Control method of three-degree-of-freedom folding structure performance device

Abstract

The invention discloses a control method of a three-degree-of-freedom folding structure control performance device, and belongs to the field of stage machinery and intelligent control. The device comprises a rotating base, a three-stage nested folding arm, a transition crank arm linkage mechanism, an overturning platform and a closed-loop servo system. The three-degree-of-freedom composite motion of horizontal rotation, large-stroke lifting and large-angle overturning is achieved through the rotary base, the three-section folding arm, crank arm sliding and hinging composite transmission. Performing error compensation on the three-stage hydraulic cylinder by using a double-channel real-time calibration algorithm, wherein the tail end inclination angle error is less than or equal to + / -2mm; the overall thickness after folding is not more than 0.4 m, and the space utilization rate is increased by not less than 40%; the method comprises the following steps of: setting C1 as a constant; counting delta C2 and C3; introducing a time-varying weight Ci (t) to carry out error compensation; and carrying out PID (Proportion Integration Differentiation) servo control. The problems that a traditional folding structure is small in freedom degree, poor in collaboration, large in occupied space and large in error accumulation are solved, and the folding structure is suitable for multiple scenes such as stages, exhibition, rescue and movies and televisions.

Description

Technical Field

[0001] This invention relates to the field of stage machinery and intelligent control technology, and in particular to a control method for a three-degree-of-freedom folding structure performance device. Background Technology

[0002] Traditional folding structures are limited by single / double degrees of freedom and low spatial efficiency, such as large unfolded volume and excessive folding redundancy, which severely restricts stage layout. At the same time, the lack of coordinated control between multiple folding points leads to the accumulation and amplification of errors, asynchronous movement of multi-level structures, and consequently, the end stage body is affected by joint linkage errors during movement, resulting in tilting, swaying, inaccurate positioning, and the inability to achieve multi-dimensional dynamic joint control such as large-stroke lifting and large-angle rotation. Summary of the Invention

[0003] The purpose of this invention is to provide a control method for a three-degree-of-freedom folding structure performance device, thereby solving the aforementioned problems existing in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A control method for a three-degree-of-freedom folding structure performance device is performed according to the following steps:

[0006] a) Set the extension / retraction length C1 of the first-stage hydraulic cylinder to a predetermined trajectory constant;

[0007] b) Based on the spatial kinematics model, calculate the change in the second-stage expansion length ΔC2 and the third-stage expansion length C3 from C1, which satisfy the following:

[0008] Δc²=b²E+|[b² 2 -a1 2 +(b2E) 2 ]|

[0009]

[0010] Where E represents the constant value for calculation;

[0011] c) A dual-channel real-time calibration algorithm is introduced, using C1 as the reference, and time-varying weights α(t) and β(t) are used to weighted compensate for the second and third stage length errors, where...

[0012] The dual-channel real-time calibration algorithm model is as follows:

[0013]

[0014]

[0015] In the formula, α(t) is the time-varying weight used to calibrate the positional deviation between the second-level telescopic length and the first-level telescopic length, and β(t) is the time-varying weight used to calibrate the positional deviation between the third-level telescopic length and the first-level telescopic length.

[0016] Among them, the value of the time-varying weight

[0017] Where α0 is the initial error of the second stretching length, β0 represents the real-time cumulative error of the dynamic changes between the second and first telescopic lengths, and β0 represents the initial error of the third telescopic length. This represents the real-time cumulative error of the dynamic changes between the third and first telescopic lengths.

[0018] d) The calibrated target length is converted into a servo valve control signal to drive the three-stage hydraulic cylinder to extend and retract in coordination, so that the end-til tilting platform can achieve a composite trajectory of horizontal rotation, vertical lifting and tilting, and the tilt angle error is ≤ ±2mm.

[0019] Furthermore, the functional relationship in step b) is achieved through the following mechanical structure:

[0020] Transitional articulated arm linkage mechanism: The lower end of the articulated arm is hinged to the second-stage piston rod and embedded in the first-stage linear slide, while the upper end is hinged to the middle of the second-stage folding arm, forming a sliding-hinged composite transmission.

[0021] Nested retraction structure: The second-stage hydraulic cylinder is fully embedded inside the first-stage folding arm and arranged parallel to the curved arm;

[0022] Triangular hinge layout: The two ends of the curved arm are respectively hinged to the upper and lower folding arms, and the included angle θ is maintained at 30°–150° to balance torque and stability.

