Steering control method, system and computer storage medium for tricycle

Abstract

This invention provides a tricycle and its steering control method, system, and computer storage medium, belonging to the field of vehicle control technology. The method includes obtaining the tricycle's desired steering angular velocity, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the left rear wheel axle; determining the desired rotational speed of the front wheel based on the desired steering angular velocity, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the left rear wheel axle; obtaining the distance between the centers of the two rear wheels and the desired forward speed of the tricycle; determining the desired linear velocity of the left rear wheel and the desired linear velocity of the right rear wheel based on the distance between the centers of the two rear wheels and the desired forward speed of the tricycle; and controlling the steering of the tricycle based on the desired rotational speeds of the front wheels, the left rear wheel, and the right rear wheel. This invention improves the stability and accuracy of the tricycle's steering by controlling the rotational speeds of the front wheels and the two rear wheels, effectively controlling the tricycle's steering trajectory.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle control, and in particular relates to a steering control method, system and computer storage medium for a tricycle. Background Art

[0002] At present, the steering method commonly used for four-wheeled vehicles is mainly Ackerman steering. Ackerman steering has low efficiency at low speeds and cannot accurately control the steering trajectory of the vehicle at low speeds. In addition, Ackerman steering cannot achieve zero-speed in-situ steering, which is not conducive to the vehicle turning in relatively narrow places. Three-wheeled vehicles have a smaller turning radius and can achieve zero-speed in-situ steering. They are more flexible in narrow spaces, so they are suitable for scenes with high requirements for steering accuracy and narrow roads.

[0003] The front wheels of the commonly used three-wheeled vehicles are universal wheels that do not provide driving force, and the rear wheels are driven by two driving wheels to achieve forward, backward and steering. The steering method is a pure rear-wheel differential steering method. However, due to the influence of road friction, the distribution of the center of gravity of three-wheeled vehicles and the accuracy of the control system, three-wheeled vehicles are prone to skidding and tail swinging at high speeds. Summary of the invention

[0004] The invention provides a steering control method and system for a tricycle and a computer storage medium to solve the problem of inaccurate steering of a tricycle in the prior art.

[0005] In a first aspect, the present invention provides a tricycle, comprising a chassis, a front wheel, a left rear wheel and a right rear wheel;

[0006] The front wheel, the left rear wheel and the right rear wheel are driven by independent power sources respectively; the left rear wheel and the right rear wheel are coaxially arranged on both sides of the chassis; the axial direction of the left rear wheel is perpendicular to the forward direction of the chassis; the front wheel is located at one end of the chassis away from the left rear wheel and the right rear wheel; the axial direction of the front wheel is parallel to the forward direction of the chassis;

[0007] A plurality of rollers are evenly arranged on the outer side of the front wheel along the circumference of the front wheel; the plane where each roller is located in the circumference is parallel to the forward direction of the chassis; when the chassis is stationary or moving, at least one roller contacts the ground.

[0008] In a second aspect, the present invention provides a steering control method for a tricycle based on the first aspect, comprising:

[0009] Obtain the desired steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel;

[0010] Determine the expected rotation speed of the front wheel according to the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel;

[0011] Get the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel;

[0012] Determine the expected linear velocity of the left rear wheel and the expected linear velocity of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel;

[0013] The steering of the tricycle is controlled according to the desired rotation speed of the front wheel, the desired linear speed of the left rear wheel and the desired linear speed of the right rear wheel.

[0014] Optionally, determining the expected rotation speed of the front wheel according to the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel includes:

[0015] Calculate the desired front wheel speed using the following formula:

[0016]

[0017] Among them, n 1 is the expected speed of the front wheel; v 1 is the expected linear velocity of the front wheel; π is the circumference of a circle; d 1 is the equivalent diameter of the front wheel; w is the desired steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0018] Optionally, determining the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel includes:

[0019] The desired linear speed of the left rear wheel and the desired linear speed of the right rear wheel are calculated according to the following formula:

[0020]

[0021] Where c is the expected linear velocity difference between the left rear wheel and the right rear wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel; R is the distance between the center of the left rear wheel and the center of the right rear wheel; v L is the expected linear velocity of the left rear wheel; v set is the expected forward speed of the tricycle; v R is the desired linear velocity of the right rear wheel.

