Magnetic levitation robot arm support system

Abstract

The present invention discloses a magnetic levitation robot arm support system, which adopts a composite structure of inner and outer stators and a supporting rotating body and a magnetic levitation support technology, so that the supporting rotating body can be rotated and positioned under the support of the inner and outer stators, and the electromagnetic attraction between the inner stator and the rotating rotor is used to absorb the mechanical pressure of the robot arm on the supporting tower, dynamically adjust the air gap between the inner stator and the supporting rotating body, realize the flexible adjustment of the axial reference of the robot arm, and the strict frictionless positioning control of the supporting rotating body, and introduce a passive damping system based on the axial magnetic ring belt of the outer stator and the magnetic slot structure of the inner rotor, passively smooth the influence of the gravity fluctuation of the robot arm system on the air gap between the stator and the rotor, and ensure the stability of the axial reference of the robot arm support system. The real practical application of this invention will effectively broaden the working space of the robot arm and solve the problems that the traditional robot arm support system cannot adjust the axial reference and the rotation positioning accuracy is not high.

Description

Technical Field

[0001] The invention relates to a robot arm support platform, in particular to a robot arm support platform with a magnetic suspension axis radial reference and two-dimensional control, belonging to the field of robot automation control. Background Art

[0002] With the improvement of the automation level of intelligent manufacturing, the automation system based on the support of robot arms has been widely used in industries related to national economy and people's livelihood such as automobile manufacturing, steel production and logistics handling, greatly improving production efficiency.

[0003] It is well known that the core component of the robot automation system is the robot support platform, which not only needs to effectively support the weight of the robot and the weight of the object being operated, but also needs to complete the two-dimensional adjustment capabilities of the robot arm axis and radial direction to reduce the difficulty of adjusting the motion trajectory of the upper robot arm and improve the working space of the robot arm. However, the current robot arm support system mostly adopts a multi-stage transmission gear and radial motor structure, but the radial motor is mostly a high-speed motor. However, the nonlinearity and instability of the robot system itself make it very easy for the robot system to become unstable due to the high reference positioning speed. For this reason, the speed change gear is often used to reduce the speed, but the problem of the gear tooth clearance can easily lead to the reference positioning accuracy error; at the same time, the heavier robot arm and the weight of the grasped object cause the robot arm to have a large friction loss in the rotation positioning process, which undoubtedly increases the power consumption of the robot arm support system; in addition, the axial reference of the traditional robot arm support system cannot be changed, and the height change of the grasped object can only be adjusted by the long and short arm angles on the upper side of the robot arm, which increases the difficulty of robot control and the failure rate. Therefore, it is necessary to study a robot arm support platform with low power consumption, flexible movement, and multiple operation modes. Summary of the invention

[0004] The main purpose of the present invention is to provide a magnetic levitation robot arm support system with flexible adjustment of axial radial reference and no friction, in order to address the problems of low positioning accuracy, high friction power consumption and inability to complete axial reference adjustment in existing robot arm support systems. The system includes a support tower, a support rotating body, a robot arm, passive damping, a main control unit, an inverter unit, an air gap sensor, a pressure sensor and an encoder to complete frictionless positioning of the robot arm's reference height and rotation angle.

[0005] The support tower includes an inner stator, an outer stator and a support base. The axial heights of the inner stator and the outer stator are consistent to determine the original reference of the supporting rotating body. The inner stator is a "T"-shaped structure, and the upper end face is a disc-shaped structure. Four orthogonally distributed pressure sensors are arranged. The pressure sensors measure the pressure of the supporting rotating body on the inner stator. The stator three-phase winding is arranged on the lower side of the upper end face and is connected to the stator converter to generate electromagnetic torque to drive the supporting rotating body to rotate and position. The outer stator is a cylindrical casing. The support base rigidly connects the inner stator and the outer stator to jointly support the axial gravity of the robot arm.

[0006] The supporting rotating body includes a supporting fixed body and a rotating body rotor. The supporting fixed body stabilizes the robot arm and limits the reference height of the robot arm. A long arm servo, an encoder and a follower bearing are arranged at the upper end. The servo motor is located at the mechanical coupling between the upper end of the supporting fixed body and the robot arm, and is connected to the servo driver to drive the robot arm to adjust the movement angle. The rotating body rotor is embedded in a chamber formed by an inner stator and an outer stator, and 16 floating windings arranged in N / S are arranged at the bottom. The floating winding is a DC excitation winding, which is connected to a floating inverter. The floating winding current is controlled by the floating inverter to generate a floating suction force to suspend the supporting rotating body.

