An Optimal Path Finding Method for a Robot Arm When Opening the Fuel Cap

Abstract

The present invention discloses a method for obtaining the optimal path for a robot arm to open a fuel cap, and relates to the technical field. The present invention comprises the following steps: defining the coordinate systems of the robot arm and the fuel cap; defining the coordinate systems of the intermediate process of the robot arm opening the fuel cap; calculating the joint angle of the robot arm corresponding to the movement of the robot arm; and calculating the optimal path for the robot arm to open a fuel cap. obj The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system; find O b The z-axis unit vector in the coordinate system is at O paw_temp The results are described in the coordinate system; based on the results, the process of the robot arm moving from its current position to the end of the fuel cap handle is derived. The present invention uses an algorithm to achieve the optimal path for the robot arm to open the fuel cap using the rotatable jaws on the fixture until the jaws align with the fuel cap handle, allowing the jaws to rotate and unscrew the fuel cap, ensuring that singularities and breakpoints are avoided as much as possible during the movement of the robot arm.

Description

Technical Field

[0001] The present invention belongs to the technical field, and in particular relates to a method for obtaining an optimal path when a robotic arm opens a fuel cap, that is, to obtain the optimal robotic arm posture and gripper rotation angle during automatic refueling of the robotic arm. Background Art

[0002] During the automatic refueling process, the robot arm first needs to use the end gripper to unscrew the fuel cap. Since most fuel caps include a handle, and the direction of the handle is random after each refueling, this results in the end tool coordinate system moving to a random position when the robot arm unscrews the fuel cap. At this time, the gripper rotation angle is closely related to the robot arm's position when unscrewing the fuel cap. If the gripper rotation angle and the robot arm's movement posture are not considered, it is very likely that the robot arm will enter a singularity or breakpoint state during movement. Therefore, under the premise of random distribution of the fuel cap's direction, how to ensure the optimal posture and gripper rotation angle of the robot arm when opening the fuel cap, so as to minimize the probability of the robot arm entering a singularity or breakpoint state.

[0003] The professional terms involved in this application document are explained as follows:

[0004] (1) Singularity: When the robot arm is in this position, a joint produces violent movement;

[0005] (2) Breakpoint: The corresponding robotic arm position when any joint of the robotic arm reaches the limit;

[0006] (3) The tool coordinate system at the end of the robot arm moves to the target pose Previously, in order to ensure that there is no collision during movement, it is necessary to ensure that the robot arm moves along the O paw Move along the z-axis of the coordinate system. A safety distance set in this direction;

[0007] (4)O 7_tar Coordinate system: with O obj The coordinate system is the same;

[0008] (5) Coordinate system Rx direction: rotation around the x direction of the coordinate system;

[0009] (6) Coordinate system Ry direction: rotation around the y direction of the coordinate system.

[0010] This application document provides a method for obtaining the optimal path when a robotic arm opens the fuel cap, that is, to solve the optimal robotic arm posture and gripper rotation angle during this movement, which can effectively solve the above problems. Summary of the Invention

[0011] The purpose of the present invention is to provide a method for obtaining the optimal path when a robotic arm opens a fuel cap. The method is implemented through an algorithm. During the process of the robotic arm opening the fuel cap, the method uses a rotatable clamp on a clamp to obtain the optimal path to unscrew the fuel cap. This method solves the problem that the robotic arm is prone to entering a singular point and a power-off state during the existing automatic refueling process of the robotic arm.

[0012] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0013] The present invention provides a method for obtaining an optimal path for a robotic arm to open a fuel cap, comprising the following steps:

[0014] Step S1: Add pictures of the fuel pump and fuel cap;

[0015] Step S2: defining the coordinate systems of the robot arm and the fuel filler port;

[0016] Step S3: defining the coordinate systems of the robot arm during the process of opening the fuel cap;

[0017] Step S4: Calculate the O of the robot arm paw The coordinate system moves to O paw_temp The corresponding joint angles of the robot arm in the coordinate system are θ1, θ2, θ3, θ4, θ5, θ6, and The corresponding angle θ7 that the gripper needs to rotate;

[0018] Step S5: Find O obj The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system;

[0019] Step S6: Find O b The z-axis unit vector in the coordinate system is at O paw_temp Description in coordinate system;

[0020] Step S7: Based on the results, deduce the process of the robot arm moving from the current position to the end to fit with the fuel cap screw handle.

