Humanoid robot magnetorheological fluid flexible joint protection mechanism

Abstract

The present application relates to the technical field of robots, and in particular to a humanoid robot magnetorheological liquid flexible joint protection mechanism, which comprises a large arm, a small arm and a magnetorheological joint, the magnetorheological joint is fixed on the large arm, and the small arm is fixed on the rotor of the magnetorheological joint. The first protection mechanism is arranged, so that when the small arm is impacted, the small arm rotates quickly relative to the large arm, so that the piston exerts an impact force on the non-Newtonian fluid in the cylinder body, the sliding of the piston is blocked under the action of the physical properties of the non-Newtonian fluid, thereby buffering the swing of the small arm caused by the impact, avoiding secondary collision caused by the rapid swing of the small arm, and with the rotation of the small arm, the connecting rod drives the cylinder body to rotate relative to the large arm, so that under the transmission action of the gear, the fan is driven to rotate quickly, heat dissipation of the magnetorheological joint during the collision is realized, and a series of problems caused by the instantaneous temperature rise of the magnetorheological liquid are avoided.

Description

Technical Field

[0001] This invention relates to the field of robotics, and in particular to a magnetorheological fluid flexible joint protection mechanism for a humanoid robot. Background Technology

[0002] Humanoid robots have been deployed on a large scale in multiple fields. As their core execution unit, the performance of joints directly determines operational reliability and human-machine safety. Collision protection, motor overload protection, and joint heat dissipation are the core bottlenecks restricting their practical application. Humanoid robots are prone to accidental collisions and motor overload caused by sudden load changes in unstructured environments. Traditional rigid joints lack buffering and force relief mechanisms, and the impact force of collisions is concentrated, which can easily damage internal precision components and lead to motor failure. Magnetorheological fluid, as an intelligent response material, can achieve the switching between joint rigidity and flexibility through magnetic field control, making it an ideal choice for balancing joint precision and safety. Magnetorheological fluid is sensitive to temperature. High temperature will cause its performance to deteriorate and will also affect the stability of internal components of the joint. When a robotic arm is subjected to an impact that causes the motor to overload, existing technologies typically protect the motor by disconnecting the transmission connection. However, this ignores the fact that after the robotic arm loses motor drive, it will swing rapidly under impact. Although magnetorheological fluid can buffer the impact, its ultimate shear resistance is limited. When the external force exceeds the threshold, the magnetic flux is sheared, resulting in a sharp drop in stiffness. At the same time, the concentrated energy input in a short period of time will cause the temperature of the magnetorheological joint to rise instantly, which will lead to a decrease in the stability of the magnetic flux structure, a decline in joint performance, or even failure of the magnetorheological fluid. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies by proposing a protective mechanism for a humanoid robot's magnetorheological fluid flexible joint. This invention, through a first protective mechanism, causes the forearm to rotate rapidly relative to the upper arm when impacted. This causes the piston to exert an impact force on the non-Newtonian fluid within the cylinder. Under the physical properties of the non-Newtonian fluid, the piston's sliding is hindered, thus buffering the forearm's swing caused by the impact and preventing secondary collisions due to rapid forearm swing. Simultaneously, as the forearm rotates, the connecting rod drives the cylinder to rotate relative to the upper arm. This, through gear transmission, causes the gearbox to drive the fan to rotate rapidly, achieving heat dissipation for the magnetorheological joint during collisions and preventing a series of problems caused by a sudden surge in magnetorheological fluid temperature.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A magnetorheological fluid flexible joint protection mechanism for a humanoid robot includes an upper arm, a lower arm, and a magnetorheological joint. The magnetorheological joint is fixed to the upper arm, and the lower arm is fixed to the rotor of the magnetorheological joint. A joint motor for driving the rotor of the magnetorheological joint is installed on the outer wall of the upper arm. The upper arm is provided with a first protection mechanism and a second protection mechanism. The first protection mechanism includes a cylinder rotatably connected to the outer wall of the upper arm via a rotating shaft. The cylinder is filled with a non-Newtonian fluid and slidably connected to a piston. Pressure sensors are provided on both ends of the piston. A connecting rod is fixed to the outer wall of the piston. The end of the connecting rod away from the cylinder is rotatably connected to the outer wall of the lower arm. A gear is fixed to the rotating shaft of the cylinder. A locking block that can engage with the gear is slidably provided on the upper arm. An electromagnet that can attract the locking block is provided on the upper arm. The auxiliary magnetic field generated by the electromagnet is superimposed in the same direction as the main magnetic field generated by the excitation coil inside the magnetorheological joint. The electromagnet and the pressure sensors are electrically connected through a robot control system.

