A spatial manipulator system for capturing a cooperative target and a servo planning method

Abstract

The application discloses a space manipulator system for capturing a cooperative target and a servo planning method, relates to the technical field of space manipulator control, and aims to solve the problem that the stability of an on-orbit capturing task cannot be ensured because the dynamic model constructed for the uncertainty of free floating is not accurate. The servo planning strategy of the application does not depend on an accurate dynamic model of the manipulator, adopts a visual closed-loop feedback mode, does not need to consider the free floating condition, reduces the calculation complexity, and ensures the stability and robustness of the system during the on-orbit capturing process. The application designs the manipulator system according to the characteristics of a cooperative satellite with a reserved standard interface, and the system is simple and reliable and does not depend on complex capturing tools and measuring means.

Description

Technical Field

[0001] This application relates to the field of aerospace robotic arm control technology, specifically a space robotic arm system for capturing cooperative targets and a servo planning method. Background Technology

[0002] With the rapid development of aerospace technology and the accelerated pace of human exploration of the universe, the number of high-value spacecraft in orbit has increased dramatically. To extend the lifespan of satellites and other spacecraft and reduce operating costs, on-orbit servicing technologies (including on-orbit refueling, maintenance, component replacement, and upgrades) have become a research hotspot in the international aerospace field. To facilitate these on-orbit maintenance operations, modern and future satellite designs increasingly incorporate standardized capture interfaces, making them "cooperative targets" with cooperative characteristics. Implementing efficient and reliable capture of these cooperative targets has extremely important strategic significance and application value for building a sustainable space infrastructure.

[0003] Space robotic arm systems are the core means to achieve the aforementioned capture and manipulation tasks in orbit. However, most existing space robotic arm planning methods consider the free-floating characteristics of space robots to construct accurate dynamic models. But due to the uncertainties of free-floating, these dynamic models are inaccurate and therefore cannot guarantee the stability of on-orbit capture tasks. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the dynamic model constructed due to the uncertainty of free-floating is inaccurate, thus failing to guarantee the stability of on-orbit capture missions, by providing a space robotic arm system and servo planning method for capturing cooperative targets.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A space robotic arm system for capturing cooperative targets and a servo planning method include the following steps:

[0007] Step 1: The robotic arm moves to the pre-capture position according to the preset trajectory, enabling the vision sensor at the end of the robotic arm to measure the marker on the target satellite's capture interface. The initial relative position of the marker's coordinate system with respect to the vision measurement coordinate system is: The initial relative attitude is ;

[0008] Step 2: The visual sensor measures the marker on the target satellite's capture interface. The relative position of the marker's coordinate system with respect to the visual measurement coordinate system is as follows: The relative attitude is ;

[0009] Step 3: In the marker coordinate system, according to and Planning the desired end effector trajectory of the robotic arm :

[0010] Step 4: Based on the relative positions in Step 2 and relative posture Calculate the pose matrix of the marker coordinate system relative to the visual measurement coordinate system. ;

[0011] ,

[0012] in, This is a function that converts pose data into a pose matrix.

[0013] Step 5: Based on the desired robotic arm end effector trajectory Pose matrix of marker coordinate system relative to visual measurement coordinate system Calculate the desired end-effector linear velocity and desired end-effector angular velocity in the visual measurement coordinate system;

[0014] Step 6: Calculate the Jacobian matrix of the robotic arm, and further calculate the inverse of the weighted Jacobian matrix after the inertia matrix;

[0015] Step 7: Calculate the expected angular velocity of the joint based on the inverse of the weighted Jacobian matrix of the inertia matrix, and in conjunction with the expected end-effector linear velocity and expected end-effector angular velocity in the visual measurement coordinate system. and joint expected angle ;

[0016] Step 8: Based on the desired angular velocity of the joint and joint expected angle The servo drive torque is generated by the joint controller of the robotic arm to drive the movement of the robotic arm and complete the servo planning.

