition, the actual current limit value of the D1 side drive unit is also set, and its size is the actual current limit value of the D2 side drive unit plus the front side slip current ΔI1, which is mathematically proved that the actual current limit value of the D1 side does not exceed the size of the current limit value of the side, and the four groups of drive units of the chassis driver can enter the right turning state under the safe operating condition. The corresponding input event is σ 27 , and the output event is λ 27 , that is:

[0171] σ 27 :

[0172] λ 27 : I lim1 =I lim2 +ΔI1, I lim3 =I lim4 +ΔI2

[0173] Turn to 4-7).

[0174] 4-7): When the expected reference current of the rear two groups of drive units D3, D4 exceeds the current limit value of the corresponding side , and the expected reference current of the front D1 side drive unit exceeds the current limit value of the side , and the expected reference current of the D2 side drive unit does not exceed the current limit value of the side , the current setting strategy sets as the actual current limit value of the D1 side drive unit, accordingly, the actual current limit value of the D2 side drive unit is the actual current limit value of the D1 side drive unit minus the front side slip current ΔI1. In the right turning working condition, the over-temperature risk of the D3 side drive unit is greater than that of the D4 side, so it is necessary to prioritize the actual current limit value of the side. The setting result is the current limit value of the temperature closed loop output of the D3 side drive unit Under the constraint of slip current, the actual current limit value of the corresponding D4 side drive unit also needs to be set accordingly. The setting result is the actual current limit value of the D3 side drive unit minus the slip current ΔI2 on the rear side. However, the relationship between this result and the current limit value on this side is unknown, and there is still a risk of thermal failure, which needs to be further determined.

[0175] If the actual current limit value I of the drive unit on the D4 side is set by the current setting strategy... lim4 Less than the current limit value of the closed-loop output of this side temperature This indicates that all four drive units of the chassis drive system are operating within safe limits. This situation is represented by the input event σ. 28 This indicates that the tuning result is represented by the output event λ. 28 express:

[0176] σ 28 :

[0177] λ 28 : I lim2 =I lim1 -ΔI1, I lim4 =I lim3 -ΔI2

[0178] If the actual current limit value I after initial setting by the current setting strategy lim4 The current limit of the closed-loop output at this temperature is greater than the limit value. If the current exceeds the limit, it indicates that the drive unit on that side still has an over-temperature risk. The current setting strategy further sets the actual current limit value of the drive unit on the D4 side to the current limit value on that side. Under differential constraint conditions, the actual current limit value of the D3 side drive unit is also set accordingly. Its magnitude is the actual current limit value of the D4 side drive unit plus the rear slip current ΔI2. Mathematical proof shows that the actual current limit value of the D3 side does not exceed the current limit value of that side. All four drive units of the chassis drive can enter the right turn state under safe operating conditions. The corresponding input event is σ. 29 The output event is λ 29 ,Right now:

[0179] σ 29 :

[0180] λ 29 : I lim2 =I lim1 +ΔI1, I lim3 =I lim4 +ΔI2

[0181] Turn into 4-8).

[0182] 4-8): When the rear two groups of driving units D3, D4 expect reference current exceeds the current limit value of the corresponding side and the D2 side driving unit expect reference current exceeds the current limit value of the side D1 side driving unit expect reference current does not exceed the current limit value of the side , the current setting strategy will as the actual current limit value of the D2 side driving unit, accordingly, the actual current limit value of the D1 side driving unit is the actual current limit value of the D2 side driving unit plus the front slip current ΔI1, in the right turn working condition, the D3 side driving unit has greater risk of over-temperature than the D4 side, so it is necessary to prioritize the actual current limit value of the side. The result of the adjustment is the current limit value of the temperature closed loop output of the D3 side driving unit Under the constraint of slip current, the actual current limit value of the corresponding D4 side driving unit also needs to be adjusted, and the result of the adjustment is the actual current limit value of the D3 side driving unit minus the rear slip current ΔI2, but the size relationship between this result and the current limit value of the side is unknown, and there is still a risk of thermal failure, which needs to be further distinguished.

[0183] If the actual current limit value I lim4 of the D4 side driving unit after being adjusted by the current adjustment strategy is less than the current limit value of the temperature closed loop output of the side , this indicates that the four groups of driving units of the chassis driver can operate within a safe limit range. This condition is represented by input event σ 30 , and the adjustment result is represented by output event λ 30 :

[0184] σ 30 :

[0185] λ 30 : I lim1 =I lim2 +ΔI1, I lim3 =I lim4 +ΔI2

[0186] If I lim4 after preliminary adjustment by the current adjustment strategy is greater than the current limit value of the temperature closed loop output of the side , it indicates that the driving unit of the side still has the risk of over-temperature, and the current adjustment strategy further adjusts the actual current limit value of the D4 side driving unit to the current limit value of the side Under the differential constraint condition, the actual current limit value of the D3 side driving unit is also set, and its size is the actual current limit value of the D4 side driving unit plus the rear differential current ΔI2. It is mathematically proved that the actual current limit value of the D3 side does not exceed the size of the current limit value of the side, and the four groups of driving units of the chassis driver can enter the right turning state under the safe running condition. The corresponding input event is σ 31 , and the output event is λ 31 , that is:

[0187] σ 31 :

[0188] λ 31 : I lim1 = I lim2 + ΔI1, I lim3 = I lim4 + ΔI2turn into 4-9).