[0023] Furthermore, the closed-loop feedback chain in step c) includes:

[0024] Displacement sensor: monitors the displacement of piston rods in each stage of hydraulic cylinders, with an accuracy of ±0.1mm;

[0025] Tilt sensor: detects the real-time tilt angle of the tilting platform with an accuracy of ±0.05°;

[0026] Encoder: Records the rotation angle of the rotating base with a resolution of 0.01°;

[0027] If any sensor feedback value deviates from the threshold, the time-varying weights α(t) and β(t) are dynamically updated.

[0028] Furthermore, the vertical lifting height H(t) of the composite trajectory is calculated using the geometric parameters of the folding arm:

[0029] H(t)=L1·sinθ1(t)+L2·sinθ2(t)+Δh,

[0030] Where L1 and L2 are the effective lengths of the first and second level folding arms, θ1 and θ2 are the real-time folding angles, and Δh is the platform hinge compensation height.

[0031] Furthermore, it also includes: a pre-start self-test procedure: detecting the zero-point deviation of C1, C2, and C3 and the integrity of sensor signals;

[0032] If the self-test fails, the system will automatically limit the maximum tilt angle of the tilting platform to 10° and output a fault code, then enter safe mode.

[0033] Furthermore, the method is applicable to stage machinery scenarios, including:

[0034] Large-stroke lifting and tilting combined motions within a limited space;

[0035] Multi-level folding structure with synchronous control improves space utilization by ≥40%;

[0036] The dynamic trajectory script can be called repeatedly, supporting quick switching for different performance needs.

[0037] Furthermore, the servo valve control signal is generated through PID mapping:

[0038]

[0039] Where Kp, Ki, and Kd are preset closed-loop parameters, and ΔC i (t) represents the calibration value at level i.

[0040] The beneficial effects of this invention are:

[0041] This invention proposes a control method for a three-degree-of-freedom folding structure performance device. Through the combined action of a rotating base and a three-section folding structure, the device can achieve complex trajectory movements with three degrees of freedom. This solves the problems of limited motion dimensions and insufficient precision caused by the limited degrees of freedom, poor coordination, and error accumulation in traditional equipment. It achieves high-precision three-degree-of-freedom coordinated motion control of the folding structure within a limited space. The optimized structure of this method reconstructs the flexibility of the stage layout, expands space utilization, and its control method reduces the cumulative error of the folding structure, enabling various complex movements in multiple dimensions and angles, and improving the coordinated control accuracy of the three-degree-of-freedom folding structure. Attached Figure Description

[0042] Figure 1 This is a diagram of the control method for the reconfigurable three-degree-of-freedom folding performance device of the present invention;

[0043] Figure 2This is a simplified diagram of the dynamic expansion and contraction relationship of the three-level folding structure of the present invention;

[0044] Figure 3 This is a schematic diagram of the reconfigurable three-degree-of-freedom folding performance device of the present invention;

[0045] Figure 4 This is a complete control flow diagram of the three-degree-of-freedom folding structure of the present invention.

[0046] In the attached diagram, 100 is the rotating base; 110 is the third hinge pin; 210 is the first folding arm; 213 is the fourth hinge pin; 220 is the second folding arm; 222 is the fifth hinge pin; 300 is the tilting platform; 310 is the central hinge seat; 410 is the first-stage hydraulic cylinder; 420 is the second-stage hydraulic cylinder; 430 is the third-stage hydraulic cylinder; 501 is the first hinge pin; and 510 is the articulated arm. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] Reference Figure 1 , Figure 2 and Figure 3 The control method for the three-degree-of-freedom folding structure performance device shown is performed according to the following steps:

[0049] S100, Set the extension / retraction length C1 of the first-stage hydraulic cylinder to a predetermined trajectory constant;

[0050] S200. Based on the spatial kinematics model, calculate the change in the second-stage expansion length ΔC2 and the third-stage expansion length C3 using C1, which satisfy...

[0051] Δc²=b²E+|[b² 2 -a1 2 +(b2E) 2 ]|

[0052]

[0053] Where E represents the constant value for calculation;

[0054] S300 introduces a dual-channel real-time calibration algorithm. Using C1 as the reference, it employs time-varying weights α(t) and β(t) to weighted compensate for the second and third stage length errors.

[0055] The dual-channel real-time calibration algorithm model is as follows:

[0056]

[0057] In the formula, α(t) is the time-varying weight used to calibrate the positional deviation between the second-level telescopic length and the first-level telescopic length, and β(t) is the time-varying weight used to calibrate the positional deviation between the third-level telescopic length and the first-level telescopic length.

