A compound action manipulator based on single motor driving

Abstract

The application relates to a single-motor-driven composite action manipulator, which comprises a motor and a clamping jaw mechanism; a transmission device for realizing clamping, stretching or rotating composite action is arranged between the motor and the clamping jaw mechanism; the clamping jaw mechanism comprises a rotating support and a clamping jaw assembly; the transmission device comprises an external shell, a screw shaft and an electromagnetic clutch assembly; the outer wall of the screw shaft is provided with external threads which are engaged with the internal threads of a hollow output shaft; the lower end of the screw shaft is connected with the output shaft of the motor, and the upper end of the screw shaft is connected with and drives the clamping jaw mechanism; the electromagnetic clutch assembly is arranged in the shell and has a locking state and a releasing state; through the direct engagement of the through hollow shaft motor and the screw shaft and the double-stable state switching mechanism of the electromagnetic clutch assembly, only one motor can be used to alternately realize the radial clamping and loosening, overall rotation and axial stretching multiple working modes; compared with the multi-motor or pneumatic scheme, the structure is compact, and the energy consumption is significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of robotics or automated end effectors and multi-mode mechanical transmission technology, specifically relating to a robotic arm based on a single motor drive that can realize clamping, rotation and telescopic compound actions. Background Technology

[0002] In automated production and robotic gripping operations, end effectors typically need to perform two types of actions: workpiece clamping and attitude adjustment (rotation). Existing technologies mainly suffer from the following shortcomings: I. Complex Structures Due to Multi-Motor or Pneumatic Drive Systems. Most existing common gripper devices employ multiple independent motor drives or pneumatic systems to separately achieve clamping and rotation functions, resulting in a large overall structure, increased weight, complex control logic, and high energy consumption. Pneumatic grippers rely on an external air source, making precise position and force control difficult, and they cannot output rotational or telescopic movements. While multi-motor solutions can control clamping and rotation separately, they increase the inertia of the end effector, raising system cost and failure rate.

[0003] Second, the single-action mode lacks flexibility. Most existing gripper devices only have a single radial clamping function and cannot complete the forward and reverse adjustment or axial feed operation of the workpiece without changing tools. When the production line requires compound actions, an additional rotary platform or telescopic mechanism is often required, resulting in low system integration and high control difficulty.

[0004] III. Limitations of Existing Electromagnetic Clutch Grippers. For example, although the applicant's previous patent (CN223477669U) uses a single motor combined with an electromagnetic clutch assembly to achieve the switching between clamping and rotation functions, its technical solution has an interlocked connection between the gripper and the push-pull plate. After disassembling the gripper, the telescopic function cannot be realized, and only one mode of clamping and rotation can be realized; the axial movement stroke is extremely short (only about 10mm), which can only meet the opening and closing requirements of the gripper and cannot realize the long-stroke telescopic function; the connecting rod lever arm is short, and the clamping force is insufficient; it only has a rotation zero-point sensor and lacks a position sensor for telescopic control.

[0005] Therefore, there is an urgent need to develop a compact, multifunctional gripper device that can achieve clamping, rotation, and extension using only a single motor, and that supports flexible switching of operating modes by changing the end components, in order to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a composite motion manipulator that is compact, easy to control, and driven by only a single motor, in order to solve the problems of bulky structure, high energy consumption, and low integration caused by multiple power sources required for clamping, rotation, and telescopic movements in the prior art.

[0007] The specific technical solution is as follows: A single-motor driven robotic arm includes a motor and a gripper mechanism. A transmission device is provided between the motor and the gripper mechanism to achieve compound actions such as clamping, extension, or rotation. The gripper mechanism includes a rotating support and a gripper assembly. The output shaft of the motor has a hollow structure, and its inner wall has an internal thread. The transmission device includes an outer housing, a lead screw shaft, and an electromagnetic clutch assembly. The lead screw shaft has an external thread on its outer wall that meshes with the internal thread of the hollow output shaft. The lower end of the lead screw shaft is connected to the motor output shaft, and the upper end is connected to and drives the gripper mechanism. At least one guide groove is formed along the axial direction on the lead screw shaft. The rotating support has a guide groove for the lead screw shaft. The slotted sliding engagement boss enables the lead screw shaft and the rotating bracket to rotate synchronously and slide relative to each other axially. The electromagnetic clutch assembly is disposed within the housing and has a locked state and a released state. In the locked state, the rotation of the lead screw shaft is locked, and the motor drives the lead screw shaft to move axially. In the released state, the motor drives the rotating bracket to rotate synchronously with the lead screw shaft. The gripper assembly is detachably mounted on the front end of the lead screw shaft, converting the axial movement of the lead screw shaft into the radial opening and closing action of the gripper. After removing the gripper assembly, the front end of the lead screw shaft directly serves as an independent telescopic output end.

