A method for calculating the speed of a distributed electric-driven articulated vehicle for mining

Abstract

The present invention belongs to the field of mining vehicle control, and discloses a method for calculating the speed of a mining distributed electric drive articulated vehicle, comprising the following steps: obtaining the measured wheel speed of each wheel, the acceleration of the front and rear vehicle bodies and the articulation angle in real time; calculating the wheel speed sampling difference threshold of each wheel in real time; then judging whether the absolute value of the difference between the current measured wheel speed of each wheel and the last wheel speed is less than the threshold, if so, saving the current measured wheel speed of each wheel, if not, discarding the current measured wheel speed of the wheel that does not meet the threshold condition, updating the current wheel speed according to its last wheel speed and saving it; calculating the real-time vehicle speed of the whole vehicle according to the current wheel speed of each wheel. The present invention improves the real-time performance of vehicle speed calculation, and can be widely used in the field of mining articulated vehicles.

Description

Technical Field

[0001] The invention belongs to the field of mining vehicle control, and in particular relates to a method for calculating the speed of a mining distributed electric-driven articulated vehicle. Background Art

[0002] Distributed wheel drive for mining is a highly potential driving method currently used in coal mines. Distributed electric drive articulated vehicles have the advantages of zero emission and pollution, compact structure, large space utilization, high transmission efficiency, small turning radius, high controllable freedom, good dynamic control performance, and good anti-skid control effect.

[0003] Due to the narrow and winding working space underground, auxiliary transport vehicles mostly use articulated bodies, usually running at low speed and high torque, and the uneven, muddy and slippery working conditions of the tunnels can easily cause the wheels of the vehicles to slip. Controlling the slip rate within an appropriate range can ensure good power and stability of the vehicle, but excessive slip will cause tire wear, energy waste and vehicle instability, which can be dangerous in severe cases. Therefore, torque control based on slip rate can effectively solve the above problems of distributed electric drive articulated vehicles for mining. The slip rate measurement requires the wheel speed and vehicle speed to be calculated. The wheel speed is easy to obtain, but the vehicle speed is difficult to measure due to slipping.

[0004] At present, Kalman filter algorithm, nonlinear state observer, sliding mode observer, neural network method, etc. are used for vehicle speed estimation, but these algorithms need to calculate complex tire models and vehicle models, which has large amount of calculation and poor real-time performance, and is limited in actual control system application. Moreover, these methods do not consider the problem of vehicle speed estimation when the vehicle is turning. Due to the particularity of turning of articulated vehicles, the change of articulation angle has a great influence on vehicle speed estimation. Therefore, it is necessary to provide a vehicle speed measurement method that considers both the straight-ahead and turning states of articulated vehicles. This is of great significance for improving the driving power and stability of vehicles, solving the difficulty of speed measurement of underground distributed drive articulated vehicles, and reducing the occurrence of underground vehicle accidents. Summary of the invention

[0005] The present invention overcomes the deficiencies of the prior art and aims to solve the technical problem of providing a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, so as to improve the real-time performance of the vehicle speed calculation and the safety of vehicle control.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for measuring the speed of a distributed electric-driven articulated vehicle for mining, wherein each wheel of the distributed electric-driven articulated vehicle is provided with an encoder, the front and rear vehicle bodies are respectively provided with accelerometers, and the hinges of the front and rear vehicle bodies are provided with angular displacement sensors, comprising the following steps:

[0007] S1, real-time acquisition of the measured wheel speed of each wheel, the acceleration and articulation angle of the front and rear vehicle bodies;

[0008] S2, according to the acceleration of the front and rear vehicle bodies, the articulation angle and the sampling accuracy, the wheel speed sampling difference threshold of each wheel is calculated in real time; then it is determined whether the absolute value of the difference between the current measured wheel speed and the previous wheel speed of each wheel is less than the threshold, if so, the current measured wheel speed of each wheel is saved as its current wheel speed and the process goes to step S4, if not, the process goes to step S3;

[0009] S3, saving the currently measured wheel speed of the wheels that meet the threshold condition, discarding the currently measured wheel speed of the wheels that do not meet the threshold condition, updating the currently measured wheel speed according to the previous wheel speed and saving it, and then entering step S4;

[0010] S4, calculating the real-time speed of the whole vehicle according to the current wheel speed of each wheel, and then returning to step S1 to repeat the calculation of the real-time speed.