[0058] Among them, the value of the time-varying weight

[0059] Where α0 is the initial error of the second extension length. β0 represents the real-time cumulative error of the dynamic changes between the second and first telescopic lengths, and β0 represents the initial error of the third telescopic length. This represents the real-time cumulative error of the dynamic changes between the third and first telescopic lengths.

[0060] S400 converts the calibrated target length into a servo valve control signal, driving the three-stage hydraulic cylinder to extend and retract in tandem, enabling the end-of-line tilting platform to achieve a composite trajectory of horizontal rotation, vertical lifting and tilting, with an tilt angle error ≤ ±2mm.

[0061] Furthermore, the functional relationship in step S200 is achieved through the following mechanical structure:

[0062] Transitional articulated arm linkage mechanism: The lower end of the articulated arm is hinged to the second-stage piston rod and embedded in the first-stage linear slide, while the upper end is hinged to the middle of the second-stage folding arm, forming a sliding-hinged composite transmission.

[0063] Nested retraction structure: The second-stage hydraulic cylinder is fully embedded inside the first-stage folding arm and arranged parallel to the curved arm;

[0064] Triangular hinge layout: The two ends of the curved arm are respectively hinged to the upper and lower folding arms, and the included angle θ is maintained at 30°–150° to balance torque and stability.

[0065] Furthermore, the closed-loop feedback link in step S300 includes:

[0066] Displacement sensor: monitors the displacement of piston rods in each stage of hydraulic cylinders, with an accuracy of ±0.1mm;

[0067] Tilt sensor: detects the real-time tilt angle of the tilting platform with an accuracy of ±0.05°;

[0068] Encoder: Records the rotation angle of the rotating base with a resolution of 0.01°;

[0069] If any sensor feedback value deviates from the threshold, the time-varying weights α(t) and β(t) are dynamically updated.

[0070] Furthermore, the vertical lifting height H(t) of the composite trajectory is calculated using the geometric parameters of the folding arm:

[0071] H(t)=L1·sinθ1(t)+L2·sinθ2(t)+Δh,

[0072] Where L1 and L2 are the effective lengths of the first and second level folding arms, θ1 and θ2 are the real-time folding angles, and Δh is the platform hinge compensation height.

[0073] Furthermore, it also includes:

[0074] Pre-start self-test procedure: checks the zero-point deviation of C1, C2, and C3 and the integrity of sensor signals;

[0075] If the self-test fails, the system will automatically limit the maximum tilt angle of the tilting platform to 10° and output a fault code, then enter safe mode.

[0076] Furthermore, the method is applicable to stage machinery scenarios, including:

[0077] Large-stroke lifting and tilting combined motions within a limited space;

[0078] Multi-level folding structure with synchronous control improves space utilization by ≥40%;

[0079] The dynamic trajectory script can be called repeatedly, supporting quick switching for different performance needs.

[0080] Furthermore, the servo valve control signal is generated through PID mapping:

[0081]

[0082] Where Kp, Ki, and Kd are preset closed-loop parameters, and ΔC i (t) represents the calibration value at level i.

[0083] Figure 4 The complete control flow of a three-degree-of-freedom folding structure performance device was demonstrated, covering the entire process from system startup to the realization of complex movements on the end platform. The following is a detailed description:

[0084] 1. System startup

[0085] System power-on: The device is powered on and all system modules are initialized.

[0086] Initialization: Configure registers, communication links, and clock synchronization to ensure the system is in its initial state.

[0087] 2. Self-test module

[0088] Zero-position detection: Check whether each stage of the hydraulic cylinder is in its initial position.

[0089] Sensor testing: Verify the signal integrity of displacement sensors, tilt sensors, and encoders.

[0090] Communication testing: Confirm whether the internal communication links of the system are normal.

[0091] 3. Self-inspection result judgment

[0092] Normal: Proceed to the next step and set the first-level trajectory.

[0093] Abnormal: Enters safety mode, limits the maximum tilt angle of the flipping platform to ±10°, and triggers the alarm light.

[0094] 4. Set the first-level trajectory

[0095] Set C1: Set the extension and retraction length C1 of the first-stage hydraulic cylinder to a predetermined trajectory constant.

[0096] 5. Spatial kinematics calculation

[0097] Calculate ΔC2 and C3: Based on the spatial kinematics model, calculate the change in the second-stage expansion length ΔC2 and the third-stage expansion length C3 from C1.

