A method for dynamic torque distribution of a six-wheel drive frame battery vehicle for mining

Abstract

The present invention belongs to the technical field of mining vehicle travel control, and provides a torque dynamic distribution algorithm for a mining six-wheel drive frame type battery vehicle, which solves the problem that the torque given by each travel motor is difficult to distribute. S1: Real-time acquisition of the speed data of the six-wheel motor, generating constraints on the output torque of the six-wheel motor; S2: Real-time acquisition of the steering angle data and vehicle load data of the vehicle, generating the real-time load pressure of the six wheels; S3: Real-time acquisition of the accelerator pedal signal, combined with the road friction coefficient and the real-time load pressure of the six wheels to generate the real-time traction of the six wheels; S4: Combined with the reduction ratio of the tire reducer and the road friction coefficient to generate the real-time output torque of the six wheels, the vehicle controller outputs the real-time output torque command of the six wheels to each actuator, and realizes the dynamic distribution of the torque of the six wheels. The present invention realizes the torque dynamic distribution function of the mining six-wheel drive frame type battery vehicle, and improves the endurance and maneuverability of the mining six-wheel drive frame type battery vehicle.

Description

Technical Field

[0001] The invention belongs to the technical field of mining vehicle travel control, and in particular relates to a torque dynamic distribution method for a mining six-wheel drive frame type battery vehicle. Background Art

[0002] Frame-type battery vehicles in coal mines are responsible for the handling and withdrawal of heavy equipment or hydraulic supports. In the past, the electric drive system of such vehicles was relatively simple, mostly using a single motor to drive the whole vehicle or dual motors to drive the front and rear axles. The accelerator pedal opening is usually directly linearly related to the motor torque output. The control strategy is also relatively simple. The torque given by each travel motor is often the same without distribution, which can only meet the basic vehicle travel. As a result, the torque output of some motors is too large during driving and slip occurs, or the torque of some motors is too small and is dragged by the whole vehicle. This will not only increase reactive power consumption and reduce the endurance of the whole vehicle, but also make it difficult to meet the precise control of vehicle travel. Summary of the invention

[0003] In order to solve at least one of the above technical problems existing in the prior art, the present invention provides a method for dynamically distributing torque of a six-wheel drive frame-type battery vehicle for mining.

[0004] The present invention is implemented by the following technical solution: a method for dynamically distributing torque of a six-wheel drive frame battery vehicle for mining, comprising the following steps:

[0005] S1: collect the speed data of the six-wheel motors in real time, and generate constraints on the output torque of the six-wheel motors in combination with the motor external characteristic curves;

[0006] According to the motor external characteristic curve, the motor output torque is constrained, and the formula for motor speed feedback and torque setting is as follows:

[0007]

[0008] Among them, T max is the peak torque of the motor, T O is the motor torque output, T min is the maximum speed torque of the motor, T pmin is the maximum speed torque at constant power, N is the motor speed, N n is the rated speed of the motor, N p is the maximum speed of the motor at constant power, N max is the maximum speed of the motor;

[0009] S2: collects the vehicle's steering angle data and vehicle load data in real time, and generates the real-time load pressure of the six wheels by combining the tire force coupling characteristics and the vehicle's mechanical structure parameters;

[0010] S3: collects accelerator pedal signals in real time, combines the road friction coefficient and the real-time load pressure of the six wheels to generate the real-time traction of the six wheels;

[0011] The calculation formula of the real-time traction of the six wheels is as follows:

[0012] F a =k*F1*μ

[0013] F b =k*F2*μ

[0014] F cd =2*k*F3*μ-F ef

[0015] F ef =k*F3*μ*(1+1.07*k*μ)

[0016] Among them, F a is the left front wheel traction, F b is the traction of the right front wheel, F cd is the traction force of the middle wheel, F ef is the traction of the rear wheels, k is the accelerator pedal opening (0-1), μ is the road friction coefficient, F1 is the load pressure of the left front wheel, F2 is the load pressure of the right front wheel, and F3 is the load pressure of any middle or rear wheel;

[0017] S4: Based on the real-time traction of the six wheels, combined with the reduction ratio of the tire reducer and the road friction coefficient, the real-time output torque of the six wheels is generated. The formula for the real-time output torque of the six wheels is as follows:

[0018]

[0019] Where i is the reduction ratio of the tire reducer, T a is the left front wheel output torque, T b is the right front wheel output torque, T cd is the output torque of the intermediate wheel, T ef is the output torque of the rear wheel;

[0020] The vehicle controller outputs the real-time output torque instructions of the six wheels to each actuator to achieve dynamic distribution of the six-wheel torque.