[0008] In a preferred embodiment of the present invention, the gripper assembly includes at least two grippers, a number of balance bars and connecting rods corresponding to the grippers; one end of the connecting rod is hinged to the front end of the lead screw shaft via a pin, and the other end is hinged to the balance bar via a pin; both ends of the balance bar are movably connected to the grippers and the rotating bracket, respectively, so that the axial movement of the lead screw shaft is converted into the radial opening and closing action of the grippers through the connecting rod and the balance bar; the gripper assembly is detachably mounted to the front end of the lead screw shaft via a snap ring.

[0009] In a preferred embodiment of the present invention, the electromagnetic clutch assembly includes a magnetic housing, a coil, a stationary friction plate, a clutch plate, a dynamic friction plate, an elastic element, and a rotating plate. The magnetic housing is fixed inside the housing, and the coil and the stationary friction plate are installed inside the magnetic housing. The clutch plate is fitted onto the lead screw shaft and rotates synchronously with the lead screw shaft via a boss that mates with the guide groove, and can slide axially. The dynamic friction plate is fixed to one side of the clutch plate. The elastic element is disposed between the clutch plate and the rotating plate, providing an elastic force to reset the clutch plate. When the coil is energized, the clutch plate is attracted, and the dynamic friction plate and the stationary friction plate are tightly fitted together, forming a locked state. When the coil is de-energized, the elastic element pushes the clutch plate to reset, and the dynamic friction plate and the rotating plate are fitted together, forming a released state.

[0010] As a preferred embodiment of the present invention, the elastic element is a spring ball plunger or a helical compression spring, and the number is three or more, and they are evenly distributed circumferentially between the clutch plate and the rotating plate.

[0011] As a preferred embodiment of the present invention, the magnetic shell is made of soft magnetic material. After the coil is energized, the magnetic field generated by the coil forms a closed magnetic circuit with the clutch plate through the magnetic shell, so that the clutch plate can be reliably engaged and the magnetic field utilization rate is high.

[0012] As a preferred embodiment of the present invention, an angle zero-point sensor and a position zero-point sensor are also provided inside the housing; the angle zero-point sensor is fixed inside the housing, and its sensing end faces the recessed feature provided on the clutch plate, for detecting the rotation angle zero point; the position zero-point sensor is fixed inside the housing, and its sensing end faces the axial limit position of the balance bar, for detecting the position zero point of the gripper; when the gripper assembly is removed, the sensing target of the position zero-point sensor is switched to the axial limit position of the telescopic output end accessory.

[0013] As a preferred embodiment of the present invention, the balance bar is provided with multiple pin holes in the middle. By selecting different pin holes to hinge with the connecting rod, the clamping force lever amplification ratio can be adjusted.

[0014] As a preferred embodiment of the present invention, the guide groove on the lead screw shaft has a rectangular cross section or a T-shaped cross section, and the number of guide grooves is at least one and is evenly distributed along the circumference.

[0015] As a preferred embodiment of the present invention, the motor is any one of a stepper motor, a servo motor, or a permanent magnet synchronous motor.

[0016] As a preferred embodiment of the present invention, it further includes a controller, which is electrically connected to the motor, the coil, the angle zero-point sensor and the position zero-point sensor; the controller automatically controls the on / off state of the coil and the forward / reverse rotation of the motor according to the feedback signals of the angle zero-point sensor and the position zero-point sensor, so as to realize the automatic switching between clamping and rotation actions.

[0017] Compared with the prior art, the present invention has the following advantages: 1. Single motor achieves compound actions. By directly meshing the through-type hollow shaft motor with the lead screw shaft and cooperating with the bistable switching mechanism of the electromagnetic clutch assembly, only one motor can alternately realize multiple working modes such as radial clamping and releasing, overall rotation and axial extension. Compared with multi-motor or pneumatic solutions, the structure is compact and energy consumption is significantly reduced.

[0018] 2. Flexible mode switching and wide range of applications. Adopting a modular, detachable gripper interface, the same device can be directly switched between two independent motion modes—axial extension and rotation—after removing the gripper assembly. The extension stroke can reach over 50mm, breaking through the technical limitation of traditional single-motor threaded drives that can only be used for short-stroke gripper opening and closing, significantly improving the operational adaptability and integration of single-power-source end effectors.