[0017] Furthermore, the specific steps of step three are as follows:

[0018] Step 31: According to Plan the desired end effector position of the robotic arm in the marker coordinate system Specifically:

[0019] ,

[0020] ,

[0021] ,

[0022] in, The set arrival time, For planning time;

[0023] Step 32: Based on The desired end-effector attitude is planned in the marker coordinate system in the form of an attitude matrix. , is represented as:

[0024] ,

[0025] ,

[0026] ,

[0027] ,

[0028] in, Let zyx be a function that transforms the system's Euler angles into an attitude matrix. This is the initial attitude deviation matrix. The function to find the trace of a matrix. From The rotation angle calculated in the middle, This is a function to extract the rotation vector from a rotation matrix. From The rotation vector calculated in the middle, This is a function that transforms a rotated vector into an antisymmetric matrix. for antisymmetric matrix, For the planned rotation angle, It is the identity matrix;

[0029] Step 33: According to and This yields the desired end trajectory in the marker coordinate system, expressed as a pose matrix. , is represented as:

[0030] ,

[0031] ,

[0032] in, It is an intermediate variable.

[0033] Furthermore, the aforementioned Represented as:

[0034] .

[0035] Furthermore, the aforementioned Represented as:

[0036] .

[0037] Furthermore, the specific steps of step five are as follows:

[0038] Step 51: Based on the desired terminal trajectory pose matrix To obtain the desired terminal trajectory , is represented as:

[0039] ,

[0040] And Convert to ,

[0041] in, The desired end-effector trajectory in the visual measurement coordinate system. The desired end-position trajectory in the visual measurement coordinate system;

[0042] Step 52: Obtain the desired end-effector linear velocity in the visual measurement coordinate system , is represented as:

[0043] ,

[0044] in, For the planning cycle;

[0045] Step 53: Based on The desired end-effector angular velocity in the visual measurement coordinate system is obtained. , is represented as:

[0046] ,

[0047] ,

[0048] ,

[0049] in, The matrix logarithm function, For the antisymmetric matrix of the angle increment, For antisymmetric matrix vectorization functions, This is the extracted angle increment.

[0050] Step 54: Based on the kinematic parameters of the robotic arm, obtain the attitude matrix of the visual measurement coordinate system relative to the robotic arm base system. and based on ,Will and Converted to the desired end effector linear velocity in the robotic arm base system and desired terminal angular velocity , is represented as:

[0051] ,

[0052] ,

[0053] in, For the kinematic parameters of the robotic arm, For the joint angles of the robotic arm, Let be the positive kinematics function of the robotic arm.

[0054] Furthermore, the Jacobian matrix of the robotic arm is expressed as:

[0055] ,

[0056] in, This is a function for calculating the Jacobian matrix of the robotic arm.

[0057] Furthermore, the inverse of the weighted Jacobian matrix of the inertia matrix is ​​expressed as:

[0058] ,

[0059] in, For the transpose of the Jacobian matrix of the robotic arm, Here is the inertia matrix of the robotic arm. It is the inverse of the Jacobian matrix after weighting the inertia matrix.

[0060] Furthermore, the desired angular velocity of the joint Represented as:

[0061] .

[0062] Furthermore, the desired angle of the joint Represented as:

[0063] .

[0064] Furthermore, the method also includes step nine:

[0065] Step 9: The relative position of the coordinate system of the marker to be measured with respect to the visual measurement coordinate system. relative posture Once converged within the capture tolerance, the capture gripper closes and locks the capture interface installed on the cooperative target, completing the capture of the cooperative target.

