Vehicle-mounted scissor structure lifting platform and double-motor synchronous control method thereof

Abstract

The present application relates to synchronous control system, specifically relates to a vehicle-mounted scissor structure lifting platform and a double-motor synchronous control method thereof, to solve the technical problems of poor anti-interference performance and poor synchronization accuracy of the double-shaft synchronous control method used in the existing vehicle-mounted lifting platform, and provide a vehicle-mounted scissor structure lifting platform and a double-motor synchronous control method thereof, in the double-motor synchronous control method, the position loop cross-coupling controller and the speed loop cross-coupling controller in the controller can effectively reduce the synchronization error caused by the coupling between the shafts through the cross-coupling control algorithm, and then the strong robustness characteristics of the sliding mode control are used, the position loop sliding mode controller and the speed loop sliding mode controller are used to eliminate the external interference of the motor, enhance the anti-interference performance of the whole lifting platform, and realize the high-speed and high-precision synchronous operation of the vehicle-mounted scissor structure lifting platform under the condition of large load through the double-shaft cross-coupling synchronization algorithm.

Description

Technical Field

[0001] This invention relates to a synchronous control system, specifically to a vehicle-mounted scissor lift platform and its dual-motor synchronous control method. Background Technology

[0002] Vehicle-mounted lifting platforms often utilize scissor lift structures to adapt to situations with limited height and space. This is because their compact structure when retracted and smooth operation make them ideal for such environments. Since scissor lift structures require significant initial power, a dual-motor, dual-screw transmission system is employed. This overcomes the power limitations of a single motor while meeting speed and cycle time requirements. Furthermore, the two motors must operate as synchronously as possible to maintain the stability of the lifting platform.

[0003] Existing dual-motor dual-axis synchronous control methods mainly include three control topologies: parallel, series (master-slave), and cross-coupling. The parallel structure features independent axes with no signal exchange and no disturbance rejection capability, making it suitable only for simple, easily controllable open-loop synchronous control topologies. The series control topology offers superior control accuracy compared to the parallel topology. It establishes inter-axis communication by transmitting the master axis's output signal to the slave axis, but slave axis control exhibits hysteresis, and slave axis disturbance errors cannot be transmitted. The lag in the master axis's action and control response worsens with increasing number of slave axis series stages. Therefore, it is often used in applications requiring low synchronization accuracy and control response. Cross-coupled control topology establishes accurate coupling between parallel control structure dual-axis motor systems. By coupling the target deviations of the two single-axis control loops and using a coupling algorithm function f(α) composed of coupling factor α to calculate new coupling error correction amounts, these corrections are distributed to the dual-axis control system to participate in the motion control of each axis motor. This establishes information sharing and deviation feedback between dual-axis or multi-axis linear motors, eliminating inter-axis response hysteresis. It boasts advantages such as strong anti-disturbance performance, high control accuracy, and fast response speed. Therefore, a new synchronous control system based on cross-coupled control topology is needed to solve the dual-motor synchronization problem of the vehicle-mounted scissor lift platform. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of poor anti-disturbance performance and poor synchronization accuracy of the existing dual-axis synchronous control method used in vehicle-mounted lifting platforms, and to provide a vehicle-mounted scissor lift platform and its dual-motor synchronous control method.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A vehicle-mounted scissor lift platform includes a base, four lifting rods arranged in a rectangle on the base, a platform mounted on the top of the four lifting rods, two lifting systems, and a controller. The lifting rods are extendable and retractable in the vertical direction. Each lifting system includes a permanent magnet linear synchronous motor mounted on the base, a ball screw assembly connected to the output shaft of the permanent magnet linear synchronous motor, a linear guide rail mounted on one side of the ball screw assembly, and a scissor lift device. The scissor lift device is connected to the platform. The permanent magnet linear synchronous motor drives two moving ends below the scissor lift device to move towards or away from each other along the linear guide rail via the ball screw assembly, thereby causing the platform to rise or fall vertically. Its unique feature is that:

[0007] The controller includes a position loop cross-coupled controller, a position loop sliding mode controller, a velocity loop cross-coupled controller, a velocity loop sliding mode controller, and a current PID controller, which are connected in sequence. The two input terminals of the position loop cross-coupled controller are respectively connected to a preset desired position control signal. There are two position loop sliding mode controllers, each with its input terminals electrically connected to the output terminal of the position loop cross-coupled controller, and its output terminals electrically connected to the first and second input terminals of the velocity loop cross-coupled controller. There are two velocity loop sliding mode controllers and two current PID controllers. The input terminals of the two velocity loop sliding mode controllers are electrically connected to the output terminals of the velocity loop cross-coupled controllers, and their output terminals are electrically connected to the two current PID controllers. The output terminals of the two current PID controllers are electrically connected to the control input terminals of two permanent magnet linear synchronous motors. The control output terminal of one permanent magnet linear synchronous motor is electrically connected to the first input terminal of the position loop cross-coupled controller, the first input terminal of the velocity loop cross-coupled controller, and the input terminal of the corresponding current PID controller. The control output terminal of the other permanent magnet linear synchronous motor is electrically connected to the second input terminal of the position loop cross-coupled controller, the second input terminal of the velocity loop cross-coupled controller, and the input terminal of the corresponding current PID controller.

[0008] Furthermore, it also includes two speed reducers mounted on the base, the input ends of the two speed reducers being connected to the output shafts of two permanent magnet linear synchronous motors respectively, and the output shafts of the speed reducers being connected to corresponding ball screw pairs.

[0009] Furthermore, it also includes sliders; the sliders include a first slider and a second slider; each ball screw pair is screwed with two first sliders, the two first sliders have opposite rotation directions, and the first sliders slide in contact with the linear guide rail;

[0010] Each scissor lift device includes multiple X-shaped forks, each fork having two hinged rods hinged at the middle; multiple forks are hinged sequentially from top to bottom to form the scissor lift device, the bottom ends of the two hinged rods of the bottommost fork are the moving ends, which are respectively hinged to two first sliders; two second sliders are slidably mounted at the bottom of the platform, and the top ends of the two hinged rods of the topmost fork are respectively hinged to the two second sliders.

[0011] Meanwhile, the present invention also provides a dual-motor synchronous control method for the above-mentioned vehicle-mounted scissor lift platform, which is characterized by including the following steps:

[0012] S1. The position feedback signals of the two permanent magnet linear synchronous motors are compared with the desired position control signal and then transmitted to the position loop cross-coupled controller respectively.

[0013] S2. The position loop cross-coupled controller processes the two position feedback information through the cross-coupled control algorithm and then inputs them into the two position loop sliding mode controllers respectively. After processing, the desired speed control signal is output.

[0014] S3. The two desired speed control signals are compared with the corresponding two motor feedback speed signals and then input into the speed loop cross-coupling controller. The speed loop cross-coupling controller processes the signals through the cross-coupling control algorithm and then inputs them into the corresponding two speed loop sliding mode controllers. The two speed loop sliding mode controllers output two current signals after processing.

[0015] S4. Compare the two current signals with the corresponding two motor feedback current signals respectively, and then output them to the two current PID controllers respectively;

[0016] S5. After processing by two current PID controllers, each controller outputs a control signal. Each control signal is superimposed with the external disturbance and then output to the corresponding permanent magnet linear synchronous motor to control its speed, thereby synchronizing the speeds of the two permanent magnet linear synchronous motors and completing the dual-motor synchronous control.

[0017] Furthermore, the mathematical expression for the position slip mode controller in step S2 is:

[0018]

[0019] In the formula: Let s be the first derivative of the displacement, s be the displacement, ε and k be the gain coefficients of the corresponding control quantities, and sgn(s) be the sign function of the displacement.

[0020] Furthermore, the mathematical expression for the speed slip mode controller in step S3 is:

[0021]

[0022] Where: m is the load mass, K f Where is the thrust coefficient, c is the control gain coefficient, and B is the thrust coefficient. v Let v be the coefficient of viscous friction, and v be the speed of the permanent magnet linear synchronous motor. This is the first derivative of the position tracking error.