[0005] This solution integrates a dual-level protection structure with a first and a second protective mechanism in the upper arm, combined with multiple technologies such as magnetorheological magnetic field synergistic enhancement, non-Newtonian fluid buffering, and electronically controlled linkage braking, to achieve full-condition overload protection of the robot joint from three dimensions: flexible buffering, magnetic field-enhanced locking, and dynamic graded disengagement.

[0006] The first protective mechanism relies on the non-Newtonian fluid inside the cylinder to form a flexible buffer pair with the piston and connecting rod. When the forearm is impacted and swings, the piston quickly squeezes the fluid, and the non-Newtonian fluid instantly shears and thickens. The impact energy is absorbed by the fluid phase change damping, blocking the instantaneous impact load from being directly transmitted to the magnetorheological joint and drive motor, thus preventing the shaft, seals, and transmission gears from breaking due to impact. The auxiliary magnetic field generated by the electromagnet is superimposed in the same direction as the main magnetic field of the excitation coil inside the magnetorheological joint, effectively increasing the yield stress of the magnetorheological fluid and instantly increasing the stiffness of the joint itself. This forms a soft and hard synergistic protection with the fluid buffer, further improving the upper limit of the joint's impact resistance. The pressure sensor monitors the pressure difference on both sides of the piston in real time, accurately feeding back the magnitude of the impact load, and providing an electronic trigger for the electromagnet to engage the locking block and lock the gear. After the locking block locks the gear, it mechanically locks the cylinder shaft, limiting the abnormal deflection of the forearm.

[0007] The second protective mechanism relies on the sliding cooperation structure of the contact plate, docking plate, and floating frame. Under overload conditions, it can cut off the power transmission between the joint motor and the magnetorheological joint to prevent the motor from stalling and burning out. In conjunction with the first protective mechanism, it can achieve full-area protection with flexible energy absorption at the front end and power isolation at the rear end.

[0008] Preferably, the outer ring wall of the piston fits into the inner ring wall of the cylinder, and the piston is provided with a plurality of throttling orifices.

[0009] Preferably, a spring is provided between the outer wall of the locking block and the main arm for pulling the locking block to reset, so as to realize the automatic locking and reset of the locking block corresponding to the switching on and off of the electromagnet.

[0010] Preferably, a mounting groove is provided on the outer wall of the upper arm, the part of the magnetorheological joint located in the mounting groove is exposed, a gearbox is installed on the top inner wall of the mounting groove, the input end of the gearbox meshes with a gear, and a fan is fixed on its output shaft.

[0011] Preferably, the second protective mechanism includes an abutment plate fixed on the magnetorheological joint rotor. The outer wall of the abutment plate is provided with a plurality of docking grooves. A transmission chamber is provided inside the main arm. A floating frame is slidably connected to the inner wall of the transmission chamber. A turntable is rotatably connected to the outer wall of the floating frame. The turntable is slidably sleeved on the outer wall of the main shaft of the joint motor. A docking plate that is slidably inserted into the docking groove is fixed on the outer wall of the turntable. A heat dissipation vent with a dust filter is provided at the bottom of the transmission chamber.