[0021] As a preferred technical solution, in step S2, the coordinate system of each part of the robot arm and the fuel filler is defined, including b 、O6、O paw , O7 and O obj ;

[0022] Among them, O b Represents the base coordinate system of the robot arm; O6 represents the default tool coordinate system of the robot arm; O paw represents the fixed jaw coordinate system, which is located on the jaw and has a fixed position relationship with the O6 coordinate system; O7 represents the rotating jaw coordinate system, which has a fixed position relationship with the O6 coordinate system. paw The z axis of the coordinate system coincides with O paw The coordinate system has the same origin; Oobj represents the target coordinate system, O obj The coordinate system is usually measured by external sensors and then sent to the robot controller.

[0023] As a preferred technical solution, in step S3, the process of the robotic arm opening the oil filler cap is as follows:

[0024] Step S31: The robot arm moves to O 7_temp posture;

[0025] Step S32: The gripper rotates θ7 so that 7_temp With O 7_tar The coordinate system pose is the same, where O 7_tar The coordinate system represents O obj Coordinate system;

[0026] Step S33: Robotic arm moves Make the tool coordinate system O7 and O 7_tar Coordinate systems coincide;

[0027] Step S34: The engagement of the clamping jaws with the oil cap screw handle is completed.

[0028] As a preferred technical solution, in step S4, the tool coordinate system O7 at the end of the robot arm must be moved to O 7_tar The pose path is optimal, then O paw_temp The coordinate system must satisfy two constraints, as follows:

[0029] The first constraint: O paw_temp The x-axis of the coordinate system is b The xoy plane of the coordinate system is parallel; the second point constraint is: O paw_temp The x-axis of the coordinate system is obj The z-axis of the coordinate system is vertical.

[0030] As a preferred technical solution, in step S5, O obj The z-axis unit vector of the coordinate system is at O paw_temp The description in the coordinate system is:

[0031]

[0032] Where, paw_temp Z 7_tar O 7_tar The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system; Indicates that the current gripper is around O paw The z-axis of the coordinate system rotates by the initial angle θ 7_0The obtained rotation matrix is used to describe the rotation jaw coordinate system O7 relative to the fixed jaw coordinate system O paw The pose transformation of The initial angle of the gripper is θ 7_0 Read out through the angle sensor.

[0033] As a preferred technical solution, the θ7 is the angle that the gripper needs to rotate, then:

[0034]

[0035] Where,

[0036] If two vectors are perpendicular, then the inner product of the two vectors is zero. paw_temp The x-axis unit vector dot product O of the coordinate system 7_tar The z-axis unit vector of the coordinate system is equal to zero, and the equation is established:

[0037]

[0038] As a preferred technical solution, in step S6, find O b The z-axis unit vector in the coordinate system is at O paw_temp The description in the coordinate system is:

[0039]

[0040] Where,

[0041]

[0042] make

[0043]

[0044] From this we can get,

[0045]

[0046] After obtaining θ7, we can get It can be obtained through the calibration result of the tool coordinate system, and then obtained,

[0047]

[0048] That is, the posture of the default tool coordinate system of the sixth axis of the robotic arm.

[0049] As a preferred technical solution, in step S7, the process of the robot arm moving from the current posture to the end to fit with the fuel cap screw handle is as follows:

[0050] Step S71: Calculate θ7 and obtain θ 7_0 The value of

[0051] Step S72: Setting a safety distance Obtain

[0052] Step S73: Calculation

[0053]

[0054] Step S74: According to the inverse kinematics equation of the robot arm, input A set of inverse solutions θ1, θ2, θ3, θ4, θ5, θ6 can be obtained;

[0055] Step S75: The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper rotates θ7;

[0056] Step S76: According to the inverse kinematics equation of the manipulator, θ7 remains unchanged and the end tool coordinate system pose is input. A new set of joint angles θ1, θ2, θ3, θ4, θ5, θ6 can be obtained;

[0057] Step S77: The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper does not rotate. At this time, the gripper is engaged with the oil cap handle, and the action is completed.