[0023] Furthermore, the mathematical expressions for the position loop cross-coupled controller in step S2 and the velocity loop cross-coupled controller in step S3 are as follows:

[0024] E ah =(I+βT)E

[0025] In the formula: β is the coupling coefficient, I is the identity matrix, T is a square matrix, (I+βT) is a positive definite matrix, and E is the position tracking error matrix.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The vehicle-mounted scissor lift platform provided by the present invention is driven by a permanent magnet linear synchronous motor and a scissor lift device, which solves the problem that the speed limit is difficult to overcome when the hydraulic lift platform is applied to scenarios requiring large load and low noise. In addition, the overall structure is simple and easy to operate.

[0028] (2) The dual-motor synchronous control method for a vehicle-mounted scissor lift platform provided by the present invention fully considers the position and speed characteristics of the motor. The position loop cross-coupled controller and the speed loop cross-coupled controller in the controller effectively reduce the synchronization error caused by the inter-axis coupling through the cross-coupling control algorithm. Then, by utilizing the strong robustness of sliding mode control, the position loop sliding mode controller and the speed loop sliding mode controller are used to eliminate external interference of the motor and enhance the anti-disturbance performance of the entire lift platform. The dual-axis cross-coupling synchronous algorithm realizes the high-speed and high-precision synchronous operation of the vehicle-mounted scissor lift platform under heavy load. Attached Figure Description

[0029] Figure 1 This is a three-dimensional structural diagram of an embodiment of the vehicle-mounted scissor lift platform of the present invention (controller not shown);

[0030] Figure 2 This is a schematic diagram of an embodiment of the dual-motor synchronous control method for the vehicle-mounted scissor lift platform of the present invention.

[0031] The annotations in the attached figures are explained as follows:

[0032] 1-Base, 2-Platform, 3-Ball screw pair, 4-Linear guide rail, 5-Slider, 51-First slider, 52-Second slider; 6-Permanent magnet linear synchronous motor, 61-Reducer; 7-Lifting rod, 8-Scissor fork lifting device, 81-Hinged rod, 9-Position ring cross-coupling controller, 10-Position ring sliding mode controller, 11-Speed ​​ring cross-coupling controller, 12-Speed ​​ring sliding mode controller, 13-Current PID controller. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0034] Reference Figure 1 The present invention provides a vehicle-mounted scissor lift platform including a base 1, on which four lifting rods 7 are arranged in a rectangular shape. The top of the four lifting rods 7 is connected to a platform 2, which is a rectangular structure. The top of the four lifting rods 7 is connected to the four corners of the platform 2 respectively. The lifting rods 7 can extend and retract in the vertical direction, which can increase the lifting stability of the platform 2.

[0035] To achieve the lifting of platform 2, two lifting systems and a controller are also provided. Each lifting system includes a ball screw pair 3, a linear guide rail 4, a slider 5, a permanent magnet linear synchronous motor 6, and a scissor lift device 8.

[0036] There are two ball screw pairs 3, located between two adjacent lifting rods 7, arranged opposite each other and parallel to each other. There are also two linear guides 4, each corresponding to one side of a ball screw pair 3, with their extension direction parallel to the axis of the ball screw pair 3. The sliders 5 include first sliders 51 screwed onto the ball screw pairs 3. Each ball screw pair 3 has two first sliders 51 screwed onto it, and the first sliders 51 slide against the linear guides 4. The linear guides 4 prevent the first sliders 51 from rotating, allowing them to move only along the axis of the ball screw pair 3. The two first sliders 51 located on the same ball screw pair 3 rotate in opposite directions, allowing them to move towards or away from each other along the linear guides 4 when the ball screw pair 3 rotates.