[0012] Preferably, a tilting frame is rotatably connected to the inner wall of the transmission chamber, a stroke groove is provided on the outer wall of the tilting frame, a linkage frame is fixed on the outer wall of the floating frame and slidably inserted into the stroke groove, and a brake block is detachably installed on the outer wall of the tilting frame near the abutment plate.

[0013] Preferably, an electric push rod is fixed on the inner wall of the transmission chamber, and the output end of the electric push rod is fixed on the outer wall of the floating frame. A torque sensor is installed on the outer wall of the upper arm and fixedly connected to the rotating shaft of the lower arm. The torque sensor and the electric push rod are electrically connected through the robot control system. The torque sensor detects the rotational torque of the lower arm and transmits the data to the control system. The control system controls the stroke of the electric push rod according to a preset load threshold to achieve overload protection.

[0014] Preferably, a limiting groove is formed on the outer wall of the main shaft of the joint motor along the axial direction, and a limiting block is fixed on the inner side of the turntable. The limiting block is slidably inserted into the limiting groove to realize circumferential force transmission and axial sliding.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention, through the first protective mechanism, causes the forearm to rotate rapidly relative to the upper arm when impacted, thereby causing the piston to exert an impact force on the non-Newtonian fluid in the cylinder. Under the physical properties of the non-Newtonian fluid, the piston's sliding is hindered, thus buffering the swing of the forearm caused by the impact and preventing secondary collisions caused by the rapid swing of the forearm. At the same time, as the forearm rotates, the connecting rod drives the cylinder to rotate relative to the upper arm, thereby causing the gearbox to drive the fan to rotate rapidly under the transmission of gears, realizing heat dissipation of the magnetorheological joint during the collision and avoiding a series of problems caused by the instantaneous rise in the temperature of the magnetorheological fluid.

[0016] 2. This invention utilizes an electromagnet so that when the pressure sensor's detection value reaches a threshold, the robot control system activates the electromagnet. Under the action of magnetic force, the locking block overcomes the spring force and engages with the gear, thereby locking the cylinder's rotational freedom. Subsequently, with the cooperation of the cylinder and the connecting rod, the forearm's rotation angle is locked, achieving joint locking upon impact. This further prevents secondary collisions caused by forearm swinging. Simultaneously, the electromagnet can apply a superimposed external magnetic field in the same direction to the magnetorheological joint, increasing the yield stress of the magnetorheological fluid and temporarily increasing the stiffness of the magnetorheological joint. This compensates for the performance loss caused by the shearing of the magnetorheological fluid flux and the sudden drop in the stiffness of the magnetorheological joint due to impact, preventing magnetorheological joint failure.

[0017] 3. The present invention, through the provision of a second protective mechanism, ensures that when the forearm is impacted, the torque sensor's detection value exceeds the threshold. At this point, the robot control system activates the electric push rod, which pushes the floating frame away from the abutment plate. The floating frame then drives the turntable away from the abutment plate, causing the turntable to detach the docking plate from the docking groove. This disconnects the transmission connection between the joint motor and the forearm, thus providing overload protection for the joint motor during impact and preventing excessive impact force from causing the joint motor to burn out. Simultaneously, after the turntable separates from the abutment plate, the joint motor drives the turntable to rotate freely, and the turntable drives the docking plate to rotate, thereby increasing airflow around the magnetorheological joint, improving heat dissipation, and further preventing the magnetorheological joint temperature from rising instantaneously during impact.

[0018] 4. This invention utilizes a flipping frame to drive a brake block to abut against a contact plate, thereby braking the rotational movement of the forearm. This prevents the forearm from swinging due to inertia after losing joint motor drive, further avoiding secondary collisions and improving safety during human-machine interaction. It also provides double protection in case the first protective mechanism fails. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of the overall structure proposed in this invention; Figure 2 This is a three-dimensional sectional view of the cylinder block proposed in this invention; Figure 3 This is a partially enlarged schematic diagram of the cylinder block proposed in this invention; Figure 4 This is a three-dimensional schematic diagram of the card block proposed in this invention; Figure 5 This is a three-dimensional sectional view of the overall structure proposed in this invention; Figure 6 This is a three-dimensional cross-sectional view of the abutment plate proposed in this invention; Figure 7This is a three-dimensional sectional view of the floating frame proposed in this invention; Figure 8 This is a three-dimensional sectional view of the upper arm proposed in this invention.

