A flexible joint of a robotic arm with adjustable damping

Abstract

The present invention relates to a flexible joint for a robotic arm with adjustable damping, comprising a forearm, a rear arm, and a magnetorheological fluid damper. The forearm is hinged to the rear arm, and the two ends of the magnetorheological fluid damper are hinged to the forearm and rear arm, respectively. When the forearm is subjected to force, the forearm rotates relative to the rear arm, thereby driving the piston rod of the magnetorheological fluid damper, which is then subjected to a damping force. An acceleration sensor is provided on the piston of the magnetorheological fluid damper. The acceleration sensor and the drive coil of the magnetorheological fluid damper are both electrically connected to a control center. The acceleration sensor is used to collect acceleration data of the piston relative to the cylinder of the magnetorheological fluid damper and transmit this data to the control center. The control center is used to control the input current of the coil to change the magnitude of the magnetic field, thereby changing the damping force and achieving feedback compensation. The present invention utilizes the characteristic of the magnetorheological fluid damper that the damping magnitude can be quickly adjusted to further greatly improve the precision control of the robotic arm.

Description

Technical Field

[0001] The present invention relates to the technical field of robotic arms, and in particular to a flexible joint of a robotic arm with adjustable damping. Background Art

[0002] In recent years, with the advancement of robotics, robotic structures requiring high speed, high precision, and a high load-to-weight ratio have attracted significant attention in the industrial and aerospace sectors. The increased flexibility of joints and linkages during motion can lead to structural deformation, compromising task accuracy. Consequently, the flexible design of robotic manipulator structures has been extensively researched, but many current flexible joint designs have drawbacks. Therefore, a flexible manipulator that achieves higher precision and feedback compensation is urgently needed. Summary of the Invention

[0003] The purpose of the present invention is to provide a flexible joint of a robotic arm with adjustable damping. By utilizing the characteristic that the damping size of the magnetorheological fluid damper can be quickly adjusted, not only can the ordinary damper be used to control the vibration of the robotic arm, but the damping size can also be quickly adjusted to achieve feedback compensation, thereby further greatly improving the precision control of the robotic arm.

[0004] To address the above-mentioned problems, the present invention provides a flexible joint for a robotic arm with adjustable damping, comprising a forearm, a rear arm, and a magnetorheological fluid damper. The forearm is hinged to the rear arm, and the two ends of the magnetorheological fluid damper are hinged to the forearm and rear arm, respectively. When a force is applied to the forearm, the forearm rotates relative to the rear arm, thereby pushing a piston rod of the magnetorheological fluid damper to move, and the piston rod is subjected to a damping force.

[0005] An acceleration sensor is provided on the piston of the magnetorheological fluid damper. The acceleration sensor and the drive coil of the magnetorheological fluid damper are both electrically connected to a control center. The acceleration sensor is used to collect acceleration data of the piston relative to the cylinder of the magnetorheological fluid damper and transmit this data to the control center. The control center is used to control the input current of the drive coil to change the size of the magnetic field, thereby causing the damping force to change and realizing feedback compensation.

[0006] Preferably, the lower end of the front arm is rotatably disposed on the rear arm via a rotating shaft.

[0007] Preferably, the magnetorheological fluid damper includes the cylinder body and an upper end cover and a lower end cover respectively sealed at the upper and lower ends of the cylinder body, and the lower end cover is rotatably connected to the rear arm;

[0008] The piston is disposed in the cylinder body, the piston is fixedly connected to the piston rod, and the piston rod passes through the upper end cover and is rotatably connected to the forearm.

[0009] Preferably, the lower end cover is rotatably arranged on the rear arm via a first bearing, and the piston rod is rotatably connected to the front arm via a second bearing.

