A robot polishing and finishing terminal three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator

Abstract

The application belongs to the technical field of mechanical transmission devices, and discloses a robot polishing and grinding terminal three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator, which is a series-parallel hybrid variable stiffness structure, a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, and a carefully designed structural member and peripheral sensor system. The application realizes three-degree-of-freedom stiffness independent adjustment and driving force decoupling control. Through the series-parallel hybrid variable stiffness structure design, the Z-direction unit and the X-Y plane parallel system are separated in the structure level, and through the parallel configuration of the electromagnetic spring unit and the voice coil direct-drive motor unit, the equivalent stiffness adjustment and the active driving force output in each direction are independent of each other, so that the stiffness coupling problem in the traditional parallel mechanism is avoided, and the continuous adjustable stiffness and high-precision force control output in the three-degree-of-freedom directions are realized.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the technical field of mechanical transmission devices, and particularly relates to a three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator for the end effector of a robot grinding and polishing device. Background Technology

[0002] In the field of robotic contact machining, especially in complex surface grinding, deburring, and precision polishing, end effectors not only need to achieve stable contact force control but also need to possess a certain degree of compliance in multiple directions to adapt to changes in workpiece curvature and machining errors. Traditional industrial robots mostly adopt rigid drive structures, that is, to transmit motion and force through a "motor + reducer + transmission mechanism + load" approach. This type of structure has the advantages of high rigidity and high control precision, but it lacks inherent compliance. When contact impact occurs, it is difficult to achieve energy buffering and absorption, which can easily lead to a decrease in machining quality or even damage to the workpiece.

[0003] To improve contact performance, existing technologies have proposed floating grinding devices or elastic compensation mechanisms, typically employing single-degree-of-freedom floating structures or simple spring-buffered structures. However, these structures mostly provide passive compliance in only one direction, making it difficult to adapt to multi-directional coupled force conditions during the processing of complex curved surfaces, and failing to meet the requirements of high-precision grinding and polishing for independent control of the three-dimensional force field.

[0004] In the design of three-degree-of-freedom force-controlled actuators, existing solutions mainly include two types: series structure and parallel structure.

[0005] (1) Series structure: Multiple drive units are connected in series. The structure is simple, but the upper drive needs to bear all the loads of the lower drive, resulting in excessive load on the first motor, increased overall system mass, and decreased dynamic response performance.

[0006] (2) Parallel structure: It has the advantages of compact structure and high load-bearing capacity, but its kinematic and mechanical characteristics have obvious coupling problems. Stiffness adjustment is often difficult to achieve independent control between degrees of freedom. The control algorithm is complicated and the system stability is reduced.

[0007] In addition, existing variable stiffness actuators mostly use mechanical spring preload adjustment, lever mechanisms or flexible hinges to achieve stiffness changes. Their adjustment range is limited, their response speed is slow, and it is difficult to achieve continuous and controllable adjustment. Moreover, existing electromagnetic drive technology is mostly used for drive output, rather than simultaneously undertaking the dual functions of "active drive + variable stiffness adjustment". An integrated structure that decouples stiffness and driving force in multiple degrees of freedom has not yet been formed.

[0008] Therefore, in complex contact operation scenarios such as robotic grinding and polishing, there is an urgent need for a series-parallel hybrid electromagnetic variable stiffness actuator structure that meets the following requirements:

[0009] (1) Possesses three degrees of freedom of motion capability;

[0010] (2) The stiffness of each degree of freedom can be adjusted independently and continuously;

[0011] (3) The driving force output and stiffness adjustment are decoupled from each other;

[0012] (4) The structure is compact and the load distribution is reasonable;

[0013] (5) It can achieve active compliant drive. Summary of the Invention

[0014] This invention provides a three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator for robotic grinding and polishing ends, overcoming the technical defects of existing multi-degree-of-freedom force-controlled actuators, such as severe degree-of-freedom coupling, inability to independently adjust stiffness, unreasonable drive load distribution, and difficulty in balancing high precision and compliance. The core of this invention lies in constructing a three-degree-of-freedom series-parallel hybrid variable stiffness architecture and designing a corresponding electromagnetic direct-drive structure based on this. The series-parallel hybrid variable stiffness architecture achieves structural decoupling of the three degrees of freedom through a hierarchical configuration of a first-level series drive unit and a second-level parallel drive unit. Simultaneously, the parallel configuration of the electromagnetic spring unit and the voice coil direct-drive motor unit ensures that the drive force output and equivalent stiffness adjustment of each degree of freedom are independent, thereby achieving continuous adjustable stiffness and active drive coordinated control of the three degrees of freedom. This comprehensive technical feature makes the actuator flexible, efficient, and adaptable in the field of robotics.