[0020] Legend: 1. Boom; 11. Arm; 12. Magnetorheological joint; 13. Joint motor; 131. Limiting groove; 14. Transmission chamber; 141. Heat dissipation vent; 15. Mounting groove; 2. Floating frame; 21. Electric push rod; 22. Torque sensor; 23. Turntable; 231. Docking plate; 232. Limiting block; 24. Abutment plate; 241. Docking groove; 25. Linkage frame; 26. Tilting frame; 261. Stroke groove; 262. Brake block; 3. Cylinder block; 31. Connecting rod; 311. Piston; 312. Throttle orifice; 313. Pressure sensor; 32. Gear; 33. Gearbox; 331. Fan; 34. Locking block; 341. Spring; 35. Electromagnet. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] See Figures 1 to 8 As shown, a humanoid robot magnetorheological fluid flexible joint protection mechanism includes an upper arm 1, a lower arm 11 and a magnetorheological joint 12. The magnetorheological joint 12 is fixed on the upper arm 1, and the lower arm 11 is fixed on the rotor of the magnetorheological joint 12. A joint motor 13 for driving the rotor of the magnetorheological joint 12 to rotate is installed on the outer wall of the upper arm 1. A first protection mechanism and a second protection mechanism are provided on the upper arm 1. The first protective mechanism includes a cylinder 3 rotatably connected to the outer wall of the upper arm 1 via a rotating shaft. The cylinder 3 is filled with a non-Newtonian fluid and slidably connected to a piston 311. Pressure sensors 313 are installed on both end faces of the piston 311. Lead wires from the pressure sensors 313 pass through sealed wiring holes on the side wall of the cylinder 3. These wiring holes are filled with sealing rings for waterproofing and dustproofing. A connecting rod 31 is fixed to the outer wall of the piston 311. The end of the connecting rod 31 away from the cylinder 3 is rotatably connected to the outer wall of the lower arm 11. A gear 32 is fixed to the rotating shaft of the cylinder 3. A locking block 34 slidably mounted on the upper arm 1, capable of engaging with the gear 32, is mounted on the upper arm 1. An electromagnet 35 is installed on the upper arm 1 to attract the locking block 34. The auxiliary magnetic field generated by electromagnet 35 is superimposed in the same direction as the main magnetic field generated by the excitation coil inside the magnetorheological joint 12. Electromagnet 35 and pressure sensor 313 are electrically connected through the robot control system. The outer ring wall of piston 311 is in contact with the inner ring wall of cylinder 3. Several throttling holes 312 are provided on piston 311. A spring 341 for pulling block 34 to reset is provided between the outer wall of block 34 and the upper arm 1. A mounting groove 15 is provided on the outer wall of the upper arm 1. The part of magnetorheological joint 12 located in the mounting groove 15 is exposed. A gearbox 33 is installed on the top inner wall of the mounting groove 15. The input end of gearbox 33 meshes with gear 32, and a fan 331 is fixed on its output shaft.

[0023] It should be noted that when the robotic arm is working, the forearm 11, as the output end, is more susceptible to impact. When the forearm 11 is impacted, it undergoes unexpected movement, rotating rapidly relative to the upper arm 1. The forearm 11 drives the connecting rod 31 to slide relative to the cylinder 3, causing the piston 311 on the connecting rod 31 to slide relative to the cylinder 3. This causes the piston 311 to exert an impact force on the non-Newtonian fluid inside the cylinder 3. Under the physical properties of the non-Newtonian fluid, the sliding of the piston 311 is hindered, thus buffering the swing of the forearm 11 caused by the impact and preventing secondary collisions caused by the rapid swing of the forearm 11. At the same time, as the forearm 11 rotates, the connecting rod 31 drives the cylinder 3 to rotate relative to the upper arm 1. This causes the gearbox 33 to drive the fan 331 to rotate rapidly under the transmission action of the gear 32, thereby cooling the magnetorheological joint 12 during collisions and preventing a series of problems caused by the instantaneous increase in the temperature of the magnetorheological fluid.