[0058] The present invention has the following beneficial effects:

[0059] The present invention is implemented through an algorithm. During the process of opening the fuel cap by the robotic arm, the optimal path for unscrewing the fuel cap by using the rotatable clamping jaws on the clamp is obtained until the clamping jaws fit with the fuel cap screw handle, so that the clamping jaws rotate to unscrew the fuel cap, ensuring that singular points and breakpoints are avoided as much as possible during the movement of the robotic arm.

[0060] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0062] Figure 1 This is a schematic diagram of the definition of the coordinate system of each position of the robot arm in Example 1;

[0063] Figure 2This is a schematic diagram of the definition of various coordinate systems during the intermediate process of the robotic arm opening the fuel cap in Example 1. DETAILED DESCRIPTION

[0064] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0065] The present invention provides a method for obtaining an optimal path for a robotic arm to open a fuel cap, comprising the following steps:

[0066] Step S1: Add pictures of the fuel pump and fuel cap;

[0067] Step S2: defining the coordinate systems of the robot arm and the fuel filler port;

[0068] Step S3: defining the coordinate systems of the robot arm during the process of opening the fuel cap;

[0069] Step S4: Calculate the O of the robot arm paw The coordinate system moves to O paw_temp The corresponding joint angles of the robot arm in the coordinate system are θ1, θ2, θ3, θ4, θ5, θ6, and The corresponding angle θ7 that the gripper needs to rotate;

[0070] Step S5: Find O obj The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system;

[0071] Step S6: Find O b The z-axis unit vector in the coordinate system is at O paw_temp Description in coordinate system;

[0072] Step S7: Based on the results, deduce the process of the robot arm moving from the current position to the end to fit with the fuel cap screw handle.

[0073] In step S2, the coordinate system of each part of the robot arm and the fuel filler is defined, including b 、O6、O paw , O7 and O obj ;

[0074] Among them, O b Represents the base coordinate system of the robot arm; O6 represents the default tool coordinate system of the robot arm; O paw represents the fixed jaw coordinate system, which is located on the jaw and has a fixed position relationship with the O6 coordinate system; O7 represents the rotating jaw coordinate system, which has a fixed position relationship with the O6 coordinate system. pawThe z axis of the coordinate system coincides with O paw The coordinate system has the same origin; O obj represents the target coordinate system, O obj The coordinate system is usually measured by external sensors and then sent to the robot controller.

[0075] In step S3, the process of the robotic arm opening the fuel cap is as follows:

[0076] Step S31: The robot arm moves to O 7_temp posture;

[0077] Step S32: The gripper rotates θ7 so that 7_temp With O 7_tar The coordinate system pose is the same, where O 7_tar The coordinate system represents O obj Coordinate system;

[0078] Step S33: Robotic arm moves Make the tool coordinate system O7 and O 7_tar Coordinate systems coincide;

[0079] Step S34: The engagement of the clamping jaws with the oil cap screw handle is completed.

[0080] In step S4, the tool coordinate system O7 at the end of the robot arm must be moved to O 7_tar The pose path is optimal, then O paw_temp The coordinate system must satisfy two constraints, as follows:

[0081] The first constraint: O paw_temp The x-axis of the coordinate system is b The xoy plane of the coordinate system is parallel; the second point constraint is: O paw_temp The x-axis of the coordinate system is obj The z-axis of the coordinate system is vertical.

