WO2021003869A1 - Screw insertion method for large-size peg-in-hole workpiece assembly - Google Patents

Screw insertion method for large-size peg-in-hole workpiece assembly Download PDF

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Publication number
WO2021003869A1
WO2021003869A1 PCT/CN2019/110631 CN2019110631W WO2021003869A1 WO 2021003869 A1 WO2021003869 A1 WO 2021003869A1 CN 2019110631 W CN2019110631 W CN 2019110631W WO 2021003869 A1 WO2021003869 A1 WO 2021003869A1
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workpiece
hole
shaft
assembled
axis
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PCT/CN2019/110631
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French (fr)
Chinese (zh)
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徐静
刘志
陈恳
吴丹
王国磊
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清华大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts

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  • the present disclosure relates to the field of assembling large-size shaft hole workpieces, in particular to a spiral inserting method for assembling large-size shaft hole workpieces.
  • Assembly operation is one of the most important links in the manufacturing process, which directly determines the final quality of the product, and shaft hole assembly is the most common and important form of cooperation in assembly operations.
  • most of the assembly links in the industrial field are still completed by manual operation or semi-automatic tooling.
  • automation technology the use of robots to achieve automated assembly operations has become a trend.
  • the mechanical jam problem in the assembly process of the shaft hole is the main reason for the failure of the automatic shaft hole assembly of the robot.
  • the gap of the shaft hole fit varies from a few millimeters to a few micrometers according to the process requirements.
  • the existing robot positioning accuracy is often difficult to meet the accuracy requirements of high-precision shaft hole assembly, and the slight posture deviation between the shaft holes will cause greater The contact force caused by mechanical jamming occurs.
  • the existing shaft hole assembly methods often use force control to realize the compliant movement of the assembly process, which mainly includes passive compliance and active compliance.
  • the passive compliance method refers to the design of a flexible wrist with characteristic compliance characteristics composed of elastic elements, and the use of structural flexibility to adaptively compensate for the posture deviation between the shaft hole workpieces, but the scope of application of this method is limited, for large-size workpieces, non-vertical Assembling operations and precision shaft hole assembly are difficult to be effective.
  • the active compliance method uses a force sensor to monitor the contact force in the shaft hole assembly process in real time, and compensates for the posture deviation between the shaft holes according to the impedance control algorithm or the force-position hybrid control algorithm.
  • the purpose of the present disclosure is to overcome the mechanical jamming problem that is likely to occur in the assembly of large-size shaft hole workpieces (span greater than 0.5m, matching aperture greater than 80mm), and propose a spiral inserting method for large-size shaft hole workpieces.
  • the present disclosure is based on the existing active and compliant assembly method, which makes it easier for the mechanical arm to avoid mechanical jams during the assembly process of large-size shaft hole workpieces.
  • the operation method is simple and easy to implement, which can effectively improve assembly efficiency and assembly success. rate.
  • the present disclosure proposes a spiral inserting method for assembling large-size shaft hole workpieces, which includes the following steps:
  • the system includes: a base, a shaft workpiece to be assembled, a hole workpiece to be assembled, a force sensor, an end effector, a robotic arm and a host computer; the hole workpiece to be assembled and a base Respectively fixed on the console, the mechanical arm is fixed on the base through a screw connection, the force sensor is fixed to the end joint of the mechanical arm through a screw connection, the force sensor is connected to the mechanical arm through a cable, and the end effector is fixed to the force sensor through a screw connection
  • the shaft workpiece to be assembled is fixed on the end effector through a threaded connection, and the upper computer is connected to the mechanical arm through a network cable;
  • ⁇ O p ⁇ takes the center of the end of the shaft as the origin, and the direction outward along the axis is the positive direction of the Z axis; set the center coordinate system of the end of the robotic arm as ⁇ O t ⁇ , after the manipulator is connected to the shaft to be assembled, the coordinates of the origin of the axis coordinate system in the coordinate system ⁇ O t ⁇ are (x p , y p , z p ), the X axis, Y axis and Z of the axis coordinate system
  • the unit direction vectors of the axis under ⁇ O t ⁇ are (n x ,n y ,n z ), (a x ,a y ,a z ) and (o x ,o y ,o z ), respectively, to get the tool coordinate system T peg , the expression is as follows:
  • the pose T 0 [X 0 ,Y 0 ,Z 0 , ⁇ x0 , ⁇ y0 , ⁇ z0 ]
  • X 0 , Y 0 and Z 0 are the position coordinates of the X, Y, and Z axes of the robot arm in the tool coordinate system
  • ⁇ x0 , ⁇ y0 and ⁇ z0 are the robot arm around X, Y, and Y in the tool coordinate system.
  • the Euler angle of the Z axis, contact force/moment F [F x ,F y ,F z ,M x ,M y ,M z ], F x , F y and F z are the contact force along the axis holes respectively;
  • step 3-2) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds the chamfer depth of the hole, and then go to step 4);
  • the mechanical arm manipulates the axis of the workpiece to be assembled to perform a reciprocating spiral assembly movement.
  • the specific steps are as follows:
  • the parameters include: the reciprocating frequency f screw of the spiral insert, the rotation angle amplitude ⁇ screw and the spiral motion pitch h.
  • the constraint expressions are as follows:
  • ⁇ is the clearance between the shaft and hole
  • d is the distance from the center of the end face of the workpiece to be assembled to the actual axis of rotation when the manipulator rotates around the Z axis of the tool coordinate system
  • f res is the resonance frequency of the manipulator
  • k int is the inertia matching Factor
  • k mate is the clearance fit factor
  • k f is the ratio of axial friction reduction
  • the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor.
  • the expression is as follows:
  • the host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
  • the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated current pose
  • the magnitude of the axial insertion force F z judges the current jamming state of the shaft hole assembly, the specific method is as follows:
  • the host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth Z goal : If the target position depth has been reached, the assembly task ends; otherwise, return to step 4).
  • the disclosed method can control the mechanical arm to realize the spiral insertion of the large-size shaft hole, can use the axial friction restraining effect of the spiral motion, effectively reduce the axial friction resistance, and use the contact force/torque data measured by the force sensor to combine
  • the impedance control algorithm adjusts the spiral inserting parameters and the relative position of the shaft hole according to the different jamming states during the assembly process.
  • This spiral inserting method makes it easier for the robot arm to avoid mechanical jams during the assembly process of large-sized shaft hole workpieces The occurrence of resistance.
  • the method uses a mechanical arm to complete the automatic assembly of large-size shaft hole workpieces, and the operation method is simple and easy to implement, and can effectively improve the assembly efficiency and the assembly success rate.
  • Fig. 1 is a schematic diagram of reducing axial friction in the method of the present disclosure.
  • Figure 2 is an overall flow chart of the method of the present disclosure.
  • Fig. 3 is a schematic diagram of the structure of the large-size shaft hole assembly system in the present disclosure.
  • FIG. 4 is a schematic diagram of the tool coordinate system of the large-size shaft hole assembly system in the present disclosure.
  • Fig. 5 is a schematic diagram of the reciprocating spiral movement of the workpiece shaft in the method of the present disclosure.
  • M is the mechanical arm
  • G is the end effector
  • S is the force sensor
  • P is the shaft workpiece to be assembled
  • H is the hole workpiece to be assembled
  • W is the base
  • C is the upper computer.
  • the present disclosure proposes a spiral inserting method for assembling a workpiece with a large-size shaft hole.
  • the disclosure will be further described in detail below with reference to the drawings and specific embodiments. The following embodiments are used to illustrate the present disclosure, but are not limited to the scope of the present disclosure.
  • the present disclosure proposes a spiral inserting method for assembling a workpiece with a large-size shaft hole.
  • the method reduces the axial frictional resistance by constructing the relative spiral movement between the shaft holes.
  • Figure 1 shows the reduced assembly process in the method of the present disclosure.
  • the basic principle of the middle axial friction force during the spiral inserting process, the workpiece shaft contacts the workpiece hole at the point C at the axial linear velocity v a and the angular velocity w around the axis.
  • the spiral movement changes the friction resistance between the shaft holes.
  • the mechanical arm receives the motion instructions from the host computer, and manipulates the large-size hole workpiece shaft to insert it into the large-size workpiece hole in the form of reciprocating spiral motion.
  • the force sensor monitors the real-time gap between the shaft holes Contact force/moment
  • the host computer uses the force/position information during the assembly process (the position of the end of the robot arm and the contact force/moment between the shaft holes) to realize the function of adjusting the relative position between the shaft holes, and also used for Monitor the jamming state of the shaft hole assembly and adjust the motion parameters of the spiral insert to reduce the frictional resistance between the large-size shaft hole workpieces and avoid the occurrence of mechanical jamming.
  • the present disclosure proposes a spiral inserting method for assembling large-size shaft hole workpieces.
  • the overall process is shown in Fig. 2 and includes the following steps:
  • the robot arm M adopts a multi-joint tandem six-degree-of-freedom robot
  • the force sensor S adopts a six-dimensional force sensor
  • the structure and connection mode of the end effector G can be based on the size of the workpiece to be assembled.
  • the structure is self-designed
  • the upper computer C uses an industrial computer or a commercial notebook
  • the matching aperture of the shaft hole workpiece to be assembled is greater than 80mm.
  • the tool coordinate system of the shaft hole assembly system is established: the shaft coordinate system ⁇ O p ⁇ is established on the shaft workpiece to be assembled, ⁇ O p ⁇ takes the center of the end of the shaft as the origin, and the outward direction along the axis is The positive direction of the Z-axis and the X-axis direction can be arbitrarily specified; suppose the center coordinate system of the end of the robot arm is ⁇ O t ⁇ , and the axis coordinate system after the robot arm is connected to the axis to be assembled and fixed is obtained from the design size and the matching size of the workpiece to be assembled The coordinates (x p , y p , z p ) of the origin in the coordinate system
  • the above reference force/torque parameters are not limited to the given range, and can be based on the shaft hole assembly process the actual measured contact force / torque magnitude appropriate adjustments; position stiffness K x and K y value in the range of 0 ⁇ 0.01, K z value in the range of 0 to 0.05 and greater than or equal to K x and K y 2 times, the attitude stiffness K ⁇ x and K ⁇ y are in the range of 0 ⁇ 0.005.
  • the above stiffness parameters can be adjusted according to the material characteristics of the shaft hole assembly workpiece;
  • pose T 0 [X 0 ,Y 0 ,Z 0 , ⁇ x0 , ⁇ y0 , ⁇ z0 ],
  • X 0 , Y 0 and Z 0 are the X, Y, Z axis of the robot arm in the tool coordinate system, respectively
  • Position coordinates, ⁇ x0 , ⁇ y0 and ⁇ z0 are the Euler angles of the robot arm around the X, Y, and Z axes in the tool coordinate system, respectively.
  • step 3-2) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds the chamfer depth of the hole, and then go to step 4);
  • the host computer obtains the current pose T 0 of the robotic arm in the tool coordinate system T peg and the current contact force/torque F measured by the force sensor”, “the host computer sends a motion instruction to make the mechanical "The arm moves to the target pose” is realized based on the host computer communication interface provided by the robotic arm, which is a function of most commercial robotic arms.
  • the parameters include the reciprocating frequency f screw of the spiral insert, the rotation angle amplitude ⁇ screw and the spiral motion pitch h (axial linear velocity at the contact point of the shaft hole
  • the constraint conditions include the assembly process requirements of the shaft hole such as fitting accuracy, inertia matching and axial friction suppression, the expression is as follows:
  • ⁇ is the clearance between the shaft and hole
  • d is the distance from the center of the end face of the workpiece to be assembled to the actual axis of rotation when the manipulator rotates around the Z axis of the tool coordinate system
  • f res is the resonance frequency of the manipulator
  • k int is the inertia matching Factor
  • k mate is the clearance fit factor
  • k f is the ratio of axial friction reduction, generally k int ⁇ 0.3, k mate ⁇ 0.3, k f ⁇ 1;
  • the initial value of the spiral assembly movement parameters is selected, and the larger pitch h is selected;
  • n s The calculation of n s first calculates the value range of n s from the value range of f screw given in step 4-1), and then selects a larger integer as the value of n s ;
  • the host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
  • the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated current pose
  • the size of the axial insertion force F z judges the current jam state of the shaft hole assembly, the specific method is:
  • the host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth Z goal : If the target position depth has been reached, the assembly task ends; otherwise, return to step 4).