[0066] The beneficial effects of this invention are:

[0067] The servo planning strategy of this application does not rely on an accurate dynamic model of the robotic arm. It adopts a visual closed-loop feedback method, eliminating the need to consider free-floating conditions. This reduces computational complexity while ensuring the stability and robustness of the system during on-orbit capture. This application designs a robotic arm system specifically for cooperative satellites with reserved standard interfaces. The system is simple and reliable, and does not rely on complex capture tools and measurement methods. Attached Figure Description

[0068] Figure 1 Schematic diagram of the space robotic arm system for capturing cooperative targets;

[0069] Figure 2 A flowchart for a space robotic arm system to capture cooperative targets;

[0070] Figure 3 A schematic diagram of the initial state of the claws used to capture a cooperative target;

[0071] Figure 4 A diagram illustrating the closed state of a hand used to capture a cooperative target;

[0072] Figure 5 A diagram illustrating the dragging state of the claws used to capture a cooperative target;

[0073] Figure 6 A diagram illustrating the locked state of the claws used to capture a target in cooperation.

[0074] Figure 7 A schematic diagram illustrating the pre-capture phase of the satellite during the capture process;

[0075] Figure 8 This is a schematic diagram illustrating the hand-eye camera-guided robotic arm movement phase during the capture process.

[0076] Figure 9 This is a schematic diagram showing the movement of the robotic arm within the capture tolerance during the capture process;

[0077] Figure 10 A schematic diagram illustrating the locking phase of the gripper during the capture process to seize a cooperative target;

[0078] Figure 11 A schematic diagram showing the planned position of joint 1 of the robotic arm;

[0079] Figure 12 A schematic diagram showing the planned position of joint 2 of the robotic arm;

[0080] Figure 13 A schematic diagram showing the planned position of joint 3 of the robotic arm;

[0081] Figure 14 A schematic diagram showing the planned position of joint 4 of the robotic arm;

[0082] Figure 15A schematic diagram showing the planned position of joint 5 of the robotic arm;

[0083] Figure 16 A schematic diagram showing the planned position of joint 6 of the robotic arm;

[0084] Figure 17 A schematic diagram showing the planned position of joint 7 of the robotic arm;

[0085] Figure 18 A schematic diagram for planning the speed of joint 1 of the robotic arm;

[0086] Figure 19 A schematic diagram for planning the speed of joint 2 of the robotic arm;

[0087] Figure 20 A schematic diagram for planning the speed of joint 3 of the robotic arm;

[0088] Figure 21 A schematic diagram for planning the speed of joint 4 of the robotic arm;

[0089] Figure 22 A schematic diagram showing the speed planning for joint 5 of the robotic arm;

[0090] Figure 23 A schematic diagram for planning the speed of joint 6 of the robotic arm;

[0091] Figure 24 A schematic diagram showing the speed planning for joint 7 of the robotic arm. Detailed Implementation

[0092] It should be noted that, where there is no conflict, the various embodiments disclosed in this application can be combined with each other.

[0093] Specific Implementation Method 1: This implementation method describes a space robotic arm system and servo planning method for capturing cooperative targets. The space robotic arm system for capturing cooperative targets consists of a robotic arm, a capture gripper, a vision sensor, and a capture interface adapted to the capture gripper. Specifically: the robotic arm is mounted on a service satellite; the capture gripper and vision sensor are mounted at the end of the robotic arm; the capture interface adapted to the capture gripper is mounted on the target satellite, and the capture interface is equipped with a marker measured by the vision sensor.

[0094] The steps include:

[0095] Step 1: The robotic arm moves to the pre-capture position according to the preset trajectory, so that the vision sensor at the end of the robotic arm can measure the marker of the target satellite's capture interface.

[0096] Step two: The visual sensor measures the marker on the target satellite's capture interface. The relative position of the marker's coordinate system with respect to the visual measurement coordinate system is... The relative attitude (zyx with the system) is The relative positions at the initial moment are: The initial relative attitude is ;

[0097] Step 3, in the marker coordinate system, according to and Plan the desired end effector trajectory of the robotic arm:

[0098] Step 31: Plan the desired end effector position of the robotic arm in the marker coordinate system :

[0099] ,

[0100] ,

[0101] ,

[0102] In the formula, The set arrival time, For planning time.