[0037] To drive the two ball screw pairs 3 to rotate, two permanent magnet linear synchronous motors 6 are provided. Both are mounted on the base 1, and their output shafts are connected to the two ball screw pairs 3 respectively. In order to increase the torque and adjust the lifting speed of the entire lifting platform, a reducer 61 is also provided. The reducer 61 is mounted on the base 1, and its input end is connected to the output shaft of the permanent magnet linear synchronous motor 6. The output shaft of the reducer 61 is connected to the corresponding ball screw pair 3. The permanent magnet linear synchronous motor 6 is mounted on the base 1 through the reducer 61.

[0038] The structure of the scissor lift device 8 is as follows: Figure 1 As shown, the device includes multiple X-shaped forks, each with two hinged rods 81 hinged together at the middle. These forks are hinged sequentially from top to bottom to form a scissor lift device 8. The bottom ends of the two hinged rods 81 of the bottommost fork are the moving ends of the scissor lift device 8, which are hinged to two first sliders 51. To achieve the lifting of the platform 2, two second sliders 52 are slidably mounted at the bottom of the platform 2. The top ends of the two hinged rods 81 of the topmost fork are hinged to the two second sliders 52. Thus, when the permanent magnet linear synchronous motor 6 drives the ball screw pair 3 to rotate, if the two first sliders 51 move towards each other, the two second sliders 52 will also move closer together, causing the scissor lift device 8 to extend and lift the platform 2. During the lifting process, the lifting rod 7 will rise synchronously with the platform 2 to ensure its stability. If the two first sliders 51 move away from each other, the scissor lift device 8 will retract, causing the platform 2 to descend.

[0039] To achieve synchronization of the two permanent magnet linear synchronous motors 6 and ensure the stability of the platform 2's lifting and lowering, a controller is also provided. This controller includes a position loop cross-coupled controller 9, a position loop sliding mode controller 10, a speed loop cross-coupled controller 11, a speed loop sliding mode controller 12, and a current PID controller 13, all electrically connected in sequence. The two input terminals of the position loop cross-coupled controller 9 are respectively connected to preset desired position control signals. There are two position loop sliding mode controllers 10, both with their input terminals electrically connected to the position loop cross-coupled controller 9, and their output terminals electrically connected to the first and second input terminals of the speed loop cross-coupled controller 11, respectively. There are two speed loop sliding mode controllers 12 and two current PID controllers 13. The input terminals of 2 are electrically connected to the speed loop cross-coupled controller 11, and the output terminals are electrically connected to two current PID controllers 13. The output terminals of the two current PID controllers 13 are electrically connected to the control input terminals of the two permanent magnet linear synchronous motors 6. The control output terminal of one permanent magnet linear synchronous motor 6 is electrically connected to the first input terminal of the position loop cross-coupled controller 9, the first input terminal of the speed loop cross-coupled controller 11, and the input terminal of the corresponding current PID controller 13. The control output terminal of the other permanent magnet linear synchronous motor 6 is electrically connected to the second input terminal of the position loop cross-coupled controller 9, the second input terminal of the speed loop cross-coupled controller 11, and the input terminal of the corresponding current PID controller 13.

[0040] This invention also provides a dual-motor synchronous control method for the above-mentioned vehicle-mounted scissor lift platform, the working principle of which is as follows: Figure 2 As shown, it includes the following steps:

[0041] S1. The position feedback signals of the two permanent magnet linear synchronous motors 6 are compared with the desired position control signal and then transmitted to the position loop cross-coupled controller 9 respectively.

[0042] S2. The position loop cross-coupled controller 9 processes the two position feedback information through the cross-coupled control algorithm and then inputs them into the two position loop sliding mode controllers 10 respectively. After processing, the desired speed control signal is output.

[0043] S3. The two desired speed control signals are compared with the corresponding two motor feedback speed signals and then input into the speed loop cross-coupling controller 11. After processing by the cross-coupling control algorithm, the speed loop cross-coupling controller 11 is input into the corresponding two speed loop sliding mode controllers 12. After processing, the two speed loop sliding mode controllers 12 output two current signals.