[0022] Optionally, controlling the steering of the tricycle according to the desired rotation speed of the front wheel, the desired linear speed of the left rear wheel, and the desired linear speed of the right rear wheel comprises:

[0023] Get the diameter d of the left rear wheel L and the diameter of the right rear wheel d R ;

[0024] Calculate the expected speed n of the left rear wheel according to the following formula: L and the desired speed n of the right rear wheel R :

[0025]

[0026] The steering of the three-wheel vehicle is controlled according to the desired rotation speed of the front wheel, the desired rotation speed of the left rear wheel, and the desired rotation speed of the right rear wheel.

[0027] In a third aspect, the present invention provides a steering control system for a tricycle based on the first aspect, comprising:

[0028] The first acquisition module is used to acquire the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel;

[0029] A first determination module is used to determine an expected rotation speed of the front wheel according to an expected steering angular velocity of the tricycle, an equivalent diameter of the front wheel, and a shortest distance from the center of the front wheel to the axis of the left rear wheel;

[0030] The second acquisition module is used to acquire the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel;

[0031] A second determination module is used to determine the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel;

[0032] The steering control module is used to control the steering of the tricycle according to the expected rotation speed of the front wheel, the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel.

[0033] Optionally, the first determining module includes:

[0034] The first calculation unit is used to calculate the expected rotation speed of the front wheel according to the following formula:

[0035]

[0036] Among them, n 1 is the expected speed of the front wheel; v 1 is the expected linear velocity of the front wheel; π is the circumference of a circle; d 1 is the equivalent diameter of the front wheel; w is the desired steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0037] Optionally, the second determining module includes:

[0038] The second calculation unit is used to calculate the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the following formula:

[0039]

[0040] Where c is the expected linear velocity difference between the left rear wheel and the right rear wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel; R is the distance between the center of the left rear wheel and the center of the right rear wheel; v L is the expected linear velocity of the left rear wheel; v set is the expected forward speed of the tricycle; v R is the desired linear velocity of the right rear wheel.

[0041] Optionally, the steering control module includes:

[0042] Acquisition unit, used to obtain the diameter d of the left rear wheel L and the diameter of the right rear wheel d R ;

[0043] The third calculation unit is used to calculate the expected speed n of the left rear wheel according to the following formula: L and the desired speed n of the right rear wheel R :

[0044]

[0045] The steering control unit is used to control the steering of the tricycle according to the desired rotation speed of the front wheel, the desired rotation speed of the left rear wheel and the desired rotation speed of the right rear wheel.

[0046] In a fourth aspect, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the steering control method for a three-wheeled vehicle described in the second aspect are implemented.

[0047] The present invention provides a steering control method, system and computer storage medium for a tricycle, wherein the method comprises determining the desired rotation speed of the front wheel according to the desired steering angular velocity of the tricycle, the equivalent diameter of the front wheel and the shortest distance from the center of the front wheel to the axis of the left rear wheel; determining the desired linear velocity of the left rear wheel and the desired linear velocity of the right rear wheel according to the desired forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel; and controlling the steering of the tricycle according to the desired rotation speed of the front wheel, the desired linear velocity of the left rear wheel and the desired linear velocity of the right rear wheel. The present invention improves the stability and accuracy of the tricycle during steering by controlling the rotation speed of the front wheel and the rotation speeds of the two rear wheels, and effectively controls the steering trajectory of the tricycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A schematic flow chart of a tricycle steering control method provided by an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of the structure of a tricycle provided by an embodiment of the present invention;

[0051] Figure 3 A top view of a tricycle provided by an embodiment of the present invention;