[0010] Preferably, a connecting rod 1 is fixedly provided on the rear arm, a bearing 1 is provided on the connecting rod 1, an inner ring of the bearing 1 is fixedly sleeved on the connecting rod 1, and an outer ring is fixedly provided in a bearing sleeve 1, and the bearing sleeve 1 is fixedly connected to the lower end cover;

[0011] A second connecting rod is fixedly arranged on the forearm, a second bearing is provided on the second connecting rod, an inner ring of the second bearing is fixedly sleeved on the second connecting rod, and an outer ring is fixedly arranged in a second bearing sleeve, and the second bearing sleeve is fixedly connected to the piston rod.

[0012] Preferably, both ends of the connecting rod 1 are provided with threads, and the threads at both ends of the connecting rod 1 are fastened to the rear arm through threaded fasteners;

[0013] Both ends of the connecting rod are provided with threads, and the threads at both ends of the connecting rod are fastened to the forearm through threaded fasteners.

[0014] Preferably, the upper end cover and the lower end cover are respectively positioned with the cylinder body by means of a connection in which a protrusion is inserted into a groove.

[0015] Preferably, the upper end cover and the lower end cover are respectively fastened to the cylinder body by threaded fasteners.

[0016] Preferably, the upper end cover and the lower end cover are sealed to the cylinder body respectively via O-rings.

[0017] Preferably, both the front arm and the rear arm adopt a rib-type structure.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] 1. The damping-adjustable flexible joint of the robotic arm provided by the present invention utilizes the characteristic of the magnetorheological fluid damper that the damping level can be quickly adjusted. This not only enables conventional dampers to control the vibration of the robotic arm, but also allows the damping level to be quickly adjusted to achieve feedback compensation, further greatly improving the precision control of the robotic arm.

[0020] 2. Both the forearm and the rear arm adopt a rib-type structural design, which can increase the strength while reducing the weight of the arm;

[0021] 3. Rolling bearings are used at the connection between the two ends of the magnetorheological fluid damper and the front arm 2 and the rear arm 1. They realize coordinated rotational motion with the entire mechanism when it moves, which can reduce friction loss, save energy and increase service life;

[0022] 4. The joints between the upper and lower end covers and the cylinder body are connected by inserting the protrusion into the groove and sealed with O-rings to further improve the sealing performance.

[0023] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts. In the drawings:

[0025] Figure 1 A schematic structural diagram of a flexible joint of a robotic arm with adjustable damping provided by a preferred embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of a rear arm provided in a preferred embodiment of the present invention;

[0027] Figure 3 A schematic structural diagram of a forearm provided for a preferred embodiment of the present invention;

[0028] Figure 4 A schematic structural diagram of a cylinder provided in a preferred embodiment of the present invention;

[0029] Figure 5 A schematic structural diagram of a lower end cover provided for a preferred embodiment of the present invention;

[0030] Figure 6 A schematic structural diagram of an upper end cover provided in a preferred embodiment of the present invention;

[0031] Figure 7 A schematic structural diagram of a piston and a piston rod provided in a preferred embodiment of the present invention;

[0032] Figure 8 A schematic structural diagram of a bearing sleeve 2 provided in a preferred embodiment of the present invention;

[0033] Figure 9 A schematic diagram of a closed-loop control system of damping force provided by a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined Figures 1 to 9A detailed description is given of a flexible joint of a robotic arm with adjustable damping provided by the present invention. This embodiment is implemented based on the technical solution of the present invention, and a detailed implementation method and specific operation process are given. However, the scope of protection of the present invention is not limited to the following embodiments. Those skilled in the art can modify and polish it without changing the spirit and content of the present invention.

[0035] Please refer to Figures 1 to 9 A flexible joint for a robotic arm with adjustable damping comprises a forearm 2, a rear arm 1, and a magnetorheological fluid damper 3. The forearm 2 is hinged to the rear arm 1, and the two ends of the magnetorheological fluid damper 3 are respectively hinged to the forearm 2 and the rear arm 1. When a force is applied to the forearm 2, the forearm 2 rotates relative to the rear arm 1, thereby pushing the piston rod 35 of the magnetorheological fluid damper 3 to move, and the piston rod 35 is subjected to the damping force.