  • the robot arm M receives the motion instruction of the upper computer control system C, and manipulates the large-sized hole workpiece axis P to insert it into the large-sized workpiece hole H in a reciprocating spiral motion, with an insertion depth of 60 mm.
  • This embodiment proposes a spiral inserting method for assembling large-size shaft hole workpieces, and the specific steps are as follows:
  • the size of the shaft to be assembled is 520mm ⁇ 300mm ⁇ 100mm, the shaft length is 150mm, the diameter is 100mm, the outer diameter of the hole to be assembled is 120mm, the inner diameter is 100mm, the shaft hole fit gap ⁇ is 0.1mm, and the hole chamfer 5mm, when the robot arm rotates around the Z axis of the tool coordinate system, the distance d from the center of the end face of the workpiece to be assembled to the actual rotation axis is 0.2mm, and the resonance frequency f r of the robot arm is 30 Hz.
  • the ABB6 degree of freedom commercial robot IRB7600 is used as the robotic arm M to complete the assembly operation, and the Lenovo ThinkPad T440P notebook is used as the upper computer control system;
  • the parameter is T peg ;
  • pose T 0 [X 0 ,Y 0 ,Z 0 , ⁇ x0 , ⁇ y0 , ⁇ z0 ],
  • X 0 , Y 0 and Z 0 are the X, Y, Z axis of the robot arm in the tool coordinate system, respectively
  • Position coordinates, ⁇ x0 , ⁇ y0 and ⁇ z0 are the Euler angles of the robot arm around the X, Y, and Z axes in the tool coordinate system, respectively.
  • step 3-2) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds 5mm, and then go to step 4);
  • the spiral inserting parameter pitch h takes a larger initial value of 66.6mm within the range that satisfies the above constraints
  • n s The calculation of n s first calculates the value range of n s from the value range of f screw given in step 4-1), and then selects a larger integer as the value of n s ;
  • the host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
  • the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated axial insertion force in the current pose
  • the size of F z judges the current jam state of the shaft hole assembly, the specific method is:
  • the jamming state is judged to be a dangerous state, the insertion speed v a is reduced by 20%, and the spiral insertion parameter h is increased by 20% to enhance the axial friction suppression effect.
  • the upper computer After the motion is completed, the upper computer obtains the contact force/torque F and judge the jamming state again, if it still meets
  • ⁇ 47.5N, the robot arm moves to the target position By analogy, until it is out of the "jammed”state; finally, adjust the relative posture of the shaft hole, the upper computer obtains and updates the current posture T 0 of the robotic arm and the current contact force/torque F measured by the force sensor, upper position The machine sends a motion instruction to move the manipulator to the target pose T g T 0 +K d (FF r ), and then proceeds to step 6);
  • the host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth of 60 mm: if the target position depth has been reached, the assembly task ends; otherwise, repeats back to step 4).

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Abstract

A screw insertion method for large-size peg-in-hole workpiece assembly. During implementation, a mechanical arm (M) receives a movement instruction of an upper computer (C), and manipulates a large-size workpiece peg (P) so as to be inserted into a large-size workpiece hole (H) in the form of reciprocating screw movement; a force sensor (S) monitors, in real time, the contact force/moment between the peg and the hole; and the upper computer (C) uses the pose of the end of the mechanical arm (M) during assembly and the contact force/moment between the peg and the hole, to implement the function of adjusting the relative pose between the peg and the hole. Furthermore, the present invention is used to monitor the jamming state of peg-in-hole assembly, and adjust movement parameters of screw insertion, so as to reduce the frictional resistance between large-size peg-in-hole workpieces, and prevent mechanical jamming.

Description

大尺寸轴孔工件装配的螺旋插装方法Spiral inserting method for assembling large-size shaft hole workpiece
相关申请的交叉引用Cross references to related applications
本公开基于申请号为201910603139.8，申请日为2019年7月5日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本公开作为参考。This disclosure is based on a Chinese patent application with an application number of 201910603139.8 and an application date of July 5, 2019, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is incorporated herein by reference.
技术领域Technical field
本公开涉及大尺寸轴孔工件装配领域，尤其涉及一种大尺寸轴孔工件装配的螺旋插装方法。The present disclosure relates to the field of assembling large-size shaft hole workpieces, in particular to a spiral inserting method for assembling large-size shaft hole workpieces.
背景技术Background technique
装配作业是生产制造过程中至关重要的环节之一，直接决定了产品的最终质量，而轴孔装配则是装配作业中最常见且最重要的一种配合形式。目前工业领域的大部分装配环节仍由人工操作或半自动化工装完成，随着自动化技术的发展，使用机器人实现自动化装配操作已成为一种趋势。Assembly operation is one of the most important links in the manufacturing process, which directly determines the final quality of the product, and shaft hole assembly is the most common and important form of cooperation in assembly operations. At present, most of the assembly links in the industrial field are still completed by manual operation or semi-automatic tooling. With the development of automation technology, the use of robots to achieve automated assembly operations has become a trend.
轴孔装配过程中的机械卡阻问题，是机器人自动化轴孔装配失败的主要原因。轴孔配合的间隙根据工艺需求，变化范围由几毫米到几微米，而现有的机器人定位精度往往难以满足高精密轴孔装配的精度要求，轴孔之间微小的位姿偏差都会造成较大的接触力，导致机械卡阻的发生。The mechanical jam problem in the assembly process of the shaft hole is the main reason for the failure of the automatic shaft hole assembly of the robot. The gap of the shaft hole fit varies from a few millimeters to a few micrometers according to the process requirements. The existing robot positioning accuracy is often difficult to meet the accuracy requirements of high-precision shaft hole assembly, and the slight posture deviation between the shaft holes will cause greater The contact force caused by mechanical jamming occurs.
为了克服轴孔装配过程中的机械卡阻问题，现有的轴孔装配方法往往采用力控来实现装配过程的柔顺运动，主要包括被动柔顺和主动柔顺两种方式。被动柔顺方法是指设计弹性元件组成的具有特性柔顺特性的柔性手腕，利用结构柔性自适应补偿轴孔工件之间的位姿偏差，但是这种方法的适用范围有限，对于大尺寸工件、非垂直装配操作以及精密轴孔装配等情况都很难奏效。主动柔顺方法则是利用力传感器实时监测轴孔装配过程中的接触力的大小，并依据阻抗控制算法或者力位混合控制算法对轴孔之间的位姿偏差进行补偿，这种方法适用范围更广。但是现有的主动柔顺装配方法在面对大尺寸工件之间的轴孔装配时仍然有一定的困难。在航空航天、船舶制造、汽车制造等领域，工件的结构较复杂，尺寸较大(跨度在0.5m以上，配合孔径在80mm以上)，重载操作使得轴孔工件在装配过程中产生了更大的接触压力和摩擦阻力，尤其是轴向的摩擦阻力的增大，使得轴孔之间更容易发生机械卡阻，而且一旦出现卡阻就很难恢复和调整。同时，过大的接触力也使得阻抗控制算法的运动步长较小，影响了轴孔装配的效率。因此，一 种针对大尺寸轴孔工件装配的机械卡阻问题的装配方法十分有必要。In order to overcome the problem of mechanical jamming during the shaft hole assembly process, the existing shaft hole assembly methods often use force control to realize the compliant movement of the assembly process, which mainly includes passive compliance and active compliance. The passive compliance method refers to the design of a flexible wrist with characteristic compliance characteristics composed of elastic elements, and the use of structural flexibility to adaptively compensate for the posture deviation between the shaft hole workpieces, but the scope of application of this method is limited, for large-size workpieces, non-vertical Assembling operations and precision shaft hole assembly are difficult to be effective. The active compliance method uses a force sensor to monitor the contact force in the shaft hole assembly process in real time, and compensates for the posture deviation between the shaft holes according to the impedance control algorithm or the force-position hybrid control algorithm. This method has a more applicable scope. wide. However, the existing active compliant assembly method still has certain difficulties when facing the shaft hole assembly between large-size workpieces. In the fields of aerospace, shipbuilding, automobile manufacturing, etc., the structure of the workpiece is relatively complex and the size is large (span is more than 0.5m, the matching aperture is more than 80mm), and the heavy load operation makes the shaft hole workpiece larger in the assembly process The contact pressure and friction resistance, especially the increase in axial friction resistance, make it easier to mechanically jam between the shaft holes, and it is difficult to recover and adjust once the jam occurs. At the same time, excessive contact force also makes the movement step length of the impedance control algorithm smaller, which affects the efficiency of shaft hole assembly. Therefore, an assembly method for the mechanical jamming problem of the assembly of large-size shaft holes is very necessary.
发明内容Summary of the invention
本公开的目的是为克服大尺寸轴孔工件(跨度大于0.5m，配合孔径大于80mm)的装配中容易出现的机械卡阻问题，提出一种大尺寸轴孔工件装配的螺旋插装方法。本公开在现有主动柔顺装配方法的基础上，使得机械臂在大尺寸轴孔工件的装配过程中更容易避免机械卡阻的发生，操作方法简单易行，能有效地提高装配效率和装配成功率。The purpose of the present disclosure is to overcome the mechanical jamming problem that is likely to occur in the assembly of large-size shaft hole workpieces (span greater than 0.5m, matching aperture greater than 80mm), and propose a spiral inserting method for large-size shaft hole workpieces. The present disclosure is based on the existing active and compliant assembly method, which makes it easier for the mechanical arm to avoid mechanical jams during the assembly process of large-size shaft hole workpieces. The operation method is simple and easy to implement, which can effectively improve assembly efficiency and assembly success. rate.