[0103] Step 32: Plan the desired end-effector attitude in the marker coordinate system using the attitude matrix. :

[0104] ,

[0105] ,

[0106] ,

[0107] ,

[0108] ,

[0109] ,

[0110] In the formula, Let zyx be a function that transforms the system's Euler angles into an attitude matrix. This is the initial attitude deviation matrix; The function to find the trace of a matrix. From The rotation angle calculated in the middle; This is a function to extract the rotation vector from a rotation matrix. From The rotation vector calculated in the middle; This is a function that transforms a rotated vector into an antisymmetric matrix. for The antisymmetric matrix; The planned rotation angle; It is the identity matrix. The desired end-effector attitude.

[0111] Step 33, according to and This yields the desired end trajectory in the marker coordinate system, expressed as a pose matrix. :

[0112] ,

[0113] ,

[0114] Step four, according to step two... and Calculate the pose matrix of the marker coordinate system relative to the visual measurement coordinate system. :

[0115] ,

[0116] In the formula, It is a function that converts pose data into a pose matrix.

[0117] Step 5: Based on the desired end trajectory in the marker coordinate system Pose matrix of marker coordinate system relative to visual measurement coordinate system Calculate the desired end-effector linear velocity and desired end-effector angular velocity in the visual measurement coordinate system;

[0118] Step 51: Calculate the desired end trajectory in the visual measurement coordinate system. :

[0119] ,

[0120] Will Written Form, among which, The desired end-effector trajectory in the visual measurement coordinate system. The desired end position trajectory in the visual measurement coordinate system.

[0121] Step 52: Calculate the desired end-effector linear velocity in the visual measurement coordinate system. :

[0122] ,

[0123] In the formula, For the planning cycle.

[0124] Step 53: Calculate the desired end-effector angular velocity in the visual measurement coordinate system. :

[0125] ,

[0126] ,

[0127] ,

[0128] In the formula, The matrix logarithm function, An antisymmetric matrix for angle increments; For antisymmetric matrix vectorization functions, This is the extracted angle increment.

[0129] Step 54: Based on the kinematic parameters of the robotic arm, calculate the attitude matrix of the visual measurement coordinate system relative to the robotic arm base system. and will and Converted to the desired end effector linear velocity in the robotic arm base system and desired terminal angular velocity :

[0130] ,

[0131] ,

[0132] In the formula, These are the kinematic parameters of the robotic arm. For the joint angles of the robotic arm, It is the positive kinematic function of the robotic arm.

[0133] Step 6: Calculate the Jacobian matrix of the robotic arm, and further calculate the inverse of the weighted Jacobian matrix after considering the inertia matrix:

[0134] ,

[0135] ,

[0136] In the formula, A function to calculate the Jacobian matrix of the robotic arm, Let Jacobian matrix be the value of the robotic arm. For the transpose of the Jacobian matrix of the robotic arm, Here is the inertia matrix of the robotic arm. It is the inverse of the Jacobian matrix after weighting the inertia matrix.

[0137] Step 7: Calculate the expected angular velocity of the joint based on the inverse of the weighted Jacobian matrix of the inertia matrix. and joint expected angle :

[0138] ,

[0139] ,

[0140] Step 8: The robotic arm joint controller generates the driving torque required for the desired angle and angular velocity of the servo joint, drives the robotic arm to move, and completes the servo planning.

[0141] Step 9: The relative position of the coordinate system of the marker to be measured with respect to the visual measurement coordinate system. relative posture Once converged within the capture tolerance, the capture gripper closes and locks the capture interface installed on the cooperative target, completing the capture of the cooperative target.

[0142] Example:

[0143] Establish as attached Figure 1 The simulation model shown depicts a space robotic arm system consisting of a robotic arm, a capture gripper, a vision sensor, and a capture interface adapted to the capture gripper.