[0019] 3. Dual-sensor precise positioning. Equipped with an angle zero-point sensor (sensing the clutch plate's indentation feature) and a position zero-point sensor (sensing the position of the balance bar or telescopic output end), it simultaneously supports rotational closed-loop control and gripper or telescopic position detection, achieving precise closed-loop control of angle and position.

[0020] 4. Reliable magnetic circuit design. A magnetically conductive shell is used to form a closed magnetic circuit, resulting in high magnetic field utilization, rapid clutch response, and reliable operation.

[0021] 5. Modular structure for easy maintenance. The grippers, balance bar, and connecting rod are connected by pins, allowing for quick disassembly and replacement; the multi-hole design in the middle of the balance bar supports adjustment of the clamping force lever amplification ratio to adapt to different clamping force requirements. Attached Figure Description

[0022] Figure 1 This is a 45-degree angle view of the overall structure of the present invention, showing the combination relationship between the motor and the compound action device; Figure 2 This is a 45-degree sectional view of the composite action gripper mechanism of the present invention, showing the positional relationship of the internal components; Figure 3 for Figure 2 A partial sectional view shows the connection relationship between the lead screw shaft, balance bar, connecting rod, rotating support, and rolling bearing. Detailed Implementation

[0023] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the indicated position or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1-3As shown, the present invention provides a compound action gripper device based on a single motor drive, comprising a motor 1 and a compound action gripper mechanism. The motor 1 is a through-type stepper motor (hollow shaft motor), which can be selected as a stepper motor, servo motor, or permanent magnet synchronous motor. The inner wall of its hollow output shaft is machined with internal threads to engage with the external threads of the lead screw shaft 30. The compound action gripper mechanism is fixedly installed at the output end of the motor 1, transmitting rotational torque and axial driving force through the hollow shaft. The compound action gripper mechanism includes: a lead screw shaft 30, a rotating bracket 21, a housing 33, an electromagnetic clutch assembly, a detachable gripper assembly, and a sensor assembly.

[0027] Lead screw shaft 30: The outer wall is provided with an external thread (preferably a trapezoidal thread) that meshes with the internal thread of the hollow shaft. At least one guide groove 301 is provided on the lead screw shaft 30 along the axial direction. The guide groove 301 has a rectangular cross section or a T-shaped cross section, and there is at least one groove, which is evenly distributed circumferentially. The front end of the lead screw shaft 30 is provided with a standard pin hole for connecting to the detachable gripper assembly via a pin.

[0028] Rotary support 21: Rotatably supported within the housing 33 by a pair of opposing rolling bearings to withstand radial and axial forces, ensuring rotational accuracy and axial stability. The rotary support 21 is provided with a rotary support boss 211 that slides into the guide groove 301.

[0029] The electromagnetic clutch assembly includes a magnetic housing 31 fixed within the outer casing 33, a coil 32 installed within the magnetic housing 31, an annular static friction plate 381, and an axially movable annular clutch plate 38. The clutch plate 38 is fitted onto the lead screw shaft 30 and rotates synchronously with the lead screw shaft 30 via a boss that mates with the guide groove 301, and can slide axially. The dynamic friction plate 382 is fixed to one side of the clutch plate 38. Elastic elements 37 are spring ball plungers or helical compression springs, numbered in the form of three or more and evenly distributed circumferentially between the clutch plate 38 and the rotating plate 39, providing an elastic force to reset the clutch plate 38. The rotating plate 39 is located within the outer casing 33 and is arranged opposite to the magnetic housing 31. The magnetic housing 31 is made of soft magnetic material, and the magnetic field generated by the coil 32 after energization forms a closed magnetic circuit through the magnetic housing 31 and the clutch plate 38.

[0030] Detachable gripper assembly: When clamping and rotation modes are required, the gripper assembly is installed on the front pin of the lead screw shaft 30, and the retaining ring 12 is then fixed on the housing 33. The gripper assembly includes at least two grippers 24, a balance bar 22, and a connecting rod 23. The front end of the lead screw shaft 30 is movably connected to one end of the connecting rod 23 via a pin, and the other end of the connecting rod 23 is hinged to the middle of the balance bar 22 via a pin. The two ends of the balance bar 22 are movably connected to the grippers 24 and the rotating bracket 21, respectively. The balance bar 22 has multiple pin holes in its middle, and the clamping force lever amplification ratio can be adjusted by selecting different pin holes to hinge with the connecting rod 23. When the lead screw shaft 30 moves axially, the connecting rod 23 swings, driving the balance bar 22, thereby driving the grippers 24 to open and close radially. When the gripper assembly is removed, the front end of the lead screw shaft 30 can be directly used as a telescopic output end, where end components such as push heads and suction cups can be installed.