[0007] The robot arm is a picking actuator of the robot arm support system, including a supporting long arm, a supporting short arm, a diagonal brace, and a picking gripper. Under the support of the base height and rotation angle of the supporting rotating body, the servo motor angle is adjusted to accurately pick up objects and optimize the trajectory operation; the passive damping is composed of two parts, a magnetic ring belt and a rotating body rotor magnetic slot. The magnetic ring belt is composed of 4 groups of axially magnetized permanent magnets and is located on the inner side of the outer stator. The rotating body rotor magnetic slot is located on the outer side of the supporting rotating body, and the axial height of the rotor magnetic slot is set to 2 / 3 of the corresponding axial height of the magnetic ring belt.

[0008] The CPU of the main control unit uses ARMSTM32, and the peripheral port is physically connected to the encoder and the air gap sensor to obtain the position of the robot arm, receive the target position set by the robot arm, and convert it into the reference height, rotation positioning angle, and pitch setting angle of the supporting long arm and the supporting short arm in real time, and transmit it to the converter unit through optical fiber; the converter unit includes a floating converter, a stator converter, a long arm servo driver and a short arm servo driver. The floating converter is an H-bridge converter, which is connected to the floating winding, adjusts the floating winding current, and controls the reference height of the supporting rotating body; the stator converter is a three-phase bridge inverter, which is connected to the three-phase rotor winding, receives the positioning rotation angle of the supporting rotating body issued by the main control unit, controls the three-phase winding current, and rotates the supporting rotating body; the long arm servo driver and the short arm servo driver are three-phase bridge inverters, which receive the pitch setting angles of the supporting long arm and the supporting short arm, control the driving torque, and adjust the angle of the robot arm.

[0009] The beneficial effects of the present invention are:

[0010] 1) The robot arm support structure adopts a dual-stator and single-rotor structure. The dual-stators work together to support the gravity of the robot arm. The single rotor and the robot arm rigidly form a supporting rotation structure. This innovatively realizes the axial and radial two-dimensional movement of the robot arm support, broadens the robot arm's working space, and effectively solves the axial reference adjustment problem that is difficult to solve in traditional robot arm support systems.

[0011] 2) Introducing magnetic levitation technology into the robot arm support system, innovatively using the suction between the stator and rotor to balance the weight of the robot arm, greatly reducing the rotational positioning friction loss caused by the mass of the robot arm. At the same time, with the help of the suction between the stator and rotor, the size of the air gap between the inner stator and the rotor is dynamically adjusted to achieve flexible adjustment of the axial reference of the robot arm;

[0012] 3) An innovative passive damping system based on the outer stator axial magnetic ring belt and the inner rotor magnetic slot structure is introduced to dynamically characterize the changes in the air gap magnetic field energy between the outer stator and the inner rotor, effectively smoothing the impact of the gravity fluctuation of the robot arm system on the air gap between the stator and the rotor, and ensuring the stability of the axial reference of the robot arm support system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the magnetic levitation robot arm support system of the present invention.

[0014] Figure 2 It is a schematic diagram of the internal and external stators and rotating rotor structure of the magnetic levitation robot arm support system of the present invention.

[0015] Figure 3 It is a working mechanism diagram of the magnetic levitation robot arm support system of the present invention.

[0016] Figure 4 It is a program flow chart of the magnetic levitation robot arm support system of the present invention.

[0017] In the figure: 1 support base, 2 outer stator, 3 magnetic ring belt, 4 rotating body rotor, 4-1 rotor magnetic slot, 5 stator winding, 6 inner stator, 6-1 inner stator back iron, 6-2 pressure sensor, 6-3 cylindrical tower, 6-4 rotor encoder, 7 floating winding, 7-1 air gap sensor, 8 support fixed body, 9 long arm servo (long arm encoder), 10 support long arm, 11 support short arm, 12 follower bearing, 13 short arm servo (short arm encoder), 14 picking gripper, 15 diagonal brace, 16-floating inverter, 17-stator inverter, 18-long arm servo driver, 19 short arm servo driver, 20 main control unit. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0019] like Figure 1 , Figure 2 As shown, a magnetic levitation robot arm support system of the present invention comprises a support tower (1, 2, 6), a support rotating body (4, 8), a robot arm (9, 10, 11, 12, 13, 14, 15), passive damping (4-1, 3), and a main control unit 20, which completes the frictionless positioning of the robot arm reference height and rotation angle; the support tower comprises an inner stator 6, an outer stator 2 and a support base 1, the inner stator 6 and the outer stator 2 have the same axial height, and the original reference of the support rotating body is determined. The inner stator is a "T"-shaped structure, and the upper end surface is a disc-shaped structure. Four orthogonally distributed pressure sensors 6-2 are arranged, and a stator three-phase winding 5 is arranged, which is connected to a stator converter 17 to generate an electromagnetic torque to drive the support rotating body to rotate and position.