[0082] In step S5, obj The z-axis unit vector of the coordinate system is at O paw_temp The description in the coordinate system is:

[0083]

[0084] Where, paw_temp Z 7_tar O 7_tar The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system; Indicates that the current gripper is around O paw The z-axis of the coordinate system rotates by the initial angle θ 7_0 The obtained rotation matrix is used to describe the rotation jaw coordinate system O7 relative to the fixed jaw coordinate system Opaw The pose transformation of The initial angle of the gripper is θ 7_0 Read out through the angle sensor. θ7 is the angle that the gripper needs to rotate, then:

[0085]

[0086] Where,

[0087] If two vectors are perpendicular, then the inner product of the two vectors is zero. paw_temp The x-axis unit vector dot product O of the coordinate system 7_tar The z-axis unit vector of the coordinate system is equal to zero, and the equation is established:

[0088]

[0089] In step S6, find O b The z-axis unit vector in the coordinate system is at O paw_temp The description in the coordinate system is:

[0090] Where,

[0091]

[0092] make

[0093]

[0094] From this we can get,

[0095]

[0096] After obtaining θ7, we can get It can be obtained through the calibration result of the tool coordinate system, and then obtained,

[0097]

[0098] That is, the posture of the default tool coordinate system of the sixth axis of the robotic arm.

[0099] In step S7, the robot arm moves from the current position to the end and fits with the fuel cap screw handle in the following process:

[0100] Step S71: Calculate θ7 and obtain θ 7_0 The value of

[0101] Step S72: Setting a safety distance Obtain

[0102] Step S73: Calculation

[0103]

[0104] Step S74: According to the inverse kinematics equation of the robot arm, input A set of inverse solutions θ1, θ2, θ3, θ4, θ5, θ6 can be obtained;

[0105] Step S75: The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper rotates θ7;

[0106] Step S76: According to the inverse kinematics equation of the manipulator, θ7 remains unchanged and the end tool coordinate system pose T7 is input. b _tar A new set of joint angles θ1, θ2, θ3, θ4, θ5, θ6 can be obtained;

[0107] Step S77: The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper does not rotate. At this time, the gripper is engaged with the oil cap handle, and the action is completed.

[0108] Example 1

[0109] When a robotic arm opens a fuel cap, it uses a rotatable gripper on a fixture to unscrew it. The process involves the robotic arm moving the end-of-line tooling gripper until it engages the cap's handle, then rotating the gripper to unscrew the cap. How can we ensure that singularities and breakpoints are avoided as much as possible during the robotic arm's movement?

[0110] See also Figure 1 As shown, Figure 1 The coordinate systems of the robot arm and the refueling port are defined, where O b Represents the base coordinate system of the robotic arm.

[0111] O6 represents the default tool coordinate system of the robot arm.

[0112] O paw Represents the fixed jaw coordinate system, which is located on the jaw and has a fixed position relationship with the O6 coordinate system.

[0113] O7 represents the rotating jaw coordinate system, which is paw The z axis of the coordinate system coincides with O paw The coordinate system has the same origin.

[0114] O obj Represents the target coordinate system, which is generally measured by external sensors and then sent to the robot controller.

[0115] See also Figure 2As shown, the above goal is converted into a mathematical problem: the robot arm first moves to O 7_temp Then the gripper rotates θ7 so that O 7_temp With O 7_tar The coordinate system pose is the same, where O 7_tar The coordinate system represents O obj Coordinate system, then the robot moves Make the tool coordinate system O7 and O 7_tar The coordinate systems are aligned, and the gripper and the oil cap screw handle can be aligned. paw The coordinate system moves to O paw_temp The corresponding joint angles of the robot arm in the coordinate system are θ1, θ2, θ3, θ4, θ5, θ6, and The corresponding gripper needs to rotate by an angle θ7.

[0116] To meet the requirements of the tool coordinate system O7 at the end of the robot arm moving to O 7_tar The pose path is optimal, O paw_temp The coordinate system must satisfy two point constraints, as follows,

[0117] (1)O paw_temp The x-axis of the coordinate system is b The coordinate system is parallel to the xoy plane.

[0118] This ensures that the robot arm will not move too much in the Rx and Ry directions of the base coordinate system, thereby reducing the probability of singular points. paw_temp The z-axis direction of the coordinate system has been determined (with O obj The z-axes of the coordinate system are in the same direction, and The pose is known), then it is equivalent to paw_temp Find a unit vector x in the plane perpendicular to the z-axis of the coordinate system (it cannot be called the xoy plane because the x-axis has not been determined at this time) so that the vector x is equal to O b The coordinate system is parallel to the xoy plane.