[0036] An acceleration sensor is provided on the piston 34 of the magnetorheological fluid damper 3. The acceleration sensor and the drive coil of the magnetorheological fluid damper 3 are electrically connected to the control center. The acceleration sensor is used to collect acceleration data of the piston 34 relative to the cylinder 31 of the magnetorheological fluid damper 3 and transmit this data to the control center. The control center is used to control the input current of the drive coil to change the size of the magnetic field, thereby causing the damping force to change and realize feedback compensation.

[0037] In this embodiment, the lower end of the forearm 2 is pivotally mounted on the rear arm 1 via a rotating shaft. Specifically, both the forearm 2 and the rear arm 1 utilize a ribbed structure, which increases strength while reducing the weight of the arm. For example, the rear arm 1 includes a base plate 1, on which three ribs 1 are fixedly mounted at intervals. The ribs 1 are arranged along the length of the base plate 1, with the ends of the ribs 1 and the base plate 1 being flush. The three ribs 1 form two strip-shaped grooves on the base plate. The base plate 1 and the three ribs 1 are integrally formed.

[0038] The forearm 2 includes a shoulder 21 and two arms 22. The arms 22 are arranged parallel to the same side of the shoulder 21, and their upper ends are fixedly connected to the shoulder 21. The arms 22 include a base 2, and a rib 2 is provided on each side of the base 2. The ribs 2 are arranged along the length of the base 2, and the ends of the ribs 2 and the base 2 are flush. The shoulder 21 is a short plate structure, and the shoulder 21 and the two arms 22 are integrally formed.

[0039] The lower ends of the two arms 22 are inserted into the two strip-shaped grooves of the forearm 2. Ribs 1 and 2 each have through-holes at corresponding locations, through which the rotating shaft passes. The rotating shaft is fixed in the through-hole of rib 1 and rotatably mounted in the through-hole of rib 2; alternatively, the rotating shaft is fixed in the through-hole of rib 2 and rotatably mounted in the through-hole of rib 1. The rotating shaft can be a pin.

[0040] In this embodiment, the magnetorheological fluid damper 3 is a single-rod, that is, there is only one piston rod 35, and the piston rod 35 is connected to the forearm 2 or the rear arm 1. In this embodiment, the connection between the piston rod 35 and the forearm 2 is taken as an example. The magnetorheological fluid damper 3 includes a cylinder body 31, an upper end cover 33 and a lower end cover 32. Both ends of the cylinder body 31 are bottomless and have a cylindrical structure. The upper end cover 33 and the lower end cover 32 are respectively connected to the cylinder body 31 by a connection method of inserting a protrusion into a groove, that is, the protrusion and the groove are respectively provided on two different components. When the two components are connected, the protrusions are respectively inserted into the grooves. For example, the inner sides of the upper end cover 33 and the lower end cover 32 are provided with a plurality of protrusions (331, 321). Correspondingly, the two ends of the cylinder body 31 are respectively provided with a plurality of grooves 311, and the plurality of protrusions (331, 321) are respectively inserted into the plurality of grooves 311. If the groove is provided on the inner side of the upper end cover 33 and the lower end cover 32, the protrusion may also be provided on the cylinder body 31. The upper end cover 33 and the lower end cover 32 are sealed to the upper and lower ends of the cylinder body 31 respectively by O-rings. The upper end cover 33 and the lower end cover 32 are fastened to the upper and lower ends of the cylinder body 31 respectively by threaded fasteners (such as screws). The lower end cover 32 is rotatably connected to the rear arm 1. A piston 34 is provided in the cylinder body 31, and the piston 34 is fixedly connected to the piston rod 35; a through hole 332 is provided on the upper end cover 33 for the piston rod 35 to pass through, and the piston rod 35 passes through this through hole 332 and is rotatably connected to the forearm 2.