[0015] The present invention is implemented as follows: a three-degree-of-freedom serial-parallel hybrid electromagnetic variable stiffness actuator for robot grinding and polishing end effector. The device is a serial-parallel hybrid variable stiffness architecture, a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, and a carefully designed structural component and peripheral sensor system.

[0016] The aforementioned series-parallel hybrid variable stiffness architecture is constructed by three sets of direct-drive variable stiffness base units connected in series and parallel.

[0017] The direct-drive variable stiffness base unit consists of a linear kinematic pair and a variable stiffness spring, which are connected in parallel.

[0018] Furthermore, the series-parallel hybrid configuration of the direct-drive variable stiffness base unit is a first-level drive unit connected in series with a second-level drive unit; wherein, the direct-drive variable stiffness base unit composed of linear kinematic pair 102 and variable stiffness spring 101 is a first-level drive unit, and the direct-drive variable stiffness base unit composed of linear kinematic pair 104 and variable stiffness spring 103 and the direct-drive variable stiffness base unit composed of linear kinematic pair 105 and variable stiffness spring 106 are connected in parallel to form a second-level drive unit.

[0019] The first-level drive unit is used to realize linear motion with a single degree of freedom and adjustable stiffness, and the second-level drive unit is used to realize linear motion with a two degree of freedom and adjustable stiffness.

[0020] The degree of freedom of motion of the first-level drive unit, i.e., the z-direction, is perpendicular to the degree of freedom of motion of the second-level drive unit, i.e., the xy-plane, when connected in series.

[0021] Furthermore, the aforementioned series-parallel hybrid variable stiffness architecture includes a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, and an external sensing system.

[0022] Furthermore, the primary drive unit is designed as a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, and the primary drive unit is designed as a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module.

[0023] Furthermore, the single-degree-of-freedom electromagnetic direct drive variable stiffness module includes a base 201, a Z electromagnetic spring stator 202, a Z electromagnetic spring mover 203, a Z mover structural component 204, a Z voice coil direct drive motor mover 205, a Z voice coil direct drive motor stator 206, and a Z linear slide rail slider 207.

[0024] The Z electromagnetic spring stator 202 and the Z voice coil direct drive motor stator 206 are fixedly connected in parallel to the base 201 to form a single-degree-of-freedom electromagnetic direct drive variable stiffness module stator.

[0025] The Z electromagnetic spring mover 203 and the Z voice coil direct drive motor mover 205 are simultaneously fixed to the Z mover structural component 204, forming a single-degree-of-freedom electromagnetic direct drive variable stiffness module mover.

[0026] The single-degree-of-freedom sliding between the mover and stator of the single-degree-of-freedom electromagnetic direct drive variable stiffness module is achieved by the Z linear slide rail slider 207.

[0027] The base 201 has a three-sided enclosure structure, with the inner sides of the two opposing sides used to install the Z-linear slide rail slider 207.

[0028] Furthermore, the two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module includes an X electromagnetic spring base 301, an X linear slide rail slider 302, a parallel linkage structure - an X electromagnetic spring 303, an X electromagnetic spring stator 304, an X electromagnetic spring mover 305, a total parallel linkage structure 306, a Y linkage linear slide rail slider group 307, an X linkage linear slide rail slider 308, and a parallel linkage structure - an X voice coil direct-drive motor 309. Mover 310, X voice coil direct drive motor stator 311, X voice coil direct drive motor base 312, Y electromagnetic spring base 313, Y electromagnetic spring stator 314, Y electromagnetic spring mover 315, parallel linkage structure component - Y voice coil direct drive motor 316, Y voice coil direct drive motor stator 317, Y voice coil direct drive motor mover 318, Y voice coil direct drive motor base 319, parallel linkage structure component - Y electromagnetic spring 320, Y linear slide rail slider 321.

[0029] Furthermore, the X electromagnetic spring base 301 and the X voice coil direct drive motor base 312 are arranged opposite to each other and fixedly installed on both sides of the Z-moving substructure 204, thereby forming an X direct drive variable stiffness base unit symmetrically arranged along the X direction, and making the single-degree-of-freedom electromagnetic direct drive variable stiffness module and the two-degree-of-freedom parallel electromagnetic direct drive variable stiffness module present a series structure.