[0098] Formula: Δc2=b2E+|[b2 2 -a1 2 +(b2E) 2 ]|

[0099]

[0100] 6. Dual-channel real-time calibration

[0101] Weight update: Time-varying weights are used to compensate for the length errors of the second and third levels.

[0102] 7. PID control law

[0103] Generate control signals: Generate servo valve control signals based on the PID control law.

[0104] 8. Servo valve drive

[0105] Hydraulic cylinder coordinated extension and retraction: The control signal is converted into a servo valve drive signal to drive the coordinated extension and retraction of three-stage hydraulic cylinders.

[0106] 9. Real-time feedback from multiple sensors

[0107] Displacement sensor: monitors the displacement of piston rods in each stage of hydraulic cylinders with an accuracy of ±0.1mm.

[0108] Tilt sensor: detects the real-time tilt angle of the flipping platform with an accuracy of ±0.05°.

[0109] Encoder: Records the rotation angle of the rotating base with a resolution of 0.01°.

[0110] 10. Error Judgment

[0111] Error detection: Determine whether the tilt angle error of the end platform is ≤ ±2mm.

[0112] Yes: Continue executing the trajectory.

[0113] No: Return to the dual-channel real-time calibration module, recalculate the weights, and update the control signal.

[0114] 11. Trajectory Completion Judgment

[0115] End of trajectory: Determines whether the trajectory is complete.

[0116] Yes: Enter mechanical lock and power failure protection.

[0117] No: Return to the first-level trajectory setting module and continue executing the next trajectory.

[0118] 12. Mechanical locking and power failure protection

[0119] Locking: The mechanical locking device locks the end platform.

[0120] Power outage: The system loses power and enters a safe state.

[0121] 13. Safe Mode

[0122] Abnormal handling: If the self-test fails, enter the safety mode, limit the maximum tilt angle of the flipping platform to ±10°, and trigger the alarm light.

[0123] In yet another embodiment, the reconfigurable three-degree-of-freedom folding performance device of this application includes the following structure:

[0124] The rotating base 100 is used to provide the first degree of freedom, namely horizontal rotational motion;

[0125] The folding arm system includes a first folding arm 210, a second folding arm 220, and an end tilting platform 300 that are pivotally connected vertically in sequence, for providing a second degree of freedom, namely vertical lifting and lowering, and a third degree of freedom, namely pitch and tilting.

[0126] The hydraulic actuator system includes at least a first-stage hydraulic cylinder 410, a second-stage hydraulic cylinder 420 and a third-stage hydraulic cylinder 430. The hydraulic cylinders are coupled to the folding arm system through hinge nodes to drive the folding / unfolding and flipping of the folding arm system.

[0127] The transition articulated arm-slide rail mechanism is used to convert the linear displacement of the second-stage hydraulic cylinder 420 into the angular displacement of the second-section folding arm 220;

[0128] The error self-calibration control unit is connected in communication with the hydraulic actuation system. It is used to perform closed-loop compensation on the extension and retraction trajectories of each hydraulic cylinder based on a real-time error weight model, so as to achieve three-degree-of-freedom coordinated motion.

[0129] This system mainly consists of the following five parts:

[0130] 1. Rotating base 100

[0131] Function: Provides the first degree of freedom—horizontal rotational motion.

[0132] Structural composition:

[0133] Slewing bearing: Fixed to the ground foundation, bearing the weight of the entire device;

[0134] Servo rotary drive: Built inside the slewing bearing, it drives the rotating base to achieve 360° continuous rotation through gear meshing;

[0135] Third hinge pin 110: used to connect to the tail end of the first-stage hydraulic cylinder 410 to form a lever fulcrum.

[0136] 2. Folding arm system

[0137] It consists of a first folding arm 210, a second folding arm 220 and an end flipping platform 300, which are sequentially hinged together, providing a second degree of freedom for vertical lifting and a third degree of freedom for pitching and flipping.

[0138] The first folding arm 210 is a box-type truss structure with an internal cavity for housing the second-stage hydraulic cylinder 420. The lower end is hinged to the rotating base via a hinge seat. The middle and lower part is hinged to the piston rod of the first-stage hydraulic cylinder 410 via a fourth hinge pin 213, forming a cross lever structure to amplify the output torque. The inner side wall is equipped with a linear slide rail to guide the sliding of the transition curved arm 510.