[0041] Specifically, both ends of connecting rod 1 (6) are threaded, and both threads are fastened to rear arm 1 via threaded fasteners (e.g., nuts). Connecting rod 1 (6) is provided with bearing 1 (4), the inner ring of which is fixedly mounted on connecting rod 1 (6), and the outer ring of which is fixedly mounted within bearing sleeve 1 (5), which is fixedly connected to lower end cap 32.

[0042] Connecting rod 7 (2) has threads on both ends, which are fastened to the upper-middle portion of forearm 2 via threaded fasteners (e.g., nuts). Connecting rod 7 (2) is provided with a second bearing, the inner ring of which is fixedly mounted on connecting rod 7 (2), while the outer ring is fixedly mounted within bearing sleeve (2). Bearing sleeve (2) has an internally threaded hole (81) defined on its outer wall. The outer end of piston rod 35 is provided with external threads, which are threadedly connected to internally threaded hole (81).

[0043] Rolling bearings are used at the connections between the two ends of the magnetorheological fluid damper 3 and the front arm 2 and the rear arm 1. When the entire mechanism moves, rolling bearings are used to achieve coordinated rotation, thereby reducing friction loss, saving energy and increasing service life.

[0044] When the front arm 2 is acted upon by a force, the piston rod 35 is pushed to move, and the piston rod 35 is acted upon by a damping force, which has the effect of shock absorption and precise control; and at this time, by changing the current in the driving coil of the magnetorheological fluid damper 3, the magnetic field strength is changed, thereby realizing dynamic control of its damping size and feedback compensation, thereby further improving the control accuracy; for the rolling bearing at the connection between the piston rod 35, the connecting rod and the robotic arm, it realizes a coordinated rotational motion therewith when the entire structure moves.

[0045] For example, when the forearm 2 is subjected to force, it rotates relative to the rear arm 1, thereby pushing the piston rod 35 of the magnetorheological fluid damper 3. At this point, the magnetorheological fluid damper 3 acts as a damper. As the piston rod 35 compresses downward, the external current increases. Due to the characteristics of the magnetic fluid, its damping force increases, generating a feedback compensation effect. The magnitude of the external current varies with its amplitude, maintaining the optimal damping force, thereby achieving more precise vibration control and compensation.

[0046] In this embodiment, the damping force of the magnetorheological fluid damper 3 can be rapidly adjusted, achieving feedback compensation while simultaneously controlling vibration, thereby achieving higher-precision control. Specifically, an acceleration sensor is provided on the piston 34. The acceleration sensor and the drive coil of the magnetorheological fluid damper 3 are both electrically connected to a control center. The acceleration sensor collects data in real time, representing the acceleration of the piston relative to the cylinder body. The acceleration sensor transmits this data to the control center. After processing the information received by the acceleration sensor, the control center automatically calculates the most reasonable current vertical value and controls the input current of the drive coil of the magnetorheological fluid damper 3 to change the magnitude of the magnetic field, thereby changing the damping force of the magnetorheological fluid damper 3.

[0047] For further information, please refer to Figure 9 The feedback system adopted by the present invention is a closed-loop control system of damping force. This system uses a specific PID control algorithm to calculate the deviation value according to the vibration feedback information, controls the driving coil current through the output parameter of the D / A converter, and under the action of the magnetic field, the damping force of the magnetorheological damper changes. Then, the acceleration sensor is further used to measure the acceleration of the piston relative to the cylinder body, and then the parameter is converted into a voltage value through the A / D converter. The voltage is fed back to the controller through the transmission circuit for parameter comparison and processing, and then the processing result is output to the D / A converter, thereby forming a closed-loop control system.