[0030] Furthermore, the X electromagnetic spring stator 304 is fixedly installed on the X electromagnetic spring base 301, while the X voice coil direct drive motor stator 311 is fixedly installed on the X voice coil direct drive motor base 312.

[0031] Furthermore, the X linear slide rail slider 302 and the X linkage linear slide rail slider 308 are respectively disposed on different connecting surfaces of the total parallel linkage structure 306, which are used to limit the degree of freedom of movement in the X direction and provide low-friction linear guidance; one end of the parallel linkage structure - X voice coil direct drive motor 309 is connected to the total parallel linkage structure 306, and the other end is connected to the X voice coil direct drive motor mover 310.

[0032] Furthermore, the Y electromagnetic spring base 313 and the Y voice coil direct drive motor base 319 are arranged opposite to each other and form a Y direct drive variable stiffness base unit symmetrically arranged along the Y direction.

[0033] The Y-linkage linear slide rail slider group 307 and the Y-linear slide rail slider 321 are respectively used to limit the degree of freedom of movement in the Y direction and provide low-friction linear guidance.

[0034] The Y-direction and X-direction are connected in the same way. The Y electromagnetic spring mover 315 and the Y electromagnetic spring stator 314 constitute an electromagnetic spring. The Y voice coil direct drive motor mover 318 and the Y voice coil direct drive motor stator 317 constitute a drive unit. They are connected to the total parallel linkage structure 306 through the parallel linkage structure component - Y electromagnetic spring 320 and the parallel linkage structure component - Y voice coil direct drive motor 316.

[0035] The total parallel linkage structure 306 serves as a force gathering and transmission component. Its center is connected to the Z-moving substructure 204. It is used to superimpose the electromagnetic stiffness force and active driving force in the X and Y directions in parallel and output them to the end effector structure.

[0036] By changing the magnitude of the current flowing through the stator of the electromagnetic spring, the equivalent stiffness in each direction can be changed independently; by changing the direction and amplitude of the stator current in the voice coil direct drive motor, the driving force output in each direction can be controlled independently.

[0037] The peripheral sensor system includes a force sensor 402 and a laser displacement sensor 401. Precise force control and displacement control can be achieved through feedback from the force sensor and the displacement sensor.

[0038] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0039] First, it achieves independent adjustable stiffness and decoupled control of driving force in three degrees of freedom. This invention utilizes a series-parallel hybrid variable stiffness architecture design to achieve functional separation between the Z-direction unit and the XY-plane parallel system at the structural level. Simultaneously, through the parallel configuration of the electromagnetic spring unit and the voice coil direct-drive motor unit, the equivalent stiffness adjustment and active driving force output in each direction are made independent, thus avoiding the stiffness coupling problem in traditional parallel mechanisms and achieving continuously adjustable stiffness and high-precision force control output in all three degrees of freedom.

[0040] This invention improves the dynamic response performance and structural compactness of the system. It replaces the traditional "motor + reducer" transmission structure with an electromagnetic direct drive method, reducing mechanical transmission chains and intermediate links, lowering backlash and hysteresis effects, and significantly improving the system's dynamic response speed. Simultaneously, the series-parallel hybrid layered configuration optimizes load distribution while ensuring load-bearing capacity, reducing the load pressure on the first-stage drive unit, making the overall structure more compact and stable.

[0041] Enhancing environmental adaptability and engineering application value. By adjusting the stiffness in three degrees of freedom in real time, the system can dynamically change the equivalent stiffness level according to the contact state and processing stage, achieving impact buffering and energy absorption while ensuring trajectory accuracy, thereby significantly improving the processing consistency and surface quality of complex curved surface grinding and polishing operations; this structure can also be extended to fields such as precision assembly, collaborative robots, and high-precision force control operation, and has good prospects for promotion and application.

[0042] Secondly, as supporting evidence of the inventiveness of this invention, it is also reflected in the following important aspects:

[0043] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are as follows: The present invention constructs a three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator, which enables the robot to achieve independent and continuous adjustment of multi-directional contact stiffness and rapid response of active driving force in complex curved surface grinding and polishing operations, thereby significantly improving processing accuracy and stability, reducing manual intervention and repeated repairs, and improving overall production efficiency; Since the non-contact force adjustment method of electromagnetic spring and voice coil direct drive motor is adopted, the wear and gap problems in the traditional mechanical deceleration and elastic compensation structure are avoided, which helps to reduce maintenance costs and extend the service life of equipment; At the same time, this technology can be extended to fields with high requirements for force control performance, such as precision assembly, medical robots, collaborative robots and micro-operating systems, and has significant industrialization potential and commercial promotion value.