[0052] Figure 4 Schematic diagram of cascade PID control provided by an embodiment of the present invention;

[0053] Figure 5 A schematic structural diagram of a tricycle steering control system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] A tricycle provided by the present invention is equipped with a circuit board, which integrates a single-chip microcomputer and interfaces corresponding to an encoder, a gyroscope, a motor drive board, a camera, and a Bluetooth module. The three wheels are respectively connected to their corresponding motors and encoders by transmission, for example, through gear meshing transmission, so as to drive the wheels and measure the speed of the wheels. The tricycle provided by the present invention can increase the playability of some scientific and technological competitions or children's educational toys, break the limitations of conventional car models, and can also be used as a mobile platform for service robots in hotel restaurants, or a mobile platform for sorting robots in logistics companies.

[0056] Example 1

[0057] like Figure 2 As shown, this embodiment provides a three-wheeled vehicle, including a chassis 1, a front wheel 2, a left rear wheel 3 and a right rear wheel 4.

[0058] The front wheel 2, the left rear wheel 3 and the right rear wheel 4 are driven by independent power sources respectively; the left rear wheel 3 and the right rear wheel 4 are coaxially arranged on both sides of the chassis 1; that is, the circumferential plane of the left rear wheel 3 is parallel to the circumferential plane of the right rear wheel 4.

[0059] The axial direction of the left rear wheel 3 is perpendicular to the forward direction of the chassis 1; the front wheel 2 is located at the end of the chassis 1 away from the left rear wheel 3 and the right rear wheel 4; the axial direction of the front wheel 2 is parallel to the forward direction of the chassis 1, that is, the circumferential plane of the front wheel 2 is perpendicular to the circumferential plane of the left rear wheel 3, and also perpendicular to the circumferential plane of the right rear wheel 4.

[0060] On the outer side of the front wheel 1, a plurality of rollers 11 are evenly arranged along the circumference of the front wheel 1; the circumferential plane of each roller 11 is parallel to the forward direction of the chassis 1; when the chassis 1 is stationary or moving, at least one roller 21 contacts the ground, that is, the number of rollers 21 satisfies that when the chassis 1 is stationary or moving, at least one roller 21 contacts the ground.

[0061] Exemplarily, the three wheels are driven by three motors respectively; the left rear wheel 3 and the right rear wheel 4 are symmetrically distributed on both sides of the front wheel 2; in this embodiment, all rollers 21 are cylindrical structures, and each roller 21 rotates along its own circumference with its own axis as the axis. When the tricycle moves forward or backward, the friction between the roller 21 and the ground is rolling friction. The output shaft of each motor is connected to an encoder, and the three encoders respectively obtain the rotation speed of the three motors. A gyroscope is provided on the tricycle to provide the posture information of the tricycle, such as the angular velocity and angular acceleration of the three axes of xyz.

[0062] The front wheel 2 is used for steering, the left rear wheel 3 and the right rear wheel 4 are mainly responsible for forward and backward movement, and assist steering in a differential manner. The control algorithm relies on three encoders and gyroscope values ​​to calculate the linear speed of the three wheels, and then programs in the microprocessor to calculate three PWM (pulse width modulation) outputs to the motor driver board using the PID controller to adjust the speed of the three motors to achieve speed closed loop and steering speed closed loop.

[0063] Example 2

[0064] like Figure 1 As shown, this embodiment provides a steering control method for a tricycle based on the embodiment 1, comprising:

[0065] Step 101, obtaining the desired steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0066] In this embodiment, the axis of the left rear wheel 2 and the axis of the right rear wheel 3 are collinear, so the axis of the left rear wheel 2 is also the axis of the right rear wheel 3 .