[0024] Furthermore, during the aforementioned process, the piston 311 experiences a reaction force from the non-Newtonian fluid. When the detection value of the pressure sensor 313 reaches the threshold, the robot control system activates the electromagnet 35. Initially, the electromagnet 35 is not energized, and the locking block 34 moves away from the gear 32 under the action of the spring 341. When the electromagnet 35 is energized, under the action of magnetic force, the locking block 34 overcomes the elastic force of the spring 341 and abuts against the gear 32, thereby locking the rotational degree of freedom of the cylinder 3. Then, under the cooperation of the cylinder 3 and the connecting rod 31, the rotation angle of the forearm 11 is locked, achieving joint locking during impact. This further avoids secondary collisions caused by the swinging of the forearm 11. At the same time, the electromagnet 35 can apply a superimposed external magnetic field in the same direction to the magnetorheological joint 12, increasing the yield stress of the magnetorheological fluid and temporarily increasing the stiffness of the magnetorheological joint 12. This compensates for the performance loss caused by the shearing of the magnetorheological fluid flux and the sudden drop in stiffness of the magnetorheological joint 12 due to the impact, thus preventing the failure of the magnetorheological joint 12.

[0025] In addition, both the magnetorheological joint 12 and the electromagnet 35 are fixed inside the upper arm 1, so that the direction of magnetic field superposition will not change with the rotation of the lower arm 11. At the same time, it prevents the electromagnet 35 from being deflected by collision. After the collision, the coil of the magnetorheological joint 12 is installed inside itself and will not rotate with the lower arm 11. The electromagnet 35 is de-energized by the robot system, and under the action of the spring 341, the locking block 34 separates from the gear 32.

[0026] In normal operation, the joint motor 13 drives the forearm 11 to rotate slowly relative to the upper arm 1. When the angle between the upper arm 1 and the forearm 11 changes, the forearm 11 drives the connecting rod 31 to slide slowly relative to the cylinder 3, thereby causing the piston 311 on the connecting rod 31 to slide slowly relative to the cylinder 3. This prevents the piston 311 from exerting an impact force on the non-Newtonian fluid inside the cylinder 3. As the forearm 11 rotates, the connecting rod 31 drives the cylinder 3 to rotate relative to the upper arm 1. This causes the gearbox 33 to drive the fan 331 to rotate rapidly under the transmission action of the gear 32, achieving continuous heat dissipation of the magnetorheological joint 12 in normal operation. The output speed of the fan 331 is changed by the gearbox 33 to ensure heat dissipation efficiency.

[0027] The second protective mechanism includes an abutment plate 24 fixed to the rotor of the magnetorheological joint 12. The outer wall of the abutment plate 24 has several mating grooves 241. A transmission chamber 14 is located inside the main arm 1. A floating frame 2 is slidably connected to the inner wall of the transmission chamber 14. A turntable 23 is rotatably connected to the outer wall of the floating frame 2. The turntable 23 is slidably mounted on the outer wall of the main shaft of the joint motor 13. A mating plate 231, which is slidably inserted into the mating grooves 241, is fixed to the outer wall of the turntable 23. A heat dissipation vent 141 with a dust filter is located at the bottom of the transmission chamber 14. A tilting frame 26 is rotatably connected to the inner wall of the transmission chamber 14. A stroke groove 261 is located on the outer wall of the tilting frame 26. The outer wall of the floating frame 2... A linkage frame 25 is fixed on the wall and slidably inserted into the stroke groove 261. A brake block 262 is detachably installed on the outer wall of the flipping frame 26 near the abutment plate 24. An electric push rod 21 is fixed on the inner wall of the transmission chamber 14. The output end of the electric push rod 21 is fixed on the outer wall of the floating frame 2. A torque sensor 22 is installed on the outer wall of the upper arm 1 and fixedly connected to the rotating shaft of the lower arm 11. The torque sensor 22 and the electric push rod 21 are electrically connected through the robot control system. A limit groove 131 is opened along the axial direction on the outer wall of the main shaft of the joint motor 13. A limit block 232 is fixed on the inner side of the turntable 23. The limit block 232 is slidably inserted into the limit groove 131 to realize circumferential force transmission and axial sliding.