[0189] 4-9): When the expected reference currents of the four groups of driving units on the current and rear sides all exceed the current limit value of the corresponding side, since the running currents of the D1 and D3 driving units on the left side of the chassis driver are greater than those of the D2 and D4 driving units on the right side in the right turning working condition, the driving units on the left side have a higher potential over-temperature risk, therefore, the current setting strategy will preferentially set the actual current limit values of the D1 and D3 driving units on the left side, and the setting results are the current limit values output by the temperature closed loop of the corresponding side driving units Since the four-wheel independent electric drive robot has a differential constraint condition in the right turning working condition, the actual current limit values of the right side driving units D2 and D4 are set to the actual current limit value of the D1 side minus the front differential current ΔI1 and the actual current limit value of the D3 side minus the rear differential current ΔI2, respectively, but the size relationship between the actual current limit values of the D2 and D4 sides after setting and the current limit values output by the temperature closed loop of the respective sides is unknown. In order to eliminate the potential thermal failure risk of the chassis driver and realize the deep excavation of the output potential, further judgment is needed.

[0190] If the actual current limit value I lim2 of the D2 side driving unit after setting by the current setting strategy is less than the current limit value output by the temperature closed loop of the side, and the actual current limit value I lim4 of the D4 side driving unit is less than the current limit value output by the temperature closed loop of the side, the four groups of driving units of the chassis driver can enter the left turning state under the safe condition, the corresponding input event is σ 32 , and the output event is λ 32 , that is:

[0191] σ32 :

[0192] λ 32 : I lim2 =I lim1 -ΔI1, I lim4 =I lim3 -ΔI2

[0193] If the actual current limit value I lim2 of the D2 side driving unit is less than the current limit value output by the temperature closed loop after the current setting strategy is set, the actual current limit value I lim4 of the D4 side driving unit is greater than the current limit value output by the temperature closed loop At this time, the D4 side driving unit still has a potential risk of thermal failure, and the current setting strategy further sets the actual current limit value of this side to the current limit value The actual current limit value of the D3 side driving unit is restricted to the actual current limit value of the D4 side plus the rear differential current ΔI2, and mathematical proof shows that the four groups of driving units of the chassis drive are within the maximum current limit value range at this time, and the four-wheel independent electric drive robot can be safely switched to the right turning state, and the corresponding input event is σ 33 , and the output event is λ 33 , that is:

[0194] σ 33 :

[0195] 33 : I lim2 =I lim1 -ΔI1, I lim3 =I lim4 +ΔI2

[0196] If the actual current limit value I lim2 of the D2 side driving unit is greater than the current limit value output by the temperature closed loop after the current setting strategy is set, the actual current limit value I lim4 of the D4 side driving unit is less than the current limit value output by the temperature closed loop At this time, the D2 side driving unit still has a potential risk of thermal failure, and the current setting strategy further sets the actual current limit value of this side to the current limit value The actual current limit of the D1 side drive unit is constrained and thus set to the actual current limit value of the D2 side plus the front slip current ΔI1. Mathematical proof shows that at this time, all four drive units of the chassis drive are within the maximum current limit value range, and the four-wheel independent electric drive robot can safely switch to the right turn state. The corresponding input event is σ. 34 The output event is λ 34 ,Right now:

[0197] σ 34 :

[0198] λ 34 : I lim1 =I lim2 +ΔI1, I lim4 =I lim3 -ΔI2

[0199] If the actual current limit value I of the drive unit on the D2 side is set by the current setting strategy... lim2 The current limit of the closed-loop output at this temperature is greater than the limit value. The actual current limit value I of the D4 side drive unit lim4 The current limit of the closed-loop output at this temperature is greater than the limit value. This indicates that the D2 and D4 side drive units still have a potential risk of thermal failure after the initial tuning. The current tuning strategy further tunes the actual current limit value of the D2 side drive unit to the current limit value. The actual current limit value of the D4 side drive unit is set to the current limit value. In right-turn mode, there is a differential current constraint between the chassis drive units. Therefore, the actual current limit values ​​of the D3 and D1 side drive units are also constrained and are respectively set to the current limit value of the temperature closed-loop output of the D4 side. Adding the slip current ΔI2 on the rear side and the current limit value of the closed-loop output temperature on the D2 side. With the front slip current ΔI1 applied, mathematical proof shows that the operating current of all four drive units of the chassis drive is within the maximum current limit range. The four-wheel independent electric drive robot can then safely enter a right turn state. The corresponding input event is σ. 35 The output event is λ 35 ,Right now:

[0200] σ 35 :

[0201] λ 35 : I lim1 =I lim2 +ΔI1, I lim3 =Ilim4 + ΔI2 turn into 4-10).