[0044] S4. Compare the two current signals with the corresponding two motor feedback current signals respectively, and then output them to the two current PID controllers 13 respectively;

[0045] S5. After processing by the two current PID controllers 13, each controller outputs a control signal. Each control signal is superimposed with the external disturbance and then output to the corresponding permanent magnet linear synchronous motor 6 to control its speed, so that the speeds of the two permanent magnet linear synchronous motors 6 are synchronized, thus completing the dual-motor synchronous control.

[0046] The present invention uses an AC permanent magnet linear synchronous motor 6. Its principle is based on the principle of action in the electromagnetic field. The moving coil with three sinusoidal currents forms a traveling wave magnetic field on the moving part of the linear motor, which changes direction sequentially along the A, B, and C phase sequence. This magnetic field interacts with the excitation magnetic field formed by the permanent magnet magnetic field of the long stator to form a horizontal thrust (Ampere force). Under the action of the Ampere force, the linear motor moves forward in a straight line along the stator direction.

[0047] The vector control of the permanent magnet linear synchronous motor 6 can also be represented by a control approach in the dq coordinate system, that is, controlling the traveling wave magnetic field of its motor mover by controlling the dq current of the permanent magnet linear synchronous motor 6. In the dq axis motor vector control, let i d (d-axis current) = 0 does not affect the magnitude of the horizontal thrust of the permanent magnet linear synchronous motor 6, which is a commonly used control method for the permanent magnet linear synchronous motor 6. Using this control method, the control and simulation of the motor become simple and easy to implement. At this point, the control of the permanent magnet linear synchronous motor 6 is transformed into the control of i... q Single-objective control of (q-axis current), based on the above analysis:

[0048] The design process of the position slip mode controller 10 in step S2 is as follows:

[0049] Determine the voltage balance equation of permanent magnet linear synchronous motor 6 in the dq coordinate system.

[0050]

[0051] In the formula: r is the stator resistance, L is the armature inductance, d = d / dt is the differential factor, τ is the pole pitch, and Ψ d and Ψ q The excitation flux linkages Ψ for the d-axis and q-axis, respectively. PM Let v be the flux linkage of the permanent magnet, v be the speed of the permanent magnet linear synchronous motor 6, and i be the flux linkage of the permanent magnet. d Let i be the d-axis current. q U is the q-axis current. d U is the d-axis voltage. q This is the q-axis voltage;

[0052] Based on the principles of energy conservation and electromagnetic power characteristics, the electromagnetic thrust F required for the operation of the permanent magnet linear synchronous motor 6 is obtained. e for:

[0053]

[0054] Since the permanent magnet linear synchronous motor 6 has a salient pole structure, then L d =L q L d L is the armature inductance along the d-axis. q Let i be the q-axis armature inductance. d If = 0, then the above expression can be expressed as:

[0055]

[0056] In the formula: K f Where p is the thrust coefficient and p is the number of pole pairs;

[0057] According to Newton's second law, the net external force on a moving object is equal to the product of its effective mass and acceleration. Therefore, the mechanical motion model of the permanent magnet linear synchronous motor 6 is as follows:

[0058]

[0059] In the formula: F l The load for the permanent magnet linear synchronous motor 6 is f, where f is the frictional force and B is the load. v F is the coefficient of viscous friction. d External interference;

[0060] Based on the mechanical motion model of the permanent magnet linear synchronous motor 6, and combining the basic mathematical relationships between motor displacement, velocity, and acceleration, the mechanical motion model of the permanent magnet linear synchronous motor 6 can be expressed as a displacement parameter model:

[0061]

[0062] In the formula: F ∑ For nonlinear interference terms, The first derivative of the motor position. F is the second derivative of the position of the permanent magnet linear synchronous motor 6, and m is the load mass; where F Σ The main manifestations are the differences in the magnitude of the load mass m and the differences in the load on the two permanent magnet linear synchronous motors 6 on the Y-axis caused by load position disturbances.

