Force-controlled mechanical arm of robot

Abstract

The invention relates to a force control mechanical arm of a robot, and belongs to the technical field of mechanical arms, the force control mechanical arm of the robot comprises a front shell and a motor shell, a speed reducer output flange is installed on the inner side of the front shell, and a plurality of second-stage planet wheel bearings are fixedly arranged on the side, away from the front shell, of the speed reducer output flange in a sleeving mode; the multiple second-stage planet wheel bearings are fixedly sleeved with second-stage planet gears, and planet carriers which are arranged on the inner sides of the multiple second-stage planet gears and engaged with the multiple second-stage planet gears are installed on the side, close to the second-stage planet gears, of the speed reducer output flange. High torque density is achieved through integration of a small high-torque motor (a motor and a main coding gear), the rotating speed and torque output in the later period are guaranteed, and the torsional rigidity and bending rigidity of the whole driving chain are greatly improved through an integrated rigid shell of a motor shell, a shorter transmission chain (without a coupler), an optimized supporting shaft system and a pre-tightening bearing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanical arms, and particularly relates to a force control mechanical arm of a robot. BACKGROUND

[0002] With the rapid development of industrial automation, medical precise operation, semiconductor manufacturing and the like, robots are increasingly widely applied in production and service scenes, and the performance of a force control mechanical arm as a core execution component for interaction between a robot and the outside world directly determines the operation precision, efficiency and safety of the robot, so a force control mechanical arm of a robot needs to be designed.

[0003] The existing force control mechanical arm adopts a transmission structure of'single-stage planetary gear + worm gear' in the industrial manufacturing field, and the sliding friction characteristics of the worm gear result in serious power loss and low transmission efficiency, which not only increases the motor energy consumption, but also accelerates the aging of components due to heat generated by friction. In the medical, semiconductor and other precise operation fields, a control architecture of'single encoder + single control board' is mostly relied on, the single encoder can only monitor the motor output speed, cannot real-time feedback the error of the planetary gear transmission link, and is difficult to meet the needs of scenes such as minimally invasive surgical instrument operation and semiconductor chip transfer, so the flexibility and convenience of the force control mechanical arm in later operation and use and the precise control performance are reduced. SUMMARY

[0004] The purpose of the application is to provide a force control mechanical arm of a robot with simple structure and reasonable design to solve the above problems.

[0005] The application achieves the above purpose through the following technical solutions: A force control mechanical arm of a robot, comprising a front shell and a motor shell, characterized in that a reducer output flange is installed on the inner side of the front shell, a plurality of second-stage planetary wheel bearings are fixed on the side of the reducer output flange away from the front shell through a limiting rod, a second-stage planetary gear is fixed on the outside of each of the second-stage planetary wheel bearings, and a planet carrier is installed on the side of the reducer output flange close to the second-stage planetary gears and is arranged inside and engaged with the second-stage planetary gears. A plurality of first-stage planetary wheel bearings are fixed on the side of the planet carrier away from the reducer output flange through a limiting rod, a first-stage planetary gear is fixed on the outside of each of the first-stage planetary wheel bearings, an inner ring gear is fixed on the outside of each of the first-stage planetary gears and the second-stage planetary gears, and the inner ring gear is engaged with the first-stage planetary gears and the second-stage planetary gears. The motor is installed on one side of the inside of the motor shell, a partition is installed on the side close to the motor of the inside of the motor shell, a primary sun gear is fixedly installed on the output end of the motor and penetrates into the inside of the partition, the primary sun gear extends into the inside of the inner gear ring and is engaged with a plurality of primary planetary gears, and the motor shell cover is installed on the outside of the front shell.

[0006] As a further optimization scheme of the present application, the rear cover is fixedly installed on the side away from the motor of the motor shell, the control board two and the control board one are fixedly installed on the inside of the rear cover respectively, the main code gear and the slave code gear are fixedly installed on the side away from the motor of the motor shell, the main code gear magnetic steel and the slave code gear magnetic steel are fixedly sleeved on the outside of the main code gear and the slave code gear respectively, the main code gear magnetic steel and the slave code gear magnetic steel are engaged, and the control board one and the control board two are electrically connected with the main code gear and the motor through wires.