[0144] To initiate the capture, please refer to the attached instructions. Figure 2 As shown:

[0145] [Step S301] The robotic arm moves to the pre-capture position according to the preset trajectory;

[0146] [Step S302] The visual sensor measures the relative position of the marker on the target satellite's capture interface relative to the visual measurement coordinate system. The relative attitude (zyx with the system) is The relative positions at the initial moment are: The relative attitude is ;

[0147] [Step S303] Plan the desired end-effector position of the robotic arm in the marker coordinate system. ;

[0148] ,

[0149] ,

[0150] ,

[0151] [Step S304] Plan the desired end pose in the marker coordinate system in the form of an attitude matrix. ;

[0152] ,

[0153] ,

[0154] ,

[0155] ,

[0156] ,

[0157] ,

[0158] [Step S305] According to and The desired terminal trajectory in the marker coordinate system is obtained. ;

[0159] ,

[0160] ,

[0161] [Step S306] According to step two... and Calculate the pose matrix of the marker coordinate system relative to the visual measurement coordinate system. ;

[0162] ,

[0163] [Step S307] According to and Calculate the desired end trajectory in the visual measurement coordinate system. and will Written form;

[0164] ,

[0165] [Step S308] Calculate the desired end-effector linear velocity in the visual measurement coordinate system. :

[0166] ,

[0167] [Step S309] Calculate the desired end-effector angular velocity in the visual measurement coordinate system. :

[0168] ,

[0169] ,

[0170] ,

[0171] [Step S310] Calculate the attitude matrix of the visual measurement coordinate system relative to the robot arm base system based on the kinematic parameters of the robot arm. and will and Converted to the desired end effector linear velocity in the robotic arm base system and desired terminal angular velocity :

[0172] ,

[0173] ,

[0174] [Step S311] Calculate the inverse of the Jacobian matrix after weighting the Jacobian matrix and the inertia matrix of the robotic arm;

[0175] ,

[0176] ,

[0177] [Step S312] Calculate the desired angular velocity of the joint. and joint expected angle ;

[0178] ,

[0179] ,

[0180] [Step S313] The robotic arm joint controller generates the driving torque required for the desired angle and angular velocity of the servo joint, drives the robotic arm to move, and completes the servo planning;

[0181] [Step S314] The relative position of the coordinate system of the marker to be measured with respect to the visual measurement coordinate system. relative posture Once converged within the capture tolerance, the capture gripper closes and locks the capture interface installed on the cooperative target, completing the capture of the cooperative target.

[0182] It should be noted that the specific embodiments are merely explanations and illustrations of the technical solution of the present invention and should not be used to limit the scope of protection. Any modifications made in accordance with the claims and specification of the present invention that are only partial should still fall within the protection scope of the present invention.

Claims

1. A space robotic arm system for capturing cooperative targets and a servo planning method, characterized in that... Includes the following steps: Step 1: The robotic arm moves to the pre-capture position according to the preset trajectory, enabling the vision sensor at the end of the robotic arm to measure the marker on the target satellite's capture interface. The initial relative position of the marker's coordinate system with respect to the vision measurement coordinate system is: The initial relative attitude is ; Step 2: The visual sensor measures the marker on the target satellite's capture interface. The relative position of the marker's coordinate system with respect to the visual measurement coordinate system is as follows: The relative attitude is ; Step 3: In the marker coordinate system, according to and Planning the desired end effector trajectory of the robotic arm : Step 4: Based on the relative positions in Step 2 and relative posture Calculate the pose matrix of the marker coordinate system relative to the visual measurement coordinate system. ; ， in, This is a function that converts pose data into a pose matrix. Step 5: Based on the desired robotic arm end effector trajectory Pose matrix of marker coordinate system relative to visual measurement coordinate system Calculate the desired end-effector linear velocity and desired end-effector angular velocity in the visual measurement coordinate system; Step 6: Calculate the Jacobian matrix of the robotic arm, and further calculate the inverse of the weighted Jacobian matrix after the inertia matrix; Step 7: Calculate the expected angular velocity of the joint based on the inverse of the weighted Jacobian matrix of the inertia matrix, and in conjunction with the expected end-effector linear velocity and expected end-effector angular velocity in the visual measurement coordinate system. and joint expected angle ; Step 8: Based on the desired angular velocity of the joint and joint expected angle The servo drive torque is generated by the joint controller of the robotic arm to drive the movement of the robotic arm and complete the servo planning.