[0202] 4-10): none of the four groups of drive units' expected reference currents exceeds the current limit value of the corresponding side, and the four groups of drive units of the chassis driver will take the expected current value issued by the remote controller as the actual current limit value. The corresponding input event is σ 36 , and the output event is λ 36 , that is:

[0203] σ 36 :

[0204] λ 36 :

[0205] The setting results of the actual current limit values of the four groups of drive units of the chassis driver under the right turn condition are respectively taken as the running reference currents, and current closed-loop control is performed, and four duty cycle signals α1, α2, α3, α4 are output to each drive unit to change the actual running current of the driver and dynamically adjust the power output state of the chassis driver.

[0206] (5) When the four-wheel independent electric drive robot switches from any state to the original steering state, at this time the running current reference value relationship of the chassis driver is: the running reference currents of the four groups of drive units are equal, and the running reference currents of the left two groups of drive units and the running reference currents of the right two groups of drive units are opposite in direction, so the remote controller can issue the following expected current values:

[0207]

[0208] In this state, the first overload current I0 is equal to the second overload current I1, and the current setting process when the robot turns around is:

[0209] First, by repeatedly comparing the expected current value and the current limit value output by the temperature closed loop of the four groups of drive units, if it exceeds the absolute value of the minimum value of the four, the actual current limit values of the four groups of drive units D1, D2, D3, D4 are simultaneously set to the size of the minimum value, and the running current reference values of the left and right drive units are opposite in direction. The corresponding input event is σ 37 , and the output event is λ 37 , that is:

[0210] σ 37 :

[0211] λ 37 :

[0212] If the expected current value does not exceed the current limit value of the temperature closed loop output The minimum value of the absolute value of the four, then the chassis driver can be issued by the remote control expected current value as the four groups of drive unit actual current limit value, corresponding to the input event σ 37 , the output event is λ 37 That is:

[0213] σ 38 :

[0214] λ 38 :

[0215] The setting results of the four groups of drive unit actual current limit value under the condition of the original steering are respectively taken as the running reference current, and the current closed loop control is carried out, four duty cycle signals α1, α2, α3, α4 are output to each drive unit so as to change the actual running current of the driver, and the power output state of the chassis driver is dynamically adjusted.

Claims

1. A flexible power control method for a four-wheeled independent electric drive robot chassis actuator, characterized in that, The steps are as follows: Step 1: The chassis driver receives the travel control command from the remote controller and sets the desired operating current for the four sets of drive units on the front and rear sides of the four-wheel independent electric drive robot chassis driver, thereby switching the robot's travel mode and proceeding to Step 2. Step 2: Calculate the output junction temperature of the power device based on the junction-shell thermal network model and the loss model of the power device, and transmit the real-time junction temperature to the temperature closed-loop fuzzy controller. Output the limit value of the chassis driver operating current and proceed to step 3. Step 3: Combining the control commands and current travel status of the four-wheeled independent electric drive robot, design a chassis drive current tuning strategy based on the finite state machine principle. This strategy interconnects and restrains the four drive units of the chassis drive. The current expected current or actual current limit value of each group is compared with the current limit value output by the temperature closed loop to dynamically tune the operating current limit of the drive, ensuring the thermal safety of the chassis drive. Based on the operating current reference value obtained after tuning, the operating current of the four drive units is controlled by current closed loop to actively adjust the power output state of the drive.

2. The flexible power control method for the chassis drive of a four-wheeled independent electric drive robot according to claim 1, characterized in that, In step 1, the chassis driver receives the travel control command from the remote controller and sets the desired operating current for the four drive units on the front and rear sides of the four-wheel independent electric drive robot chassis driver, thereby switching the robot's travel mode, as follows: The control commands issued by the remote controller to the four-wheeled independent electric drive robot include travel commands, steering commands, throttle commands, and slewing commands. Specifically, the robot obtains the start signal and direction of travel through the travel command; the steering command obtains left turn, right turn, and stationary turn signals; the throttle command obtains the expected operating current values ​​of the four drive units during robot travel; and the slewing command obtains the steering amplitude of the robot during turning, represented by the slip current ΔI. Furthermore, to improve the load-carrying capacity of the four-wheeled independent electric drive robot, the remote controller sends expected reference current values ​​to the chassis drive system based on the robot's operating conditions, including the rated current value I of the controlled motor. N The first overload current value I0 and the second overload current value I1, the drive units on the left and right sides of the same side generate a constraint relationship through the first steering current difference ΔI1 and the second steering current difference ΔI2 when turning, so that at least one of the controlled motors of the drive unit on the same side reaches the overload output state.