[0044] (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad: At present, most existing robot end effectors adopt single-degree-of-freedom floating structures or traditional rigid drive structures, which are difficult to achieve structural decoupling, independent stiffness adjustment and decoupling control of driving force output in three-degree-of-freedom space at the same time. Although existing parallel mechanisms have high load-bearing capacity, they generally have the problems of severe stiffness coupling and difficulty in adjustment. The present invention, through a hybrid architecture design combining first-level series and second-level parallel, and introducing electromagnetic springs and voice coil direct drive units in parallel configuration, constructs a complete three-degree-of-freedom electromagnetic variable stiffness realization path at the structural level and driving principle level, forming a new actuator system with both structural compactness and control independence, filling the technical gap in the system integration of multi-degree-of-freedom electromagnetic adjustable stiffness actuators.

[0045] (3) Whether the technical solution of the present invention solves the technical problem that people have long wanted to solve but have never been able to solve: In the field of robot contact processing, there has long been a contradiction between high stiffness to ensure positioning accuracy and high compliance to adapt to environmental changes. Traditional structures often have to make compromises between the two and it is difficult to achieve dynamic balance in the same actuator. The present invention achieves real-time continuous adjustment of equivalent stiffness through electromagnetic springs and achieves rapid active drive through direct drive motors, so that the system can dynamically adjust the stiffness level according to the processing stage and contact state, thereby achieving impact buffering and force stability control while ensuring trajectory accuracy, breaking through the technical bottleneck that it is difficult to balance high precision control and compliance.

[0046] (4) Does the technical solution of the present invention overcome technical bias? Traditional view generally holds that multi-degree-of-freedom parallel mechanisms inevitably have stiffness coupling problems, and high-precision actuators must adopt high-rigidity designs and it is difficult to introduce adjustable compliance mechanisms. At the same time, it is believed that variable stiffness structures will increase system complexity and reduce response performance. The present invention achieves functional separation of each degree of freedom in structure through a series-parallel hybrid layered configuration design. It achieves stiffness adjustment and decoupling control of drive output through the parallel combination of electromagnetic springs and voice coil direct drive units. It fundamentally changes the traditional understanding that stiffness and precision cannot be achieved at the same time, and proves that under a reasonable architecture design, high precision, fast response and adjustable compliance can be unified in the same system, thereby overcoming the long-standing technical bias of structural design. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of a series-parallel hybrid variable stiffness architecture provided by the present invention;

[0048] Figure 2 This is a schematic diagram of the single-degree-of-freedom electromagnetic direct-drive variable stiffness module structure provided by the present invention;

[0049] Figure 3 This is a schematic diagram of the two-degree-of-freedom electromagnetic direct-drive variable stiffness module structure provided by the present invention;

[0050] Figure 4 This is a schematic diagram of the axonal structure of the XY dual-degree-of-freedom precision motion mechanism provided by the present invention.

[0051] Figure 5 This is a schematic diagram of a three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator for the end effector of a robot grinding and polishing process provided by the present invention.

[0052] Figure 6 This is a physical image of the three-degree-of-freedom series-parallel hybrid electromagnetic variable stiffness actuator for robot grinding and polishing end provided by the present invention.

[0053] Figure 7 This is a physical image of the prototype provided by this invention.

[0054] Figure 8 This is a graph showing the performance test results of the three-degree-of-freedom force-controlled actuator provided by the present invention.

[0055] In the diagram: 101: Variable stiffness spring; 102: Linear kinematic pair; 103: Variable stiffness spring; 104: Linear kinematic pair; 105: Linear kinematic pair; 106: Variable stiffness spring; 201: Base; 202: Z electromagnetic spring stator; 203: Z electromagnetic spring mover; 204: Z mover structural component; 205: Z voice coil direct drive motor mover; 206: Z voice coil direct drive motor stator; 207: Z linear slide rail slider; 301: X electromagnetic spring base; 302: X linear slide rail slider; 303: Parallel linkage structural component - X electromagnetic spring; 304: X electromagnetic spring stator; 305: X electromagnetic spring mover; 306: Total parallel linkage structural component; 307: Y linkage 308: X-linkage linear slide rail slider assembly; 309: Parallel linkage structure - X-voice coil direct drive motor; 310: X-voice coil direct drive motor mover; 311: X-voice coil direct drive motor stator; 312: X-voice coil direct drive motor base; 313: Y-electromagnetic spring base; 314: Y-electromagnetic spring stator; 315: Y-electromagnetic spring mover; 316: Parallel linkage structure - Y-voice coil direct drive motor; 317: Y-voice coil direct drive motor stator; 318: Y-voice coil direct drive motor mover; 319: Y-voice coil direct drive motor base; 320: Parallel linkage structure - Y-electromagnetic spring; 321: Y-linear slide rail slider; 401: Laser displacement sensor; 402: Force sensor. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0057] The present invention is implemented as follows: a three-degree-of-freedom serial-parallel hybrid electromagnetic variable stiffness actuator for robot grinding and polishing end effector, characterized by a serial-parallel hybrid variable stiffness architecture, a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, and a carefully designed structural component and peripheral sensor system.