[0067] Step 102, determining the expected rotation speed of the front wheel according to the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0068] In this step, illustratively, the expected rotation speed of the front wheel is calculated according to the following formula:

[0069]

[0070] Among them, n 1 is the expected speed of the front wheel; v 1 is the expected linear velocity of the front wheel; π is the circumference of a circle; d 1 is the equivalent diameter of the front wheel; w is the desired steering angular velocity of the tricycle; Figure 3 As shown, L is the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0071] In this step, the cascade PID algorithm is used, such as Figure 4 The PID flow chart shown in the figure has the input of the set steering speed and the output of the PWM square wave. The front wheel motor is regulated to avoid the unstable steering of the tricycle, which is manifested as the angular velocity value oscillation or large value. To suppress this situation, the inner loop is set as the angular velocity loop and the outer loop is set as the steering speed loop to achieve stable steering. The angular velocity value of the z-axis collected by the gyroscope is limited, and the limiting conditions are: wg=wg, wmin<wg<wmax; wg=wmax, wg>wmax; wg=wmin, wg<wmin.

[0072] In the limiting formula, wg is the angular velocity collected by the gyroscope. If wg is greater than 0, it means clockwise rotation, and if it is less than 0, it means counterclockwise rotation. wmax is the maximum allowable clockwise angular velocity, and wmin is the maximum allowable counterclockwise angular velocity.

[0073] The PID controller is composed of proportional, integral and differential links. Since the inner loop is used to prevent the tricycle from oscillating left and right, the inner loop only calculates the proportional part. The inner loop formula is Pin = kp·wg; Pin is the PWM value calculated by the inner loop, i.e. the angular velocity loop, and kp is the proportional coefficient of the cascade PID inner loop. The size of the kp value determines the influence of the gyroscope angular velocity value on the steering of the tricycle. The larger the kp value, the greater the damping feeling of the tricycle steering, and vice versa.

[0074] The outer loop is the steering speed loop, which requires three quantities to represent the output of the three links of proportion, integration and differentiation. The proportion link is related to the response speed of the tricycle steering. If the proportional coefficient is too large, it will cause the tricycle steering system to be unstable or even oscillate. Therefore, the segmented PID algorithm is introduced to adjust the value of the proportional coefficient according to the size of the error. The formula is as follows:

[0075] kp2=1,|error(t)| <e1;

[0076] kp2=2,e1≤|error(t)| <e2;

[0077] kp2=3,e2≤|error(t)| <e3;

[0078] kp2=4,e3≤|error(t)| <e4;

[0079] kp2=5,e4≤|error(t)| <e5;

[0080] kp2=6,e5≤|error(t)|;

[0081] Among them, kp2 refers to the coefficient of the proportional part, e1 is the preset first constant; e2 is the preset second constant; e3 is the preset third constant; e4 is the preset fourth constant; e5 is the preset fifth constant; |error(t)| refers to the absolute value of the error at this time (time t), and different values ​​are assigned to kp2 according to the size of the absolute value of the error.

[0082] The calculation formula of the steering speed loop is as follows:

[0083] error(t)=w set -w;

[0084] Pout = kp2·error(t);

[0085] Iout = ki ∫error dt;

[0086] Dout=kd·[error(t)-error(t-1)];

[0087] Among them, w set Refers to the set steering speed; w is the actual steering angular velocity of the tricycle; Pout refers to the variable of the outer loop proportional part, Iout refers to the variable of the outer loop integral part, ki refers to the coefficient of the integral part, Dout refers to the variable of the differential part, and kd refers to the coefficient of the differential part. error(t) refers to the error at this time (time t), and error(t-1) refers to the error at time t-1. The integral part continuously integrates the error to eliminate the steady-state error. The differential part calculates the rate of change of the error so that it can smoothly approach the set steering speed to avoid overshoot.

[0088] Finally, the PWM value P1 output to the front wheel is calculated as P1 = Pin + Pout + Iout + Dout.

[0089] Step 103, obtaining the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel.

[0090] Step 104, determining the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel.