Claims

1. A flexible joint of a robotic arm with adjustable damping, characterized in that: The device comprises a forearm, a rear arm, and a magnetorheological fluid damper. The forearm is hinged to the rear arm, and both ends of the magnetorheological fluid damper are hinged to the forearm and rear arm, respectively. When a force is applied to the forearm, the forearm rotates relative to the rear arm, thereby pushing the piston rod of the magnetorheological fluid damper to move, and the piston rod is subjected to the damping force. The forearm and rear arm both adopt a ribbed structure. An acceleration sensor is provided on the piston of the magnetorheological fluid damper. The acceleration sensor and the drive coil of the magnetorheological fluid damper are both electrically connected to a control center. The acceleration sensor is used to collect acceleration data of the piston relative to the cylinder of the magnetorheological fluid damper and transmit this data to the control center. The control center is used to control the input current of the drive coil to change the magnitude of the magnetic field, thereby causing the damping force to change and realizing feedback compensation. Rolling bearings are used at the connections between the two ends of the magnetorheological fluid damper and the forearm and the rear arm. The rear arm includes a bottom plate, on which three ribs are fixed at intervals, the ribs being arranged along the length direction of the bottom plate, and the ends of the ribs are flush with the ends of the bottom plate, and the three ribs form two strip grooves on the bottom plate; the forearm includes a shoulder and two arms, the two arms are arranged parallel to the same side of the shoulder, and the upper ends thereof are fixedly connected to the shoulders, the arm includes a bottom plate, and two ribs are respectively arranged on both sides of the bottom plate, the ribs are arranged along the length direction of the bottom plate, and the ends of the ribs are flush with the ends of the bottom plate; the lower ends of the two arms are respectively inserted into the two strip grooves of the rear arm.

2. A flexible joint for a mechanical arm with adjustable damping according to claim 1, characterized in that: The lower end of the front arm is rotatably arranged on the rear arm through a rotating shaft.

3. The damping-adjustable flexible joint of a robotic arm according to claim 1, wherein: The magnetorheological fluid damper includes the cylinder body and an upper end cover and a lower end cover respectively sealed at the upper and lower ends of the cylinder body, and the lower end cover is rotatably connected to the rear arm; The piston is disposed in the cylinder body, the piston is fixedly connected to the piston rod, and the piston rod passes through the upper end cover and is rotatably connected to the forearm.

4. A damping-adjustable flexible joint for a robotic arm as claimed in claim 3, characterized in that: The lower end cover is rotatably arranged on the rear arm through a first bearing, and the piston rod is rotatably connected to the front arm through a second bearing.

5. A flexible joint for a mechanical arm with adjustable damping according to claim 4, characterized in that: A connecting rod 1 is fixedly provided on the rear arm, a bearing 1 is provided on the connecting rod 1, an inner ring of the bearing 1 is fixedly sleeved on the connecting rod 1, and an outer ring is fixedly provided in a bearing sleeve 1, and the bearing sleeve 1 is fixedly connected to the lower end cover; A second connecting rod is fixedly arranged on the forearm, a second bearing is provided on the second connecting rod, an inner ring of the second bearing is fixedly sleeved on the second connecting rod, and an outer ring is fixedly arranged in a second bearing sleeve, and the second bearing sleeve is fixedly connected to the piston rod.

6. A flexible joint for a mechanical arm with adjustable damping according to claim 5, characterized in that: Both ends of the connecting rod are provided with threads, and the threads at both ends of the connecting rod are fastened to the rear arm through threaded fasteners; Both ends of the connecting rod are provided with threads, and the threads at both ends of the connecting rod are fastened to the forearm through threaded fasteners.

7. The damping-adjustable flexible joint of a robotic arm according to claim 3, wherein: The upper end cover and the lower end cover are respectively positioned with the cylinder body by connecting the protrusions into the grooves.

8. The damping-adjustable flexible joint of a robotic arm according to claim 3, wherein: The upper end cover and the lower end cover are respectively fastened to the cylinder body through threaded fasteners.

9. The damping-adjustable flexible joint of a robotic arm according to claim 3, wherein: The upper end cover and the lower end cover are respectively sealed with the cylinder body via O-rings.

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