2. The space robotic arm system and servo planning method for capturing cooperative targets according to claim 1, characterized in that... The specific steps of step three are as follows: Step 31: According to Plan the desired end effector position of the robotic arm in the marker coordinate system Specifically: ， ， ， in, The set arrival time, For planning time; Step 32: Based on The desired end-effector attitude is planned in the marker coordinate system in the form of an attitude matrix. , is represented as: ， ， ， ， in, Let zyx be a function that transforms the system's Euler angles into an attitude matrix. This is the initial attitude deviation matrix. The function to find the trace of a matrix. From The rotation angle calculated in the middle, This is a function to extract the rotation vector from a rotation matrix. From The rotation vector calculated in the middle, This is a function that transforms a rotated vector into an antisymmetric matrix. for antisymmetric matrix, For the planned rotation angle, It is the identity matrix; Step 33: According to and This yields the desired end trajectory in the marker coordinate system, expressed as a pose matrix. , is represented as: ， ， in, It is an intermediate variable.

3. The space robotic arm system and servo planning method for capturing cooperative targets according to claim 2, characterized in that... The Represented as: 。 4. The space robotic arm system and servo planning method for capturing cooperative targets according to claim 3, characterized in that... The Represented as: 。 5. The space robotic arm system and servo planning method for capturing cooperative targets according to claim 4, characterized in that... The specific steps of step five are as follows: Step 51: Based on the desired terminal trajectory pose matrix To obtain the desired terminal trajectory , is represented as: ， And Convert to , in, The desired end-effector trajectory in the visual measurement coordinate system. The desired end-position trajectory in the visual measurement coordinate system; Step 52: Obtain the desired end-effector linear velocity in the visual measurement coordinate system , is represented as: ， in, For the planning cycle; Step 53: Based on The desired end-effector angular velocity in the visual measurement coordinate system is obtained. , is represented as: ， ， ， in, The matrix logarithm function, For the antisymmetric matrix of the angle increment, For antisymmetric matrix vectorization functions, For the extracted angle increment; Step 54: Based on the kinematic parameters of the robotic arm, obtain the attitude matrix of the visual measurement coordinate system relative to the robotic arm base system. and based on ,Will and Converted to the desired end effector linear velocity in the robotic arm base system and desired terminal angular velocity , is represented as: ， ， in, For the kinematic parameters of the robotic arm, For the joint angles of the robotic arm, Let be the positive kinematics function of the robotic arm.

6. The space robotic arm system and servo planning method for capturing cooperative targets according to claim 5, characterized in that... The Jacobian matrix of the robotic arm is represented as: ， in, This is a function for calculating the Jacobian matrix of the robotic arm.

7. A space robotic arm system and servo planning method for capturing cooperative targets according to claim 6, characterized in that... The inverse of the weighted Jacobian matrix of the inertia matrix is ​​expressed as: ， in, For the transpose of the Jacobian matrix of the robotic arm, Here is the inertia matrix of the robotic arm. It is the inverse of the Jacobian matrix after weighting the inertia matrix.

8. The space robotic arm system and servo planning method for capturing cooperative targets according to claim 7, characterized in that... The desired angular velocity of the joint Represented as: 。 9. A space robotic arm system for capturing cooperative targets and a servo planning method according to claim 8, characterized in that... The desired angle of the joint Represented as: 。 10. A space robotic arm system for capturing cooperative targets and a servo planning method according to claim 9, characterized in that... The method further includes step nine: Step 9: The relative position of the coordinate system of the marker to be measured with respect to the visual measurement coordinate system. relative posture Once converged within the capture tolerance, the capture gripper closes and locks the capture interface installed on the cooperative target, completing the capture of the cooperative target.

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