[0011] In step S2, the calculation formula of the wheel speed sampling difference threshold of each wheel is:

[0012] When δ = 0,

[0013]

[0014] When δ≠0,

[0015]

[0016]

[0017]

[0018]

[0019] Among them, A fl , A fr , A rl , A rr Indicates the wheel speed sampling difference threshold of the left front wheel, right front wheel, left rear wheel, and right rear wheel, L 1 is the distance from the front wheel axle to the hinge point, L 2 is the distance from the rear wheel axle to the hinge point, B is the wheelbase, δ is the hinge angle, T is the sampling time interval, ξ represents the correction coefficient, and a f and a r Represent the front and rear accelerations of the vehicle respectively.

[0020] The correction coefficient ξ is set according to the accuracy of the accelerometer.

[0021] In step S3, the specific method for updating the current wheel speed according to the previous wheel speed is:

[0022] The last wheel speed plus a correction value is used as the current wheel speed data.

[0023] In step S3, the specific method for updating the current wheel speed according to the previous wheel speed is:

[0024] When δ = 0,

[0025]

[0026]

[0027]

[0028]

[0029] When δ≠0,

[0030]

[0031]

[0032]

[0033]

[0034] in, Respectively represent the last wheel speed data of the left front wheel, right front wheel, left rear wheel and right rear wheel, Respectively represent the current wheel speed data of the left front wheel, right front wheel, left rear wheel and right rear wheel, L 1 is the distance from the front wheel axle to the hinge point, L 2 is the distance from the rear wheel axle to the hinge point, B is the wheelbase, δ is the hinge angle, T is the sampling time interval, a f and a r Represent the front and rear accelerations of the vehicle respectively.

[0035] In step S4, the calculation formula of the real-time vehicle speed is:

[0036]

[0037] Among them, V a Indicates the real-time speed of the vehicle.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention provides a method for calculating the speed of a distributed electric-driven articulated vehicle for mining. The limiting filter algorithm is used for speed estimation, which can effectively eliminate pulse interference and solve the problems of large calculation amount and poor real-time performance of the current commonly used speed estimation algorithm.

[0040] 2. When calculating the vehicle speed, the present invention fully considers the influence of the change of the articulation angle of the articulated vehicle on the vehicle speed estimation. In particular, when turning, the wheel center movement speed of the inner and outer wheels will change with the change of the articulation angle. The present invention improves the accuracy of the articulated vehicle speed estimation by constructing a mathematical model of the articulated vehicle steering and estimating the vehicle speed of the articulated vehicle based on the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic flow chart of a method for calculating the speed of a distributed electric-driven articulated vehicle for mining provided by an embodiment of the present invention;

[0042] Figure 2 It is a schematic diagram of the kinematic model of a distributed electric drive articulated vehicle in an embodiment of the present invention;

[0043] Figure 3 A detailed flow chart of a method for calculating the speed of a distributed electric-driven articulated vehicle for mining provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] Embodiment 1

[0046] like Figure 1 As shown, the first embodiment of the present invention provides a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, comprising the following steps:

[0047] S1. Obtain the measured wheel speed of each wheel, the acceleration of the front and rear vehicle bodies and the articulation angle; wherein, each wheel of the distributed electric drive articulated vehicle is provided with an encoder, the encoder is used to obtain the measured wheel speed of each wheel, the front and rear vehicle bodies are respectively provided with accelerometers, the accelerometers are used to measure the acceleration of the corresponding vehicle bodies, and the front and rear vehicle bodies are provided with angular displacement sensors at the articulations for measuring the articulation angle of the vehicle bodies.

[0048] like Figure 2 As shown, O 0 represents the hinge point, O 1 represents the center of mass of the front vehicle, O 2 represents the center of mass of the rear vehicle body, and the distance between the two wheels 1 is B.

[0049] S2. Calculate the wheel speed sampling difference threshold of each wheel in real time according to the acceleration of the front and rear vehicle bodies, the articulation angle and the sampling accuracy; then determine whether the absolute value of the difference between the current measured wheel speed and the previous wheel speed of each wheel is less than the threshold. If so, save the current measured wheel speed of each wheel as its current wheel speed and enter step S4. If not, enter step S3.