本公开提出一种大尺寸轴孔工件装配的螺旋插装方法，包括以下步骤：The present disclosure proposes a spiral inserting method for assembling large-size shaft hole workpieces, which includes the following steps:
1)搭建大尺寸轴孔装配系统；所述系统包括：基座、待装配轴工件、待装配孔工件、力传感器、末端执行器、机械臂和上位机；所述待装配孔工件和基座分别固定于操作台上，机械臂通过螺纹连接固定在基座上，力传感器通过螺纹连接固定于机械臂的最末关节，力传感器通过电缆连接机械臂，末端执行器通过螺纹连接固定于力传感器上，待装配轴工件通过螺纹连接固定于末端执行器上，上位机通过网线连接机械臂；1) Build a large-size shaft hole assembly system; the system includes: a base, a shaft workpiece to be assembled, a hole workpiece to be assembled, a force sensor, an end effector, a robotic arm and a host computer; the hole workpiece to be assembled and a base Respectively fixed on the console, the mechanical arm is fixed on the base through a screw connection, the force sensor is fixed to the end joint of the mechanical arm through a screw connection, the force sensor is connected to the mechanical arm through a cable, and the end effector is fixed to the force sensor through a screw connection On the upper, the shaft workpiece to be assembled is fixed on the end effector through a threaded connection, and the upper computer is connected to the mechanical arm through a network cable;
2)操作机械臂完成轴孔粗对准，使得待装配轴工件的轴位于待装配孔工件的孔的上方且轴与孔的同轴度不超过待装配孔工件孔倒角宽度；2) Operate the mechanical arm to complete the rough alignment of the shaft hole, so that the shaft of the shaft workpiece to be assembled is located above the hole of the workpiece to be assembled and the coaxiality of the shaft and the hole does not exceed the chamfer width of the workpiece to be assembled;
在待装配轴工件上建立轴心坐标系{O p},{O p}以轴的末端圆心为原点，沿轴线朝外方向为Z轴正方向；设机械臂末端中心坐标系为{O t}，机械臂与待装配轴连接固定后轴心坐标系原点在坐标系{O t}下的坐标为(x p,y p,z p)，轴心坐标系的X轴、Y轴和Z轴在{O t}下的单位方向向量分别为(n x,n y,n z)、(a x,a y,a z)和(o x,o y,o z)，得到工具坐标系T peg，表达式如下： Establish the axis coordinate system {O p } on the workpiece to be assembled, {O p } takes the center of the end of the shaft as the origin, and the direction outward along the axis is the positive direction of the Z axis; set the center coordinate system of the end of the robotic arm as {O t }, after the manipulator is connected to the shaft to be assembled, the coordinates of the origin of the axis coordinate system in the coordinate system {O t } are (x p , y p , z p ), the X axis, Y axis and Z of the axis coordinate system The unit direction vectors of the axis under {O t } are (n x ,n y ,n z ), (a x ,a y ,a z ) and (o x ,o y ,o z ), respectively, to get the tool coordinate system T peg , the expression is as follows:
Figure PCTCN2019110631-appb-000001
Figure PCTCN2019110631-appb-000001
3)机械臂操纵待装配轴工件的轴完成柔顺入孔阶段，使得待装配孔工件的孔的插入深度超过孔的倒角深度；具体步骤如下：3) The mechanical arm manipulates the shaft of the shaft workpiece to be assembled to complete the stage of compliant hole insertion, so that the insertion depth of the hole of the workpiece to be assembled exceeds the chamfer depth of the hole; the specific steps are as follows:
3-1)设定初始的阻抗控制参数，包括插入速度v a、参考力和参考力矩组成的向量
Figure PCTCN2019110631-appb-000002
控制刚度K p＝[K x,K y,K z,K θx,K θy,0]和调姿刚度K d＝[K x,K y,0,K θx,K θy,0]，其中
Figure PCTCN2019110631-appb-000003
和
Figure PCTCN2019110631-appb-000004
分别是沿X、Y、Z方向的参考接触力，
Figure PCTCN2019110631-appb-000005
和
Figure PCTCN2019110631-appb-000006
分别是绕X、Y轴的参考接触力矩，K x、K y和K z分别是X、Y、Z方向的位置刚度，K θx和K θy分别是绕X方向和Y方向的姿态刚度； 3-1) Set the initial impedance control parameters, including the vector of insertion speed v a , reference force and reference torque
Figure PCTCN2019110631-appb-000002
Control stiffness K p =[K x ,K y ,K z ,K θx ,K θy ,0] and attitude adjustment stiffness K d =[K x ,K y ,0,K θx ,K θy ,0], where
Figure PCTCN2019110631-appb-000003
with
Figure PCTCN2019110631-appb-000004
Are the reference contact forces along the X, Y, and Z directions,
Figure PCTCN2019110631-appb-000005
with
Figure PCTCN2019110631-appb-000006
Are the reference contact moments around the X and Y axes, K x , Ky and K z are the position stiffnesses in the X, Y, and Z directions respectively, and K θx and K θy are the attitude stiffnesses around the X and Y directions respectively;
3-2)上位机获取机械臂在工具坐标系T peg下的当前位姿T 0和力传感器测量的当前的接触力/力矩F，并计算下一时刻机械臂的目标位姿T d＝T 0+K p(F-F ref)，上位机发送运动指令使机械臂运动到目标位姿T d；其中位姿T 0＝[X 0,Y 0,Z 0,θ x0,θ y0,θ z0]，X 0、Y 0和Z 0分别是机械 臂在工具坐标系下X、Y、Z轴的位置坐标，θ x0、θ y0和θ z0分别是机械臂在工具坐标系下绕X、Y、Z轴的欧拉角，接触力/力矩F＝[F x,F y,F z,M x,M y,M z]，F x、F y和F z分别是轴孔之间接触力沿X、Y、Z轴方向的分量，M x、M y和M z分别是轴孔之间接触力矩绕X、Y、Z轴的分量； 3-2) The host computer obtains the current pose T 0 of the robotic arm in the tool coordinate system T peg and the current contact force/torque F measured by the force sensor, and calculates the target pose T d = T of the robotic arm at the next moment 0 +K p (FF ref ), the host computer sends a motion instruction to move the robotic arm to the target pose T d ; where the pose T 0 =[X 0 ,Y 0 ,Z 0 ,θ x0 ,θ y0 ,θ z0 ] , X 0 , Y 0 and Z 0 are the position coordinates of the X, Y, and Z axes of the robot arm in the tool coordinate system, θ x0 , θ y0 and θ z0 are the robot arm around X, Y, and Y in the tool coordinate system. The Euler angle of the Z axis, contact force/moment F=[F x ,F y ,F z ,M x ,M y ,M z ], F x , F y and F z are the contact force along the axis holes respectively The components in the X, Y, and Z axis directions, M x , My and M z are the components of the contact torque between the shaft holes around the X, Y, and Z axes respectively;
3-3)重复步骤3-2)，直至待装配轴工件的轴插入待装配孔工件的孔的深度超过孔的倒角深度,进入步骤4)；3-3) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds the chamfer depth of the hole, and then go to step 4);
4)机械臂操纵待装配轴工件的轴执行往复螺旋式装配运动，具体步骤如下：4) The mechanical arm manipulates the axis of the workpiece to be assembled to perform a reciprocating spiral assembly movement. The specific steps are as follows:
4-1)计算螺旋式装配运动参数的取值范围，所述参数包括：螺旋插装的往复运动频率f screw、旋转角度幅值θ screw和螺旋运动节距h，约束条件表达式如下： 4-1) Calculate the value range of the spiral assembly motion parameters. The parameters include: the reciprocating frequency f screw of the spiral insert, the rotation angle amplitude θ screw and the spiral motion pitch h. The constraint expressions are as follows:
Figure PCTCN2019110631-appb-000007
Figure PCTCN2019110631-appb-000007
其中，δ是轴孔配合的间隙，d是机械臂绕工具坐标系Z轴旋转时待装配轴工件的端面圆心到实际旋转轴线的距离，f res为机械臂的共振频率，k int为惯量匹配因子，k mate为间隙配合因子，k f为轴向摩擦力减小的比例； Among them, δ is the clearance between the shaft and hole, d is the distance from the center of the end face of the workpiece to be assembled to the actual axis of rotation when the manipulator rotates around the Z axis of the tool coordinate system, f res is the resonance frequency of the manipulator, and k int is the inertia matching Factor, k mate is the clearance fit factor, k f is the ratio of axial friction reduction;
第一次执行螺旋式装配运动时，在满足上述约束条件的范围内，选取螺旋式装配运动参数的初始值；When performing the spiral assembly motion for the first time, select the initial values of the spiral assembly motion parameters within the range that meets the above constraints;
4-2)计算螺旋式装配运动过程中机械臂在工具坐标系下的位置总增量ΔX、ΔY、ΔZ和绕X、Y轴的欧拉角总增量Δθ x、Δθ y； 4-2) Calculate the total increment ΔX, ΔY, ΔZ of the position of the robot arm in the tool coordinate system and the total increment Δθ x , Δθ y of the Euler angle around the X and Y axes during the spiral assembly movement;
上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，依据阻抗控制算法，表达式如下： The host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor. According to the impedance control algorithm, the expression is as follows:
Figure PCTCN2019110631-appb-000008
Figure PCTCN2019110631-appb-000008
4-3)计算螺旋插装运动指令的步数n s和绕工具坐标系Z轴旋转的角度幅值θ screw，表达式如下： 4-3) Calculate the number of steps n s of the spiral inserting motion instruction and the angular amplitude θ screw about the Z axis of the tool coordinate system, the expression is as follows:
Figure PCTCN2019110631-appb-000009
Figure PCTCN2019110631-appb-000009
4-4)计算每一步螺旋运动指令的目标位姿T i d，i＝1,2…n s，表达式如下： 4-4) Calculate the target pose T i d of each step of the spiral motion instruction, i=1, 2...n s , the expression is as follows:
Figure PCTCN2019110631-appb-000010
Figure PCTCN2019110631-appb-000010
其中
Figure PCTCN2019110631-appb-000011
每一步的位姿增量
Figure PCTCN2019110631-appb-000012
且满足： among them
Figure PCTCN2019110631-appb-000011
Pose increment for each step
Figure PCTCN2019110631-appb-000012
And satisfy:
Figure PCTCN2019110631-appb-000013
Figure PCTCN2019110631-appb-000013
其中
Figure PCTCN2019110631-appb-000014
ΔY i d和
Figure PCTCN2019110631-appb-000015
是第i步指令中机械臂在工具坐标系下分别沿X、Y、Z轴的位置增量，
Figure PCTCN2019110631-appb-000016
和
Figure PCTCN2019110631-appb-000017
分别是第i步指令中机械臂在工具坐标系下绕X、Y、Z轴的欧拉角增量； among them
Figure PCTCN2019110631-appb-000014
ΔY i d and
Figure PCTCN2019110631-appb-000015
Is the position increment of the robot arm along the X, Y, and Z axes in the tool coordinate system in the i-th instruction,
Figure PCTCN2019110631-appb-000016
with
Figure PCTCN2019110631-appb-000017
They are the Euler angle increments of the robot arm around the X, Y, and Z axes in the tool coordinate system in the i-th instruction;
4-5)上位机将4-4)中计算得到的n s步螺旋运动指令发送给机械臂，使机械臂操纵工件轴进行往复螺旋式的装配运动； 4-5) The host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
5)机械臂进行完n s步往复螺旋式的装配运动后，上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，并依据更新后的当前位姿下的轴向插装力F z的大小判断轴孔装配当前的卡阻状态，具体方法如下： 5) After the manipulator has completed the n s- step reciprocating spiral assembly movement, the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated current pose The magnitude of the axial insertion force F z judges the current jamming state of the shaft hole assembly, the specific method is as follows:
5-1)当
Figure PCTCN2019110631-appb-000018
时，判断卡阻状态为安全状态，则令插入速度v a增大10％，螺旋插装参数h增大10％，然后进入步骤6)； 5-1) When
Figure PCTCN2019110631-appb-000018
When it is judged that the jamming state is a safe state, increase the insertion speed v a by 10%, and increase the spiral insertion parameter h by 10%, and then enter step 6);
5-2)当
Figure PCTCN2019110631-appb-000019
时，判断卡阻状态为危险状态，则令插入速度v a减小20％，螺旋插装参数h增大20％，同时调整轴孔的相对姿态，计算目标位姿T g＝T 0+K d(F-F r)，上位机发送运动指令使机械臂运动到目标位姿T g，然后进入步骤6)； 5-2) When
Figure PCTCN2019110631-appb-000019
When the jamming state is judged to be a dangerous state, the insertion speed v a is reduced by 20%, and the spiral insertion parameter h is increased by 20%. At the same time, adjust the relative posture of the shaft hole to calculate the target posture T g = T 0 +K d (FF r ), the host computer sends a motion instruction to move the robot arm to the target pose T g , and then enters step 6);
5-3)当
Figure PCTCN2019110631-appb-000020
时，判断卡阻状态为已发生卡阻，首先，调整运动参数，即轴向插入速度v a减小30％，螺旋插装参数h减小30％；然后，机械臂运动到目标位姿位姿
Figure PCTCN2019110631-appb-000021
其中
Figure PCTCN2019110631-appb-000022
为步骤4-4)中第n s-1步螺旋式装配运动指令的目标位姿，使得工件轴反向螺旋后退至上一条运动位姿以缓解卡阻，运动完成后上位机获取接触力/力矩F并再次判断卡阻状态，如果仍满足
Figure PCTCN2019110631-appb-000023
则机械臂运动到目标位置
Figure PCTCN2019110631-appb-000024
直到机械臂运动目标位置
Figure PCTCN2019110631-appb-000025
时消除已发生卡阻状态，上位机获取并更新机械臂的当前位姿T 0和力传感器测量的当前的接触力/力矩F；最后，调整轴孔的相对姿态,上位机获取并更新机械臂的当前位姿T 0和力传感器测量的当前的接触力/力矩F,上位机发送运动指令使机械臂运动到目标位姿 T g＝T 0+K d(F-F r)，然后进入步骤6)； 5-3) When
Figure PCTCN2019110631-appb-000020
When the jamming state is judged as jam has occurred, first, adjust the motion parameters, that is, the axial insertion speed v a is reduced by 30%, and the spiral insertion parameter h is reduced by 30%; then, the mechanical arm moves to the target position posture
Figure PCTCN2019110631-appb-000021
among them
Figure PCTCN2019110631-appb-000022
It is the target pose of the screw assembly motion instruction in step n s -1 in step 4-4), so that the workpiece axis spirals backward to the previous motion pose to relieve jamming. After the motion is completed, the upper computer obtains the contact force/torque F and judge the jam state again, if it still meets
Figure PCTCN2019110631-appb-000023
Then the robotic arm moves to the target position
Figure PCTCN2019110631-appb-000024
Until the robot arm moves to the target position
Figure PCTCN2019110631-appb-000025
When the jamming state is eliminated, the upper computer obtains and updates the current pose T 0 of the manipulator and the current contact force/torque F measured by the force sensor; finally, adjust the relative posture of the shaft hole, and the upper computer obtains and updates the manipulator The current pose T 0 and the current contact force/torque F measured by the force sensor, the upper computer sends a motion instruction to move the manipulator to the target pose T g ＝T 0 +K d (FF r ), and then go to step 6) ；
6)上位机获取并更新机械臂当前位姿T 0，判断当前轴向插入深度Z 0是否到达目标位置深度Z goal：如果已达到目标位置深度，则装配任务结束；否则重新返回步骤4)。 6) The host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth Z goal : If the target position depth has been reached, the assembly task ends; otherwise, return to step 4).