[0007] As a further optimization scheme of the present application, the four-point contact bearing is installed on the inside of the front shell, the four-point contact bearing is installed at the edge of the inside of the front shell and is sleeved on the outside of the reducer output flange, and the four-point contact bearing cooperates with the reducer output flange.

[0008] As a further optimization scheme of the present application, a plurality of front shell fixing screws are screwed through the inside of the front shell, and the plurality of front shell fixing screws extend into the inside of the inner gear ring and cooperate therewith.

[0009] As a further optimization scheme of the present application, the flange cover is covered on the side away from the four-point contact bearing of the inside of the front shell, a plurality of flange cover screws are screwed through the inside of the flange cover, and the plurality of flange cover screws extend into the inside of the reducer output flange and cooperate therewith.

[0010] As a further optimization scheme of the present application, the double absolute magnetic encoder and the temperature sensor are integrally installed on one side of the control board one, the double absolute magnetic encoder cooperates with the primary planetary gear and the secondary planetary gear, and the rear cover is made of aluminum-magnesium alloy.

[0011] As a further optimization scheme of the present application, the power supply interface and the signal interface are respectively arranged on the two sides of the outside of the rear cover, and the power supply interface and the signal interface are respectively electrically connected with the control board two and the control board one through wires.

[0012] As a further optimization scheme of the present application, the secondary sun gear is fixedly installed at the middle position of the side close to the reducer output flange of the planet carrier, and the secondary sun gear is arranged on the inside of the plurality of secondary planetary gears and engaged therewith.

[0013] The present application has the following advantages: 1. The force control mechanical arm designed by the present application can realize compact structure, high torque density of integrated small high-torque motor (motor, main encoding gear), guarantee the speed and torque of the output, and greatly improve the torsional stiffness and bending stiffness of the entire drive chain through the integral rigid shell of the motor shell, shorter transmission chain (without coupling), optimized support shaft and preloaded bearing.

[0014] 2. The force control mechanical arm designed by the present application has high internal rotational inertia efficiency, high stiffness transmission, low inertia and high response performance, and finally realizes the functions of small vibration and noise, torque and transmission torque and speed fluctuation are less than 5%, and noise joint operation is less than 70dB. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the overall structure of the present application main view side view explosion Figure 1 ; Figure 2 is the overall structure of the present application main view side view explosion Figure 2 ; Figure 3 is the overall structure of the present application main view side view Figure 1 ; Figure 4 is the overall structure of the present application main view side view Figure 2 ; Figure 5 is the overall structure of the present application Figure 1 A enlarged view; Figure 6 is the overall structure of the present application Figure 1 B enlarged view; Figure 7 is the overall structure of the present application flow chart.

[0016] In the figure: 1, flange cover screw; 2, flange cover; 3, front shell fixing screw; 4, front shell; 5, four-point contact bearing; 6, reducer output flange; 7, two-stage planetary gear; 8, two-stage planetary gear bearing; 9, planetary carrier; 10, one-stage planetary gear; 11, one-stage planetary gear bearing; 12, inner ring gear; 13, spacer; 14, motor; 15, motor shell; 16, main encoding gear; 17, slave encoding gear; 18, main encoding gear magnetic steel; 19, slave encoding gear magnetic steel; 20, control board one; 21, control board two; 22, rear cover; 23, one-stage sun gear; 24, two-stage sun gear. DETAILED DESCRIPTION

[0017] The application will be described in further detail below with reference to the drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application. Those skilled in the art can make some non-essential improvements and adjustments to the application according to the above application content.