[0063] The position tracking error state equation of one of the permanent magnet linear synchronous motors 6 is as follows:

[0064]

[0065] In the formula: x d Let x represent the desired synchronous position of the two permanent magnet linear synchronous motors 6, and let e represent the position tracking error of a single permanent magnet linear synchronous motor 6. The first derivative of the position tracking error. The first derivative of the desired synchronization position, The first derivative of the position of a single permanent magnet linear synchronous motor 6;

[0066] Determine the state equations of the second-order sliding mode control basis:

[0067]

[0068] In the formula: x is the system state variable, x∈R n u is the system control input, and S(t,x) is the system sliding mode variable. Let f(t,x) be the first derivative of the system state variable, f(t,x) be the control system, g(t,x) be the nonlinear control gain, and S be the modal variable value.

[0069] If a system satisfies the closed-loop stability condition and the system's sliding modal variable S(t,x) has an r-th derivative, then the system is said to have r-th order sliding motion if the system's state space satisfies the following conditions.

[0070] Specifically, when r = 2, we have The system then possesses a second-order sliding mode. Second-order sliding mode is a special form of higher-order sliding mode. Compared with traditional modes, it has strong robustness and is insensitive to external disturbances. It can effectively eliminate the control chattering problem of traditional modes. Compared with higher-order sliding mode control, second-order sliding mode controllers have a fixed and accurate expression method and a simple structure, making it the most widely used higher-order sliding mode control scheme.

[0071] Design the sliding surface function based on the second-order sliding mode control basis state equations:

[0072]

[0073] In the formula: c is the control gain coefficient;

[0074] Sliding mode control is essentially a variable structure control method. It calculates the state equations of the control system, analyzes and selects sliding mode state variables closely related to the control output. During actual control, the sliding mode controller continuously switches the sliding mode approaching rule based on the calculated state variables, ensuring that the system control quantity always approaches the sliding surface along the updated switching rule. For complex controlled objects and control systems, sliding mode control does not require system identification; the sliding trajectory is only related to the sliding surface structure and the system state equations. The most significant characteristic of sliding mode control is its strong robustness, exhibiting strong resistance to disturbances and model errors in the controlled object. It is a typical nonlinear system control method.

[0075] Based on the displacement parameter model of the permanent magnet linear synchronous motor 6, we have:

[0076]

[0077] In the formula: The second derivative of the desired synchronization position, This is the second derivative of the position tracking error;

[0078] To eliminate high-frequency chattering, the approach rate function H of the position slip mode controller 10 adopts an exponential approach rate function:

[0079]

[0080] ε>0, k>0

[0081] The power-law rule for the rate of convergence function is expressed as:

[0082]

[0083] k>0, 0<α<1

[0084] This approach rate, by adjusting α and k, can realize the approach speed of the system state variables to the sliding surface, thus eliminating chattering;

[0085] Combining the power-law approach rule of the approach rate function, the single-position sliding mode control rate is derived as follows:

[0086]

[0087] In the formula: ε and k are the gain coefficients of the corresponding control quantities, α is the exponent, and s is the displacement;

[0088] The mathematical expression for the position slip mode controller 10 is obtained as follows:

[0089]

[0090] Based on Lyapunov stability analysis, the Lyapunov function is taken as V′=(1 / 2)s 2 If the derivative of V′ is less than 0, the system is stable. Therefore, the mathematical expression for the position slip mode controller 10 can be obtained as follows:

[0091]

[0092] In the formula: Let sgn(s) be the first derivative of the displacement, and let sgn(s) be the sign function of the displacement.

[0093] The design process of the speed loop sliding mode controller 12 in step S3 is as follows:

[0094] Based on the state equations of the second-order sliding mode control basis, the following relationship holds:

[0095]

[0096] In the formula: v d To achieve the desired synchronization speed;

[0097] The mathematical expression for the velocity slip mode controller 12, calculated using the exponential rate of convergence function, is as follows:

[0098]

[0099] The design methods for the position loop cross-coupled controller 9 in step S2 and the velocity loop cross-coupled controller 11 in step S3 are as follows:

[0100] The position tracking error of a single permanent magnet linear synchronous motor 6 is defined as e. i :

[0101] e i =x d -x i

[0102] In the formula, x d x represents the desired synchronization position of the two permanent magnet linear synchronous motors 6. i Position feedback for a single permanent magnet linear synchronous motor 6;

[0103] Based on the synchronization error and the position tracking error of a single permanent magnet linear synchronous motor 6, the dual-axis synchronization error is established as follows:

[0104]

[0105] In the formula: ε1 and ε2 are the dual-axis synchronization errors of the two permanent magnet linear synchronous motors 6, and e1 and e2 are the position tracking errors of the two permanent magnet linear synchronous motors 6.