[0091] In this step, illustratively, the desired linear velocity of the left rear wheel and the desired linear velocity of the right rear wheel are calculated according to the following formula:

[0092]

[0093] Where c is the expected linear velocity difference between the left rear wheel and the right rear wheel; w is the expected steering angular velocity of the tricycle; Figure 3 As shown, L is the shortest distance from the center of the front wheel to the axis of the left rear wheel; R is the distance between the center of the left rear wheel and the center of the right rear wheel; v L is the expected linear velocity of the left rear wheel; v set is the expected forward speed of the tricycle; v R is the desired linear velocity of the right rear wheel.

[0094] The speed values ​​of the two rear wheels are obtained separately and low-pass filtered to avoid sudden changes in values ​​causing instability in the car model system. The filtering formula is as follows:

[0095] n2'(t)=k1×n2(t)+k2×n2(t-1)+k3×n2(t-2);

[0096] n3'(t)=k1×n3(t)+k2×n3(t-1)+k3×n3(t-2);

[0097] Among them, n2'(t) is the speed value of the left rear wheel calculated by the filtering formula at the current moment (t moment); n2(t) is the speed value (r / s) of the left rear wheel read by the encoder at the current moment (t moment); n2(t-1) is the speed value (r / s) of the left rear wheel read by the encoder at t-1 moment; n2(t-2) is the speed value (r / s) of the left rear wheel read by the encoder at t-2 moment. n3'(t) is the speed value of the right rear wheel calculated by the filtering formula at the current moment (t moment); n3(t) is the speed value (r / s) of the right rear wheel read by the encoder at the current moment (t moment); n3(t-1) is the speed value (r / s) of the right rear wheel read by the encoder at t-1 moment; n3(t-2) is the speed value (r / s) of the right rear wheel read by the encoder at t-2 moment. k1, k2 and k3 are three coefficients, the sum of which is 1. They represent the influence of the values ​​at each moment in the filtering algorithm on the final value. If k1 is large and k2 and k3 are small, it means that it is more dependent on the current value, otherwise it is more dependent on the past value. Next, calculate the linear speed of the left and right rear wheels. The formula is as follows:

[0098] v2=n2'(t)×π×d L ;

[0099] v3=n3'(t)×π×d R ;

[0100] Among them, v2 is the linear velocity of the left rear wheel at the current moment, and v3 is the linear velocity of the right rear wheel at the current moment.

[0101] Step 105, controlling the steering of the tricycle according to the desired rotation speed of the front wheel, the desired linear speed of the left rear wheel, and the desired linear speed of the right rear wheel.

[0102] This step, illustratively, includes:

[0103] Get the diameter d of the left rear wheel L and the diameter of the right rear wheel d R .

[0104] Calculate the expected speed n of the left rear wheel according to the following formula: L and the desired speed n of the right rear wheel R :

[0105]

[0106] The steering of the three-wheel vehicle is controlled according to the desired rotation speed of the front wheel, the desired rotation speed of the left rear wheel, and the desired rotation speed of the right rear wheel.

[0107] Use position PID to close the speed loop of the two rear wheels. The speed closing method of the two wheels is the same. Position PID only needs two parameters, P and I, to complete the closed loop. The implementation method is:

[0108] Taking the left rear wheel as an example, first calculate the output value of the proportional link. The formula is as follows:

[0109] errorL(t)=v2-v L ;

[0110] Pout2 = kpL × errorL(t);

[0111] Among them, errorL(t) is the linear speed error of the left rear wheel at the current moment (time t); Pout2 is the output value of the proportional link in the left rear wheel speed closed loop, and kpL is the proportional coefficient of the left rear wheel speed closed loop.