[0050] In step S2, the calculation formula of the wheel speed sampling difference threshold of each wheel is:

[0051] When δ = 0,

[0052]

[0053] When δ≠0,

[0054]

[0055]

[0056]

[0057]

[0058] Among them, A fl , A fr , A rl , A rr Indicates the wheel speed sampling difference threshold of the left front wheel, right front wheel, left rear wheel, and right rear wheel, L 1 is the distance from the front wheel axle to the hinge point, L 2 is the distance from the rear wheel axle to the hinge point, B is the wheelbase, δ is the hinge angle, T is the sampling time interval, ξ represents the correction coefficient, and a f and a r Respectively represent the front and rear vehicle accelerations of this measurement.

[0059] In this embodiment, when the vehicle is moving straight, the calculation is performed using formula (1), and when the vehicle is turning, the left front wheel, right front wheel, left rear wheel, and right rear wheel are calculated using formulas (2)(3)(4)(5) respectively. ξ is set according to the accuracy of the accelerometer. To ensure the accuracy of the limiting filter algorithm, it is recommended that the accelerometer sensitivity deviation is no more than 5%, and 1<ξ≤1.05.

[0060] In this embodiment, the following judgment is performed each time a new wheel speed signal is obtained:

[0061] If the absolute value of the difference between the current measured wheel speed and the previous wheel speed is less than or equal to the wheel speed sampling difference threshold of the corresponding wheel, the current wheel speed data is valid and is retained;

[0062] If the absolute value of the difference between the current wheel speed and the previous wheel speed is greater than the wheel speed sampling difference threshold of the corresponding wheel, the current wheel speed data is invalid, the current wheel speed data is abandoned, and the previous wheel speed data is used to replace the current wheel speed data.

[0063] S3, save the currently measured wheel speed of the wheels that meet the threshold conditions, discard the currently measured wheel speed of the wheels that do not meet the threshold conditions, update the current wheel speed according to the previous wheel speed and save it, and then enter step S4.

[0064] In step S3, the specific method for updating the current wheel speed according to the previous wheel speed is:

[0065] The last wheel speed plus a correction value is used as the current wheel speed data, that is:

[0066] V t =V t-1 +k (6).

[0067] Among them, V t-1 Indicates the last wheel speed, V t represents the current wheel speed, and k represents the correction value.

[0068] This correction value k is calculated from the acceleration and sampling time, but the calculation formula is different when the vehicle is moving straight and turning.

[0069] When the vehicle is moving straight (δ = 0), the calculation formula of the correction value k is:

[0070]

[0071] When the vehicle is turning (δ≠0), the calculation formula of the correction value k is:

[0072]

[0073]

[0074]

[0075]

[0076] Therefore, in step S3 of this embodiment, the specific method for updating the current wheel speed according to the previous wheel speed is:

[0077] When δ = 0,

[0078]

[0079]

[0080]

[0081]

[0082] When δ≠0,

[0083]

[0084]

[0085]

[0086]

[0087] in, Respectively represent the last wheel speed data of the left front wheel, right front wheel, left rear wheel and right rear wheel, Respectively represent the current wheel speed data of the left front wheel, right front wheel, left rear wheel and right rear wheel, L 1 is the distance from the front wheel axle to the hinge point, L 2 is the distance from the rear wheel axle to the hinge point, B is the wheelbase, δ is the hinge angle, T is the sampling time interval, a f and a r Respectively represent the front and rear vehicle accelerations of this measurement.

[0088] S4, calculating the real-time speed of the whole vehicle according to the current wheel speed of each wheel, and then returning to step S1 to repeat the calculation of the real-time speed.

[0089] In step S4, the calculation formula of the real-time vehicle speed is:

[0090]

[0091] Among them, V a Indicates the real-time speed of the vehicle.

[0092] Embodiment 2

[0093] like Figure 3 As shown, the second embodiment of the present invention provides a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, comprising the following steps:

[0094] S1. Obtain the measured wheel speed of each wheel, the acceleration of the front and rear vehicle bodies and the articulation angle in real time through the encoder.

[0095] S2. Determine whether the vehicle is going straight based on the size of the articulation angle. If not, calculate the wheel speed sampling difference threshold and correction value of each wheel in real time based on the acceleration of the front and rear vehicle bodies, the articulation angle and the sampling accuracy. The calculation formula is formula (2) to (5) and formula (8) to (11) in the first embodiment. If yes, directly calculate the wheel speed sampling difference threshold A and correction value k based on the acceleration of the front and rear vehicle bodies and the sampling accuracy. The calculation formula is:

[0096]

[0097]

[0098] Where ξ represents the correction coefficient, a f and a r They represent the front and rear vehicle accelerations respectively, and T is the sampling time interval.