[0021] Preferably, in step S2, the calculation formula of the real-time load pressure of the six wheels is as follows:

[0022]

[0023] Among them, F1 is the load pressure of the left front wheel, F2 is the load pressure of the right front wheel, F3 is the load pressure of any middle or rear wheel, β is the steering angle, F v is the vehicle's unloaded weight, F cis the weight of the cargo carried by the vehicle, B1 is the distance from the hinge point to the center of the rear wheel, B2 is the distance from the center of gravity of the front frame to the hinge point, B3 is the distance from the center of gravity of the rear frame to the center of the rear four wheels, B8 is the length of the shovel board, β max is the maximum steering angle that the vehicle can achieve, F f is the front rack weight.

[0024] Preferably, when the output traction of the rear two wheels reaches the maximum, the middle two wheels still have surplus and can supplement and output greater traction. At this time, the calculation formula of the traction of the middle wheels is as follows:

[0025]

[0026] Among them, F cd is the traction force of the middle wheel, F ef is the traction of the rear wheel, k is the accelerator pedal opening (0-1), μ is the road friction coefficient, i is the reduction ratio of the tire reducer, T max is the peak torque of the motor, and F3 is the load pressure of any middle or rear wheel.

[0027] Preferably, the vehicle controller is connected to a signal converter and a motor controller. The signal converter is used to convert the received accelerator pedal opening signal, vehicle steering angle signal, and vehicle load signal and transmit them to the vehicle controller. The road friction coefficient and the reduction ratio of the tire reducer are stored in the vehicle controller. The speed signals of the six-wheel motors are collected by an encoder or a rotary transformer and transmitted to the motor controller, which then transmits them to the vehicle controller. The vehicle controller transmits the final calculated real-time output torque instructions for the six wheels to the motor controller. The motor controller controls the six-wheel motors to output the distributed torques respectively. The vehicle controller, the signal converter, and the motor controller are all powered by a DC / DC power supply.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention performs a dynamic analysis on the six electric wheels of the vehicle, reduces slip and drag while ensuring vehicle stability (optimal slip rate), realizes the dynamic torque distribution function of the mining six-wheel drive frame type battery vehicle, more reasonably distributes the six-wheel drive energy, reduces reactive power loss, and improves the endurance and maneuverability of the mining six-wheel drive frame type battery vehicle.

[0030] The invention constructs a six-wheel drive torque distribution efficiency model and realizes drive anti-skid control under complex road conditions. In the extreme case of full load or even overload, the supplementary torque of the intermediate wheel can still ensure the vehicle's running operation while taking into account the longitudinal driving stability of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a schematic diagram of the process from vehicle starting to torque output of the present invention;

[0033] Figure 2 is a schematic diagram of the control hardware of the present invention;

[0034] Figure 3 is a motor torque constraint curve diagram of the present invention;

[0035] Figure 4 A schematic structural diagram of the electric drive system of a mining six-drive frame-type battery vehicle of the present invention. DETAILED DESCRIPTION

[0036] In conjunction with the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions under which the present invention can be implemented, so they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention. It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0038] The present invention provides an embodiment:

[0039] A method for dynamically distributing torque of a six-wheel drive frame battery vehicle for mining comprises the following steps:

[0040] S1: collect the speed data of the six-wheel motors in real time, and generate constraints on the output torque of the six-wheel motors in combination with the motor external characteristic curves;

[0041] S2: collects the vehicle's steering angle data and vehicle load data in real time, and generates the real-time load pressure of the six wheels by combining the tire force coupling characteristics and the vehicle's mechanical structure parameters;

[0042] S3: collects accelerator pedal signals in real time, combines the road friction coefficient and the real-time load pressure of the six wheels to generate the real-time traction of the six wheels;

[0043] S4: Based on the real-time traction of the six wheels, combined with the reduction ratio of the tire reducer and the road friction coefficient, the real-time output torque of the six wheels is generated. The vehicle controller outputs the real-time output torque instructions of the six wheels to each actuator to realize dynamic distribution of the torque of the six wheels.