[0112] Next, calculate the output value of the integral link, the formula is as follows:

[0113] errorsum=∫errorL dt=∑errorL(t);

[0114] Iout2 = kiL × errorsum;

[0115] Among them, errorsum is the accumulated value of the error, the error value of the past moment is integrated to eliminate the steady-state error, kiL is the integral coefficient of the left rear wheel speed closed loop, and Pout2 is the output value of the integral link in the left rear wheel speed closed loop. Since the position PID algorithm has a certain hysteresis effect and a long rise time, the bangbang control algorithm is introduced to improve the proportional link to achieve the effect of improved position PID. When the system output is lower than the set value, the control signal will be set to a predetermined maximum value (usually positive). When the system output exceeds the set value, the control signal will be set to a predetermined minimum value (usually negative). The bangbang control strategy adopts the idea of ​​binary control and only switches between two limit states to adjust the system output close to the set value.

[0116] The specific ways of improvement are as follows:

[0117] 1) Introduce a dead zone, that is, determine a set value, set it as deadhead, and the value is positive;

[0118] 2) Set a maximum positive output value, set to ukmax;

[0119] 3) Set a negative maximum output value, set to ukmin;

[0120] 4) Compare the linear speed error of the left rear wheel with the set value to determine the output value. The formula is as follows:

[0121] Pout2=ukmin,errorL(t)<-deadhead;

[0122] Pout2=kpL×errorL(t), -deadhead≤errorL(t)<deadhead;

[0123] Pout2=ukmax,deadhead≤errorL(t);

[0124] Among them, errorL(t) is compared with the set dead zone to determine the output value.

[0125] The final PWM value calculation formula for the left rear wheel output is as follows:

[0126] PWML=Pout2+Iout2;

[0127] Among them, PWML is the value used to input the speed control of the left rear wheel motor.

[0128] PWM speed regulation refers to the microprocessor sending a PWM signal to the motor driver board. PWM is a square wave signal that adjusts its duty cycle to achieve the speed regulation effect. After receiving the PWM signal, the motor driver board will adjust the voltage across the motor. According to the DC motor equivalent model, In the formula is the magnetic flux of the motor armature, n is the speed, Ia is the armature current, Ra is the resistance value of the armature winding, and Ua is the voltage across the motor. The greater the voltage, the higher the speed. Therefore, the motor drive board achieves speed regulation by adjusting the voltage across the motor.

[0129] In summary, the steering control method for a tricycle provided in this embodiment improves the stability and accuracy of the tricycle during steering by controlling the rotation speed of the front wheel and the rotation speed of the two rear wheels, and effectively controls the steering trajectory of the tricycle.

[0130] Example 3

[0131] Based on the same inventive concept as Example 2, this example provides a steering control system for a tricycle based on Example 1. Since the principle of solving the problem by this system is similar to that of the aforementioned steering control method, the implementation of this system can refer to the implementation of the steering control method.

[0132] like Figure 5 As shown, the steering control system of the tricycle comprises:

[0133] The first acquisition module 10 is used to acquire the desired steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0134] The first determination module 20 is used to determine the expected rotation speed of the front wheel according to the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel and the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0135] The second acquisition module 30 is used to acquire the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel.

[0136] The second determination module 40 is used to determine the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel.

[0137] The steering control module 50 is used to control the steering of the tricycle according to the desired rotation speed of the front wheels, the desired linear speed of the left rear wheel and the desired linear speed of the right rear wheel.

[0138] Exemplarily, the first determining module includes:

[0139] The first calculation unit is used to calculate the expected rotation speed of the front wheel according to the following formula:

[0140]

[0141] Among them, n 1 is the expected speed of the front wheel; v 1 is the expected linear velocity of the front wheel; π is the circumference of a circle; d 1 is the equivalent diameter of the front wheel; w is the desired steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel.

[0142] Exemplarily, the second determining module includes:

[0143] The second calculation unit is used to calculate the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the following formula:

[0144]

[0145] Where c is the expected linear velocity difference between the left rear wheel and the right rear wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel; v L is the expected linear velocity of the left rear wheel; v set is the expected forward speed of the tricycle; v R is the desired linear velocity of the right rear wheel.