3. The flexible power control method for the four-wheel independent electric drive robot chassis actuator according to claim 2, characterized in that, The junction-shell thermal network model in step 2 is as follows: The junction-shell thermal network model uses the measured case temperature as the boundary condition for estimating the junction temperature of the power device, and the device power loss as the input condition. The junction temperature is calculated by iteratively solving a system of differential equations. The calculation process is as follows: In the formula, P is the total loss of the power device, and T is the total loss of the power device. j T is the junction temperature of the power device. c The case temperature of the power device, T1 to T m C represents the temperature of each node in the junction-shell network. i Let R be the heat capacity of the i-th node. i Let be the thermal resistance of the i-th node, where i = 1, 2, ..., m, and m is the total order of the thermal network model; After discretizing equation (1), we get: In the formula, T j (k) represents the junction temperature of the power device to be determined at the current moment, T j (k-1) represents the junction temperature of the power device at the previous moment, P(k) represents the device loss at the current moment, and T represents the junction temperature of the device at the previous moment. m (k) represents the node temperature in the junction-shell thermal network, and Δt represents the discrete time step.

4. The flexible power control method for the four-wheel independent electric drive robot chassis actuator according to claim 3, characterized in that, The loss model of the power device in step 2 is as follows: The power device is a MOSFET, and its loss model is established using a loss calculation method based on the datasheet. The loss calculation process is as follows: During each switching cycle, the total loss of a MOSFET includes the switching loss of the MOSFET itself, the conduction loss of the MOSFET itself, the conduction loss of the body diode, and the reverse recovery loss of the body diode. The calculation process for the MOSFET's own losses is as follows: In the formula, P c_MOS For the conduction loss of the device itself, P sw_MOS R is the switching loss of the device itself. DS_on (T j I is the on-state resistance, and its value is related to the junction temperature. Drms U is the effective value of the on-state current of the device itself. D i is the input voltage value of the device itself. a i b t represents the current values ​​at the moment the device is turned on and the moment it is turned off, respectively. on t off f represents the device's own turn-on and turn-off times. sw The switching frequency of the device itself; The loss calculation process for the body diode is as follows: In the formula, P c_Diode For the conduction loss of the body diode, P rr_Diode Q is the reverse recovery loss of the body diode. rr and u do These are the reverse recovery charge and the forward voltage drop of the body diode, respectively, obtained by consulting the power device's datasheet. R d I is the on-state resistance of the body diode. fav and I frms These are the average and effective values ​​of the on-state current of the body diode, respectively.

5. The flexible power control method for the chassis drive of a four-wheeled independent electric drive robot according to claim 4, characterized in that, In step 2, the real-time junction temperature is transmitted to the temperature closed-loop fuzzy controller, which outputs the limit value of the chassis driver's operating current, as follows: By comparing the real-time junction temperature and preset temperature threshold of each drive unit in the four-wheel independent electric drive robot chassis driver, the error quantity e and error change rate ec input to the fuzzy controller are obtained. After fuzzification, the precise input quantities e and ec are converted into corresponding fuzzy error quantities E and fuzzy error change rate quantities EC. Fuzzy inference is performed according to the fuzzy control rules, and the inference result is then converted into precise quantities for actual control, i.e., defuzzification. The fuzzy controller performs online self-tuning of the PID parameters of the temperature closed loop of each power device based on the temperature feedback error and error change rate. Each group of drive units outputs four power device current limit values, and the minimum value is selected as the current limit value of the group of drive units at the current temperature. Therefore, the current limit values ​​of the four groups of drive units in the chassis driver are: in, This is the current limit value for the first drive unit. This is the current limit value for the second drive unit. This is the operating current limit value for the third drive unit. This is the current limit value for the fourth drive unit. These are the four sets of power device current limit values ​​output by the first drive unit. These are the four sets of power device current limit values ​​output by the second drive unit. These are the four sets of power device current limit values ​​output by the third drive unit. These are the current limit values ​​for the four power devices output by the fourth drive unit; The effect of temperature changes in the power devices of the chassis driver on the current limit value is as follows: When the actual temperature of the chassis drive is lower than the preset temperature value, the temperature closed-loop fuzzy controller will increase the current limit value. When the actual temperature of the chassis drive exceeds the preset temperature value, the temperature closed-loop fuzzy controller will reduce the current limit value. When the actual temperature of the chassis drive equals the preset temperature value, the temperature closed-loop fuzzy controller maintains the current limit value at a stable level.