[0139] The second folding arm 220: its upper end is hinged to the center of the tilting platform 300 through the fifth hinge pin 222; its middle part is hinged to the upper end of the transition curved arm 510 through the second hinge pin 502, forming a triangular hinge structure to improve rigidity; the side wall is provided with a hinge seat for connecting the tail end of the cylinder body of the third-stage hydraulic cylinder 430.

[0140] The flipping platform 300 has a central hinge seat 310 that is hinged to the top of the second folding arm; an ear plate at the bottom that is hinged to the piston rod of the third-stage hydraulic cylinder 430; the platform adopts a modular design, consisting of a central frame and detachable side wing modules, and the platform area can be quickly adjusted by a quick-lock pin; a MEMS tilt sensor is installed on the bottom surface for real-time monitoring of the platform tilt angle.

[0141] 3. The hydraulic actuation system includes three sets of hydraulic cylinders, each driving three degrees of freedom of motion:

[0142] The first-stage hydraulic cylinder 410 is installed between the rotating base and the first folding arm to drive the first folding arm to lift and lower, thereby achieving lifting and lowering motion.

[0143] The second-stage hydraulic cylinder 420 is installed inside the cavity of the first folding arm and is used to transition the articulated arm 510 to drive the second folding arm to unfold / fold.

[0144] The third-stage hydraulic cylinder 430 is installed between the second folding arm and the tilting platform to tilt the platform and achieve pitch tilting.

[0145] The second-stage hydraulic cylinder 420 adopts a nested retractable structure, which is completely hidden inside the first folding arm, saving space.

[0146] All hydraulic cylinders are equipped with magnetostrictive displacement sensors for real-time detection of piston rod displacement.

[0147] 4. Transition articulated arm-slide rail mechanism

[0148] Composition: Curved arm 510: The lower end slides on the linear guide rail of the first folding arm, and the upper end is hinged to the middle of the second folding arm;

[0149] First hinge pin 501: connects the lower end of the crank arm to the piston rod of the second-stage hydraulic cylinder;

[0150] Second hinge pin 502: connects the upper end of the curved arm to the middle of the second folding arm;

[0151] Function: Converts the linear displacement of the second-stage hydraulic cylinder into the angular displacement of the second-section folding arm to achieve folding / unfolding action;

[0152] Structural advantages: The articulated arm, the first folding arm, and the second folding arm form a triangular hinge structure, which improves the stiffness and stability of torque conversion.

[0153] 5. Error self-calibration control unit

[0154] Composition: Magnetostrictive displacement sensor: installed on the outer wall of each hydraulic cylinder barrel to detect piston rod displacement;

[0155] MEMS tilt sensor: Installed on the bottom of the tilting platform to detect the tilt angle of the platform;

[0156] Absolute encoder: Installed on the servo rotary drive to detect the rotation angle;

[0157] Control unit: Based on a real-time error weighting model, closed-loop compensation is used to compensate for the extension and retraction trajectory errors of each stage of the hydraulic cylinder;

[0158] Function: To achieve three-degree-of-freedom coordinated motion control, with the tilt angle error of the end platform controlled within ±2mm.

[0159] Preferably, the second-stage hydraulic cylinder 420 is integrally embedded in the box-shaped cavity of the first folding arm 210, and its cylinder tail end is hinged to the rear end wall of the cavity. The piston rod end of the second-stage hydraulic cylinder 420 is hinged to the lower end of the transition arm-slide rail mechanism through the first hinge pin 501 so that it is completely hidden in the box-shaped cavity in the folded state.

[0160] The transition articulated arm-slide rail mechanism includes:

[0161] The lower end of the articulated arm 510 is slidably mounted on the linear slide rail of the first folding arm 210 and hinged to the piston rod end of the second-stage hydraulic cylinder 420, while the upper end is hinged to the middle of the second folding arm 220 via the second hinge pin 502.

[0162] The articulated arm 510, the first folding arm 210, and the second folding arm 220 form a triangular hinge structure to improve the torque conversion stiffness.

[0163] I. Nested and concealed structure of the second-stage hydraulic cylinder

[0164] The first folding arm 210 is a box-type truss structure with a through cavity inside; the second-stage hydraulic cylinder 420 is embedded in the cavity and arranged parallel to the arm body.

[0165] The cylinder body is hinged to the rear wall of the cavity via a hinge seat, forming a fixed fulcrum. The hinge seat adopts a double ear plate + pin structure, which allows the cylinder body to swing slightly around the vertical axis and absorb lateral forces.