[0106] Then we have Ξ = [ε1ε2] T E = [e1e2]

[0107] Where: Ξ is the transpose of the position tracking error matrix, E is the position tracking error matrix, and T is a square matrix;

[0108] To reduce position tracking and synchronization errors, a position coupling error E is established. ah for:

[0109]

[0110] Combining the position tracking error of a single permanent magnet linear synchronous motor 6, the dual-axis synchronization error, and the position coupling error E ah The mathematical expression for the position loop cross-coupled controller 9 or the velocity loop cross-coupled controller 11 is calculated as follows:

[0111] E ah =(I+βT)E

[0112] In the formula: β is the coupling coefficient, I is the identity matrix, and (I+βT) is a positive definite matrix.

[0113] The present invention provides a dual-motor synchronous control method for a vehicle-mounted scissor lift platform. This method fully considers the position and speed characteristics of the permanent magnet linear synchronous motor 6. The position loop cross-coupled controller 9 and the speed loop cross-coupled controller 11 in the controller effectively reduce the synchronization error caused by inter-axis coupling through the cross-coupling control algorithm. Furthermore, by utilizing the strong robustness of sliding mode control, the position loop sliding mode controller 10 and the speed loop sliding mode controller 12 are used to eliminate external interference of the permanent magnet linear synchronous motor 6, thereby enhancing the anti-disturbance performance of the entire lift platform. The dual-axis cross-coupling synchronization algorithm enables high-speed and high-precision synchronous operation of the vehicle-mounted scissor lift platform under heavy load conditions.

[0114] The embodiments described above are merely illustrative of specific implementations of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A vehicle-mounted scissor lift platform, comprising a base (1), four lifting rods (7) rectangularly distributed on the base (1), a platform (2) mounted on the top of the four lifting rods (7), two lifting systems, and a controller, wherein the lifting rods (7) are extendable and retractable in the vertical direction; each lifting system comprises a permanent magnet linear synchronous motor (6) mounted on the base (1), a ball screw pair (3) connected to the output shaft of the permanent magnet linear synchronous motor (6), a linear guide rail (4) mounted on one side of the ball screw pair (3), and a scissor lift device (8), wherein the scissor lift device (8) is connected to the platform (2), and the permanent magnet linear synchronous motor (6) drives the two moving ends below the scissor lift device (8) to move towards or away from each other along the linear guide rail (4) through the ball screw pair (3), thereby causing the platform (2) to rise or fall in the vertical direction, characterized in that: The controller includes a position loop cross-coupled controller (9), a position loop sliding mode controller (10), a velocity loop cross-coupled controller (11), a velocity loop sliding mode controller (12), and a current PID controller (13) connected in sequence. The two input terminals of the position loop cross-coupled controller (9) are respectively connected to a preset desired position control signal. There are two position loop sliding mode controllers (10), each with its input terminals electrically connected to the output terminal of the position loop cross-coupled controller (9), and its output terminals electrically connected to the first and second input terminals of the velocity loop cross-coupled controller (11). There are two velocity loop sliding mode controllers (12) and two current PID controllers (13), with the input terminals of the two velocity loop sliding mode controllers (12) respectively connected to the velocity loop cross-coupled controller (9). The output terminal of the coupling controller (11) is electrically connected to two current PID controllers (13), and the output terminals of the two current PID controllers (13) are electrically connected to the control input terminals of two permanent magnet linear synchronous motors (6). The control output terminal of one of the permanent magnet linear synchronous motors (6) is electrically connected to the first input terminal of the position loop cross-coupling controller (9), the first input terminal of the speed loop cross-coupling controller (11), and the input terminal of the corresponding current PID controller (13). The control output terminal of the other permanent magnet linear synchronous motor (6) is electrically connected to the second input terminal of the position loop cross-coupling controller (9), the second input terminal of the speed loop cross-coupling controller (11), and the input terminal of the corresponding current PID controller (13).