[0028] It should be noted that in the initial state, the electric push rod 21 drives the floating frame 2 to approach the abutment plate 24, and the docking plate 231 on the turntable 23 is inserted into the docking groove 241 on the abutment plate 24. Under the cooperation of the limiting block 232 and the limiting groove 131, the joint motor 13 can drive the turntable 23 to rotate, so that the turntable 23 drives the forearm 11 to rotate through the abutment plate 24. The torque sensor 22 detects the rotational torque of the forearm 11.

[0029] When the forearm 11 is impacted, the torque sensor 22 detects a value exceeding the threshold. At this time, the robot control system activates the electric push rod 21, which pushes the floating frame 2 away from the abutment plate 24. The floating frame 2 then drives the turntable 23 away from the abutment plate 24, causing the turntable 23 to detach the docking plate 231 from the docking groove 241. This disconnects the transmission connection between the joint motor 13 and the forearm 11, thus providing overload protection for the joint motor 13 during impact and preventing it from burning out due to excessive impact force. Simultaneously, after the turntable 23 separates from the abutment plate 24, the joint motor 13 drives the turntable 23 to rotate freely, which in turn drives the docking plate 231 to rotate. This increases airflow around the magnetorheological joint 12, improves heat dissipation, and further prevents the magnetorheological joint 12 from experiencing a sudden temperature increase during impact. After the impact, the robot system controls the electric push rod 21 to reset.

[0030] Furthermore, during the aforementioned process, the floating frame 2 drives the linkage frame 25 to move away from the abutment plate 24 simultaneously. Under the combined action of the linkage frame 25 and the stroke groove 261, the linkage frame 25 pulls the tilting frame 26 to rotate, thereby causing the tilting frame 26 to drive the brake block 262 to abut against the abutment plate 24, achieving the effect of braking the rotational movement of the forearm 11. This reduces the rotational speed of the cylinder 3, thereby increasing the success rate of the engagement between the locking block 34 and the gear 32. This prevents the forearm 11 from swinging under inertia after losing the drive of the joint motor 13, further avoiding secondary collisions and improving safety during human-machine interaction. At the same time, it provides double protection when the first protective mechanism fails. The brake block 262 is a detachable module that can be replaced after wear.

[0031] The bottom of the transmission chamber 14 is provided with a heat dissipation vent 141 with a dust filter. The heat dissipation vent 141 can not only improve the heat dissipation effect around the magnetorheological joint 12, but also make it easier for staff to observe the docking and mating status of the docking plate 231 and the docking groove 241 from the outside.