本公开的特点及有益效果在于：The features and beneficial effects of the present disclosure are:
本公开方法可控制机械臂实现大尺寸轴孔的螺旋插装，能够利用螺旋运动的轴向摩擦抑制作用，有效地减小轴向摩擦阻力，并利用力传感器测量的接触力/力矩数据，结合阻抗控制算法，针对装配过程中不同的卡阻状态，调整螺旋插装参数和轴孔的相对位姿，该螺旋插装方法使得机械臂在大尺寸轴孔工件的装配过程中更容易避免机械卡阻的发生。该方法使用机械臂完成大尺寸轴孔工件的自动化装配，操作方法简单易行，能有效地提高装配效率和装配成功率。The disclosed method can control the mechanical arm to realize the spiral insertion of the large-size shaft hole, can use the axial friction restraining effect of the spiral motion, effectively reduce the axial friction resistance, and use the contact force/torque data measured by the force sensor to combine The impedance control algorithm adjusts the spiral inserting parameters and the relative position of the shaft hole according to the different jamming states during the assembly process. This spiral inserting method makes it easier for the robot arm to avoid mechanical jams during the assembly process of large-sized shaft hole workpieces The occurrence of resistance. The method uses a mechanical arm to complete the automatic assembly of large-size shaft hole workpieces, and the operation method is simple and easy to implement, and can effectively improve the assembly efficiency and the assembly success rate.
附图说明Description of the drawings
图1是本公开方法中减小轴向摩擦力的原理图。Fig. 1 is a schematic diagram of reducing axial friction in the method of the present disclosure.
图2是本公开方法的整体流程图。Figure 2 is an overall flow chart of the method of the present disclosure.
图3是本公开中大尺寸轴孔装配系统结构示意图。Fig. 3 is a schematic diagram of the structure of the large-size shaft hole assembly system in the present disclosure.
图4是本公开中大尺寸轴孔装配系统的工具坐标系示意图。4 is a schematic diagram of the tool coordinate system of the large-size shaft hole assembly system in the present disclosure.
图5是本公开方法中工件轴往复式螺旋运动的示意图。Fig. 5 is a schematic diagram of the reciprocating spiral movement of the workpiece shaft in the method of the present disclosure.
图中，M为机械臂，G为末端执行器，S为力传感器，P为待装配轴工件，H为待装配孔工件，W为基座，C为上位机。In the figure, M is the mechanical arm, G is the end effector, S is the force sensor, P is the shaft workpiece to be assembled, H is the hole workpiece to be assembled, W is the base, and C is the upper computer.
具体实施方式Detailed ways
本公开提出提出一种大尺寸轴孔工件装配的螺旋插装方法，下面结合附图和具体实施例对本公开进一步详细说明如下。以下实施例用于说明本公开，但不限于本公开的范围。The present disclosure proposes a spiral inserting method for assembling a workpiece with a large-size shaft hole. The disclosure will be further described in detail below with reference to the drawings and specific embodiments. The following embodiments are used to illustrate the present disclosure, but are not limited to the scope of the present disclosure.
本公开提出一种大尺寸轴孔工件装配的螺旋插装方法，该方法通过构造轴孔之间的相对螺旋运动以减小轴向摩擦阻力，图1给出了本公开方法中减小装配过程中轴向摩擦力的基本原理：螺旋插装过程中，工件轴以轴向线速度v a和绕轴线的角速度w与工件孔接触于点C，螺旋运动改变了轴孔之间的摩擦阻力，即在接触压力N和总摩擦阻力f C不变的同时，引入了绕轴向的切向摩擦力f t，对轴孔之间的摩擦阻力产生了重新分配的效果，使得轴向摩擦力
Figure PCTCN2019110631-appb-000026
切向摩擦力
Figure PCTCN2019110631-appb-000027
其中r是待装配轴工件的轴半径，螺旋运动的节距
Figure PCTCN2019110631-appb-000028
通过减小螺旋运动的节距h，可以减小轴向摩擦力，进而减小机械卡阻的发生概率。轴向摩擦抑制的效果对于更大的工件轴尺寸更明显，适用于大尺寸轴孔的装配应用。 The present disclosure proposes a spiral inserting method for assembling a workpiece with a large-size shaft hole. The method reduces the axial frictional resistance by constructing the relative spiral movement between the shaft holes. Figure 1 shows the reduced assembly process in the method of the present disclosure. The basic principle of the middle axial friction force: during the spiral inserting process, the workpiece shaft contacts the workpiece hole at the point C at the axial linear velocity v a and the angular velocity w around the axis. The spiral movement changes the friction resistance between the shaft holes. That is, while the contact pressure N and the total friction resistance f C remain unchanged, the tangential friction force f t around the axial direction is introduced, which has a redistribution effect on the friction resistance between the shaft holes, so that the axial friction force
Figure PCTCN2019110631-appb-000026
Tangential friction
Figure PCTCN2019110631-appb-000027
Where r is the shaft radius of the shaft workpiece to be assembled, and the pitch of the spiral motion
Figure PCTCN2019110631-appb-000028
By reducing the pitch h of the spiral motion, the axial friction can be reduced, thereby reducing the probability of mechanical jamming. The effect of axial friction suppression is more obvious for larger workpiece shaft sizes, and is suitable for assembly applications of large-size shaft holes.
在本公开方法的具体实现过程中，机械臂接收上位机的运动指令，操纵大尺寸孔工件轴以往复式螺旋运动的形式插入大尺寸工件孔中，过程中力传感器实时监测轴孔之间的接触力/力矩，上位机利用装配过程中的力/位信息(机械臂末端的位姿和轴孔之间的接触力/力矩)，实现调整轴孔之间相对位姿的功能，同时用于监测轴孔装配的卡阻状态，调整螺旋插装的运动参数，以减小大尺寸轴孔工件之间的摩擦阻力，避免机械卡阻的发生。In the specific implementation process of the disclosed method, the mechanical arm receives the motion instructions from the host computer, and manipulates the large-size hole workpiece shaft to insert it into the large-size workpiece hole in the form of reciprocating spiral motion. In the process, the force sensor monitors the real-time gap between the shaft holes Contact force/moment, the host computer uses the force/position information during the assembly process (the position of the end of the robot arm and the contact force/moment between the shaft holes) to realize the function of adjusting the relative position between the shaft holes, and also used for Monitor the jamming state of the shaft hole assembly and adjust the motion parameters of the spiral insert to reduce the frictional resistance between the large-size shaft hole workpieces and avoid the occurrence of mechanical jamming.
本公开提出一种大尺寸轴孔工件装配的螺旋插装方法，整体流程如图2所示，包括以下步骤：The present disclosure proposes a spiral inserting method for assembling large-size shaft hole workpieces. The overall process is shown in Fig. 2 and includes the following steps:
1)搭建大尺寸轴孔装配系统；所述系统结构如图3所示，包括：基座W、待装配轴工件P、待装配孔工件H、力传感器S、末端执行器G、机械臂M以及上位机C；所述待装配孔工件H和基座W分别固定于操作台上，机械臂M通过螺纹连接固定于基座W上，力传感器S通过螺纹连接固定于机械臂M的最末关节，并通过电缆连接机械臂M，末端执行器G通过螺纹连接固定于力传感器S上，待装配轴工件P通过螺纹连接固定于末端执行器G上，上位机C通过网线连接机械臂M；本系统各部件均可采用常规型号，其中所述机械臂M采用多关节串联式六自由度机器人，力传感器S采用六维力传感器，末端执行器G的结构和连接方式可根据待装配工件的结构自行设计，上位机C选用工控机或商用笔记本，所述待装配轴孔工件的配合孔径大于80mm。1) Build a large-size shaft hole assembly system; the system structure is shown in Figure 3, including: base W, shaft workpiece to be assembled P, workpiece to be assembled hole H, force sensor S, end effector G, robotic arm M And the host computer C; the to-be-assembled hole workpiece H and the base W are respectively fixed on the operating table, the mechanical arm M is fixed to the base W through a screw connection, and the force sensor S is fixed to the end of the mechanical arm M through a screw connection The joint is connected to the mechanical arm M through a cable, the end effector G is fixed to the force sensor S through a threaded connection, the shaft workpiece P to be assembled is fixed to the end effector G through a threaded connection, and the upper computer C is connected to the mechanical arm M through a network cable; All components of the system can adopt conventional models. The robot arm M adopts a multi-joint tandem six-degree-of-freedom robot, the force sensor S adopts a six-dimensional force sensor, and the structure and connection mode of the end effector G can be based on the size of the workpiece to be assembled. The structure is self-designed, the upper computer C uses an industrial computer or a commercial notebook, and the matching aperture of the shaft hole workpiece to be assembled is greater than 80mm.