[0020] The supporting rotating body includes a supporting fixed body 8 and a rotating body rotor 4. The supporting fixed body 8 stabilizes the robot arm, and a long arm servo 9, an encoder and a follower bearing 12 are arranged at the upper end; the rotating body rotor 4 is embedded in a chamber formed by an inner stator 6 and an outer stator 2, and 16 floating windings 7 arranged in N / S are arranged at the bottom. The floating winding 7 is a DC excitation winding connected to a floating converter 16; the passive damping is composed of two parts: a magnetic ring belt 3 and a rotating body rotor magnetic slot 4-1.

[0021] like Figure 3 , Figure 4 As shown, the operating mechanism of the present invention is as follows: the main control unit 20 first obtains the current state through the pressure sensor 6-2, the air gap sensor 7-1, the rotor encoder 6-4, the long arm encoder 9 and the short arm encoder 13 Then read the target setting Determine the axial motion mode of the supporting rotating body, and adjust the floating converter to complete the axial reference control of the supporting rotating body; then adjust the three-phase stator converter 17 to control the rotation speed and angle of the supporting rotating body, and implement the rotation positioning of the supporting rotating body; then adjust the robot arm, control the servo driver, control the servo driver of the long and short arms, and implement the precise positioning of the two robot support arms; the detailed steps are as follows:

[0022] Step 1: Set the axial height of the supporting rotating body to ref Different from the original reference δ0 (δ0=0), the supporting rotating body has two working modes. ref When δ0 is equal to δ0, the supporting rotating body operates in the axial pressure control mode. ref When δ0 and δ1 are not equal, the supporting rotating body operates in the axial positioning mode.

[0023] 1) Axial pressure control mode: Control the pressure of the supporting rotating body on the inner stator to strictly control it to zero. At this time, the rotation positioning friction loss of the supporting rotating body is 0. The control method adopts a double closed-loop control strategy based on pressure and floating winding current. The pressure p and the reference pressure p are measured by the pressure sensor 6-2. ref =0, adopt PI pressure control strategy, give floating current reference in real time, control the duty cycle of floating converter 16 based on real-time monitored floating current, adjust the current and electromagnetic attraction of floating winding 7, make the electromagnetic attraction always equal to the gravity of supporting rotating body and robot arm, ensure the pressure of supporting rotating body is 0, realize zero friction loss of rotation positioning of supporting rotating body, and then achieve rotation positioning control.

[0024] 2) Axial positioning mode: Control the axial height of the supporting rotating body to δ ref , so that it meets the axial reference positioning requirements of the robot arm. The control method adopts a double closed-loop control strategy based on the axial height and the floating winding current. At this time, the current height is detected by the air gap sensor 7-1, and the axial height reference δ ref The axial height deviation is obtained, and the air gap deviation and PI control strategy are adopted to obtain the floating current reference in real time. The current value is measured by the real-time current sensor. Through the current inner loop PI control, the duty cycle of the floating inverter 16 is controlled, and the current and electromagnetic attraction of the floating winding 7 are adjusted to achieve flexible changes in the axial height of the supporting rotating body and ensure the stability of the reference height of the robot arm.

[0025] Step 2: Rotation positioning control: Control the rotation positioning of the supporting rotating body to θ ref , regulate the duty cycle of the three-phase stator converter 17 and the current flowing into the three-phase stator winding 5, and use the speed reference ωref as the target for ultra-low speed rotation positioning. At this time, ω and θ are obtained by the speed encoder 6-4 in real time. The rotor flux directional decoupling strategy is adopted to decouple the stator current into the excitation current id and the torque current iq, and then the angle positioning constraint, the speed outer loop and the current inner loop double closed-loop collaborative control strategy are adopted. The rotation positioning constant speed adopts traditional PID control, sets the torque current iq reference, and sets the excitation current id to zero. The current inner loop PI control is adopted to adjust the duty cycle of the three-phase converter, and dynamically change the current of the three-phase stator winding 5 until θ is reached. ref At this time, the rotation positioning of the supporting rotating body is completed.