[0044] In step S1, the motor external characteristic curve generally includes a constant torque section, a constant power section and a high speed section. n Speed ​​section, which belongs to the motor constant torque section, or low speed and high torque stage, is mainly used for heavy load starting and full load climbing. The maximum output torque of the motor can usually reach 2 to 5 times the rated torque, which can give full play to the torque overload capacity of the drive system. n ~N p Speed ​​stage, which belongs to the constant power stage. Most of the time, the vehicle works in this stage. It is mainly used for full-load flat road driving. The maximum power limit is set to the rated power. According to the load conditions, the motor speed is adjusted to give full play to the power of the traction system, realize the difference-free control of traction power, and achieve high-speed traction. p ~N max The speed section belongs to the high-speed walking stage and can be used for no-load driving, making full use of the high-speed characteristics of the drive system, reducing the load torque, increasing the motor speed, and accelerating the vehicle speed. max Rear motor protection to prevent vehicle overspeed.

[0045] like Figure 3 As shown, according to the motor external characteristic curve, the motor output torque is constrained, and the least square method is used to obtain an approximate fitting curve of the motor speed feedback and the output torque. The formula for constraining the output torque of each walking motor is as follows:

[0046]

[0047] Among them, T max is the peak torque of the motor, T O is the motor torque output, T min is the maximum speed torque of the motor, T pmin is the maximum speed torque at constant power, N is the motor speed, N n is the rated speed of the motor, N p is the maximum speed of the motor at constant power, N max The maximum speed of the motor.

[0048] When N <N n When N is the constant torque stage, the motor output torque can be maintained at the peak torque as the motor speed increases. It is usually used for heavy-load starting and full-load climbing, and the vehicle exhibits low-speed and high-torque characteristics. n ≤N≤N p When N, the motor enters the constant power stage. As the motor speed continues to increase, the motor output torque begins to decrease, the output power remains constant, and the vehicle enters the stable driving operation stage. p <N<N max When the motor output torque and output power begin to decrease until the motor reaches its maximum speed, it is suitable for the vehicle's no-load fast driving stage. When the speed exceeds the motor's maximum speed, the motor is protected from overspeed.

[0049] It should be noted that in step S1, the speed sampling elements are six encoders or rotary transformers or other types of motor speed measuring devices, which are installed inside the motor to synchronously sample the motor speed and send the collected six-wheel motor speeds to their respective motor controllers, and finally transmit them to the vehicle controller.

[0050] In step S2, the main influencing factors of the real-time load pressure of the six wheels include: the load of the whole vehicle, including the empty vehicle weight and the external load. The six-wheel drive battery frame vehicle to which the present invention is applicable has a battery located in the front frame and an external load located in the rear frame. Therefore, when the load is increased, the force on the front two wheels changes less, and the force on the rear four wheels changes more. Therefore, it can be regarded that the sum of the load pressure of the front two wheels remains basically unchanged, and the external load is mainly applied to the rear four wheels of the vehicle. Steering angle, when the vehicle turns left, the force on the left tire increases, and the force on the right tire decreases; conversely, when the vehicle turns right, the force on the right tire increases, and the force on the left tire decreases. Specifically, the calculation formula for the real-time load pressure of the six wheels is as follows:

[0051]

[0052] Among them, F1 is the load pressure of the left front wheel, F2 is the load pressure of the right front wheel, F3 is the load pressure of any middle or rear wheel, β is the steering angle, F v is the vehicle's unloaded weight, F c is the weight of the cargo carried by the vehicle, B1 is the distance from the hinge point to the center of the rear wheel, B2 is the distance from the center of gravity of the front frame to the hinge point, B3 is the distance from the center of gravity of the rear frame to the center of the rear four wheels, B8 is the length of the shovel board, β max is the maximum steering angle that the vehicle can achieve, F f is the front rack weight.

[0053] In step S2, the vehicle load is measured by a pressure sensor, the road condition is estimated by an acceleration sensor, the steering angle can be calculated by an inclination sensor or a displacement sensor or other angle measuring equipment, and other parameters such as mass and length are fixed attributes of the vehicle and can be actually measured according to the specific vehicle model.