2)手动操作机械臂完成轴孔粗对准，使得待装配轴工件的轴位于待装配孔工件的孔的上方，并保证轴与孔的同轴度不超过待装配孔工件孔倒角宽度；如图4所示，建立轴孔装配系统的工具坐标系：在待装配轴工件上建立轴心坐标系{O p},{O p}以轴的末端圆心为原点，沿轴线朝外方向为Z轴正方向，X轴方向可任意指定；设机械臂末端中心坐标系为{O t}，由待装配轴工件的设计尺寸和配合尺寸得到机械臂与待装配轴连接固定后轴心坐标系原点在坐标系{O t}下的坐标(x p,y p,z p)和轴心坐标系的X轴、Y轴和Z轴在{O t}下的单位方向向量分别为(n x,n y,n z)、(a x,a y,a z)和(o x,o y,o z)，最终可以得到用于装配操作的工具坐标系T peg，表达式如下： 2) Manually operate the mechanical arm to complete the rough alignment of the shaft hole, so that the shaft of the shaft workpiece to be assembled is above the hole of the workpiece to be assembled, and ensure that the coaxiality of the shaft and the hole does not exceed the chamfer width of the workpiece to be assembled; As shown in Figure 4, the tool coordinate system of the shaft hole assembly system is established: the shaft coordinate system {O p } is established on the shaft workpiece to be assembled, {O p } takes the center of the end of the shaft as the origin, and the outward direction along the axis is The positive direction of the Z-axis and the X-axis direction can be arbitrarily specified; suppose the center coordinate system of the end of the robot arm is {O t }, and the axis coordinate system after the robot arm is connected to the axis to be assembled and fixed is obtained from the design size and the matching size of the workpiece to be assembled The coordinates (x p , y p , z p ) of the origin in the coordinate system {O t } and the unit direction vectors of the X, Y, and Z axes of the axis coordinate system in {O t } are (n x ,n y ,n z ), (a x ,a y , az ) and (o x ,o y ,o z ), and finally the tool coordinate system T peg used for assembly operations can be obtained, the expression is as follows:
Figure PCTCN2019110631-appb-000029
Figure PCTCN2019110631-appb-000029
3)机械臂操纵待装配轴工件的轴完成柔顺入孔阶段，使得待装配孔工件的孔的插入深度(相对于孔端面)超过孔的倒角深度；具体步骤如下：3) The mechanical arm manipulates the shaft of the shaft workpiece to be assembled to complete the stage of compliant hole insertion, so that the insertion depth of the hole of the workpiece to be assembled (relative to the hole end surface) exceeds the chamfer depth of the hole; the specific steps are as follows:
3-1)设定初始的阻抗控制参数，包括插入速度v a、参考力和参考力矩组成的向量
Figure PCTCN2019110631-appb-000030
控制刚度K p＝[K x,K y,K z,K θx,K θy,0]和调姿刚度K d＝[K x,K y,0,K θx,K θy,0]，其中
Figure PCTCN2019110631-appb-000031
和
Figure PCTCN2019110631-appb-000032
分别是沿X、Y、Z方向的参考接触力，
Figure PCTCN2019110631-appb-000033
和
Figure PCTCN2019110631-appb-000034
分别是绕X、Y轴的参考接触力矩，K x、K y和K z分别是X、Y、Z方向的位置刚度，K θx和K θy分别是绕X方向和Y方向的姿态刚度；一般情况下，参考接触力
Figure PCTCN2019110631-appb-000035
参考接触力矩
Figure PCTCN2019110631-appb-000036
Figure PCTCN2019110631-appb-000037
均设为0，参考接触力
Figure PCTCN2019110631-appb-000038
可为20N～100N(正负号由实际接触力在力传感器测得的数值的符号决定，通常为负号)，以上参考力/力矩参数不限于给定的范围，可根据轴孔装配过程中的实际测得的接触力/力矩大小进行适当调整；位置刚度K x和K y取值在0～0.01范围内，K z取值在0～0.05范围内并大于或等于K x和K y的2倍，姿态刚度K θx和K θy取值在0～0.005范围内，以上刚度参数可根据轴孔装配工件的材料特性做适当调整； 3-1) Set the initial impedance control parameters, including the vector of insertion speed v a , reference force and reference torque
Figure PCTCN2019110631-appb-000030
Control stiffness K p =[K x ,K y ,K z ,K θx ,K θy ,0] and attitude adjustment stiffness K d =[K x ,K y ,0,K θx ,K θy ,0], where
Figure PCTCN2019110631-appb-000031
with
Figure PCTCN2019110631-appb-000032
Are the reference contact forces along the X, Y, and Z directions,
Figure PCTCN2019110631-appb-000033
with
Figure PCTCN2019110631-appb-000034
Are the reference contact moments around the X and Y axes, K x , Ky and K z are the position stiffnesses in the X, Y, and Z directions respectively, and K θx and K θy are the posture stiffness around the X and Y directions respectively; Case, reference contact force
Figure PCTCN2019110631-appb-000035
Reference contact torque
Figure PCTCN2019110631-appb-000036
Figure PCTCN2019110631-appb-000037
All set to 0, reference contact force
Figure PCTCN2019110631-appb-000038
It can be 20N～100N (the sign of the actual contact force is determined by the sign of the value measured by the force sensor, usually a negative sign). The above reference force/torque parameters are not limited to the given range, and can be based on the shaft hole assembly process the actual measured contact force / torque magnitude appropriate adjustments; position stiffness K x and K y value in the range of 0 ~ 0.01, K z value in the range of 0 to 0.05 and greater than or equal to K x and K y 2 times, the attitude stiffness K θx and K θy are in the range of 0～0.005. The above stiffness parameters can be adjusted according to the material characteristics of the shaft hole assembly workpiece;
3-2)上位机获取机械臂在工具坐标系T peg下的当前位姿T 0和力传感器测量的当前的接触力/力矩F，并计算下一时刻机械臂的目标位姿T d＝T 0+K p(F-F ref)，上位机发送运动指令使机械臂运动到目标位姿T d。其中位姿T 0＝[X 0,Y 0,Z 0,θ x0,θ y0,θ z0]，X 0、Y 0和Z 0分别是机械臂在工具坐标系下X、Y、Z轴的位置坐标，θ x0、θ y0和θ z0分别是机械臂在工具坐标系下绕X、Y、Z轴的欧拉角，接触力/力矩F＝[F x,F y,F z,M x,M y,M z]，F x、F y和F z分别是轴孔之间接触力沿X、Y、Z轴方向的分量，M x、M y和M z分别是轴孔之间接触力矩绕X、Y、Z轴的分量； 3-2) The host computer obtains the current pose T 0 of the robotic arm in the tool coordinate system T peg and the current contact force/torque F measured by the force sensor, and calculates the target pose T d = T of the robotic arm at the next moment 0 +K p (FF ref ), the upper computer sends a motion command to move the manipulator to the target pose T d . Among them, pose T 0 =[X 0 ,Y 0 ,Z 0 ,θ x0 ,θ y0 ,θ z0 ], X 0 , Y 0 and Z 0 are the X, Y, Z axis of the robot arm in the tool coordinate system, respectively Position coordinates, θ x0 , θ y0 and θ z0 are the Euler angles of the robot arm around the X, Y, and Z axes in the tool coordinate system, respectively. Contact force/moment F=[F x ,F y ,F z ,M x ,M y ,M z ], F x , F y and F z are the components of the contact force between the shaft holes along the X, Y, and Z axis directions, respectively, and M x , My and M z are the contact between the shaft holes, respectively Component of moment around X, Y, Z axis;
3-3)重复步骤3-2)，直至待装配轴工件的轴插入待装配孔工件的孔的深度超过孔的倒角深度,进入步骤4)；3-3) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds the chamfer depth of the hole, and then go to step 4);
这里需要补充说明的是，所述“上位机获取机械臂在工具坐标系T peg下的当前位姿T 0和力传感器测量的当前的接触力/力矩F”，“上位机发送运动指令使机械臂运动到目标位姿”，都是基于机械臂提供的上位机通讯接口实现的，是大多数商用机械臂自带的功能。 What needs to be added here is that “the host computer obtains the current pose T 0 of the robotic arm in the tool coordinate system T peg and the current contact force/torque F measured by the force sensor”, “the host computer sends a motion instruction to make the mechanical "The arm moves to the target pose" is realized based on the host computer communication interface provided by the robotic arm, which is a function of most commercial robotic arms.
4)机械臂操纵待装配轴工件的轴执行如图5所示的往复螺旋式装配运动，即待装配轴工件的轴以轴向线速度v a和绕轴线的角速度w(旋转方向周期性变换)向下插入待装配孔工件的孔中，具体步骤如下： 4) The mechanical arm manipulates the shaft of the shaft workpiece to be assembled to perform the reciprocating spiral assembly movement as shown in Figure 5, that is, the shaft of the shaft workpiece to be assembled has an axial linear velocity v a and an angular velocity w around the axis (the rotation direction is periodically changed ) Insert down into the hole of the workpiece to be assembled, the specific steps are as follows:
4-1)计算螺旋式装配运动参数的取值范围，参数包括螺旋插装的往复运动频率f screw、旋转角度幅值θ screw和螺旋运动节距h(轴孔接触点处的轴向线速度和绕轴旋转的角速度的比值)，约束条件包括配合精度、惯量匹配和轴向摩擦抑制等轴孔装配工艺需求，表达式如下： 4-1) Calculate the value range of the spiral assembly motion parameters. The parameters include the reciprocating frequency f screw of the spiral insert, the rotation angle amplitude θ screw and the spiral motion pitch h (axial linear velocity at the contact point of the shaft hole The ratio between the angular velocity and the angular velocity of the rotation around the axis), the constraint conditions include the assembly process requirements of the shaft hole such as fitting accuracy, inertia matching and axial friction suppression, the expression is as follows:
Figure PCTCN2019110631-appb-000039
Figure PCTCN2019110631-appb-000039
其中，δ是轴孔配合的间隙，d是机械臂绕工具坐标系Z轴旋转时待装配轴工件的端面圆心到实际旋转轴线的距离，f res为机械臂的共振频率，k int为惯量匹配因子，k mate为间隙 配合因子，k f为轴向摩擦力减小的比例，一般取k int≤0.3，k mate≤0.3，k f≤1； Among them, δ is the clearance between the shaft and hole, d is the distance from the center of the end face of the workpiece to be assembled to the actual axis of rotation when the manipulator rotates around the Z axis of the tool coordinate system, f res is the resonance frequency of the manipulator, and k int is the inertia matching Factor, k mate is the clearance fit factor, k f is the ratio of axial friction reduction, generally k int ≤0.3, k mate ≤0.3, k f ≤1;
第一次执行螺旋式装配运动时，在满足上述约束条件的范围内，选取螺旋式装配运动参数的初始值，其中取较大的节距h；When the spiral assembly movement is executed for the first time, within the range that satisfies the above constraints, the initial value of the spiral assembly movement parameters is selected, and the larger pitch h is selected;
4-2)计算螺旋式装配运动过程中机械臂在工具坐标系下的位置总增量ΔX、ΔY、ΔZ和绕X、Y轴的欧拉角总增量Δθ x、Δθ y。上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，依据阻抗控制算法，表达式如下： 4-2) Calculate the total increment ΔX, ΔY, ΔZ of the position of the robot arm in the tool coordinate system and the total increment Δθ x , Δθ y of the Euler angle around the X and Y axes during the spiral assembly movement. The host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor. According to the impedance control algorithm, the expression is as follows:
Figure PCTCN2019110631-appb-000040
Figure PCTCN2019110631-appb-000040
4-3)计算螺旋插装运动指令的步数n s和绕工具坐标系Z轴旋转的角度幅值θ screw，表达式如下： 4-3) Calculate the number of steps n s of the spiral inserting motion instruction and the angular amplitude θ screw about the Z axis of the tool coordinate system, the expression is as follows:
Figure PCTCN2019110631-appb-000041
Figure PCTCN2019110631-appb-000041
其中n s的计算首先由步骤4-1)中给出的f screw的取值范围计算得到n s的取值范围，然后选取较大的整数作为n s的取值； The calculation of n s first calculates the value range of n s from the value range of f screw given in step 4-1), and then selects a larger integer as the value of n s ;
4-4)计算每一步螺旋运动指令的目标位姿T i d，i＝1,2…n s，表达式如下： 4-4) Calculate the target pose T i d of each step of the spiral motion instruction, i=1, 2...n s , the expression is as follows:
Figure PCTCN2019110631-appb-000042
Figure PCTCN2019110631-appb-000042
其中
Figure PCTCN2019110631-appb-000043
每一步的位姿增量
Figure PCTCN2019110631-appb-000044
且满足： among them
Figure PCTCN2019110631-appb-000043
Pose increment for each step
Figure PCTCN2019110631-appb-000044
And satisfy:
Figure PCTCN2019110631-appb-000045
Figure PCTCN2019110631-appb-000045
其中
Figure PCTCN2019110631-appb-000046
ΔY i d和
Figure PCTCN2019110631-appb-000047
是第i步指令中机械臂在工具坐标系下分别沿X、Y、Z轴的位置增量，
Figure PCTCN2019110631-appb-000048
和
Figure PCTCN2019110631-appb-000049
分别是第i步指令中机械臂在工具坐标系下绕X、Y、Z轴的欧拉角增量； among them
Figure PCTCN2019110631-appb-000046
ΔY i d and
Figure PCTCN2019110631-appb-000047
Is the position increment of the robot arm along the X, Y, and Z axes in the tool coordinate system in the i-th instruction,
Figure PCTCN2019110631-appb-000048
with
Figure PCTCN2019110631-appb-000049
They are the Euler angle increments of the robot arm around the X, Y, and Z axes in the tool coordinate system in the i-th instruction;
4-5)上位机将4-4)中计算得到的n s步螺旋运动指令发送给机械臂，使机械臂操纵工件轴进行往复螺旋式的装配运动； 4-5) The host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
5)机械臂进行完n s步往复螺旋式的装配运动后，上位机获取并更新机械臂当前位姿T 0 和力传感器测量的接触力/力矩F，并依据更新后的当前位姿下的轴向插装力F z的大小判断轴孔装配当前的卡阻状态，具体方法是： 5) After the manipulator has completed the n s- step reciprocating spiral assembly movement, the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated current pose The size of the axial insertion force F z judges the current jam state of the shaft hole assembly, the specific method is:
当
Figure PCTCN2019110631-appb-000050
时，判断卡阻状态为安全状态，则令插入速度v a增大10％，螺旋插装参数h增大10％，然后进入步骤6)； when
Figure PCTCN2019110631-appb-000050
When it is judged that the jamming state is a safe state, increase the insertion speed v a by 10%, and increase the spiral insertion parameter h by 10%, and then enter step 6);
当
Figure PCTCN2019110631-appb-000051
时，判断卡阻状态为危险状态，则令插入速度v a减小20％，螺旋插装参数h增大20％，以增强轴向摩擦抑制效果，同时调整轴孔的相对姿态，计算目标位姿T g＝T 0+K d(F-F r)，上位机发送运动指令使机械臂运动到目标位姿T g，然后进入步骤6)； when
Figure PCTCN2019110631-appb-000051
When the jamming state is judged to be a dangerous state, the insertion speed v a is reduced by 20%, and the spiral insertion parameter h is increased by 20% to enhance the axial friction suppression effect. At the same time, the relative posture of the shaft hole is adjusted to calculate the target position Posture T g = T 0 +K d (FF r ), the upper computer sends a motion instruction to move the robotic arm to the target posture T g , and then enters step 6);
当
Figure PCTCN2019110631-appb-000052
时，判断卡阻状态为已发生卡阻，首先，调整运动参数，即轴向插入速度v a减小30％，螺旋插装参数h减小30％；然后，机械臂运动到目标位姿位姿
Figure PCTCN2019110631-appb-000053
其中
Figure PCTCN2019110631-appb-000054
为步骤4-4)中第n s-1步螺旋式装配运动指令的目标位姿，使得工件轴反向螺旋后退至上一条运动位姿以缓解卡阻，运动完成后上位机获取接触力/力矩F并再次判断卡阻状态，如果仍满足
Figure PCTCN2019110631-appb-000055
则机械臂运动到目标位置
Figure PCTCN2019110631-appb-000056
依次类推，直至脱离“已发生卡阻”状态；最后，调整轴孔的相对姿态,上位机获取并更新机械臂的当前位姿T 0和力传感器测量的当前的接触力/力矩F,上位机发送运动指令使机械臂运动到目标位姿T g＝T 0+K d(F-F r)，然后进入步骤6)； when
Figure PCTCN2019110631-appb-000052
When the jamming state is judged as jam has occurred, first, adjust the motion parameters, that is, the axial insertion speed v a is reduced by 30%, and the spiral insertion parameter h is reduced by 30%; then, the mechanical arm moves to the target position posture
Figure PCTCN2019110631-appb-000053
among them
Figure PCTCN2019110631-appb-000054
It is the target pose of the screw assembly motion instruction in step n s -1 in step 4-4), so that the workpiece axis spirals backward to the previous motion pose to relieve jamming. After the motion is completed, the upper computer obtains the contact force/torque F and judge the jam state again, if it still meets
Figure PCTCN2019110631-appb-000055
Then the robotic arm moves to the target position
Figure PCTCN2019110631-appb-000056
By analogy, until it is out of the "blocked"state; finally, adjust the relative posture of the shaft hole, the upper computer obtains and updates the current posture T 0 of the manipulator and the current contact force/torque F measured by the force sensor. Send a movement instruction to move the manipulator to the target pose T g = T 0 +K d (FF r ), and then go to step 6);
6)上位机获取并更新机械臂当前位姿T 0，判断当前轴向插入深度Z 0是否到达目标位置深度Z goal：如果已达到目标位置深度，则装配任务结束；否则重新返回步骤4)。 6) The host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth Z goal : If the target position depth has been reached, the assembly task ends; otherwise, return to step 4).