[0119] (2)O paw_temp The x-axis of the coordinate system is obj The z-axis of the coordinate system is vertical.

[0120] The above two constraints are sorted out and described mathematically to obtain:

[0121] O paw_temp The x-axis unit vector of the coordinate system is equal to O obj The inner product of the unit vectors along the z-axis of the coordinate system is zero.

[0122] O paw_temp The x-axis unit vector of the coordinate system is equal to O bThe inner product of the unit vectors on the z-axis of the coordinate system is zero. A mathematical equation is established around the above conditions:

[0123] ① Find O obj The z-axis unit vector of the coordinate system is at O paw_temp Description of the coordinate system.

[0124]

[0125] in,

[0126] paw_temp Z 7_tar O 7_tar The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system.

[0127] Indicates that the current gripper is around O paw The z-axis of the coordinate system rotates by the initial angle θ 7_0 The obtained rotation matrix is used to describe the rotation jaw coordinate system O7 relative to the fixed jaw coordinate system O paw The posture transformation of Initial angle of the gripper θ 7_0 Can be read out by an angle sensor.

[0128] θ7 is the angle that the gripper needs to rotate, which is the term to be determined.

[0129]

[0130] in,

[0131] θ 7_0 It is known that θ7 is the term to be determined.

[0132] According to the theorem: if two vectors are perpendicular, then the inner product of the two vectors is zero, so we can get,

[0133] O paw_temp The x-axis unit vector dot product O of the coordinate system 7_tar The z-axis unit vector of the coordinate system is equal to zero, and the equation is established.

[0134]

[0135] Why is the above formula itself equal to zero without the need for external conditions to be equal to zero?

[0136] Because the above calculation only involves Rotz(θ 7_0 +θ7), the implicit condition is that only the z-axis is rotated and the z-axis itself is perpendicular to the x-axis.

[0137] ②Find O bThe z-axis unit vector in the coordinate system is at O paw_temp Description in coordinate system,

[0138]

[0139] in,

[0140]

[0141] make

[0142]

[0143] From this we can get,

[0144]

[0145] After obtaining θ7, we can get It can be obtained through the calibration result of the tool coordinate system, and then obtained,

[0146]

[0147] That is, the posture of the default tool coordinate system of the sixth axis of the robotic arm.

[0148] Example 2

[0149] Based on the first embodiment and according to the above derivation process, it can be concluded that the steps of the robot arm moving from the current posture to the end to fit with the fuel cap screw handle are as follows:

[0150] 1. Calculate θ7 and obtain θ 7_0 value.

[0151] 2. Set a safe distance Obtain

[0152]

[0153] 3. Calculation

[0154]

[0155] 4. According to the inverse kinematics equation of the robotic arm, input A set of inverse solutions θ1, θ2, θ3, θ4, θ5, θ6 can be obtained;

[0156] 5. The arm joints move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper rotates θ7;

[0157] 6. According to the inverse kinematics equation of the manipulator, θ7 remains unchanged and the position of the end tool coordinate system is input. A new set of joint angles θ1, θ2, θ3, θ4, θ5, θ6 can be obtained;

[0158] 7. The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper does not rotate. At this time, the gripper fits into the oil cap handle, and the action is completed.

[0159] It is worth noting that in the above system embodiment, the various units included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0160] In addition, those skilled in the art will appreciate that all or part of the steps in the above-mentioned embodiments can be accomplished by instructing related hardware through a program, and the corresponding program can be stored in a computer-readable storage medium.