[0166] The piston rod end is connected to the lower end of the transition crank arm 510 via a first hinge pin 501; the hinge pin is a floating structure, allowing the crank arm to slide slightly in the slide rail direction.

[0167] When the first folding arm is fully folded, the second-stage hydraulic cylinder is completely hidden inside the box-shaped cavity and is not exposed. The overall structure has no protruding parts, thus minimizing space.

[0168] II. Structural Composition of the Transition Crank Arm-Slide Rail Mechanism

[0169] The curved arm 510 is an irregular curved arm structure. Its upper end is hinged to the middle of the second folding arm 220 through the second hinge pin 502, and its lower end is provided with a slider embedded in the linear slide rail 211 of the first folding arm. The curved arm slides in the slide rail and rotates around the pin, forming a sliding-hinged composite motion.

[0170] The linear guide rail 211 is a double-row linear guide rail, fixed to the inner wall of the first folding arm. The slider is hinged to the lower end of the curved arm. The length of the guide rail = the effective stroke of the curved arm = the tangent function of the unfolding angle of the second folding arm. Mechanical limit blocks are provided at both ends of the guide rail to prevent overshoot.

[0171] Triangular hinge structure: The curved arm 510, the first folding arm 210 and the second folding arm 220 form a triangular hinge closed loop; this structure converts the linear thrust of the second-stage hydraulic cylinder into the angular displacement of the second folding arm, significantly improving the torque conversion stiffness and avoiding elastic deformation.

[0172] III. Coordinated Motion Process (Folding / Unfolding)

[0173] Unfolding process:

[0174] The piston rod of the second-stage hydraulic cylinder 420 extends, pushing the lower end of the crank arm 510 to slide forward along the linear slide rail 211;

[0175] The upper end of the curved arm drives the second folding arm 220 to rotate clockwise around its hinge point with the first folding arm, thus unfolding it;

[0176] The curved arm and the two folding arms form a triangular support, providing high rigidity and preventing swaying.

[0177] Folding process:

[0178] The piston rod of the second-stage hydraulic cylinder 420 retracts, and the lower end of the crank arm slides backward along the slide rail;

[0179] The upper end of the curved arm drives the second folding arm to rotate counterclockwise, thus achieving folding;

[0180] After the second-stage hydraulic cylinder is fully retracted, the entire unit is hidden inside the cavity of the first folding arm, reducing the size of the device by 30%.

[0181] Compared with traditional structures, the structure of this invention is as follows:

[0182] This invention features a nested and concealed hydraulic cylinder with no exposed parts; traditional structures use externally mounted hydraulic cylinders, resulting in a large volume. This invention employs a triangular hinge structure, increasing rigidity by 50%, while traditional structures use a single-point hinge, which is prone to swaying.

[0183] The motion of this invention is converted into a sliding-hinged composite transmission, which has high precision; the traditional structure is a direct hinge, which has large error.

[0184] The box-shaped cavity of this invention can be opened for inspection and maintenance; the traditional structure is an external structure that is easily damaged by collision.

[0185] Preferably, the tail end of the cylinder body of the first-stage hydraulic cylinder 410 is hinged to the front end of the upper surface of the rotating base 100 through the third hinge pin 110, and the piston rod end of the first-stage hydraulic cylinder 410 is hinged to the lower middle part of the first folding arm 210 through the fourth hinge pin 213, and is arranged in a cross lever arrangement with the first folding arm 210 to amplify the output torque.

[0186] The central hinge 310 of the tilting platform 300 is hinged to the top of the second folding arm 220 via the fifth hinge pin 222. The tail end of the cylinder of the third-stage hydraulic cylinder 430 is hinged to the side wall of the second folding arm 220, and the piston rod end of the third-stage hydraulic cylinder 430 is hinged to the bottom ear plate of the tilting platform 300, so as to independently drive the tilting platform 300 to pitch and tilt around the fifth hinge pin 222.

[0187] I. The "cross lever" arrangement structure of the first-stage hydraulic cylinder is as follows:

[0188] Cylinder tail end: Hinged to the front end of the upper surface of the rotating base 100 by the third hinge pin 110; the third hinge pin is a double ear plate + high-strength alloy steel pin structure, with a pin diameter ≥ φ40mm, allowing the cylinder to swing ±5° around the vertical axis to counteract lateral forces.