下面结合一个具体实施例，对本公开进一步详细说明如下：The following further describes the present disclosure in detail with reference to a specific embodiment as follows:
在本公开的实施例中，机械臂M接收上位机控制系统C的运动指令，操纵大尺寸孔工件轴P以往复螺旋运动的形式插入大尺寸工件孔H中，插入深度为60mm。本实施例提出一种大尺寸轴孔工件装配的螺旋插装方法，具体步骤如下：In the embodiment of the present disclosure, the robot arm M receives the motion instruction of the upper computer control system C, and manipulates the large-sized hole workpiece axis P to insert it into the large-sized workpiece hole H in a reciprocating spiral motion, with an insertion depth of 60 mm. This embodiment proposes a spiral inserting method for assembling large-size shaft hole workpieces, and the specific steps are as follows:
1)搭建大尺寸轴孔装配系统；所述系统结构如图3所示，包括：基座W、待装配轴工件P、待装配孔工件H、力传感器S、末端执行器G、机械臂M以及上位机C；所述待装配孔工件H和基座W分别固定于操作台上，机械臂M通过螺纹连接固定于基座W上，力传感器S通过螺纹连接固定于机械臂M的最末关节，并通过电缆连接机械臂M，末端执行器G通过螺纹连接固定于力传感器上，待装配轴工件P通过螺纹连接固定于末端执行器G夹最末关节上，上位机C通过网线连接机械臂M。1) Build a large-size shaft hole assembly system; the system structure is shown in Figure 3, including: base W, shaft workpiece to be assembled P, workpiece to be assembled hole H, force sensor S, end effector G, robotic arm M And the host computer C; the to-be-assembled hole workpiece H and the base W are respectively fixed on the operating table, the mechanical arm M is fixed to the base W through a screw connection, and the force sensor S is fixed to the end of the mechanical arm M through a screw connection The joint is connected to the mechanical arm M through a cable, the end effector G is fixed to the force sensor through a threaded connection, the shaft workpiece P to be assembled is fixed to the last joint of the end effector G clamp through a threaded connection, and the upper computer C is connected to the machine through a network cable Arm M.
本实施例中待装配轴工件尺寸为520mm×300mm×100mm，轴长度为150mm，直径为100mm， 待装配孔工件外径为120mm,内径为100mm，轴孔配合间隙δ为0.1mm，孔倒角5mm，机械臂绕工具坐标系Z轴旋转时待装配轴工件的端面圆心到实际旋转轴线的距离d为0.2mm，机械臂的共振频率f r为30Hz。ABB6自由度商业机器人IRB7600作为完成装配操作的机械臂M，联想ThinkPad T440P笔记本作为上位机控制系统； In this embodiment, the size of the shaft to be assembled is 520mm×300mm×100mm, the shaft length is 150mm, the diameter is 100mm, the outer diameter of the hole to be assembled is 120mm, the inner diameter is 100mm, the shaft hole fit gap δ is 0.1mm, and the hole chamfer 5mm, when the robot arm rotates around the Z axis of the tool coordinate system, the distance d from the center of the end face of the workpiece to be assembled to the actual rotation axis is 0.2mm, and the resonance frequency f r of the robot arm is 30 Hz. The ABB6 degree of freedom commercial robot IRB7600 is used as the robotic arm M to complete the assembly operation, and the Lenovo ThinkPad T440P notebook is used as the upper computer control system;
2)手动操作机械臂完成轴孔粗对准，使得待装配轴工件的轴位于待装配孔工件的孔的上方，并保证轴与孔的同轴度不超过5mm；建立轴孔装配系统的工具坐标系：在待装配轴工件上建立轴心坐标系{O p},{O p}以轴的末端圆心为原点，沿轴线朝外方向为Z轴正方向，X轴方向可任意指定；设机械臂末端中心坐标系为{O t}，由待装配轴工件的设计尺寸和配合尺寸得到机械臂与待装配轴连接固定后轴心坐标系原点在坐标系{O t}下的坐标(0,0,300)和轴心坐标系的X轴、Y轴和Z轴在{O t}下的方向向量分别为(1,0,0)、(0,1,0)和(0,0,1)，最终可以得到用于装配操作的工具坐标系T peg： 2) Manually operate the mechanical arm to complete the rough alignment of the shaft hole, so that the shaft of the shaft workpiece to be assembled is above the hole of the workpiece to be assembled, and ensure that the coaxiality of the shaft and the hole does not exceed 5mm; tools for establishing the shaft hole assembly system Coordinate system: establish the axis coordinate system {O p } on the workpiece to be assembled, {O p } takes the center of the end of the axis as the origin, and the direction outward along the axis is the positive direction of the Z axis, and the X axis direction can be arbitrarily specified; The center coordinate system of the end of the robot arm is {O t }, and the coordinate (0 t ) of the origin of the axis coordinate system after the robot arm is connected and fixed with the shaft to be assembled is obtained from the design dimensions and matching dimensions of the workpiece to be assembled. ,0,300) and the direction vectors of the X-axis, Y-axis and Z-axis of the axis coordinate system under {O t } are (1,0,0), (0,1,0) and (0,0,1) ), and finally the tool coordinate system T peg used for assembly operations can be obtained:
Figure PCTCN2019110631-appb-000057
Figure PCTCN2019110631-appb-000057
在机械臂控制器中设置装配工具坐标系，参数为T peg； Set the assembly tool coordinate system in the robotic arm controller, the parameter is T peg ;
3)机械臂操纵待装配轴工件的轴完成柔顺入孔阶段，使得待装配孔工件的孔的插入深度(相对于孔端面)超过孔的倒角深度；具体步骤如下：3) The mechanical arm manipulates the shaft of the shaft workpiece to be assembled to complete the stage of compliant hole insertion, so that the insertion depth of the hole of the workpiece to be assembled (relative to the hole end surface) exceeds the chamfer depth of the hole; the specific steps are as follows:
3-1)设定初始的阻抗控制参数，包括插入速度v a＝5mm/s、参考力和参考力矩组成的向量F ref＝[0,0,-50N,0,0,0]、控制刚度K p＝[0.005,0.005,0.01,0.001,0.001,0]和调姿刚度K d＝[0.005,0.005,0,0.001,0.001,0]，其中
Figure PCTCN2019110631-appb-000058
和
Figure PCTCN2019110631-appb-000059
分别是沿X、Y、Z方向的参考接触力，
Figure PCTCN2019110631-appb-000060
和
Figure PCTCN2019110631-appb-000061
分别是绕X、Y轴的参考接触力矩，K x、K y和K z分别是X、Y、Z方向的位置刚度，K θx和K θy分别是绕X方向和Y方向的姿态刚度； 3-1) Set the initial impedance control parameters, including insertion speed v a = 5mm/s, reference force and reference torque composed of vector F ref = [0,0,-50N,0,0,0], control stiffness K p =[0.005,0.005,0.01,0.001,0.001,0] and posture adjustment stiffness K d =[0.005,0.005,0,0.001,0.001,0], where
Figure PCTCN2019110631-appb-000058
with
Figure PCTCN2019110631-appb-000059
Are the reference contact forces along the X, Y, and Z directions,
Figure PCTCN2019110631-appb-000060
with
Figure PCTCN2019110631-appb-000061
Are the reference contact moments around the X and Y axes, K x , Ky and K z are the position stiffnesses in the X, Y, and Z directions respectively, and K θx and K θy are the attitude stiffnesses around the X and Y directions respectively;
3-2)上位机获取机械臂在工具坐标系T peg下的当前位姿T 0和力传感器测量的当前的接触力/力矩F，并计算下一时刻机械臂的目标位姿T d＝T 0+K p(F-F ref)，上位机发送运动指令使机械臂运动到目标位姿T d。其中位姿T 0＝[X 0,Y 0,Z 0,θ x0,θ y0,θ z0]，X 0、Y 0和Z 0分别是机械臂在工具坐标系下X、Y、Z轴的位置坐标，θ x0、θ y0和θ z0分别是机械臂在工具坐标系下绕X、Y、Z轴的欧拉角，接触力/力矩F＝[F x,F y,F z,M x,M y,M z]，F x、F y和F z分别是轴孔之间接触力沿X、Y、Z轴方向的分量，M x、M y和M z分别是轴孔之间接触力矩绕X、Y、Z轴的分量； 3-2) The host computer obtains the current pose T 0 of the robotic arm in the tool coordinate system T peg and the current contact force/torque F measured by the force sensor, and calculates the target pose T d = T of the robotic arm at the next moment 0 +K p (FF ref ), the upper computer sends a motion command to move the manipulator to the target pose T d . Among them, pose T 0 =[X 0 ,Y 0 ,Z 0 ,θ x0 ,θ y0 ,θ z0 ], X 0 , Y 0 and Z 0 are the X, Y, Z axis of the robot arm in the tool coordinate system, respectively Position coordinates, θ x0 , θ y0 and θ z0 are the Euler angles of the robot arm around the X, Y, and Z axes in the tool coordinate system, respectively. Contact force/moment F=[F x ,F y ,F z ,M x ,M y ,M z ], F x , F y and F z are the components of the contact force between the shaft holes along the X, Y, and Z axis directions, respectively, and M x , My and M z are the contact between the shaft holes, respectively Component of moment around X, Y, Z axis;
3-3)重复步骤3-2)，直至待装配轴工件的轴插入待装配孔工件的孔的深度超过5mm,进入步骤4)；3-3) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds 5mm, and then go to step 4);
4)机械臂操纵待装配轴工件的轴执行如图5所示的往复螺旋式装配运动，即待装配轴工件的轴以轴向线速度v a和绕轴线的角速度w(旋转方向周期性变换)向下插入待装配孔工件的孔中，具体步骤如下： 4) The mechanical arm manipulates the shaft of the shaft workpiece to be assembled to perform the reciprocating spiral assembly movement as shown in Figure 5, that is, the shaft of the shaft workpiece to be assembled has an axial linear velocity v a and an angular velocity w around the axis (the rotation direction is periodically changed ) Insert down into the hole of the workpiece to be assembled, the specific steps are as follows:
4-1)计算螺旋式装配运动参数的取值范围，参数包括螺旋插装的往复运动频率f screw、旋转角度幅值θ screw和螺旋运动节距h(轴孔接触点处的轴向线速度和绕轴旋转的角速度的比值)，约束条件包括配合精度、惯量匹配和轴向摩擦抑制等轴孔装配工艺需求，取惯量匹配因子k int＝0.1，间隙配合因子k mate＝0.2，轴向摩擦力减小的比例k f＝0.8；计算得到取值范围如下： 4-1) Calculate the value range of the spiral assembly motion parameters. The parameters include the reciprocating frequency f screw of the spiral insert, the rotation angle amplitude θ screw and the spiral motion pitch h (axial linear velocity at the contact point of the shaft hole And the ratio of the angular velocity of the rotation around the axis), the constraint conditions include fitting accuracy, inertia matching and axial friction suppression and other shaft hole assembly process requirements, take the inertia matching factor k int = 0.1, clearance fit factor k mate = 0.2, axial friction The ratio of force reduction k f =0.8; the calculated value range is as follows:
Figure PCTCN2019110631-appb-000062
Figure PCTCN2019110631-appb-000062
第一次执行螺旋插装操作时，在满足上述约束条件的范围内，螺旋插装参数节距h取较大的初始值66.6mm；When the spiral inserting operation is performed for the first time, the spiral inserting parameter pitch h takes a larger initial value of 66.6mm within the range that satisfies the above constraints;
4-2)计算螺旋式装配运动过程中机械臂在工具坐标系下的位置总增量ΔX、ΔY、ΔZ和绕X、Y轴的欧拉角总增量Δθ x、Δθ y。上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，依据阻抗控制算法，表达式如下： 4-2) Calculate the total increment ΔX, ΔY, ΔZ of the position of the robot arm in the tool coordinate system and the total increment Δθ x , Δθ y of the Euler angle around the X and Y axes during the spiral assembly movement. The host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor. According to the impedance control algorithm, the expression is as follows:
Figure PCTCN2019110631-appb-000063
Figure PCTCN2019110631-appb-000063
4-3)计算螺旋插装运动指令的步数n s和绕工具坐标系Z轴旋转的角度幅值θ screw，表达式如下： 4-3) Calculate the number of steps n s of the spiral inserting motion instruction and the angular amplitude θ screw about the Z axis of the tool coordinate system, the expression is as follows:
Figure PCTCN2019110631-appb-000064
Figure PCTCN2019110631-appb-000064
其中n s的计算首先由步骤4-1)中给出的f screw的取值范围计算得到n s的取值范围，然后选取较大的整数作为n s的取值； The calculation of n s first calculates the value range of n s from the value range of f screw given in step 4-1), and then selects a larger integer as the value of n s ;
4-4)计算每一步螺旋运动指令的目标位姿T i d，i＝1,2…n s，表达式如下：当前位姿下，表达式如下： 4-4) Calculate the target pose T i d of each step of the spiral motion instruction, i=1, 2...n s , the expression is as follows: in the current pose, the expression is as follows:
Figure PCTCN2019110631-appb-000065
Figure PCTCN2019110631-appb-000065
其中
Figure PCTCN2019110631-appb-000066
每一步的位姿增量
Figure PCTCN2019110631-appb-000067
且满足： among them
Figure PCTCN2019110631-appb-000066
Pose increment for each step
Figure PCTCN2019110631-appb-000067
And satisfy:
Figure PCTCN2019110631-appb-000068
Figure PCTCN2019110631-appb-000068
其中
Figure PCTCN2019110631-appb-000069
ΔY i d和
Figure PCTCN2019110631-appb-000070
是第i步指令中机械臂在工具坐标系下分别沿X、Y、Z轴的位置增量，
Figure PCTCN2019110631-appb-000071
和
Figure PCTCN2019110631-appb-000072
分别是第i步指令中机械臂在工具坐标系下绕X、Y、Z轴的欧拉角增量； among them
Figure PCTCN2019110631-appb-000069
ΔY i d and
Figure PCTCN2019110631-appb-000070
Is the position increment of the robot arm along the X, Y, and Z axes in the tool coordinate system in the i-th instruction,
Figure PCTCN2019110631-appb-000071
with
Figure PCTCN2019110631-appb-000072
They are the Euler angle increments of the robot arm around the X, Y, and Z axes in the tool coordinate system in the i-th instruction;
4-5)上位机将4-4)中计算得到的n s步螺旋运动指令发送给机械臂，使机械臂操纵工件轴进行往复螺旋式的装配运动； 4-5) The host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
5)机械臂进行完n s步运动后，上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，并依据更新后的当前位姿下的轴向插装力F z的大小判断轴孔装配当前的卡阻状态，具体方法是： 5) After the manipulator has performed n s steps, the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated axial insertion force in the current pose The size of F z judges the current jam state of the shaft hole assembly, the specific method is:
当|F z|≤40N时，判断卡阻状态为安全状态，则令插入速度v a增大10％，螺旋插装参数h增大10％，然后进入步骤6)； When |F z |≤40N, the jamming state is judged to be a safe state, and the insertion speed v a is increased by 10%, and the spiral insertion parameter h is increased by 10%, and then step 6);
当40N<|F z|<47.5N时，判断卡阻状态为危险状态，则令插入速度v a减小20％，螺旋插装参数h增大20％，以增强轴向摩擦抑制效果，同时调整轴孔的相对姿态，计算目标位姿T g＝T 0+K d(F-F r)，上位机发送运动指令使机械臂运动到目标位姿T g，然后进入步骤6)； When 40N<|F z |<47.5N, the jamming state is judged to be a dangerous state, the insertion speed v a is reduced by 20%, and the spiral insertion parameter h is increased by 20% to enhance the axial friction suppression effect. Adjust the relative posture of the shaft hole, calculate the target posture T g = T 0 +K d (FF r ), the upper computer sends a motion instruction to move the manipulator to the target posture T g , and then enter step 6);
当|Fz|≥47.5N时，判断卡阻状态为已发生卡阻，首先，调整运动参数，即轴向插入速度v a减小30％，螺旋插装参数h减小30％；然后，机械臂运动到目标位姿位姿
Figure PCTCN2019110631-appb-000073
其中
Figure PCTCN2019110631-appb-000074
为步骤4-4)中第n s-1步螺旋式装配运动指令的目标位姿，使得工件轴反向螺旋后退至上一条运动位姿以缓解卡阻，运动完成后上位机获取接触力/力矩F并再次判断卡阻状态，如果仍满足|F z|≥47.5N，则机械臂运动到目标位置
Figure PCTCN2019110631-appb-000075
依次类推，直至脱离“已发生卡阻”状态；；最后，调整轴孔的相对姿态,上位机获取并更新机械臂的当前位姿T 0和力传感器测量的当前的接触力/力矩F,上位机发送运动指令使机械臂运动到目标位姿T g＝T 0+K d(F-F r)，然后进入步骤6)； When |Fz|≥47.5N, it is judged that the jam has occurred. First, adjust the motion parameters, that is, the axial insertion speed v a is reduced by 30%, and the spiral insertion parameter h is reduced by 30%; then, the mechanical Arm movement to target pose
Figure PCTCN2019110631-appb-000073
among them
Figure PCTCN2019110631-appb-000074
It is the target pose of the screw assembly motion instruction in step n s -1 in step 4-4), so that the workpiece axis spirals backward to the previous motion pose to relieve jamming. After the motion is completed, the upper computer obtains the contact force/torque F and judge the jamming state again, if it still meets |F z |≥47.5N, the robot arm moves to the target position
Figure PCTCN2019110631-appb-000075
By analogy, until it is out of the "jammed"state; finally, adjust the relative posture of the shaft hole, the upper computer obtains and updates the current posture T 0 of the robotic arm and the current contact force/torque F measured by the force sensor, upper position The machine sends a motion instruction to move the manipulator to the target pose T g = T 0 +K d (FF r ), and then proceeds to step 6);
6)上位机获取并更新机械臂当前位姿T 0，判断当前轴向插入深度Z 0是否到达目标位置深度60mm：如果已达到目标位置深度，则装配任务结束；否则重复返回步骤4)。 6) The host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth of 60 mm: if the target position depth has been reached, the assembly task ends; otherwise, repeats back to step 4).

Claims (1)

  1. 一种大尺寸轴孔工件装配的螺旋插装方法，其特征在于，包括以下步骤：A spiral inserting method for assembling large-size shaft hole workpieces is characterized in that it comprises the following steps:
    1)搭建大尺寸轴孔装配系统；所述系统包括：基座、待装配轴工件、待装配孔工件、力传感器、末端执行器、机械臂和上位机；所述待装配孔工件和基座分别固定于操作台上，机械臂通过螺纹连接固定在基座上，力传感器通过螺纹连接固定于机械臂的最末关节，力传感器通过电缆连接机械臂，末端执行器通过螺纹连接固定于力传感器上，待装配轴工件通过螺纹连接固定于末端执行器上，上位机通过网线连接机械臂；1) Build a large-size shaft hole assembly system; the system includes: a base, a shaft workpiece to be assembled, a hole workpiece to be assembled, a force sensor, an end effector, a robotic arm and a host computer; the hole workpiece to be assembled and a base Respectively fixed on the console, the mechanical arm is fixed on the base through a screw connection, the force sensor is fixed to the end joint of the mechanical arm through a screw connection, the force sensor is connected to the mechanical arm through a cable, and the end effector is fixed to the force sensor through a screw connection On the upper, the shaft workpiece to be assembled is fixed on the end effector through a threaded connection, and the upper computer is connected to the mechanical arm through a network cable;
    2)操作机械臂完成轴孔粗对准，使得待装配轴工件的轴位于待装配孔工件的孔的上方且轴与孔的同轴度不超过待装配孔工件孔倒角宽度；2) Operate the mechanical arm to complete the rough alignment of the shaft hole, so that the shaft of the shaft workpiece to be assembled is located above the hole of the workpiece to be assembled and the coaxiality of the shaft and the hole does not exceed the chamfer width of the workpiece to be assembled;
    在待装配轴工件上建立轴心坐标系{O p},{O p}以轴的末端圆心为原点，沿轴线朝外方向为Z轴正方向；设机械臂末端中心坐标系为{O t}，机械臂与待装配轴连接固定后轴心坐标系原点在坐标系{O t}下的坐标为(x p,y p,z p)，轴心坐标系的X轴、Y轴和Z轴在{O t}下的单位方向向量分别为(n x,n y,n z)、(a x,a y,a z)和(o x,o y,o z)，得到工具坐标系T peg，表达式如下： Establish the axis coordinate system {O p } on the workpiece to be assembled, {O p } takes the center of the end of the shaft as the origin, and the direction outward along the axis is the positive direction of the Z axis; set the center coordinate system of the end of the robotic arm as {O t }, after the manipulator is connected to the shaft to be assembled, the coordinates of the origin of the axis coordinate system in the coordinate system {O t } are (x p , y p , z p ), the X axis, Y axis and Z of the axis coordinate system The unit direction vectors of the axis under {O t } are (n x ,n y ,n z ), (a x ,a y ,a z ) and (o x ,o y ,o z ), respectively, to get the tool coordinate system T peg , the expression is as follows:
    Figure PCTCN2019110631-appb-100001
    Figure PCTCN2019110631-appb-100001
    3)机械臂操纵待装配轴工件的轴完成柔顺入孔阶段，使得待装配孔工件的孔的插入深度超过孔的倒角深度；具体步骤如下：3) The mechanical arm manipulates the shaft of the shaft workpiece to be assembled to complete the stage of compliant hole insertion, so that the insertion depth of the hole of the workpiece to be assembled exceeds the chamfer depth of the hole; the specific steps are as follows:
    3-1)设定初始的阻抗控制参数，包括插入速度v a、参考力和参考力矩组成的向量
    Figure PCTCN2019110631-appb-100002
    控制刚度K p＝[K x,K y,K z,K θx,K θy,0]和调姿刚度K d＝[K x,K y,0,K θx,K θy,0]，其中
    Figure PCTCN2019110631-appb-100003
    和
    Figure PCTCN2019110631-appb-100004
    分别是沿X、Y、Z方向的参考接触力，
    Figure PCTCN2019110631-appb-100005
    和
    Figure PCTCN2019110631-appb-100006
    分别是绕X、Y轴的参考接触力矩，K x、K y和K z分别是X、Y、Z方向的位置刚度，K θx和K θy分别是绕X方向和Y方向的姿态刚度；     3-1) Set the initial impedance control parameters, including the vector of insertion speed v a , reference force and reference torque
    Figure PCTCN2019110631-appb-100002
    Control stiffness K p =[K x ,K y ,K z ,K θx ,K θy ,0] and attitude adjustment stiffness K d =[K x ,K y ,0,K θx ,K θy ,0], where
    Figure PCTCN2019110631-appb-100003
    with
    Figure PCTCN2019110631-appb-100004
    Are the reference contact forces along the X, Y, and Z directions,
    Figure PCTCN2019110631-appb-100005
    with
    Figure PCTCN2019110631-appb-100006
    Are the reference contact moments around the X and Y axes, K x , Ky and K z are the position stiffnesses in the X, Y, and Z directions respectively, and K θx and K θy are the attitude stiffnesses around the X and Y directions respectively;