[0031] Sensor assembly: Includes an angle zero-point sensor 35 and a position zero-point sensor 34, both fixed within the housing 33. The sensing end of the angle zero-point sensor 35 faces the recessed feature on the clutch plate 38 and is used to detect the zero point of rotation angle. The sensing end of the position zero-point sensor 34 faces the extreme position of the balance bar 22 when it is fully extended (when the gripper assembly is included), or faces the retracted extreme position of the telescopic output accessory (when the gripper assembly is removed), and is used to detect the zero point of the gripper or telescopic output.

[0032] The operating principle of this invention – two modes Mode 1: Clamping and Rotation (with gripper assembly) Clamping or releasing action: When coil 32 is energized, a closed magnetic circuit is formed between magnetic shell 31 and clutch plate 38, clutch plate 38 is attracted, moving friction plate 382 and stationary friction plate 381 are tightly fitted, and rotating bracket 21 is locked. At this time, the hollow shaft of motor 1 rotates, driving lead screw shaft 30 to move axially (short stroke, about 35mm) through the meshing of internal and external threads. Lead screw shaft 30 drives connecting rod 23 to swing, and connecting rod 23 drives gripper 24 to open and close radially through balance bar 22, realizing clamping or releasing of workpiece. Position zero point sensor 34 detects the fully open position of balance bar 22.

[0033] Rotation action: When coil 32 is de-energized, elastic element 37 pushes clutch plate 38 to make moving friction plate 382 fit against rotating plate 39. At this time, rotating bracket 21 and lead screw shaft 30 are coupled through guide groove 301 and rotating bracket boss 211. When motor 1 rotates, torque is transmitted through rotating plate 39, clutch plate 38 boss, and lead screw shaft 30 guide groove 301 to rotating bracket boss 211 and rotating bracket 21, driving the gripper assembly to rotate as a whole. Angle zero point sensor 35 detects the indentation feature on clutch plate 38 to determine the initial position of rotation.

[0034] Mode 2: Extension and Rotation (Removal of Gripper Assembly) Telescopic Action: After the gripper assembly is removed, the front end of the lead screw shaft 30 becomes a free telescopic end. When the coil 32 is energized, the clutch plate 38 is attracted and locked to the rotating bracket 21. The motor 1 drives the lead screw shaft 30 to move axially, with a stroke exceeding 50mm (determined by the lead screw length), thus achieving the telescopic extension of the push rod. The zero-point position sensor 34 senses the retraction limit position of the telescopic output end accessory to determine the retraction zero point.

[0035] Rotation action: When coil 32 is de-energized, clutch plate 38 is unlocked. Elastic element 37 pushes clutch plate 38 to make moving friction plate 382 fit against rotating plate 39. Motor 1 drives lead screw shaft 30 to rotate continuously without angle limitation. Angle zero point sensor 35 detects the indentation feature on clutch plate 38 to determine the initial position of rotation.

[0036] Composite motion: By controlling the on / off timing of coil 32, a composite motion of extension and rotation can be achieved. For example, a brief power outage during extension can cause rotation at a certain angle, or the motion can be performed alternately to meet the needs of complex working conditions.

[0037] The device also includes a control system (not shown in the figure), which is electrically connected to the motor 1, coil 32, angle zero-point sensor 35, and position zero-point sensor 34. Based on feedback signals from the angle zero-point sensor 35 and the position zero-point sensor 34, the control system automatically controls the on / off state of the coil 32 and the forward / reverse rotation of the motor 1 to achieve automatic switching between clamping / unclamping, rotation, and extension / retraction actions. The control system may also include a current monitoring module to determine the clamping force of the gripper 24 by monitoring changes in the operating current of the motor 1, preventing excessive clamping force from damaging the workpiece.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A composite motion manipulator based on a single motor drive, characterized in that, include: The motor (1) has a hollow output shaft with an internal thread on its inner wall; the gripper mechanism (2) includes a rotating bracket (21) and a gripper assembly; and the transmission device (3) is located between the motor (1) and the gripper mechanism (2). The transmission device (3) includes: a housing (33); a lead screw shaft (30) with an external thread on its outer wall that meshes with the internal thread of the output shaft, and the lead screw shaft (30) has at least one guide groove (301) along its axial direction. The upper end of the lead screw shaft (30) is connected to and drives the gripper mechanism (2); the rotating bracket (21) has a boss (211) that slides with the guide groove (301), so that the lead screw shaft (30) and the rotating bracket (21) can rotate synchronously and It can slide relative to the axial direction; and an electromagnetic clutch assembly is disposed in the housing (33) and has a locked state and a released state; wherein: in the locked state, the rotation of the lead screw shaft (30) is locked, and the motor (1) drives the lead screw shaft (30) to move axially; in the released state, the electromagnetic clutch assembly releases the lead screw shaft (30), and the motor (1) drives the rotating bracket (21) to rotate synchronously with the lead screw shaft (30); the gripper assembly is detachably installed at the front end of the lead screw shaft (30) and converts the axial movement of the lead screw shaft (30) into the radial opening and closing action of the gripper assembly; after the gripper assembly is removed, the front end of the lead screw shaft (30) directly serves as an independent telescopic output end.