6. The flexible power control method for the chassis drive of a four-wheeled independent electric drive robot according to claim 5, characterized in that, The fuzzy controller in step 2 is a two-dimensional fuzzy controller, that is, it has two input variables e and ec; the membership function is a triangular membership function; the fuzzy inference method is the Mamdani method, which quantizes the output fuzzy value according to the fuzzy control rules; the defuzzification method is the area centroid method, which converts the output of the fuzzy controller into the actual accurate value.

7. The flexible power control method for the chassis drive of a four-wheeled independent electric drive robot according to claim 6, characterized in that, In step 3, the finite state machine is a Mealy-type six-tuple mathematical model, represented as: M = (S, s0, ∑, Λ, G, T) (5) where S is a finite set of states, S = {s0, s1, s2, s3, s4, s5}, s0 is the initial state, the four-wheeled independent electric drive robot has the following travel states: stop, straight, turn left, turn right, and turn in place, which correspond to s1, s2, s3, s4, and s5 respectively, and ∑ is the input event, represented as ∑ = σ i Let Λ be the set of output events, Λ = {λ1, λ2, ..., λ3} l }, where G is the set of output functions and T is the set of state transition functions; since the four sets of drive units of the chassis driver are independent of each other, the operating current of each drive unit often differs in different travel modes, resulting in differences in the temperature rise state and output margin on each side. Therefore, the current tuning strategy takes the target state of the robot as a premise, and takes the relationship between the current expected current or actual current limit value and the current limit value output by the temperature closed loop as the input event to tune the actual current limit value of each set of drive units, thereby completing the flexible control of the chassis driver power.