[0189] Piston rod end: Hinged to the lower part of the first folding arm 210 via the fourth hinge pin 213; the fourth hinge pin is located 1 / 3 below the center of gravity of the first folding arm, forming a lever fulcrum and amplifying the output torque of the hydraulic cylinder.

[0190] Movement process: The hydraulic cylinder extends → the first folding arm rotates counterclockwise around the bottom hinge point → achieving upward movement; the hydraulic cylinder retracts → the first folding arm rotates clockwise → achieving downward movement; the entire process is controlled by a closed-loop magnetostrictive displacement sensor, with a displacement error of <±1mm.

[0191] Preferably, the rotating base 100 includes:

[0192] Slewing bearing, fixed to the foundation surface;

[0193] The servo rotary drive, built into the slewing bearing, has its output gear meshing with the gear ring of the rotating base 100 to achieve 360° precise rotation;

[0194] The error self-calibration control unit includes:

[0195] Magnetostrictive displacement sensors are installed on the outer wall of the cylinder barrel of each hydraulic cylinder to detect the displacement of the piston rod in real time.

[0196] MEMS tilt sensors are installed on the bottom surface of the tilting platform 300 to detect the tilt angle of the platform in real time.

[0197] An absolute encoder, coaxially mounted on a servo rotary drive, is used to detect the rotation angle in real time.

[0198] All sensors are connected to the input terminal of the control unit via shielded cables.

[0199] I. The slewing bearing structure of the rotating base 100 includes:

[0200] The slewing bearing, which is a rolling element slewing bearing (also known as a slewing bearing), consists of an inner ring, an outer ring, rolling elements (balls / rollers), and spacers.

[0201] Load-bearing characteristics: It can simultaneously withstand axial load (equipment weight + load), radial load (lateral force) and overturning moment (eccentric load of the tilting platform), and is suitable for heavy-duty stage machinery.

[0202] Installation method: Vertical seat installation is adopted, and the inner ring is set with a positioning stop to ensure that the coaxiality between the rotating base and the foundation is ≤0.1mm, so as to avoid rotational wobble.

[0203] II. Servo Rotary Driver (Built-in)

[0204] Drive type: AC permanent magnet synchronous servo motor + planetary reducer integrated design, built into the center hole of the slewing bearing, forming a three-in-one drive unit of "motor-reducer-gear".

[0205] Transmission method: The output shaft of the servo motor is connected to a pinion (module m = 4~6), which meshes with the gear ring (internal or external gear) of the outer ring of the slewing bearing to form a gear-driven rotary mechanism;

[0206] Control Principle: The servo driver receives pulse and direction signals (or EtherCAT bus commands) and adjusts the motor speed and position in real time through a closed-loop PID algorithm to ensure that the rotation angle error is ≤ ±0.05°.

[0207] III. Sensor Configuration of the Error Self-Calibration Control Unit

[0208] Magnetostrictive displacement sensor: installed on the outer wall of the cylinder barrel of the first-stage hydraulic cylinder 410, the second-stage hydraulic cylinder 420, and the third-stage hydraulic cylinder 430;

[0209] MEMS tilt sensor: Installed at the center of the bottom surface of the 300-degree tilting platform, it adopts the principle of a three-axis MEMS accelerometer to detect the platform's pitch and roll angles in real time.

[0210] Absolute encoder: Coaxially mounted at the end of the servo rotary drive motor shaft, using photoelectric or magnetoelectric multi-turn absolute encoder;

[0211] Signal transmission: All sensors are connected to the distributed I / O module (such as Beckhoff EL series) via shielded twisted-pair cables, and then transmitted to the PLC or motion controller via EtherCAT or Profinet bus to avoid electromagnetic interference.

[0212] IV. Closed-loop control process (error self-calibration)

[0213] 1. Data acquisition: Magnetostrictive sensors provide real-time feedback on hydraulic cylinder displacement; tilt sensors provide feedback on platform attitude angle; encoders provide feedback on rotation angle.

[0214] 2. The error calculation controller compares the sensor feedback values ​​with the preset trajectory parameters (C1, ΔC2, C3) to calculate the displacement error and angle error.

[0215] 3. Weight calibration adopts a dual-channel real-time weight algorithm to dynamically adjust the opening of the hydraulic cylinder servo valve and compensate for cumulative errors.

[0216] 4. Real-time correction: When the error exceeds ±2mm displacement or ±0.5° (angle), the controller immediately recalculates the weights and updates the servo valve control signal until convergence.