[0099] S3. Determine whether the absolute value of the difference between the current measured wheel speed and the previous wheel speed of each wheel is less than a threshold value. If so, save the current measured wheel speed of each wheel as its current wheel speed and proceed to step S5. If not, proceed to step S4.

[0100] S4, save the currently measured wheel speed of the wheels that meet the threshold conditions, discard the currently measured wheel speed of the wheels that do not meet the threshold conditions, update the current wheel speed according to the previous wheel speed and save it, and then enter step S5.

[0101] In this embodiment, the effective wheel speed data is stored in The wheel that does not retain the current wheel speed data uses the following calculation method: use the previous wheel speed data and add a correction value k as the current wheel speed data and store it in That is to say, the wheel speed sampling difference threshold and correction value calculated in the above step S2 are substituted into the above formula (6), and the current wheel speed can be updated.

[0102] S5. Calculate the real-time speed of the whole vehicle according to the current wheel speed of each wheel, then return to step S1 to repeat the calculation of the real-time speed.

[0103] To sum up, the vehicle speed measurement method of the distributed electric-driven articulated truck for mining provided by the present invention measures the vehicle speed through limiting filtering and correction compensation. The method and principle are simple, and can solve the problems of complex modeling, large amount of calculation, and poor real-time performance of the current control algorithm. It provides a reference for the speed measurement and wheel slip rate calculation of the current distributed-driven articulated truck in coal mines.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the speed of a distributed electric-driven articulated vehicle for mining. It is characterized in that The distributed electric drive articulated vehicle is provided with encoders on each wheel, accelerometers are provided on the front and rear vehicle bodies respectively, and angular displacement sensors are provided at the hinges of the front and rear vehicle bodies, including the following steps: S1, real-time acquisition of the measured wheel speed of each wheel, the acceleration and articulation angle of the front and rear vehicle bodies; S2, according to the acceleration of the front and rear vehicle bodies, the articulation angle and the sampling accuracy, the wheel speed sampling difference threshold of each wheel is calculated in real time; then it is determined whether the absolute value of the difference between the current measured wheel speed and the previous wheel speed of each wheel is less than the threshold, if so, the current measured wheel speed of each wheel is saved as its current wheel speed and the process goes to step S4, if not, the process goes to step S3; S3, saving the currently measured wheel speed of the wheels that meet the threshold condition, discarding the currently measured wheel speed of the wheels that do not meet the threshold condition, updating the currently measured wheel speed according to the previous wheel speed and saving it, and then entering step S4; S4, calculating the real-time speed of the vehicle according to the current wheel speed of each wheel, and then returning to step S1 to repeat the calculation of the real-time speed; In step S2, the calculation formula of the wheel speed sampling difference threshold of each wheel is: When δ=0, When δ≠0, in, A fl , A fr , A rl , A rr Indicates the wheel speed sampling difference threshold of the left front wheel, right front wheel, left rear wheel, and right rear wheel, L 1 is the distance from the front wheel axle to the hinge point, L 2 is the distance from the rear wheel axle to the hinge point, B is the wheelbase, δ is the hinge angle, T is the sampling time interval, ξ is the correction coefficient, a f and a r Represent the front and rear accelerations of the vehicle respectively.

2. According to claim 1, a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, It is characterized in that The correction coefficient ξ is set according to the accuracy of the accelerometer.

3. According to claim 1, a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, It is characterized in that In step S3, the specific method for updating the current wheel speed according to the previous wheel speed is: The last wheel speed plus a correction value is used as the current wheel speed data.

4. According to claim 3, a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, It is characterized in that In step S3, the specific method for updating the current wheel speed according to the previous wheel speed is: When δ=0, When δ≠0, in, Respectively represent the last wheel speed data of the left front wheel, right front wheel, left rear wheel and right rear wheel, Respectively represent the current wheel speed data of the left front wheel, right front wheel, left rear wheel and right rear wheel, L 1 is the distance from the front wheel axle to the hinge point, L 2 is the distance from the rear wheel axle to the hinge point, B is the wheelbase, δ is the hinge angle, T is the sampling time interval, a f and a r Represent the front and rear accelerations of the vehicle respectively.

5. According to claim 3, a method for calculating the speed of a distributed electric-driven articulated vehicle for mining, It is characterized in that In step S4, the calculation formula of the real-time vehicle speed is: in, Indicates the real-time speed of the vehicle.

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