8. The flexible power control method for the chassis drive of a four-wheeled independent electric drive robot according to claim 7, characterized in that, In step 3, the chassis driver has four independent drive units. When the chassis driver is running, the current tuning strategy based on the finite state machine closely links the operating reference currents of the four drive units according to the actual travel state of the robot. Under the switching of different travel states and while ensuring the thermal safety of the chassis driver, it can still achieve precise tuning of the driver's operating current limit value, achieving a coordinated control effect of mutual restriction and constraint among the drive units. Since the chassis driver operates under constant voltage conditions, the dynamic tuning of the chassis driver's operating current will directly realize the elastic adjustment of the operating power. The operating states of the four-wheeled independent electric drive robot include straight, left turn, right turn, stationary turn, and stop. The chassis driver is divided into the first drive unit D1 on the front left, the second drive unit D2 on the front right, the third drive unit D3 on the rear left, and the fourth drive unit D4 on the rear right according to the position. The chassis driver dynamically tunes the current of each drive unit according to the robot's operating state requirements. The specific implementation process of the current tuning strategy based on the finite state machine is as follows: 1) When the four-wheeled independent electric drive robot switches from any state to the straight-line state, the reference current values ​​of the four drive units of the chassis drive should be equal. The remote controller sends an equal amount of the desired current value in the same direction to each drive wheel to achieve the forward or backward movement posture. Since the actual difference between the robot's forward and backward movement is only the forward and reverse rotation of the motor. Taking the implementation process of the forward-state strategy as an example, the remote controller sends the following desired current to each drive unit: First, by comparing the expected current value with the current limit value of the temperature closed-loop output in the four sets of drive units, if it exceeds the current limit value of the temperature closed-loop output of each drive unit... If the minimum value among the four is selected, the actual current limit values ​​of the four drive units D1, D2, D3, and D4 will be set to the minimum value. If the minimum value is not exceeded, the chassis driver will use the expected current value sent by the remote control as the actual current limit value of the four drive units, so that the operating current of the four drive units of the chassis driver is within the safe range. 2) When the four-wheel independent electric drive robot switches from any state to the left-turn state, the reference values ​​of the chassis drive's operating current are as follows: Reference current value of the second drive unit on the front right side. It should be greater than the operating reference current value of the first drive unit on the left. The operating reference current value of the fourth drive unit on the rear right side It should be greater than the operating reference current value of the third drive unit on the left. Therefore, the remote control emits the following desired current value: In the formula, These correspond to the expected reference current values ​​sent by the remote controller to drive units D4, D3, D2, and D1, respectively. To improve the power output of the chassis drive, first and second overload currents I0 and I1 are set, respectively. ΔI1 is the front slip current of the four-wheeled independent electric drive robot, and ΔI2 is the rear slip current of the four-wheeled independent electric drive robot. The current setting process when the robot turns left is as follows: 2-1): When the desired reference current of drive unit D4 The current exceeds the temperature closed-loop output current limit of the drive unit. And the expected reference current of drive unit D3 The current limit is less than the temperature closed-loop output current limit of the drive unit. The current setting strategy will be based on As the actual current limit value for the D4-side drive unit, due to the slip current constraint relationship between drive units D3 and D4, setting the actual current limit value for the D4 side also has a restraining effect on the D3 side. The magnitude of its actual current limit value is equal to the actual current limit value I of the D4 side. lim4 Reduce the slip current ΔI2 on the rear side; similarly, when the desired reference current of the drive unit D2 is... The current exceeds the temperature closed-loop output current limit of the drive unit. At that time, and the desired reference current of drive unit D1 The current limit is less than the temperature closed-loop output current limit of the drive unit. The current setting strategy will be based on As the actual current limit value of this drive unit, the magnitude of the actual current limit value on the D1 side after being affected by the D2 side is the actual current limit value I on the D2 side. lim2 Subtract the slip current ΔI1 from the front side. After mathematical verification, the actual current limit values ​​of the four drive units at this time have not exceeded the current limit values ​​of the corresponding sides. Proceed to 2-2). 2-2): When the desired reference current of drive unit D3 The current exceeds the temperature closed-loop output current limit of the drive unit. And the expected reference current of drive unit D4 The current limit is less than the temperature closed-loop output current limit of the drive unit. The current setting strategy will be based on As the actual current limit value of this drive unit, to meet the left-turn requirements of the four-wheel independent electric drive robot, the magnitude of the actual current limit value on the D4 side after being affected by the D3 side is the actual current limit value I on the D3 side. lim3 Add the slip current ΔI2 on the rear side; similarly, when the desired reference current of the drive unit D1 is... The current exceeds the temperature closed-loop output current limit of the drive unit. And the expected reference current of drive unit D2 The current limit is less than the temperature closed-loop output current limit of the drive unit. The current setting strategy will be based on As the actual current limit value of this drive unit, the magnitude of the operating reference current on the D2 side after being affected by the D1 side is the actual current limit value I on the D1 side. lim1 Add the front slip current ΔI1. After mathematical verification, the actual current limit values ​​of the four drive units at this time do not exceed the current limit values ​​of the corresponding sides. Under safe conditions, the four drive units of the chassis drive enter the left turn state and turn into 2-3). 