2. The composite motion manipulator based on single-motor drive according to claim 1, characterized in that, The gripper assembly includes at least two grippers (24), a number of balance bars (22) corresponding to the grippers (24), and connecting rods (23); one end of the connecting rod (23) is hinged to the front end of the lead screw shaft (30) by a pin, and the other end is hinged to the balance bar (22) by a pin. The two ends of the balance bar (22) are movably connected to the grippers (24) and the rotating bracket (21) respectively, so that the axial movement of the lead screw shaft (30) is converted into the radial opening and closing action of the grippers (24) through the connecting rod (23) and the balance bar (22).

3. The composite motion manipulator based on single-motor drive according to claim 2, characterized in that, The balance bar (22) has multiple pin holes in the middle. By selecting different pin holes to hinge with the connecting rod (23), the clamping force lever amplification ratio can be adjusted.

4. The composite motion manipulator based on single-motor drive according to claim 1, characterized in that, The electromagnetic clutch assembly includes: a magnetic housing (31) fixed inside the housing (33); a coil (32) installed inside the magnetic housing (31); a static friction plate (381) installed inside the magnetic housing (31); a clutch plate (38) fitted onto the lead screw shaft (30) and rotating synchronously with the lead screw shaft (30) via a boss that mates with the guide groove (301) and can slide axially; a dynamic friction plate (382) fixed to one side of the clutch plate (38); a rotating plate (39) disposed inside the housing (33); and An elastic element (37) is disposed between the clutch plate (38) and the rotating plate (39) to provide an elastic force for resetting the clutch plate (38); wherein: when the coil (32) is energized, the clutch plate (38) is attracted, and the moving friction plate (382) and the stationary friction plate (381) are tightly attached to form the locked state; when the coil (32) is de-energized, the elastic element (37) pushes the clutch plate (38) to reset, and the moving friction plate (382) and the rotating plate (39) are attached to form the released state.

5. The composite motion manipulator based on single-motor drive according to claim 4, characterized in that, The elastic element (37) is a spring ball plunger or a helical compression spring, and there are three or more of them, which are evenly distributed in the circumferential direction between the clutch plate (38) and the rotating plate (39).

6. The composite motion manipulator based on single-motor drive according to claim 4, characterized in that, The magnetic shell (31) is made of soft magnetic material. After the coil (32) is energized, the magnetic field generated by the coil (32) forms a closed magnetic circuit with the clutch plate (38) through the magnetic shell (31), so that the clutch plate (38) can be reliably engaged.

7. The composite motion manipulator based on a single motor drive according to any one of claims 1 to 6, characterized in that, The housing (33) is also provided with an angle zero-point sensor (35) and a position zero-point sensor (34); the angle zero-point sensor (35) is fixed inside the housing (33), and its sensing end faces the recessed feature provided on the clutch plate (38) for detecting the rotation angle zero point; the position zero-point sensor (34) is fixed inside the housing (33), and its sensing end faces the axial limit position for detecting the position zero point of the gripper (24); when the gripper assembly is removed, the sensing target of the position zero-point sensor (34) is switched to the axial limit position of the telescopic output end.

8. The composite motion manipulator based on single-motor drive according to claim 7, characterized in that, It also includes a controller, which is electrically connected to the motor (1), the coil (32), the angle zero-point sensor (35) and the position zero-point sensor (34); the controller automatically controls the on and off of the coil (32) and the forward and reverse rotation of the motor (1) according to the feedback signals of the angle zero-point sensor (35) and the position zero-point sensor (34) to realize the automatic switching of clamping and rotation actions.

9. The composite motion manipulator based on single-motor drive according to claim 1, characterized in that, The guide groove (301) on the lead screw shaft (30) has a rectangular or T-shaped cross section, and the number of guide grooves (301) is at least one and is evenly distributed along the circumference.

10. The composite motion manipulator based on single-motor drive according to claim 1, characterized in that, The motor (1) is any one of a stepper motor, a servo motor or a permanent magnet synchronous motor.

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