[0054] In step S3, based on the tire force dynamic efficiency matrix, a weighted least squares optimization function for torque distribution considering different working conditions is established, and the torque distribution result is obtained by combining the constraint range of the output torque. It can be understood that when a six-wheel drive battery-driven vehicle is driving without load, the center of gravity of the vehicle is close to the front wheels, so the whole vehicle is mainly driven by the front two wheels, and the rear four wheels only provide a small torque; when fully loaded, the center of gravity of the vehicle is closer to the rear wheels, and the rear four wheels will provide greater traction. The calculation formula for the real-time traction of the six wheels is as follows:

[0055] F a =k*F1*μ

[0056] F b =k*F2*μ

[0057] F cd =2*k*F3*μ-F ef

[0058] F ef =k*F3*μ*(1+1.07*k*μ)

[0059] Among them, F a is the left front wheel traction, F b is the traction of the right front wheel, F cd is the traction force of the middle wheel, F ef is the traction of the rear wheels, k is the accelerator pedal opening (0~1), μ is the road friction coefficient, F1 is the load pressure of the left front wheel, f2 is the load pressure of the right front wheel, and f3 is the load pressure of any middle or rear wheel.

[0060] Under extreme working conditions (as the external load increases, the load pressure of the middle two wheels and the rear two wheels increases, the load pressure of the rear two wheels is greater, and the output traction of the rear two wheels reaches the maximum. When the output of the rear two wheel motor reaches the maximum, the middle two wheels still have margin and begin to supplement the output of greater torque), the calculation formula for the traction of the middle wheel at this time is as follows:

[0061]

[0062] Among them, F cd is the traction force of the middle wheel, F ef is the traction of the rear wheel, k is the accelerator pedal opening (0-1), μ is the road friction coefficient, i is the reduction ratio of the tire reducer, T maxis the peak torque of the motor, and F3 is the load pressure of any middle or rear wheel.

[0063] In step S4, it can be understood that the torque output of each wheel can be obtained according to the traction force of the six wheels, and the torque distribution ratio changes to achieve dynamic distribution of the six-wheel drive torque. The formula is as follows:

[0064]

[0065] Where i is the reduction ratio of the tire reducer, T a is the left front wheel output torque, T b is the right front wheel output torque, T cd is the output torque of the intermediate wheel, T ef is the output torque to the rear wheels.

[0066] The road surface used by the vehicle applied to the present invention is relatively fixed, usually a sandy coal seam road surface in a coal mine, and the friction coefficient is relatively fixed, usually does not change much, and is close to a dry asphalt road surface, so the friction coefficient can be approximately 0.6; limited by the mechanical structure of the pedal, the pedal opening usually forms an angle range physically, and the pedal opening usually also generates a corresponding electrical signal, such as a voltage signal, a current signal or other communication signal. The throttle pedal opening can be converted into a specific numerical range, such as 0 to 1, through mathematical conversion or signal processing. The output torque of the motor increases with the depth of the driver's pedal, and the maximum speed limit of the motor torque also increases; the reduction ratio is the speed ratio of the motor and its reduction mechanism. The travel motor and tire of most current vehicles are connected by a reducer or other forms of reduction mechanisms. It is not ruled out that some types of vehicles are directly driven by motors and do not contain reduction mechanisms. In this case, i=1, which does not affect the application of the present invention.

[0067] The torque distribution of the six driving modes basically follows this rule: when the vehicle is unloaded, the center of gravity of the vehicle is forward, the front two wheels output a larger torque, and the rear four wheels output a smaller torque; when the vehicle is heavily loaded, the rear two wheels output a larger torque, and the middle two wheels output a smaller torque. When the output of the rear two wheel motors reaches the maximum, the middle two wheels increase the supplementary torque. By distributing the torque of the six travel motors, the vehicle is always kept running at the optimal slip rate. The output torque of the motor increases with the depth of the driver's pedal, and the upper limit of the maximum speed of the motor's torque mode also increases.

[0068] The vehicle controller is connected to a signal converter and a motor controller. The signal converter is used to convert the received accelerator pedal opening signal, vehicle steering angle signal, and vehicle load signal and transmit them to the vehicle controller. The road friction coefficient and the reduction ratio of the tire reducer are stored in the vehicle controller. The speed signal of the six-wheel motor is collected by an encoder or a rotary transformer and transmitted to the motor controller, which then transmits it to the vehicle controller. The vehicle controller transmits the final calculated six-wheel real-time output torque command to the motor controller. The motor controller controls the six-wheel motors to output the allocated torque respectively. The vehicle controller, signal converter, and motor controller are all powered by a DC / DC power supply. The vehicle controller is mainly used for signal sampling, protocol conversion, data solution and fusion, and completes the final six-wheel torque output.