2. The vehicle-mounted scissor lift platform according to claim 1, characterized in that: It also includes two speed reducers (61) mounted on the base (1), the input ends of the two speed reducers (61) are respectively connected to the output shafts of two permanent magnet linear synchronous motors (6), and the output shafts of the speed reducers (61) are connected to the corresponding ball screw pairs (3).

3. The vehicle-mounted scissor lift platform according to claim 2, characterized in that: It also includes a slider (5); the slider (5) includes a first slider (51) and a second slider (52); each ball screw pair (3) is screwed with two first sliders (51), the two first sliders (51) have opposite rotation directions, and the first sliders (51) slide in cooperation with the linear guide (4); Each scissor lift device (8) includes multiple X-shaped forks, each fork including two hinge rods (81), the two hinge rods (81) are hinged in the middle; multiple forks are hinged from top to bottom to form the scissor lift device (8), the bottom ends of the two hinge rods (81) of the fork at the bottom are the moving ends, which are respectively hinged to two first sliders (51); two second sliders (52) are slidably assembled at the bottom of the platform (2), and the top ends of the two hinge rods (81) of the fork at the top are respectively hinged to the two second sliders (52).

4. A dual-motor synchronous control method for a vehicle-mounted scissor lift platform as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. The position feedback signals of the two permanent magnet linear synchronous motors (6) are compared with the desired position control signal and then transmitted to the position loop cross-coupled controller (9) respectively; S2. The position loop cross-coupled controller (9) processes the two position feedback information through the cross-coupled control algorithm and then inputs them into the two position loop sliding mode controllers (10). After processing, the desired speed control signal is output. S3. The two desired speed control signals are compared with the corresponding two motor feedback speed signals and then input into the speed loop cross-coupling controller (11). The speed loop cross-coupling controller (11) is processed by the cross-coupling control algorithm and then input into the corresponding two speed loop sliding mode controllers (12). The two speed loop sliding mode controllers (12) output two current signals after processing. S4. The two current signals are compared with the corresponding two motor feedback current signals and then output to the two current PID controllers (13) respectively; S5. After processing by the two current PID controllers (13), each controller outputs a control signal. Each control signal is superimposed with the external disturbance and output to the corresponding permanent magnet linear synchronous motor (6) to control its speed, so that the speeds of the two permanent magnet linear synchronous motors (6) are synchronized, thus completing the dual-motor synchronous control.

5. The dual-motor synchronous control method for the vehicle-mounted scissor lift platform according to claim 4, characterized in that: The mathematical expression of the position slip mode controller (10) in step S2 is: In the formula: Let s be the first derivative of the displacement, s be the displacement, ε and k be the gain coefficients of the corresponding control quantities, and sgn(s) be the sign function of the displacement.

6. The dual-motor synchronous control method for the vehicle-mounted scissor lift platform according to claim 5, characterized in that: The mathematical expression of the speed loop mode controller (12) in step S3 is: Where: m is the load mass, K f Where is the thrust coefficient, c is the control gain coefficient, and B is the thrust coefficient. v Here, v is the coefficient of viscous friction, and v is the speed of the permanent magnet linear synchronous motor (6). This is the first derivative of the position tracking error.

7. The dual-motor synchronous control method for the vehicle-mounted scissor lift platform according to claim 6, characterized in that: The mathematical expressions for the position loop cross-coupled controller (9) in step S2 and the velocity loop cross-coupled controller (11) in step S3 are as follows: AND ah =(I+βT)E In the formula: β is the coupling coefficient, I is the identity matrix, T is a square matrix, (I+βT) is a positive definite matrix, and E is the position tracking error matrix.

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