[0146] Exemplarily, the steering control module includes:

[0147] Acquisition unit, used to obtain the diameter d of the left rear wheel L and the diameter of the right rear wheel d R ;

[0148] The third calculation unit is used to calculate the expected speed n of the left rear wheel according to the following formula: L and the desired speed n of the right rear wheel R :

[0149]

[0150] The steering control unit is used to control the steering of the tricycle according to the desired rotation speed of the front wheel, the desired rotation speed of the left rear wheel and the desired rotation speed of the right rear wheel.

[0151] For more specific working processes of the above modules, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0152] Example 4

[0153] This embodiment provides a computer device, including a processor and a memory; wherein the processor implements the steps of the steering control method described in Example 2 when executing a computer program stored in the memory.

[0154] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0155] Example 5

[0156] This embodiment provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the steering control method described in Embodiment 2 are implemented.

[0157] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0158] Example 6

[0159] This embodiment provides a computer program product, including computer executable instructions or a computer program. When the computer executable instructions or the computer program are executed by a processor, the steps of the steering control method described in Example 2 are implemented.

[0160] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 2, which will not be repeated here.

[0161] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the systems, devices, storage media, and computer program products disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0162] Those skilled in the art can clearly understand that the technology in the embodiments of the present invention can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution in the embodiments of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention or some parts of the embodiments.

[0163] In some embodiments, computer executable instructions may be in the form of a program, software, software module, script or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0164] As an example, computer-executable instructions may, but need not, correspond to a file in a file system, may be stored as part of a file that stores other programs or data, such as in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files storing one or more modules, subroutines, or code portions).

[0165] As an example, computer executable instructions may be deployed to be executed on one electronic device, or on multiple electronic devices located at one site, or on multiple electronic devices distributed at multiple sites and interconnected by a communication network.

[0166] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A steering control method for a tricycle, characterized in that: The tricycle comprises a chassis (1), a front wheel (2), a left rear wheel (3) and a right rear wheel (4); the front wheel (2), the left rear wheel (3) and the right rear wheel (4) are driven by independent power sources respectively; the left rear wheel (3) and the right rear wheel (4) are coaxially arranged on both sides of the chassis (1); the axial direction of the left rear wheel (3) is perpendicular to the forward direction of the chassis (1); the front wheel (2) is located at one end of the chassis (1) away from the left rear wheel (3) and the right rear wheel (4); the axial direction of the front wheel (2) is parallel to the forward direction of the chassis (1); A plurality of rollers (21) are evenly arranged on the outer side of the front wheel (2) along the circumference of the front wheel (2); the plane where each roller (21) is located in the circumference is parallel to the forward direction of the chassis (1); When the chassis (1) is stationary or moving, at least one of the rollers (21) is in contact with the ground; The steering control method comprises: Obtain the desired steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel; Determine the expected rotation speed of the front wheel according to the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel; Get the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel; Determine the expected linear velocity of the left rear wheel and the expected linear velocity of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel; The steering of the tricycle is controlled according to the desired rotation speed of the front wheel, the desired linear speed of the left rear wheel and the desired linear speed of the right rear wheel.

2. The steering control method according to claim 1, characterized in that: Determining the expected rotation speed of the front wheel according to the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel includes: Calculate the desired front wheel speed using the following formula: Among them, n1 is the expected rotation speed of the front wheel; v1 is the expected linear velocity of the front wheel; π is pi; d1 is the equivalent diameter of the front wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel.

3. The steering control method according to claim 1, characterized in that: The method of determining the expected linear velocity of the left rear wheel and the expected linear velocity of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel comprises: The desired linear speed of the left rear wheel and the desired linear speed of the right rear wheel are calculated according to the following formula: Where c is the expected linear velocity difference between the left rear wheel and the right rear wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel; R is the distance between the center of the left rear wheel and the center of the right rear wheel; v L is the expected linear velocity of the left rear wheel; v set is the expected forward speed of the tricycle; v R is the desired linear velocity of the right rear wheel.