[0018] Embodiment 1: as shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 A force-controlled mechanical arm of a robot, comprising a front shell 4, a motor shell 15, a planetary gear transmission assembly, a motor drive assembly and a coding control assembly, wherein the planetary gear transmission assembly comprises a two-stage planetary bearing 8, a two-stage planetary gear 7, a planet carrier 9 and the like installed on the inner side of the front shell 4, responsible for power transmission and speed reduction, the motor drive assembly comprises a motor 14, a spacer 13 and the like integrated inside the motor shell 15, providing power input for the mechanical arm, the coding control assembly comprises a main coding gear 16, a control board one 20 and the like installed on the side of the motor shell 15 away from the motor 14, realizing operation state monitoring and precise control, the motor shell 15 is installed on the outside of the front shell 4 to form a complete mechanical arm main structure, the rigid-flex coupling structure is optimized, the shell topological structure is optimized through finite element analysis (FEA), and the natural frequency is >800Hz, avoiding resonance to cause precision loss.

[0019] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 The front shell 4 is the front end support structure of the mechanical arm, and the planetary gear transmission assembly is integrated on the inner side thereof. First, a four-point contact bearing 5 is installed at the edge of the inner side of the front shell 4 through interference fit. The four-point contact bearing 5 is used to support the reducer output flange 6 assembled subsequently and reduce friction when the reducer output flange 6 rotates, so as to ensure transmission stability. The inner ring of the four-point contact bearing 5 is inserted into the reducer output flange 6 installed on the inner side of the front shell 4, so that the reducer output flange 6 is tightly matched with the four-point contact bearing 5. At this time, the reducer output flange 6 can rotate flexibly around its own axis. Subsequently, a plurality of two-stage planetary bearings 8 are fixed by a limiting rod on the side of the reducer output flange 6 away from the front shell 4, i.e. the side towards the motor shell 15. The number of the two-stage planetary bearings 8 is usually 3-4 according to the transmission requirement, and they are uniformly distributed along the circumferential direction of the reducer output flange 6.

[0020] As shown in Figure 1 , Figure 2 , Figure 5 , Figure 6As shown, outside each secondary planetary gear bearing 8, the secondary planetary gear 7 is fixed by interference fit, so that the secondary planetary gear 7 can rotate around the axis of the secondary planetary gear bearing 8. The outside of the first limiting rod is fixed with the inner ring of the secondary planetary gear bearing 8, and the secondary planetary gear 7 is fixed with the outer ring of the secondary planetary gear bearing 8, which facilitates the installation and rotation of the secondary planetary gear 7 and the secondary planetary gear bearing 8. Then the planet carrier 9 is installed on the side of the reducer output flange 6 close to the secondary planetary gear 7, ensuring that the planet carrier 9 is placed inside the plurality of secondary planetary gears 7, and the planet carrier 9 is engaged with the secondary planetary gears 7. At this time, the secondary planetary gears 7 can drive the planet carrier 9 to rotate synchronously.

[0021] As shown in Figure 1 , Figure 2 , Figure 5 , Figure 6 As shown, on the side of the planet carrier 9 away from the reducer output flange 6, a plurality of primary planetary gear bearings 11 are fixed by the second limiting rod. The number of the plurality of primary planetary gear bearings 11 is consistent with and corresponds to the position of the secondary planetary gear bearing 8. Outside each primary planetary gear bearing 11, the primary planetary gear 10 is fixed by interference fit, so that the primary planetary gear 10 can rotate around the axis of the primary planetary gear bearing 11. The outside of the second limiting rod is fixed with the inner ring of the primary planetary gear bearing 11, and the primary planetary gear 10 is fixed with the outer ring of the primary planetary gear bearing 11, which facilitates the installation and rotation of the primary planetary gear 10 and the primary planetary gear bearing 11.

[0022] As shown in Figure 1 , Figure 2 , Figure 5 , Figure 6 As shown, the outside of the plurality of primary planetary gears 10 and the secondary planetary gears 7 is collectively sleeved with an inner ring gear 12, ensuring that the inner side tooth surface of the inner ring gear 12 is engaged with the primary planetary gears 10 and the secondary planetary gears 7 at the same time. Then, a plurality of front shell fixing screws 3 are uniformly screwed in the circumferential direction inside the front shell 4, so that the front shell fixing screws 3 extend into the inside of the inner ring gear 12 and are screwed with it, thereby fixing the inner ring gear 12 inside the front shell 4, preventing displacement of the inner ring gear 12 during transmission.