2-3): The expected reference currents of the current-side drive units D1 and D2 and the rear-side drive units D3 and D4 all exceed the current limit values ​​of the corresponding side temperature closed-loop output. Considering that the operating current of the D4 side needs to be greater than the operating current of the D3 side and the operating current of the D2 side needs to be greater than the operating current of the D1 side when the robot is turning left, under the same conditions, the power devices of the D4 and D2 side drive units have a higher risk of thermal failure than those of the D3 and D1 sides. Therefore, the current tuning strategy first tunes the current of the D4 and D2 side drive units, setting the actual current limit value of the D4 side drive unit to the current limit value of the temperature closed-loop output of that side. Under differential constraint conditions, the actual current limit of the D3-side drive unit is the actual current limit of the D4-side drive unit minus the rear slip current ΔI2. Similarly, the current tuning strategy tunes the actual current limit of the D2-side drive unit to the current limit of the temperature closed-loop output on that side. Under differential constraint conditions, the actual current limit value of the D1-side drive unit is also set accordingly. Its magnitude is the actual current limit value of the D2 side minus the slip current ΔI1 on the front side. However, after the initial setting, the relationship between the actual current limit values ​​of the D3 and D1-side drive units and the current limit values ​​of the corresponding temperature closed-loop output is still unclear, so further determination is needed. If, after initial current setting, the actual current limit values ​​of the D3 and D1 side drive units are both less than the corresponding side current limit values, then all four drive units of the chassis drive can operate within a safe limit range, and the four-wheel independent electric drive robot enters the left turn state. If, after initial tuning using the current tuning strategy, the actual current limit value I of the D3-side drive unit is... lim3 Greater than the current limit value on this side And the actual current limit value I of the D1 side drive unit lim1 Less than the current limit value on this side At this point, the D3-side drive unit still faces a potential risk of thermal failure. The current tuning strategy further tunes the actual current limit value on this side to the current limit value of the temperature closed-loop output. To meet the differential speed requirements of the robot in the left turn state, the actual current limit value of the D4 side drive unit is also set to the actual current limit value of the D3 side drive unit plus the rear slip current ΔI2. At this time, all four drive units of the chassis drive can operate within the safe limit range, and the four-wheel independent electric drive robot enters the left turn state. If, after initial tuning using the current tuning strategy, the actual current limit value I of the D3-side drive unit is... lim3 Less than the current limit value on this side And the actual current limit value I of the D1 side drive unit lim1 Greater than the current limit value on this side At this point, the D1-side drive unit still faces a potential risk of thermal failure. The current tuning strategy further tunes the actual current limit value on this side to the current limit value of the temperature closed-loop output. To meet the differential speed requirements of the robot in the left turn state, the actual current limit value of the D2 side drive unit is also set to the actual current limit value of the D1 side drive unit plus the front slip current ΔI1. At this time, all four drive units of the chassis drive can operate within the safe limit range, and the four-wheel independent electric drive robot enters the left turn state. If, after initial tuning using the current tuning strategy, the actual current limit value I of the D3-side drive unit is... lim3 Greater than the current limit value on this side And the actual current limit value I of the D1 side drive unit lim1 It is also greater than the current limit value on that side. At this point, both the D3 and D1 side drive units are at potential thermal failure risk. The current tuning strategy further tunes the actual current limit value of the D3 side drive unit to the current limit value of the temperature closed-loop output on that side. The actual current limit value of the D1-side drive unit is tuned to the current limit value of the temperature closed-loop output on that side. Under the left-turn differential constraint condition of the four-wheel independent electric drive robot, the actual current limit values ​​of the drive units on the D4 and D2 sides are also constrained and are subsequently set to the actual current limit value of the drive unit on the D3 side plus the rear slip current ΔI2, and the actual current limit value of the drive unit on the D1 side plus the front slip current ΔI1. It has been mathematically proven that at this time, the actual current limit values ​​of the four drive units are all less than the current limit values ​​of their respective sides, and the four-wheel independent electric drive robot can safely enter the left-turn state (turning into 2-4). 2-4): If the expected reference current of the four sets of drive units on the rear side does not exceed the current limit value of the corresponding side, the four sets of drive units of the chassis drive will use the expected current value sent by the remote controller as the operating reference current to enter the left turn state. 3) When the four-wheel independent electric drive robot switches from any state to the right-turn state, the reference values ​​of the chassis drive's operating current are as follows: Reference current value of the second drive unit on the front right side. It should be less than the operating reference current value of the first drive unit on the left. The operating reference current value of the fourth drive unit on the rear right side It should be less than the operating reference current value of the third drive unit on the left. Therefore, the remote control can emit the following desired current value: The current setting process when the robot turns right is as follows: 3-1): When the desired reference current of drive unit D3 The current exceeds the temperature closed-loop output limit of the drive unit. value The current setting strategy will be based on As the actual current limit value of this drive unit, due to the slip current constraint relationship between drive units D4 and D3, while setting the operating reference current on the D3 side, the D4 side will also be constrained. Its actual current limit value is equal to the actual current limit value I on the D3 side. lim3 Reduce the slip current ΔI2 on the rear side; similarly, when the desired reference current of drive unit D1 is... The current limit of the drive unit on this side is greater than the current limit value. At that time, the current setting strategy will be based on As the actual current limit value of this drive unit, the magnitude of the operating reference current on the D2 side after being affected by the D1 side is the actual current limit value I on the D1 side. lim1 Reduce the front slip current ΔI1, then proceed to step 3-2); 3-2): When the desired reference current of drive unit D4 The current exceeds the temperature closed-loop output current limit of the drive unit. And the actual current limit value I of the D3 side drive unit lim3 Less than the current limit value on this side The current setting strategy will be based on As the actual current limit value of this drive unit, the magnitude of the actual current limit value of the drive unit on the D3 side after being affected by the D4 side is the actual current limit value I on the D4 side. lim4 Add the slip current ΔI2 on the rear side; similarly, when the desired reference current of the drive unit D2 is... The current limit of the drive unit is greater than the current limit value. And the actual current limit value I of the D1 side drive unit lim1 Less than the current limit value on this side The current setting strategy will be based on As the actual current limit value of this drive