[0069] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for dynamic torque distribution of a six-wheel drive frame battery vehicle for mining, characterized in that: The following steps are included: S1: collect the speed data of the six-wheel motors in real time, and generate constraints on the output torque of the six-wheel motors in combination with the motor external characteristic curves; According to the motor external characteristic curve, the motor output torque is constrained, and the formula for motor speed feedback and torque setting is as follows: Among them, T max is the peak torque of the motor, T O is the motor torque output, T min is the maximum speed torque of the motor, T pmin is the maximum speed torque at constant power, N is the motor speed, N n is the rated speed of the motor, N p is the maximum speed of the motor at constant power, N max is the maximum speed of the motor; S2: collects the vehicle's steering angle data and vehicle load data in real time, and generates the real-time load pressure of the six wheels by combining the tire force coupling characteristics and the vehicle's mechanical structure parameters; S3: collects accelerator pedal signals in real time, combines the road friction coefficient and the real-time load pressure of the six wheels to generate the real-time traction of the six wheels; The calculation formula of the real-time traction of the six wheels is as follows: F a =k*F1*μ F b =k*F2*μ F cd =2*k*F3*μ-F ef F ef =k*F3*μ*(1+1.07*k*μ) Among them, F a is the traction of the left front wheel, F b is the traction of the right front wheel, F cd is the traction force of the middle wheel, F ef is the traction of the rear wheels, k is the accelerator pedal opening (0-1), μ is the road friction coefficient, F1 is the load pressure of the left front wheel, F2 is the load pressure of the right front wheel, and F3 is the load pressure of any middle or rear wheel; S4: Based on the real-time traction of the six wheels, combined with the reduction ratio of the tire reducer and the road friction coefficient, the real-time output torque of the six wheels is generated. The formula for the real-time output torque of the six wheels is as follows: Where i is the reduction ratio of the tire reducer, T a is the left front wheel output torque, T b is the right front wheel output torque, T cd is the output torque of the intermediate wheel, T ef is the output torque of the rear wheel; The vehicle controller outputs the real-time output torque instructions of the six wheels to each actuator to achieve dynamic distribution of the six-wheel torque.

2. A method for dynamic torque distribution of a six-wheel drive frame battery vehicle for mining according to claim 1, characterized in that: In step S2, the calculation formula of the real-time load pressure of the six wheels is as follows: Among them, F1 is the load pressure of the left front wheel, F2 is the load pressure of the right front wheel, F3 is the load pressure of any middle or rear wheel, β is the steering angle, F v is the vehicle's unloaded weight, F c is the weight of the cargo carried by the vehicle, B1 is the distance from the hinge point to the center of the rear wheel, B2 is the distance from the center of gravity of the front frame to the hinge point, B3 is the distance from the center of gravity of the rear frame to the center of the rear four wheels, B8 is the length of the shovel board, β max is the maximum steering angle that the vehicle can achieve, F f is the front rack weight.

3. A method for dynamic torque distribution of a six-wheel drive frame battery vehicle for mining according to claim 2, characterized in that: When the output traction of the rear two wheels reaches the maximum, the middle two wheels still have surplus and can supplement the output of greater traction. At this time, the calculation formula of the traction of the middle wheels is as follows: Among them, F cd is the traction force of the middle wheel, F ef is the traction of the rear wheel, k is the accelerator pedal opening (0-1), i is the reduction ratio of the tire reducer, μ is the road friction coefficient, T max is the peak torque of the motor, and F3 is the load pressure of any middle or rear wheel.

4. A method for dynamic torque distribution of a six-wheel drive frame battery vehicle for mining according to claim 1, characterized in that: The vehicle controller is connected to a signal converter and a motor controller. The signal converter is used to convert the received accelerator pedal opening signal, vehicle steering angle signal, and vehicle load signal and transmit them to the vehicle controller. The road friction coefficient and the reduction ratio of the tire reducer are stored in the vehicle controller. The speed signal of the six-wheel motor is collected by an encoder or a rotary transformer and transmitted to the motor controller, and the motor controller transmits it to the vehicle controller. The vehicle controller transmits the final calculated six-wheel real-time output torque command to the motor controller, and the motor controller controls the six-wheel motors to output the distributed torque respectively. The vehicle controller, the signal converter and the motor controller are all powered by a DC / DC power supply.

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