[0217] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained:

[0218] This invention, through its three-degree-of-freedom integrated folding design, millisecond-level error self-calibration, and multiple safety redundancies, enables the device to achieve ±2mm end-positioning accuracy while reducing its footprint by 30%, completely eliminating the drawbacks of traditional stage machinery such as large size, simple movements, and error accumulation. The modular platform can expand its area in 30 seconds, and the quick-locking pin and drag chain system reduces maintenance time by 60%. It not only meets complex stage design concepts but also significantly reduces operating and relocation costs, truly achieving "small size, big movements, zero accidents, and low cost".

[0219] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for a three-degree-of-freedom folding structure performance device, characterized in that, Follow these steps: a) Set the extension / retraction length C1 of the first-stage hydraulic cylinder to a predetermined trajectory constant; b) Based on the spatial kinematics model, calculate the change in the second-stage expansion length ΔC2 and the third-stage expansion length C3 from C1, which satisfy the following: Δc2=b2E+|[b2 2 -a1 2 +(b2E) 2 ]| Where E represents the constant value for calculation; c) A dual-channel real-time calibration algorithm is introduced, using C1 as the reference, and time-varying weights α(t) and β(t) are used to weighted compensate for the second and third stage length errors, where... The dual-channel real-time calibration algorithm model is as follows: In the formula, α(t) is the time-varying weight used to calibrate the positional deviation between the second-level telescopic length and the first-level telescopic length, and β(t) is the time-varying weight used to calibrate the positional deviation between the third-level telescopic length and the first-level telescopic length. Among them, the value of the time-varying weight Where α0 is the initial error of the second extension length. β0 represents the real-time cumulative error of the dynamic changes between the second and first telescopic lengths, and β0 represents the initial error of the third telescopic length. This represents the real-time cumulative error of the dynamic changes between the third and first telescopic lengths. d) The calibrated target length is converted into a servo valve control signal to drive the three-stage hydraulic cylinder to extend and retract in coordination, so that the end-til tilting platform can achieve a composite trajectory of horizontal rotation, vertical lifting and tilting, and the tilt angle error is ≤ ±2mm.

2. The method according to claim 1, characterized in that, The functional relationship in step b) is achieved through the following mechanical structure: Transitional articulated arm linkage mechanism: The lower end of the articulated arm is hinged to the second-stage piston rod and embedded in the first-stage linear slide, while the upper end is hinged to the middle of the second-stage folding arm, forming a sliding-hinged composite transmission. Nested retraction structure: The second-stage hydraulic cylinder is fully embedded inside the first-stage folding arm and arranged parallel to the curved arm; Triangular hinge layout: The two ends of the curved arm are respectively hinged to the upper and lower folding arms, and the included angle θ is maintained at 30°–150° to balance torque and stability.

3. The method according to claim 2, characterized in that, The closed-loop feedback chain in step c) includes: Displacement sensor: monitors the displacement of piston rods in each stage of hydraulic cylinders, with an accuracy of ±0.1mm; Tilt sensor: detects the real-time tilt angle of the tilting platform with an accuracy of ±0.05°; Encoder: Records the rotation angle of the rotating base with a resolution of 0.01°; If any sensor feedback value deviates from the threshold, the time-varying weights α(t) and β(t) are dynamically updated.

4. The method according to any one of claims 1-3, characterized in that, The vertical lifting height H(t) of the composite trajectory is calculated from the geometric parameters of the folding arm: H(t)=L1·sinθ1(t)+L2·sinθ2(t)+Δh, Where L1 and L2 are the effective lengths of the first and second level folding arms, θ1 and θ2 are the real-time folding angles, and Δh is the platform hinge compensation height.

5. The method according to claim 4, characterized in that, Also includes: Pre-start self-test procedure: checks the zero-point deviation of C1, C2, and C3 and the integrity of sensor signals; If the self-test fails, the system will automatically limit the maximum tilt angle of the tilting platform to 10° and output a fault code, then enter safe mode.

6. The method according to claim 5, characterized in that, The method is applicable to stage machinery scenarios, including: Large-stroke lifting and tilting combined motions within a limited space; Multi-level folding structure with synchronous control improves space utilization by ≥40%; The dynamic trajectory script can be called repeatedly, supporting quick switching for different performance needs.

7. The method according to claim 6, characterized in that, The servo valve control signal is generated through PID mapping: Where Kp, Ki, and Kd are preset closed-loop parameters, and ΔC i (t) represents the calibration value at level i.

Images