[0023] As shown in Figure 1 , Figure 2 , Figure 5 , Figure 6 As shown, the flange cover 2 is closed at the opening at the front end of the inside of the front shell 4 away from the four-point contact bearing 5. A plurality of flange cover screws 1 are uniformly screwed in the circumferential direction inside the flange cover 2, so that the flange cover screws 1 extend into the inside of the reducer output flange 6 and are screwed with it. The inside components of the front shell 4 are sealed and protected by the flange cover 2, and the axial position of the reducer output flange 6 is further fixed.

[0024] As Figure 1 , Figure 2 , Figure 5 , Figure 6 shown, the motor shell 15 is the bearing structure of the motor drive assembly, which cooperates with the front shell 4 to realize power input. On the side of the motor shell 15 inside, i.e. close to the front shell 4, the partition plate 13 is fixedly installed by bolts. The partition plate 13 is used to separate the motor 14 and the planetary gear transmission assembly to prevent mutual contamination of oil stains. On the side of the motor shell 15 inside close to the partition plate 13, i.e. the side of the partition plate 13 away from the front shell 4, the motor 14 is fixedly installed by bolts to ensure that the output end of the motor 14 faces the partition plate 13.

[0025] As Figure 1 , Figure 2 , Figure 5 , Figure 6 shown, on the output end of the motor 14, the primary sun gear 23 is fixedly installed by key connection, so that the primary sun gear 23 penetrates into the inside of the partition plate 13. The motor shell 15 is closed towards the front shell 4, so that the primary sun gear 23 extends into the inside of the inner ring gear 12 and meshes with the primary planetary gear 10. Through the assembly work of the primary planetary gear 10 and the planet carrier 9, the motor 14 can drive the primary sun gear 23 to rotate. At this time, through the meshing of the primary sun gear 23 and the primary planetary gear 10, the primary planetary gear 10 can be driven to rotate around its own axis, and the planet carrier 9 can be driven to revolve around the inner ring gear 12, so that the power of the motor 14 can be transmitted to the planet carrier 9 and subsequent components through the primary sun gear 23.

[0026] As Figure 1 , Figure 2 , Figure 5 , Figure 6 shown, at the middle position of the planet carrier 9 close to the reducer output flange 6, the secondary sun gear 24 is fixedly installed, and the secondary sun gear 24 is placed on the inside of the plurality of secondary planetary gears 7 and meshes with them. Then the planet carrier 9 can revolve around the secondary sun gear 24. At this time, through the meshing of the secondary sun gear 24 and the secondary planetary gears 7, the secondary planetary gears 7 can be driven to rotate along the axial direction of the secondary planetary wheel bearing 8, and the reducer output flange 6 can be driven to work by the inner ring gear 12. The secondary sun gear 24 further optimizes the power transmission path and improves the transmission stability.

[0027] As Figure 1 , Figure 2 , Figure 5 , Figure 6As shown, the rear cover 22 is fixed by bolt cover on the side of the motor shell 15 away from the motor 14, i.e. the rear end opening. The rear cover 22 is made of aluminum magnesium alloy, which has the characteristics of light weight and high strength, and can protect the rear end components of the motor shell 15. Inside the rear cover 22, the control board two 21 and the control board one 20 are fixed and installed by bolts. The control board one 20 and the control board two 21 are distributed along the axial direction of the rear cover 22, and the two are electrically connected by wires.

[0028] As shown in Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 1 The encoding control assembly is used to monitor the running state of the mechanical arm and realize precise control. The main encoding gear 16 and the slave encoding gear 17 are rotatably installed on the side of the motor shell 15 away from the motor 14, i.e. the end face close to the rear cover 22. The main encoding gear 16 is in transmission connection with the output end of the motor 14 through a gear or a shaft coupling. The slave encoding gear 17 is arranged adjacent to the main encoding gear 16. The main encoding gear magnetic steel 18 is fixedly sleeved on the outside of the main encoding gear 16 by interference fit. The slave encoding gear magnetic steel 19 is fixedly sleeved on the outside of the slave encoding gear 17 by interference fit, and the main encoding gear magnetic steel 18 and the slave encoding gear magnetic steel 19 are ensured to be engaged to realize synchronous rotation of the two.