unit, the magnitude of the actual current limit value of the drive unit on the D1 side after being affected by the D2 side is the actual current limit value I on the D2 side. lim2 Apply the front slip current ΔI1, then proceed to step 3-3); 3-3): The expected reference current of all four drive units on the front and rear sides exceeds the current limit value of their respective sides. Considering that the operating current of the D3 side needs to be greater than that of the D4 side and the operating current of the D1 side needs to be greater than that of the D2 side when the robot is turning right, under the same conditions, the power devices of the D3 and D1 side drive units have a higher risk of thermal failure compared to those of the D4 and D2 sides. Therefore, the current tuning strategy will first tune the actual operating current of the D3 and D1 side drive units. The tuning results are as follows: the current limit value of the temperature closed-loop output of the D3 and D1 side drive units is... To meet the differential steering requirements of the four-wheel independent electric drive robot, the actual current limits of the D4 and D2 side drive units are constrained by D3 and D1, and are respectively set as the actual current limit of the D3 side drive unit minus the rear slip current ΔI2, and the actual current limit of the D1 side drive unit minus the front slip current ΔI1. However, after the initial setting, the relationship between the actual current limits of the D4 and D2 side drive units and the current limits of the corresponding side temperature closed-loop output is still unclear, so further determination is needed. If, after initial current setting, the actual current limit values ​​of the drive units on the D4 and D2 sides are both less than the corresponding side current limit values, then all four drive units of the chassis drive can operate within a safe limit range, and the four-wheel independent electric drive robot can safely enter the right turn state. If, after initial current setting using the current setting strategy, the actual current limit value I of the D4-side drive unit is... lim4 Greater than the current limit value on this side And the actual current limit value I of the D2 side drive unit lim2 Less than the current limit value on this side At this point, the D4-side drive unit still faces a potential risk of thermal failure. The current tuning strategy further tunes the actual current limit value on this side to the current limit value of the temperature closed-loop output. To meet the differential speed requirements of the robot in the right turn state, the actual current limit value of the D3 side drive unit is also set to the actual current limit value of the D4 side drive unit plus the rear slip current ΔI2. At this time, all four drive units of the chassis drive can operate within the safe limit range, and the four-wheel independent electric drive robot can safely enter the right turn state. If, after initial current setting using the current setting strategy, the actual current limit value I of the D4-side drive unit is... lim4 Less than the current limit value on this side And the actual current limit value I of the D2 side drive unit lim2 Greater than the current limit value on this side At this point, the D2-side drive unit still faces a potential risk of thermal failure. The current tuning strategy further tunes the actual current limit value on this side to the current limit value of the temperature closed-loop output. Meanwhile, in order to meet the differential speed requirements of the robot in the right turn state, the actual current limit value of the D1 side drive unit is also set to the actual current limit value of the D2 side drive unit plus the front slip current ΔI1. At this time, all four drive units of the chassis drive can operate within the safe limit range, and the four-wheel independent electric drive robot can safely enter the right turn state. If, after initial current setting using the current setting strategy, the actual current limit value I of the D4-side drive unit is... lim4 Greater than the current limit value on this side And the actual current limit value I of the D2 side drive unit lim2 It is also greater than the current limit value on that side. At this point, both the D4 and D2 side drive units are at potential thermal failure risk. The current tuning strategy further tunes the actual current limit value of the D4 side drive unit to the current limit value of the temperature closed-loop output on that side. The actual current limit value of the D2-side drive unit is tuned to the current limit value of the temperature closed-loop output on that side. Under the right-turn differential constraint condition of the four-wheel independent electric drive robot, the actual current limit values ​​of the drive units on the D3 and D1 sides are also constrained and are subsequently set to the actual current limit value of the drive unit on the D4 side plus the rear slip current ΔI2, and the actual current limit value of the drive unit on the D2 side plus the front slip current ΔI1. It has been mathematically proven that at this time, the actual current limit values ​​of the four drive units are all less than the current limit values ​​of their respective sides, and the four-wheel independent electric drive robot safely enters the right-turn state (turning into 3-4). 3-4): The expected reference current of the four sets of drive units on the rear side has not exceeded the current limit value of the corresponding side. The four sets of drive units of the chassis drive will use the expected current value sent by the remote controller as the operating reference current. 4) When the four-wheel independent electric drive robot switches from any state to the stationary turning state, the reference values ​​of the chassis drive current are as follows: the magnitudes of the reference currents of the four drive units are equal, and the reference currents of the two drive units on the left and the two drive units on the right are in opposite directions. Therefore, the remote controller can output the following desired current value: In this state, the first overload current I0 is equal to the second overload current I1. The current setting process when the robot turns in place is as follows: First, by repeatedly comparing the desired current value with the reference current limit value of the temperature closed-loop output in the four sets of drive units, if it exceeds... The minimum absolute value among the four is used to set the actual current limit values ​​of the four drive units D1, D2, D3, and D4 to that value simultaneously, and the actual current limit values ​​of the left and right drive units are in opposite directions. If the value is not exceeded, the chassis driver can use the expected current value sent by the remote control as the actual current limit value of the four drive units. Finally, the actual current limit value of the chassis driver is within the safe range. 5) When the four-wheeled independent electric drive robot switches from any state to a stopped state, the reference value of the operating current of the four drive units is...

9. The flexible power control method for the chassis drive of a four-wheeled independent electric drive robot according to claim 8, characterized in that, In step 3, the actual current limit values ​​of the four drive units of the chassis driver obtained by the current tuning strategy are used as the input reference current for the current closed-loop control, so as to realize the dynamic correction of the driver current and the flexible control of the operating power.

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