[0058] like Figure 1As shown, a series-parallel hybrid variable stiffness architecture is constructed by three sets of direct-drive variable stiffness base units connected in series and parallel. Each direct-drive variable stiffness base unit consists of a linear kinematic pair and a variable stiffness spring, and their combination is in parallel. The series-parallel hybrid connection of the direct-drive variable stiffness base units is a first-level drive unit connected in series with a second-level drive unit. Among them, the direct-drive variable stiffness base unit composed of linear kinematic pair 102 and variable stiffness spring 101 is the first-level drive unit, and the direct-drive variable stiffness base unit composed of linear kinematic pair 104 and variable stiffness spring 103 and the direct-drive variable stiffness base unit composed of linear kinematic pair 105 and variable stiffness spring 106 are connected in parallel to form the second-level drive unit.

[0059] The first-level drive unit is used to realize linear motion with a single degree of freedom and adjustable stiffness, and the second-level drive unit is used to realize linear motion with a two degree of freedom and adjustable stiffness. The degree of freedom of the first-level drive unit is the z-direction, which is perpendicular to the degree of freedom of the second-level drive unit when connected in series, i.e., the xy-plane.

[0060] A series-parallel hybrid variable stiffness architecture includes a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, and an external sensing system; the first-level drive unit is designed as a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, and the first-level drive unit is designed as a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module.

[0061] like Figure 2 As shown, the single-degree-of-freedom electromagnetic direct drive variable stiffness module includes a base 201, a Z electromagnetic spring stator 202, a Z electromagnetic spring mover 203, a Z mover structural component 204, a Z voice coil direct drive motor mover 205, a Z voice coil direct drive motor stator 206, and a Z linear slide rail slider 207.

[0062] The Z electromagnetic spring stator 202 and the Z voice coil direct drive motor stator 206 are fixedly connected in parallel to the base 201 to form a single-degree-of-freedom electromagnetic direct drive variable stiffness module stator.

[0063] The Z electromagnetic spring mover 203 and the Z voice coil direct drive motor mover 205 are simultaneously fixed to the Z mover structural component 204 to form a single-degree-of-freedom electromagnetic direct drive variable stiffness module mover.

[0064] The single-degree-of-freedom sliding between the mover and stator of the single-degree-of-freedom electromagnetic direct drive variable stiffness module is achieved by the Z linear slide rail slider 207;

[0065] The base 201 has a three-sided enclosure structure, with the inner sides of the two opposing sides used to install the Z linear slide rail slider 207;

[0066] like Figure 3As shown, the two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module includes an X electromagnetic spring base 301, an X linear slide rail slider 302, a parallel linkage structure - X electromagnetic spring 303, an X electromagnetic spring stator 304, an X electromagnetic spring mover 305, a total parallel linkage structure 306, a Y linkage linear slide rail slider group 307, an X linkage linear slide rail slider 308, a parallel linkage structure - X voice coil direct drive motor 309, an X voice coil direct drive motor mover 310, an X voice coil direct drive motor stator 311, an X voice coil direct drive motor base 312, a Y electromagnetic spring base 313, a Y electromagnetic spring stator 314, a Y electromagnetic spring mover 315, a parallel linkage structure - Y voice coil direct drive motor 316, a Y voice coil direct drive motor stator 317, a Y voice coil direct drive motor mover 318, a Y voice coil direct drive motor base 319, a parallel linkage structure - Y electromagnetic spring 320, and a Y linear slide rail slider 321.

[0067] The X electromagnetic spring base 301 and the X voice coil direct drive motor base 312 are arranged opposite to each other and fixedly installed on both sides of the Z-moving substructure 204, thereby forming an X direct drive variable stiffness base unit symmetrically arranged along the X direction, and making the single-degree-of-freedom electromagnetic direct drive variable stiffness module and the two-degree-of-freedom parallel electromagnetic direct drive variable stiffness module present a series structure.