[0029] As shown in Figure 2 , Figure 5 , Figure 6 , Figure 1 , Figure 2 Figure 5 Figure 6 Figure 1 Figure 2 Figure 5 Figure 6 Figure 7 Figure 1 Figure 2 Figure 5 Figure 6 Figure 7 The control board is electrically connected with the encoding assembly and the motor. The control board one 20 is electrically connected with the main encoding gear 16, the slave encoding gear 17 and the motor 14 through wires. The control board two 21 is electrically connected with the control board one 20 and external equipment through wires. On one side of the control board one 20, a double absolute magnetic encoder and a temperature sensor are integrated and installed. The double absolute magnetic encoder cooperates with the primary planetary gear 10 and the secondary planetary gear 7 to monitor the rotation speed and angle of the planetary gear in real time. The temperature sensor monitors the working temperature of the motor 14 and the transmission assembly. The joint internal encoder precision drift compensation maintains temperature stability in the whole temperature range. On both sides of the rear cover 22, a power supply interface and a signal interface are respectively arranged. The power supply interface is electrically connected with the control board two 21 through wires to supply power to the whole control assembly. The signal interface is electrically connected with the control board one 20 through wires to realize input and output of control signals. The integrated design reduces exposed cables and mechanical interfaces. The standard protection level is IP54, and the customized protection level can reach IP67.

[0030] It should be noted that the force control robot arm, when the mechanical arm is started, the external power supply supplies power to the control board 1 20 and the control board 2 21 through the power supply interface on the rear cover 22, the operator inputs the control instruction through the signal interface, the instruction is transmitted to the control board 1 20 through the control board 2 21, the control board 1 20 drives the motor 14 to start, the first sun gear 23 at the output end of the motor 14 rotates, drives the first planetary gear 10 to rotate around its axis through the meshing with the first planetary gear 10, and the first planetary gear 10 revolves around the axis of the first sun gear 23 under the constraint of the inner ring gear 12, thereby driving the planet carrier 9 to rotate.

[0031] When the planet carrier 9 rotates, on the one hand, the second planetary gear 7 is driven to rotate through the second planetary gear bearing 8, and the second planetary gear 7 further improves the speed reduction ratio under the constraint of the inner ring gear 12, and the power is transmitted to the reducer output flange 6, so that the reducer output flange 6 drives the mechanical arm end effector to move, on the other hand, the planet carrier 9 drives the second sun gear 24 to rotate, and the second sun gear 24 meshes with the second planetary gear 7, thereby further optimizing the stability of power transmission.

[0032] In the running process, the double absolute magnetic encoders on the control board 1 20 monitor the rotation speed and angle of the first planetary gear 10 and the second planetary gear 7 in real time, and feed back the data to the control board 1 20, and the control board 1 20 adjusts the output speed and torque of the motor 14 in combination with the preset parameters, realizes the force control function, at the same time, the main encoding gear 16 rotates synchronously with the output end of the motor 14, the driven encoding gear 17 is driven to rotate through the meshing of the main encoding gear magnetic steel 18 and the driven encoding gear magnetic steel 19, and the rotation speed signals of the two are transmitted to the control board 1 20, forming double rotation speed monitoring, ensuring the running accuracy, and the temperature sensor monitors the temperature of the motor 14 and the transmission assembly in real time, if the temperature exceeds the threshold, the control board 1 20 immediately issues an alarm and controls the motor 14 to stop, ensuring the safety of the equipment.