    3-2)上位机获取机械臂在工具坐标系T peg下的当前位姿T 0和力传感器测量的当前的接触力/力矩F，并计算下一时刻机械臂的目标位姿T d＝T 0+K p(F-F ref)，上位机发送运动指令使机械臂运动到目标位姿T d；其中位姿T 0＝[X 0,Y 0,Z 0,θ x0,θ y0,θ z0]，X 0、Y 0和Z 0分别是机械臂在工具坐标系下X、Y、Z轴的位置坐标，θ x0、θ y0和θ z0分别是机械臂在工具坐标系下绕X、Y、Z轴的欧拉角，接触力/力矩F＝[F x,F y,F z,M x,M y,M z]，F x、F y和F z分别是轴孔之间接触力沿X、Y、Z轴方向的分量，M x、M y和M z分别是轴孔之间接触力矩绕X、Y、Z轴的分量； 3-2) The host computer obtains the current pose T 0 of the robotic arm in the tool coordinate system T peg and the current contact force/torque F measured by the force sensor, and calculates the target pose T d = T of the robotic arm at the next moment 0 +K p (FF ref ), the host computer sends a motion instruction to move the robotic arm to the target pose T d ; where the pose T 0 =[X 0 ,Y 0 ,Z 0 ,θ x0 ,θ y0 ,θ z0 ] , X 0 , Y 0 and Z 0 are the position coordinates of the X, Y, and Z axes of the robot arm in the tool coordinate system, θ x0 , θ y0 and θ z0 are the robot arm around X, Y, and Y in the tool coordinate system. The Euler angle of the Z axis, contact force/moment F=[F x ,F y ,F z ,M x ,M y ,M z ], F x , F y and F z are the contact force along the axis holes respectively The components in the X, Y, and Z axis directions, M x , My and M z are the components of the contact torque between the shaft holes around the X, Y, and Z axes respectively;
    3-3)重复步骤3-2)，直至待装配轴工件的轴插入待装配孔工件的孔的深度超过孔的倒角深度,进入步骤4)；3-3) Repeat step 3-2) until the depth of the shaft of the workpiece to be assembled into the hole of the workpiece to be assembled exceeds the chamfer depth of the hole, and then go to step 4);
    4)机械臂操纵待装配轴工件的轴执行往复螺旋式装配运动，具体步骤如下：4) The mechanical arm manipulates the axis of the workpiece to be assembled to perform a reciprocating spiral assembly movement. The specific steps are as follows:
    4-1)计算螺旋式装配运动参数的取值范围，所述参数包括：螺旋插装的往复运动频率f screw、旋转角度幅值θ screw和螺旋运动节距h，约束条件表达式如下： 4-1) Calculate the value range of the spiral assembly motion parameters. The parameters include: the reciprocating frequency f screw of the spiral insert, the rotation angle amplitude θ screw and the spiral motion pitch h. The constraint expressions are as follows:
    Figure PCTCN2019110631-appb-100007
    Figure PCTCN2019110631-appb-100007
    其中，δ是轴孔配合的间隙，d是机械臂绕工具坐标系Z轴旋转时待装配轴工件的端面圆心到实际旋转轴线的距离，f res为机械臂的共振频率，k int为惯量匹配因子，k mate为间隙配合因子，k f为轴向摩擦力减小的比例； Among them, δ is the clearance between the shaft and hole, d is the distance from the center of the end face of the workpiece to be assembled to the actual axis of rotation when the manipulator rotates around the Z axis of the tool coordinate system, f res is the resonance frequency of the manipulator, and k int is the inertia matching Factor, k mate is the clearance fit factor, k f is the ratio of axial friction reduction;
    第一次执行螺旋式装配运动时，在满足上述约束条件的范围内，选取螺旋式装配运动参数的初始值；When performing the spiral assembly motion for the first time, select the initial values of the spiral assembly motion parameters within the range that meets the above constraints;
    4-2)计算螺旋式装配运动过程中机械臂在工具坐标系下的位置总增量ΔX、ΔY、ΔZ和绕X、Y轴的欧拉角总增量Δθ x、Δθ y； 4-2) Calculate the total increment ΔX, ΔY, ΔZ of the position of the robot arm in the tool coordinate system and the total increment Δθ x , Δθ y of the Euler angle around the X and Y axes during the spiral assembly movement;
    上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，依据阻抗控制算法，表达式如下： The host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor. According to the impedance control algorithm, the expression is as follows:
    Figure PCTCN2019110631-appb-100008
    Figure PCTCN2019110631-appb-100008
    4-3)计算螺旋插装运动指令的步数n s和绕工具坐标系Z轴旋转的角度幅值θ screw，表达式如下： 4-3) Calculate the number of steps n s of the spiral inserting motion instruction and the angular amplitude θ screw about the Z axis of the tool coordinate system, the expression is as follows:
    Figure PCTCN2019110631-appb-100009
    Figure PCTCN2019110631-appb-100009
    4-4)计算每一步螺旋运动指令的目标位姿
    Figure PCTCN2019110631-appb-100010
    表达式如下：     4-4) Calculate the target pose of each spiral motion instruction
    Figure PCTCN2019110631-appb-100010
    The expression is as follows:
    Figure PCTCN2019110631-appb-100011
    Figure PCTCN2019110631-appb-100011
    其中
    Figure PCTCN2019110631-appb-100012
    每一步的位姿增量
    Figure PCTCN2019110631-appb-100013
    且满足：     among them
    Figure PCTCN2019110631-appb-100012
    Pose increment for each step
    Figure PCTCN2019110631-appb-100013
    And satisfy:
    Figure PCTCN2019110631-appb-100014
    Figure PCTCN2019110631-appb-100014
    其中
    Figure PCTCN2019110631-appb-100015
    和
    Figure PCTCN2019110631-appb-100016
    是第i步指令中机械臂在工具坐标系下分别沿X、Y、Z轴的位置增量，
    Figure PCTCN2019110631-appb-100017
    和
    Figure PCTCN2019110631-appb-100018
    分别是第i步指令中机械臂在工具坐标系下绕X、Y、Z轴的欧拉角增量；     among them
    Figure PCTCN2019110631-appb-100015
    with
    Figure PCTCN2019110631-appb-100016
    Is the position increment of the robot arm along the X, Y, and Z axes in the tool coordinate system in the i-th command,
    Figure PCTCN2019110631-appb-100017
    with
    Figure PCTCN2019110631-appb-100018
    They are the Euler angle increments of the robot arm around the X, Y, and Z axes in the tool coordinate system in the i-th instruction;
    4-5)上位机将4-4)中计算得到的n s步螺旋运动指令发送给机械臂，使机械臂操纵工件轴进行往复螺旋式的装配运动； 4-5) The host computer sends the n s- step spiral motion instructions calculated in 4-4) to the robotic arm, so that the robotic arm manipulates the workpiece axis to perform a reciprocating spiral assembly movement;
    5)机械臂进行完n s步往复螺旋式的装配运动后，上位机获取并更新机械臂当前位姿T 0和力传感器测量的接触力/力矩F，并依据更新后的当前位姿下的轴向插装力F z的大小判断轴孔装配当前的卡阻状态，具体方法如下： 5) After the manipulator has completed the n s- step reciprocating spiral assembly movement, the host computer obtains and updates the current pose T 0 of the manipulator and the contact force/torque F measured by the force sensor, and based on the updated current pose The magnitude of the axial insertion force F z judges the current jamming state of the shaft hole assembly, the specific method is as follows:
    5-1)当
    Figure PCTCN2019110631-appb-100019
    时，判断卡阻状态为安全状态，则令插入速度v a增大10％，螺旋插装参数h增大10％，然后进入步骤6)；     5-1) When
    Figure PCTCN2019110631-appb-100019
    When it is judged that the jamming state is a safe state, increase the insertion speed v a by 10%, and increase the spiral insertion parameter h by 10%, and then enter step 6);
    5-2)当
    Figure PCTCN2019110631-appb-100020
    时，判断卡阻状态为危险状态，则令插入速度v a减小20％，螺旋插装参数h增大20％，同时调整轴孔的相对姿态，计算目标位姿T g＝T 0+K d(F-F r)，上位机发送运动指令使机械臂运动到目标位姿T g，然后进入步骤6)；     5-2) When
    Figure PCTCN2019110631-appb-100020
    When the jamming state is judged to be a dangerous state, the insertion speed v a is reduced by 20%, and the spiral insertion parameter h is increased by 20%. At the same time, adjust the relative posture of the shaft hole to calculate the target posture T g = T 0 +K d (FF r ), the host computer sends a motion instruction to move the manipulator to the target pose T g , and then enters step 6);
    5-3)当
    Figure PCTCN2019110631-appb-100021
    时，判断卡阻状态为已发生卡阻，首先，调整运动参数，即轴向插入速度v a减小30％，螺旋插装参数h减小30％；然后，机械臂运动到目标位姿位姿
    Figure PCTCN2019110631-appb-100022
    其中
    Figure PCTCN2019110631-appb-100023
    为步骤4-4)中第n s-1步螺旋式装配运动指令的目标位姿，使得工件轴反向螺旋后退至上一条运动位姿以缓解卡阻，运动完成后上位机获取接触力/力矩F并再次判断卡阻状态，如果仍满足
    Figure PCTCN2019110631-appb-100024
    则机械臂运动到目标位置
    Figure PCTCN2019110631-appb-100025
    直到机械臂运动目标位置
    Figure PCTCN2019110631-appb-100026
    时消除已发生卡阻状态，上位机获取并更新机械臂的当前位姿T 0和力传感器测量的当前的接触力/力矩F；最后，调整轴孔的相对姿态,上位机获取并更新机械臂的当前位姿T 0和力传感器测量的当前的接触力/力矩F,上位机发送运动指令使机械臂运动到目标位姿T g＝T 0+K d(F-F r)，然后进入步骤6)；     5-3) When
    Figure PCTCN2019110631-appb-100021
    When the jamming state is judged as jam has occurred, first, adjust the motion parameters, that is, the axial insertion speed v a is reduced by 30%, and the spiral insertion parameter h is reduced by 30%; then, the mechanical arm moves to the target position posture
    Figure PCTCN2019110631-appb-100022
    among them
    Figure PCTCN2019110631-appb-100023
    It is the target pose of the screw assembly motion instruction in step n s -1 in step 4-4), so that the workpiece axis spirals backward to the previous motion pose to relieve jamming. After the motion is completed, the upper computer obtains the contact force/torque F and judge the jam state again, if it still meets
    Figure PCTCN2019110631-appb-100024
    Then the robotic arm moves to the target position
    Figure PCTCN2019110631-appb-100025
    Until the robot arm moves to the target position
    Figure PCTCN2019110631-appb-100026
    When the jamming state is eliminated, the upper computer obtains and updates the current pose T 0 of the manipulator and the current contact force/torque F measured by the force sensor; finally, adjust the relative posture of the shaft hole, and the upper computer obtains and updates the manipulator The current pose T 0 and the current contact force/torque F measured by the force sensor, the upper computer sends a motion instruction to move the manipulator to the target pose T g ＝T 0 +K d (FF r ), and then go to step 6) ；
    6)上位机获取并更新机械臂当前位姿T 0，判断当前轴向插入深度Z 0是否到达目标位置深度Z goal：如果已达到目标位置深度，则装配任务结束；否则重新返回步骤4)。 6) The host computer obtains and updates the current pose T 0 of the robotic arm, and judges whether the current axial insertion depth Z 0 reaches the target position depth Z goal : If the target position depth has been reached, the assembly task ends; otherwise, return to step 4).
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