[0068] The X electromagnetic spring stator 304 is fixedly installed on the X electromagnetic spring base 301, while the X voice coil direct drive motor stator 311 is fixedly installed on the X voice coil direct drive motor base 312.

[0069] The X linear slide rail slider 302 and the X linkage linear slide rail slider 308 are respectively disposed on different connecting surfaces of the total parallel linkage structure 306, which are used to limit the degree of freedom of movement in the X direction and provide low-friction linear guidance; one end of the parallel linkage structure - X voice coil direct drive motor 309 is connected to the total parallel linkage structure 306, and the other end is connected to the X voice coil direct drive motor mover 310.

[0070] The Y electromagnetic spring base 313 and the Y voice coil direct drive motor base 319 are arranged opposite to each other and form a Y direct drive variable stiffness base unit symmetrically arranged along the Y direction.

[0071] The Y-linkage linear slide rail slider group 307 and the Y-linear slide rail slider 321 are respectively used to limit the degree of freedom of movement in the Y direction and provide low-friction linear guidance.

[0072] The Y-direction and X-direction are connected in the same way. The Y electromagnetic spring mover 315 and the Y electromagnetic spring stator 314 constitute an electromagnetic spring. The Y voice coil direct drive motor mover 318 and the Y voice coil direct drive motor stator 317 constitute a drive unit. They are connected to the total parallel linkage structure 306 through the parallel linkage structure component - Y electromagnetic spring 320 and the parallel linkage structure component - Y voice coil direct drive motor 316.

[0073] The total parallel linkage structure 306 serves as a force gathering and transmission component. Its center is connected to the Z-moving substructure 204. It is used to superimpose the electromagnetic stiffness force and active driving force in the X and Y directions in parallel and output them to the end effector structure.

[0074] By changing the magnitude of the current flowing through the stator of the electromagnetic spring, the equivalent stiffness in each direction can be changed independently; by changing the direction and amplitude of the stator current in the voice coil direct drive motor, the driving force output in each direction can be controlled independently.

[0075] like Figure 4 and Figure 5 As shown, the integrated structure includes a force sensor (402) and a laser displacement sensor (401). Precise force control and displacement control can be achieved through feedback from the force sensor and the displacement sensor.

[0076] This series-parallel hybrid variable stiffness architecture consists of a primary drive unit and a secondary drive unit connected in series. The primary drive unit realizes single-degree-of-freedom motion and stiffness adjustment in the Z direction, while the secondary drive unit realizes dual-degree-of-freedom motion and stiffness adjustment in the X and Y planes. The two units are spatially perpendicular to each other, thus forming a three-degree-of-freedom spatial motion and variable stiffness output capability. Its working process is as follows:

[0077] In the primary drive unit, the Z electromagnetic spring stator 202 and the Z voice coil direct drive motor stator 206 are fixedly mounted on the base 201, forming a stable stator section. The Z electromagnetic spring mover 203 and the Z voice coil direct drive motor mover 205 are jointly fixed to the Z mover structure 204, forming the mover section. The Z mover structure 204 forms a single-degree-of-freedom linear guide with the base 201 through the Z linear slide rail slider 207, thereby ensuring that the mover only performs low-friction linear motion along the Z direction. During operation, by adjusting the current flowing through the Z electromagnetic spring stator 202, the electromagnetic force exerted by the electromagnetic spring on the Z electromagnetic spring mover 203 can be changed, thereby achieving continuous adjustment of the equivalent stiffness in the Z direction. Simultaneously, by adjusting the current direction and amplitude of the Z voice coil direct drive motor stator 206, the Z voice coil direct drive motor mover 205 generates a corresponding driving force, driving the Z mover structure 204 to displace along the Z direction, achieving coordinated control of active drive and stiffness adjustment.

[0078] In the secondary drive unit, both the X and Y directions are constructed using parallel direct-drive variable stiffness base units with symmetrical structures. Taking the X direction as an example, the X electromagnetic spring base 301 and the X voice coil direct-drive motor base 312 are fixedly installed on both sides of the Z-mover structure 204, allowing the entire secondary drive unit to move synchronously with the primary drive unit. The X electromagnetic spring stator 304 is installed on the X electromagnetic spring base 301, and the X voice coil direct-drive motor stator 311 is installed on the X voice coil direct-drive motor base 312; the corresponding X electromagnetic spring mover 305 and X voice coil direct-drive motor mover 310 are connected to the total parallel linkage structure 306 through the parallel linkage structure - X electromagnetic spring 303 and the parallel linkage structure - X voice coil direct-drive motor 309. The total parallel linkage structure 306 is guided by the X linear slide rail slider 302 and the X linkage linear slide rail slider 308, allowing movement only in the X direction. The equivalent stiffness in the X direction can be adjusted by regulating the current of the X electromagnetic spring stator 304; the driving force in the X direction can be output by regulating the current of the X voice coil direct drive motor stator 311.