[0032] Working principle: In normal operation, the joint motor 13 drives the forearm 11 to rotate slowly relative to the upper arm 1. When the angle between the upper arm 1 and the forearm 11 changes, the forearm 11 drives the connecting rod 31 to slide slowly relative to the cylinder 3, thereby causing the piston 311 on the connecting rod 31 to slide slowly relative to the cylinder 3. This prevents the piston 311 from exerting an impact force on the non-Newtonian fluid inside the cylinder 3. As the forearm 11 rotates, the connecting rod 31 drives the cylinder 3 to rotate relative to the upper arm 1. This causes the gearbox 33 to drive the fan 331 to rotate rapidly under the transmission action of the gear 32, thereby achieving continuous heat dissipation of the magnetorheological joint 12 in normal operation. Under the action of the first protective mechanism, when the forearm 11 is impacted, the forearm 11 rotates rapidly relative to the upper arm 1. The forearm 11 drives the connecting rod 31 to slide relative to the cylinder 3, thereby causing the piston 311 on the connecting rod 31 to slide relative to the cylinder 3. This causes the piston 311 to exert an impact force on the non-Newtonian fluid in the cylinder 3. Under the action of the physical properties of the non-Newtonian fluid, the sliding of the piston 311 is hindered, thereby buffering the swing of the forearm 11 caused by the impact and preventing the rapid swing of the forearm 11 from causing a secondary collision. At the same time, as the forearm 11 rotates, the connecting rod 31 drives the cylinder 3 to rotate relative to the upper arm 1. This causes the gearbox 33 to drive the fan 331 to rotate rapidly under the transmission action of the gear 32, thereby achieving heat dissipation of the magnetorheological joint 12 during the collision and avoiding a series of problems caused by the instantaneous rise in the temperature of the magnetorheological fluid. Furthermore, during the aforementioned process, the piston 311 is subjected to a reaction force from the non-Newtonian fluid. When the detection value of the pressure sensor 313 reaches the threshold, the robot control system activates the electromagnet 35. Since the electromagnet 35 is not energized in the initial state, the locking block 34 moves away from the gear 32 under the action of the spring 341. When the electromagnet 35 is energized, under the action of magnetic force, the locking block 34 overcomes the elastic force of the spring 341 and abuts against the gear 32, thereby locking the rotational degree of freedom of the cylinder 3. Then, under the cooperation of the cylinder 3 and the connecting rod 31, the rotation angle of the forearm 11 is locked, realizing joint locking during impact, further avoiding secondary collisions caused by the swing of the forearm 11. At the same time, the electromagnet 35 can apply a superimposed external magnetic field in the same direction to the magnetorheological joint 12, which increases the yield stress of the magnetorheological fluid, thereby temporarily increasing the stiffness of the magnetorheological joint 12, compensating for the performance loss caused by the shearing of the magnetorheological fluid magnetic flux and the sudden drop in stiffness of the magnetorheological joint 12 due to the impact, and preventing the failure of the magnetorheological joint 12. Under the action of the second protective mechanism, when the forearm 11 is impacted, the detection value of the torque sensor 22 exceeds the threshold. At this time, the robot control system activates the electric push rod 21, which pushes the floating frame 2 away from the abutment plate 24. The floating frame 2 drives the turntable 23 away from the abutment plate 24, causing the turntable 23 to drive the docking plate 231 to fall out of the docking groove 241, thereby disconnecting the transmission connection between the joint motor 13 and the forearm 11. This achieves overload protection for the joint motor 13 during impact, preventing the joint motor 13 from burning out due to excessive impact force. At the same time, after the turntable 23 separates from the abutment plate 24, the joint motor 13 drives the turntable 23 to rotate freely, and the turntable 23 drives the docking plate 231 to rotate, thereby increasing the air circulation around the magnetorheological joint 12, improving the heat dissipation effect, and further preventing the magnetorheological joint 12 from experiencing a sudden temperature rise during impact. Furthermore, during the aforementioned process, the floating frame 2 drives the linkage frame 25 to move away from the abutment plate 24 simultaneously. Under the combined action of the linkage frame 25 and the stroke groove 261, the linkage frame 25 pulls the tilting frame 26 to rotate, thereby causing the tilting frame 26 to drive the brake block 262 to abut against the abutment plate 24, achieving the effect of braking the rotational movement of the forearm 11. This prevents the forearm 11 from swinging under inertia after losing the drive of the joint motor 13, further avoiding secondary collisions and improving safety during human-machine interaction. At the same time, it provides double protection when the first protective mechanism fails. The brake block 262 is a detachable module that can be replaced after wear.