[0033] Flow description: ① The host computer gives relevant instructions; ② The driver outputs current; ③ The motor rotor moves to drive the first sun gear to rotate; ④ The first sun gear meshes with the first planetary gear; ⑤ The first planet carrier outputs (the second sun gear rotates); ⑥ The second sun gear meshes with the second planetary gear; ⑦ The second planet carrier outputs (joint output end); ⑧ The input end encoder detects the motor rotor position / speed in real time, realizes motor closed-loop control, and the output end encoder detects the output end position in real time, realizes joint position full closed-loop control through transmission error compensation The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A force-controlled robotic arm, comprising a front housing (4) and a motor housing (15), characterized in that, The inner side of the front housing (4) is equipped with a reducer output flange (6). On the side of the reducer output flange (6) away from the front housing (4), a plurality of secondary planetary gear bearings (8) are fixedly fitted by a limiting rod. A secondary planetary gear (7) is fixedly fitted on the outside of the plurality of secondary planetary gear bearings (8). A planet carrier (9) is installed on the side of the reducer output flange (6) close to the secondary planetary gear (7) and is placed inside the plurality of secondary planetary gears (7) and meshes with them. On the side of the planetary carrier (9) away from the output flange (6) of the reducer, multiple first-stage planetary bearings (11) are fixed together by two sets of limit rods. A first-stage planetary gear (10) is fixed to the outside of each of the multiple first-stage planetary bearings (11). An internal gear ring (12) is fitted together on the outside of the multiple first-stage planetary gears (10) and the second-stage planetary gears (7). The internal gear ring (12) meshes with the first-stage planetary gears (10) and the second-stage planetary gears (7). A motor (14) is installed on one side inside the motor housing (15). A partition (13) is installed on the side of the motor housing (15) near the motor (14). A first-stage sun gear (23) is fixedly installed at the output end of the motor (14) and extends through the partition (13). The first-stage sun gear (23) extends into the interior of the internal gear ring (12) and meshes with multiple first-stage planetary gears (10). The motor housing (15) is covered and installed on the outside of the front housing (4).

2. The force-controlled robotic arm of a robot according to claim 1, characterized in that: The motor housing (15) is covered and fixed with a rear cover (22) on the side away from the motor (14). The rear cover (22) is fixedly installed with a control board two (21) and a control board one (20). The motor housing (15) is fixedly installed with a main encoder gear (16) and a slave encoder gear (17) on the side away from the motor (14). The main encoder gear (16) and the slave encoder gear (17) are both fixedly fitted with a main encoder gear magnet (18) and a slave encoder gear magnet (19), and the main encoder gear magnet (18) and the slave encoder gear magnet (19) mesh with each other. The control board one (20) and the control board two (21) are electrically connected to the main encoder gear (16) and the motor (14) through wires.

3. The force-controlled robotic arm of a robot according to claim 1, characterized in that: A four-point contact bearing (5) is installed on the inner side of the front housing (4). The four-point contact bearing (5) is installed at the edge of the inner side of the front housing (4) and fits onto the outside of the reducer output flange (6). The four-point contact bearing (5) is in cooperation with the reducer output flange (6).

4. The force-controlled robotic arm of a robot according to claim 1, characterized in that: The front housing (4) has internal threads through which a plurality of front housing fixing screws (3) extend into and engage with the internal gear ring (12).

5. The force-controlled robotic arm of a robot according to claim 1, characterized in that: The front housing (4) is covered by a flange cover (2) on the side away from the four-point contact bearing (5). The flange cover (2) has multiple flange cover screws (1) through its internal threads. The multiple flange cover screws (1) extend into the interior of the reducer output flange (6) and cooperate with it.

6. The force-controlled robotic arm of a robot according to claim 2, characterized in that: The control board (20) is equipped with a dual absolute magnetic encoder and a temperature sensor on one side. The dual absolute magnetic encoder is engaged with a first-stage planetary gear (10) and a second-stage planetary gear (7). The rear cover (22) is made of aluminum-magnesium alloy.

7. A force-controlled robotic arm according to claim 2, characterized in that: The back cover (22) has a power interface and a signal interface on its two outer sides respectively. The power interface and the signal interface are connected to the control board 2 (21) and the control board 1 (20) respectively by wires.

8. The force-controlled robotic arm of a robot according to claim 1, characterized in that: The planetary carrier (9) is fixedly installed with a secondary sun gear (24) at the middle position on the side near the output flange (6) of the reducer. The secondary sun gear (24) is placed inside the multiple secondary planetary gears (7) and meshes with them.

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