[0079] The Y-direction structure is consistent with the X-direction structure, consisting of a Y electromagnetic spring base 313, a Y electromagnetic spring stator 314, a Y electromagnetic spring mover 315, a Y voice coil direct drive motor stator 317, a Y voice coil direct drive motor mover 318, and corresponding parallel linkage components. Guided movement along the Y direction only is achieved through the Y-linkage linear slide rail slider group 307 and the Y linear slide rail slider 321. Stiffness is adjusted by controlling the current of the Y electromagnetic spring stator 314, and drive output is achieved by controlling the current of the Y voice coil direct drive motor stator 317.

[0080] During the overall operation, the parallel linkage structure 306 serves as the force convergence and transmission node. Its center is connected to the Z-moving sub-structure 204, which parallel and superimposes the driving forces and electromagnetic stiffness forces in the X and Y directions, and outputs them as a whole with the Z-direction movement, thereby realizing three-degree-of-freedom spatial motion and independently adjustable stiffness in each direction. In the peripheral sensing system, the laser displacement sensor 401 is used to detect displacement changes in each direction, and the force sensor 402 is used to detect the output force. Through feedback, precise control of the driving force and stiffness in each direction is achieved.

[0081] Evidence related to the technical effects obtained by the embodiments of the present invention.

[0082] This invention has built a prototype, such as Figure 7 .

[0083] Experimental results are as follows Figure 8As shown, the data curves are stable and controllable, with small tracking errors and fast dynamic response. Coupling interference between degrees of freedom is effectively suppressed, and the decoupling effect is significant. Simultaneously, the device can achieve precise force output, wide-range continuous stiffness adjustment, and high-precision position tracking. The test results fully verify the feasibility and superiority of the proposed structural scheme and control strategy, proving that the device possesses excellent force control stability, variable stiffness adaptive capability, and high-precision position control performance. Its overall comprehensive control performance is good, meeting the requirements for flexible operation and precision grinding and polishing of composite materials under complex working conditions.

[0084] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A robotic grinding and polishing end effector, characterized in that, include: A single-stage drive unit enables single-degree-of-freedom linear motion and adjustable stiffness; A two-stage drive unit enables two-degree-of-freedom linear motion and adjustable stiffness; The motion degree of freedom direction of the first-level drive unit is perpendicular to the motion degree of freedom plane of the second-level drive unit; The primary drive unit and the secondary drive unit are connected in series. The secondary drive unit is composed of two direct-drive variable stiffness base units connected in parallel, and the motion degrees of freedom of the two direct-drive variable stiffness base units are perpendicular to each other. Each direct-drive variable stiffness base unit consists of a linear kinematic pair and a variable stiffness spring connected in parallel.

2. The robotic grinding and polishing end effector according to claim 1, characterized in that, The primary drive unit is a single-degree-of-freedom electromagnetic direct drive variable stiffness module, which includes a base, a Z electromagnetic spring stator, a Z electromagnetic spring mover, a Z mover structural component, a Z voice coil direct drive motor mover, a Z voice coil direct drive motor stator, and a Z linear slide rail slider. The Z electromagnetic spring stator and the Z voice coil direct drive motor stator are fixedly connected in parallel to the base to form a primary drive unit stator; The Z electromagnetic spring mover and the Z voice coil direct drive motor mover are simultaneously fixedly connected to the Z mover structure to form a first-stage drive unit mover. The single-degree-of-freedom sliding between the mover of the first-stage drive unit and the stator of the first-stage drive unit is achieved by the Z-linear slide rail slider.

3. The robotic grinding and polishing end effector according to claim 1, characterized in that, The secondary drive unit is a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, including an X electromagnetic spring base, an X linear slide rail slider, a parallel linkage structure - X electromagnetic spring, X electromagnetic spring stator, X electromagnetic spring mover, a total parallel linkage structure, a Y linkage linear slide rail slider group, an X linkage linear slide rail slider, a parallel linkage structure - X voice coil direct drive motor, X voice coil direct drive motor mover, X voice coil direct drive motor stator, X voice coil direct drive motor base, a Y electromagnetic spring base, a Y electromagnetic spring stator, a Y electromagnetic spring mover, a parallel linkage structure - Y voice coil direct drive motor, Y voice coil direct drive motor stator, Y voice coil direct drive motor mover, Y voice coil direct drive motor base, a parallel linkage structure - Y electromagnetic spring, and a Y linear slide rail slider.