[0161] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for obtaining the optimal path for a robotic arm to open a fuel cap, characterized in that: The steps include: Step S1: Add images of the gripper and fuel cap; Step S2: defining the coordinate systems of the robot arm and the fuel filler port; Step S3: defining the coordinate systems of the robot arm during the process of opening the fuel cap; Step S4: Calculate the O of the robot arm paw The coordinate system moves to O paw_temp The corresponding joint angles of the robot arm in the coordinate system are θ1, θ2, θ3, θ4, θ5, θ6, and The corresponding angle θ7 that the gripper needs to rotate; Step S5: Find O obj The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system; Step S6: Find O b The z-axis unit vector in the coordinate system is at O paw_temp Description in coordinate system; Step S7: Based on the results, deduce the process of the robot arm moving from the current posture to the end portion fitting with the fuel cap screw handle; In step S4, it is necessary to satisfy the requirement that O7 moves to O 7_tar The pose path is optimal, then O paw_temp The coordinate system must satisfy two constraints, as follows: The first constraint: O paw_temp The x-axis of the coordinate system is b The xoy plane of the coordinate system is parallel; The second constraint: O paw_temp The x-axis of the coordinate system is obj The z-axis of the coordinate system is vertical; In the step S5, obj The z-axis unit vector of the coordinate system is at O paw_temp The description in the coordinate system is: Where, paw_temp Z 7_tar O 7_tar The z-axis unit vector of the coordinate system is at O paw_temp Description in coordinate system; Indicates that the current gripper is around O paw The z-axis of the coordinate system rotates by the initial angle θ 7_0 The obtained rotation matrix is used to describe the rotation jaw coordinate system O7 relative to the fixed jaw coordinate system O paw The pose transformation of The initial angle of the gripper is θ 7_0 Read out through the angle sensor; described θ7 is the angle that the gripper needs to rotate, then: Where, If two vectors are perpendicular, then the inner product of the two vectors is zero. paw_temp The x-axis unit vector dot product O of the coordinate system 7_tar The z-axis unit vector of the coordinate system is equal to zero; In step S6, find O b The z-axis unit vector in the coordinate system is at O paw_temp The description in the coordinate system is: Where, make From this we can get, After obtaining θ7, we can get It can be obtained through the calibration result of the tool coordinate system, and then obtained, That is, the posture of the default tool coordinate system of the sixth axis of the robot arm; In step S2, the coordinate system of each part of the robot arm and the fuel filler is defined, including b 、O6、O paw , O7 and O obj ; Among them, O b Represents the base coordinate system of the robot arm; O6 represents the default tool coordinate system of the robot arm; O paw represents the fixed jaw coordinate system, which is located on the jaw and has a fixed position relationship with the O6 coordinate system; O7 represents the rotating jaw coordinate system, which has a fixed position relationship with the O6 coordinate system. paw The z axis of the coordinate system coincides with O paw The coordinate system has the same origin; O obj represents the target coordinate system, O obj The coordinate system is measured by external sensors and then sent to the robot controller.

2. The method for obtaining the optimal path for a robot arm to open a fuel cap according to claim 1, characterized in that: In step S3, the process of opening the fuel cap by the robotic arm is as follows: Step S31: The robot arm moves to O 7_temp posture; Step S32: The gripper rotates θ7 so that 7_temp With O 7_tar The coordinate system pose is the same, where O 7_tar The coordinate system represents O obj Coordinate system; Step S33: Robotic arm moves Make the tool coordinate system O7 and O 7_tar Coordinate systems coincide; Step S34: The engagement of the clamping jaws with the oil cap screw handle is completed.

3. The method for obtaining the optimal path for a robot arm to open a fuel cap according to claim 1, characterized in that: In step S7, the process of the robot arm moving from the current position to the end to align with the fuel cap screw handle is as follows: Step S71: Calculate θ7 and obtain θ 7_0 The value of Step S72: Setting a safety distance Obtain Step S73: Calculation Step S74: According to the inverse kinematics equation of the robot arm, input A set of inverse solutions θ1, θ2, θ3, θ4, θ5, θ6 can be obtained; Step S75: The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper rotates θ7; Step S76: According to the inverse kinematics equation of the manipulator, θ7 remains unchanged and the end tool coordinate system pose is input. A new set of joint angles θ1, θ2, θ3, θ4, θ5, θ6 can be obtained; Step S77: The joints of the robotic arm move to θ1, θ2, θ3, θ4, θ5, and θ6, and the gripper does not rotate. At this time, the gripper is engaged with the oil cap handle, and the action is completed.

Images