[0033] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A magnetorheological fluid flexible joint protection mechanism for a humanoid robot, comprising a large arm (1), a forearm (11), and a magnetorheological joint (12), wherein the magnetorheological joint (12) is fixed on the large arm (1), the forearm (11) is fixed on the rotor of the magnetorheological joint (12), and a joint motor (13) for driving the rotor of the magnetorheological joint (12) to rotate is installed on the outer wall of the large arm (1), characterized in that: The upper arm (1) is provided with a first protective mechanism and a second protective mechanism; The first protective mechanism includes a cylinder (3) rotatably connected to the outer wall of the upper arm (1) via a rotating shaft. The cylinder (3) is filled with a non-Newtonian fluid, and a piston (311) is slidably connected inside the cylinder. Pressure sensors (313) are provided on both ends of the piston (311). A connecting rod (31) is fixed on the outer wall of the piston (311). The end of the connecting rod (31) away from the cylinder (3) is rotatably connected to the outer wall of the lower arm (11). A gear (32) is fixed on the rotating shaft of the cylinder (3). A locking block (34) that can engage with the gear (32) is slidably provided on the upper arm (1). An electromagnet (35) that can attract the locking block (34) is provided on the upper arm (1). The auxiliary magnetic field generated by the electromagnet (35) is superimposed in the same direction as the main magnetic field generated by the excitation coil inside the magnetorheological joint (12). The electromagnet (35) and the pressure sensor (313) are electrically connected through the robot control system.

2. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 1, characterized in that: The outer ring wall of the piston (311) is in contact with the inner ring wall of the cylinder (3), and the piston (311) is provided with a plurality of throttling holes (312).

3. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 1, characterized in that: A spring (341) for pulling the block (34) back to its original position is provided between the outer wall of the block (34) and the upper arm (1).

4. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 1, characterized in that: The outer wall of the upper arm (1) is provided with a mounting groove (15), and the part of the magnetorheological joint (12) located in the mounting groove (15) is exposed. A gearbox (33) is installed on the top inner wall of the mounting groove (15). The input end of the gearbox (33) meshes with the gear (32), and a fan (331) is fixed on its output shaft.

5. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 1, characterized in that: The second protective mechanism includes an abutment plate (24) fixed on the rotor of the magnetorheological joint (12). The outer wall of the abutment plate (24) is provided with several docking slots (241). The upper arm (1) is provided with a transmission chamber (14). A floating frame (2) is slidably connected to the inner wall of the transmission chamber (14). A turntable (23) is rotatably connected to the outer wall of the floating frame (2). The turntable (23) is slidably sleeved on the outer wall of the main shaft of the joint motor (13). A docking plate (231) is fixed on the outer wall of the turntable (23) and slidably inserted into the docking slots (241). A heat dissipation vent (141) with a dust filter is provided at the bottom of the transmission chamber (14).

6. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 5, characterized in that: A tilting frame (26) is rotatably connected to the inner wall of the transmission chamber (14). A stroke groove (261) is provided on the outer wall of the tilting frame (26). A linkage frame (25) is fixed on the outer wall of the floating frame (2) and slidably inserted into the stroke groove (261). A brake block (262) is detachably installed on the outer wall of the tilting frame (26) near the abutment plate (24).

7. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 6, characterized in that: An electric push rod (21) is fixed on the inner wall of the transmission chamber (14). The output end of the electric push rod (21) is fixed on the outer wall of the floating frame (2). A torque sensor (22) is installed on the outer wall of the upper arm (1) and is fixedly connected to the rotating shaft of the lower arm (11). The torque sensor (22) and the electric push rod (21) are electrically connected through the robot control system.

8. The magnetorheological fluid flexible joint protection mechanism for a humanoid robot according to claim 5, characterized in that: A limiting groove (131) is provided on the outer wall of the main shaft of the joint motor (13) along the axial direction. A limiting block (232) is fixed inside the turntable (23). The limiting block (232) is slidably inserted into the limiting groove (131) to realize circumferential force transmission and axial sliding.

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