4. The robotic grinding and polishing end effector according to claim 3, characterized in that, The X electromagnetic spring base is positioned opposite to the X voice coil direct drive motor base and is fixedly installed on both sides of the Z-moving substructure to form an X direct drive variable stiffness base unit symmetrically arranged along the X direction. The X electromagnetic spring stator is fixedly installed on the X electromagnetic spring base, and the X voice coil direct drive motor stator is fixedly installed on the X voice coil direct drive motor base. The X-linear slide rail slider and the X-linkage linear slide rail slider are respectively disposed on different connecting surfaces of the total parallel linkage structure to limit the X-direction motion degree of freedom. One end of the parallel linkage structure - the X voice coil direct drive motor - is connected to the total parallel linkage structure, and the other end is connected to the X voice coil direct drive motor mover.

5. The robotic grinding and polishing end effector according to claim 3, characterized in that, The Y electromagnetic spring base and the Y voice coil direct drive motor base are arranged opposite to each other, forming a Y direct drive variable stiffness base unit symmetrically arranged along the Y direction; The Y-linkage linear slide rail slider group and the Y-linear slide rail slider are respectively used to limit the degree of freedom of movement in the Y direction; The total parallel linkage structure serves as a force convergence and transmission component, and its center is connected to the Z-moving sub-structure. By changing the magnitude of the current flowing through the electromagnetic spring stator, the equivalent stiffness in each direction can be changed independently; by changing the direction and amplitude of the current in the voice coil direct drive motor stator, the driving force output in each direction can be controlled independently. The actuator also includes a peripheral sensing system, which includes a force sensor and a laser displacement sensor. Force control and displacement control are achieved through feedback from the force sensor and the laser displacement sensor.

6. A series-parallel hybrid variable stiffness architecture for robotic grinding and polishing ends, characterized in that, include: 3 sets of direct-drive variable stiffness base elements; Of the three sets of direct-drive variable stiffness base units, one set serves as a first-level drive unit, and the remaining two sets are connected in parallel to form a second-level drive unit. The primary drive unit and the secondary drive unit are connected in series. The motion degree of freedom direction of the first-level drive unit is perpendicular to the motion degree of freedom plane of the second-level drive unit; Each direct-drive variable stiffness base unit consists of a linear kinematic pair and a variable stiffness spring connected in parallel.

7. The series-parallel hybrid variable stiffness architecture according to claim 6, characterized in that, The first-level drive unit has a linear motion degree of freedom in the Z direction, and the second-level drive unit has two linear motion degrees of freedom in the XY plane, with the Z direction perpendicular to the XY plane.

8. The series-parallel hybrid variable stiffness architecture according to claim 6, characterized in that, The first-level drive unit realizes single-degree-of-freedom linear motion and adjustable stiffness, and the second-level drive unit realizes two-degree-of-freedom linear motion and adjustable stiffness; the first-level drive unit is a single-degree-of-freedom electromagnetic direct-drive variable stiffness module, and the second-level drive unit is a two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module.

9. A driving and stiffness control method for a three-degree-of-freedom electromagnetic variable stiffness actuator, characterized in that, Includes the following steps: One single-degree-of-freedom electromagnetic direct-drive variable stiffness module and one two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module are connected in series, and the motion degree-of-freedom direction of the single-degree-of-freedom electromagnetic direct-drive variable stiffness module is perpendicular to the motion degree-of-freedom plane of the two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module. Inside the two-degree-of-freedom parallel electromagnetic direct-drive variable stiffness module, two direct-drive variable stiffness base units are set in parallel, and the motion degree-of-freedom directions of the two direct-drive variable stiffness base units are perpendicular to each other. In each direct-drive variable stiffness base unit, linear kinematic pairs and variable stiffness springs are combined in parallel to achieve independent control of motion output and stiffness output.

10. The driving and stiffness control method for a three-degree-of-freedom electromagnetic variable stiffness actuator according to claim 9, characterized in that, It also includes the following steps: By changing the magnitude of the current flowing through the electromagnetic spring stator, the equivalent stiffness in each direction of motion can be changed independently. By changing the current direction and current amplitude of the voice coil direct drive motor stator, the driving force output in each direction of motion can be independently controlled. Closed-loop regulation of force control and displacement control is achieved through feedback from force sensors and laser displacement sensors.

Images