[0026] Step 3: Robot arm control

[0027] 1) Long arm servo drive control: The long arm servo driver 18 receives instructions from the main control unit 20 - the long arm rotation angle First determine the 10° angle of the supporting long arm and Are they equal? ​​If they are equal, the long arm servo 9 keeps working and the long arm angle remains unchanged; otherwise, the long arm servo driver 18 is started, with ω Lref As the reference speed, based on the actual speed measured by the long arm encoder 18, the speed and current double closed-loop control strategy is adopted to adjust the duty cycle of the long arm servo driver 18, change the current of the long arm servo 9, and strictly control the running speed of the supporting long arm 10 to be constant. As the long arm servo 9 runs, the angle of the supporting long arm 10 is gradually adjusted until the target is reached. The long arm servo drive 18 stops.

[0028] 2) Short arm servo drive control: The short arm servo driver 19 receives the short arm rotation angle setting value from the main control unit 20 First, determine the actual measured angle of the current supporting short arm 11 and Are they equal? ​​If they are equal, the short arm servo 13 keeps working and the short arm angle remains unchanged; otherwise, the short arm servo driver 19 is started and the angle is ω Sref As the reference speed, based on the actual speed measured by the short arm encoder 13, a speed and current double closed-loop control strategy is adopted to adjust the duty cycle of the short arm servo driver 19, change the current of the short arm servo 13, strictly control the running speed of the supporting short arm 10 to be constant, and gradually adjust the angle of the supporting short arm 11 until the target angle is reached. The short arm servo driver 19 stops.

Claims

1. A magnetic levitation robot arm support system, characterized in that: It includes a support tower, a support rotating body, a robot arm, passive damping, a main control unit, an inverter unit, an air gap sensor, a pressure sensor, and an encoder to complete the frictionless positioning of the robot arm's reference height and rotation angle; the support tower includes an inner stator, an outer stator and a support base, the inner stator and the outer stator have the same axial height to determine the original reference of the support rotating body, the inner stator is a "T"-shaped structure, the upper end face is a disc-shaped structure, and 4 orthogonally distributed pressure sensors are arranged, the pressure sensor measures the pressure of the support rotating body on the inner stator, the stator three-phase winding is arranged on the lower side of the upper end face, and is connected to the stator inverter to generate electromagnetic torque, drive the support rotating body to rotate and position, and the outer stator The support base is a cylindrical casing, and the inner stator and the outer stator are rigidly connected to each other to support the axial gravity of the robot arm; the supporting rotating body includes a supporting fixed body and a rotating body rotor, the supporting fixed body stabilizes the robot arm and limits the reference height of the robot arm, and a long arm servo motor, an encoder and a follower bearing are arranged at the upper end, and the long arm servo motor is located at the mechanical coupling between the upper end of the supporting fixed body and the robot arm, and is connected to the servo driver to drive the robot arm to adjust the movement angle; the rotating body rotor is embedded in the chamber formed by the inner stator and the outer stator, and 16 floating windings arranged in N / S are arranged at the bottom, and the floating winding is a DC excitation winding, which is connected to the floating converter, and the floating winding current It is controlled by the floating converter to generate a suspension suction force to suspend and support the rotating body; the robot arm is the object-grabbing actuator of the robot arm support system, including a supporting long arm, a supporting short arm, a diagonal support, and an object-grabbing gripper. Under the support of the base height and rotation angle of the supporting rotating body, the servo motor angle is adjusted to accurately pick up objects and optimize the trajectory operation; the passive damping is composed of two parts: 4 magnetic ring belts and the rotating body rotor magnetic slot. The magnetic ring belt is composed of 4 axially magnetized permanent magnets and is located on the inner side of the outer stator. The rotating body rotor magnetic slot is located on the outer side of the supporting rotating body, and the axial height of the rotor magnetic slot is set to 2 / 3 of the corresponding axial height of the magnetic ring belt; the main control unit CPU is ARMSTM32, and the peripheral The port is physically connected to the encoder and the air gap sensor to obtain the position of the robot arm, receive the target position set by the robot arm, and convert it into the reference height, rotation positioning angle, pitch setting angle of the supporting long arm and the supporting short arm in real time, and transmit it to the converter unit through the optical fiber; the converter unit includes a floating converter, a stator converter, a long arm servo driver and a short arm servo driver, the floating converter is an H-bridge converter, which is connected to the floating winding, adjusts the floating winding current, and controls the reference height of the supporting rotating body; the stator converter is a three-phase bridge inverter, which is connected to the three-phase winding, receives the positioning rotation angle of the supporting rotating body issued by the main control unit, controls the three-phase winding current, and rotates the supporting rotating body; The long arm servo driver and the short arm servo driver are three-phase bridge inverters, which receive the pitch setting angles of the supporting long arm and the supporting short arm, control the driving torque, and adjust the angle of the robot arm.

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