4. The steering control method according to claim 1, characterized in that: The method of controlling the steering of the tricycle according to the desired rotation speed of the front wheel, the desired linear speed of the left rear wheel and the desired linear speed of the right rear wheel comprises: Get the diameter d of the left rear wheel L and the diameter of the right rear wheel d R ; Calculate the expected speed n of the left rear wheel according to the following formula: L and the desired speed n of the right rear wheel R : The steering of the three-wheel vehicle is controlled according to the desired rotation speed of the front wheel, the desired rotation speed of the left rear wheel, and the desired rotation speed of the right rear wheel.

5. A steering control system for a tricycle, characterized in that: The tricycle comprises a chassis (1), a front wheel (2), a left rear wheel (3) and a right rear wheel (4); the front wheel (2), the left rear wheel (3) and the right rear wheel (4) are driven by independent power sources respectively; the left rear wheel (3) and the right rear wheel (4) are coaxially arranged on both sides of the chassis (1); the axial direction of the left rear wheel (3) is perpendicular to the forward direction of the chassis (1); the front wheel (2) is located at one end of the chassis (1) away from the left rear wheel (3) and the right rear wheel (4); the axial direction of the front wheel (2) is parallel to the forward direction of the chassis (1); A plurality of rollers (21) are evenly arranged on the outer side of the front wheel (2) along the circumference of the front wheel (2); the plane where each roller (21) is located in the circumference is parallel to the forward direction of the chassis (1); When the chassis (1) is stationary or moving, at least one of the rollers (21) is in contact with the ground; The steering control system comprises: The first acquisition module is used to acquire the expected steering angular velocity of the tricycle, the equivalent diameter of the front wheel, and the shortest distance from the center of the front wheel to the axis of the left rear wheel; A first determination module is used to determine an expected rotation speed of the front wheel according to an expected steering angular velocity of the tricycle, an equivalent diameter of the front wheel, and a shortest distance from the center of the front wheel to the axis of the left rear wheel; The second acquisition module is used to acquire the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel; A second determination module is used to determine the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the expected forward speed of the tricycle and the distance between the center of the left rear wheel and the center of the right rear wheel; The steering control module is used to control the steering of the tricycle according to the expected rotation speed of the front wheel, the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel.

6. The steering control system according to claim 5, characterized in that: The first determining module comprises: The first calculation unit is used to calculate the expected rotation speed of the front wheel according to the following formula: Among them, n1 is the expected rotation speed of the front wheel; v1 is the expected linear velocity of the front wheel; π is pi; d1 is the equivalent diameter of the front wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel.

7. The steering control system according to claim 5, characterized in that: The second determining module comprises: The second calculation unit is used to calculate the expected linear speed of the left rear wheel and the expected linear speed of the right rear wheel according to the following formula: Where c is the expected linear velocity difference between the left rear wheel and the right rear wheel; w is the expected steering angular velocity of the tricycle; L is the shortest distance from the center of the front wheel to the axis of the left rear wheel; R is the distance between the center of the left rear wheel and the center of the right rear wheel; v L is the expected linear velocity of the left rear wheel; v set is the expected forward speed of the tricycle; v R is the desired linear velocity of the right rear wheel.

8. The steering control system according to claim 5, characterized in that: The steering control module comprises: Acquisition unit, used to obtain the diameter d of the left rear wheel L and the diameter of the right rear wheel d R ; The third calculation unit is used to calculate the expected speed n of the left rear wheel according to the following formula: L and the desired speed n of the right rear wheel R : The steering control unit is used to control the steering of the tricycle according to the desired rotation speed of the front wheel, the desired rotation speed of the left rear wheel and the desired rotation speed of the right rear wheel.

9. A computer-readable storage medium, characterized in that: Used to store computer programs; when the computer programs are executed by the processor, the steps of the steering control method for a three-wheeled vehicle according to any one of claims 1 to 4 are implemented.

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