A configuration design method for space manipulator to capture non-cooperative targets

Abstract

A method for designing a configuration of a space manipulator for capturing a non-cooperative target is characterized by comprising the following steps: Step 1, establishing a space robot simulation model and a manipulator motion constraint library, wherein the space robot comprises a base (1) and a manipulator (2); Step 2, designing a manipulator target position according to the task constraint of capturing the non-cooperative target; Step 3, obtaining an inverse solution for the manipulator and selecting a configuration that satisfies the task constraint. The present invention avoids contact, collision or interference between the manipulator and the base or target through on-orbit configuration design of the manipulator, thereby ensuring the safety of the space robot in executing tasks under multiple constraint conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of space robots, and in particular relates to a configuration design method for a space robot arm to capture a non-cooperative target. Background Art

[0002] With the advancement of space technology, space service vehicles (space robots) equipped with robotic arms have gradually become a mainstream direction in the development of on-orbit maintenance and service. Space robots can be used to capture non-cooperative and cooperative targets and clear space debris; they are capable of retrieving and placing tools on-orbit and completing multiple manipulation tasks; they can also load and unload payloads, assist in connecting bases to targets, and lay the foundation for refueling operations. As space robots become more powerful, they can carry more equipment and have more compact space arrangements, placing higher demands on the configuration and movement of the robotic arms.

[0003] This paper proposes a configuration design method for a space robot arm to capture non-cooperative targets. This method can effectively reduce the obstruction of the visual measurement equipment's field of view, the interference of the thruster plume, and avoid the motion envelope of the rotatable accessories. It can also prevent contact, collision or interference between the robot arm and the base or target, thereby improving the safety of space robot missions. Summary of the Invention

[0004] Aiming at the problem of manipulator arm configuration design under multi-constraint conditions of space robots, the present invention provides a configuration design method for a space manipulator to capture non-cooperative targets. Through motion simulation, the method reduces the obstruction of the visual measurement equipment's field of view, the interference of the thruster plume, and the motion envelope of the rotatable accessories, thereby improving the safety of space robot missions.

[0005] In order to achieve the above object, the present invention discloses the following technical solution to achieve the above object: a method for designing a configuration for a space manipulator to capture a non-cooperative target, characterized in that it includes the following steps:

[0006] Step 1: Establish a space robot simulation model and a robotic arm motion constraint library, wherein the space robot includes a base 1 and a robotic arm 2;

[0007] Step 2: Design the target position of the manipulator according to the task constraints of capturing the non-cooperative target;

[0008] Step 3: Find the inverse solution of the robotic arm and select the configuration that meets the task constraints.

[0009] Furthermore, a visual measurement device 4 and a first thruster 31 are arranged on the top of the base 1; a data transmission antenna 6, a solar cell wing 5, a robotic arm 2, and a second thruster 32 are arranged on the side; the robotic arm 2 is arranged on the side of the base 1, and is connected by a series of rigid links through rotating joints, with no more than seven degrees of freedom, and a hand-eye camera and tools are configured at the end.

[0010] Furthermore, in step 1, the robotic arm motion constraint library includes the field of view of the visual measurement device, the motion envelope and field of view of the digital antenna, the motion envelope of the solar cell wing and the plume field of the thruster, and the non-cooperative target capture position.

[0011] Furthermore, in step 1, the space robot simulation model includes a space robot geometric model, a robotic arm motion model, a visual measurement equipment model, a digital antenna field of view model, a solar cell wing motion envelope model, and a thruster plume field model.

[0012] Furthermore, the robotic arm motion model includes a robotic arm inverse solution model and a robotic arm geometric model.

[0013] Furthermore, the space robot simulation models are all in the space robot reference coordinate system o f -x f y f z f The following means:

[0014] The vision measurement equipment model is: the vision measurement equipment reference point relative reference coordinate system transformation matrix T fs , field of view angle θ, the coordinates of the four corner points of the field of view relative to the reference point of the visual measurement equipment are (x 0i y 0i 0)(i=1,2,3,4), the Z direction is the field of view direction, and the field of view cross section is a rectangle, then the distance from the reference point z i The four points in the field of view section can be represented as:

[0015] z=z i

[0016]

[0017]

[0018] Let P = [x i y i z i ] T , E is a 3×3 matrix, then the transformation matrix of the corner point relative to the reference point coordinate system of the visual measurement equipment is The transformation matrix of the corner point relative to the reference point coordinate system of the space robot is T fs =T fs T si ;

[0019] The solar panel motion envelope model is: The solar panel reference point relative to the reference coordinate system transformation matrix T ft The Y direction of the solar cell wing is the rotation axis direction, the rotation radius is R, the Y direction length is L, and the point on the rotation axis is P in the solar cell wing reference coordinate system.t =[0 y t 0] T (0≤y t ≤L), The transformation matrix of the point on the rotation axis relative to the reference coordinate system of the space robot is T fc =T ft T tc ;

[0020] The data transmission antenna field of view model is: the data transmission antenna reference point relative to the reference coordinate system transformation matrix T fc , the universal joint's rotation axis θ1, θ2, the field of view reference point relative to the data transmission antenna reference point coordinate system transformation matrix T cc =RotX(θ1)·RotY(θ2), the field of view is a cylindrical surface with a radius of R1. The field of view model of the digital transmission antenna in the field of view reference point coordinate system can be expressed as The transformation matrix of the point on the rotation axis relative to the reference coordinate system of the space robot is T fc =T fc T cc T cp ;

[0021] The thruster plume field model is a cone model, and the thruster reference point relative to the reference coordinate system transformation matrix T fy , plume angle α, Z is the plume direction of the thruster, and the plume field equation can be expressed in the thruster reference point coordinate system as The point on the thruster center axis is in the thruster reference point coordinate system The transformation matrix of the point on the central axis relative to the reference coordinate system of the space robot is T fy =T fy T yy .

[0022] Furthermore, in step 2, the task constraints are: before capture, the manipulator and the tool do not interfere with the motion envelope of the solar cell wing and the data transmission antenna, and do not enter the field of view of the visual measurement equipment and the data transmission antenna and the thruster plume field; when preparing to capture, the part of the non-cooperative target to be captured is within the field of view of the hand-eye camera at the end of the manipulator and the ΔL position in front of the tool capture, and blocks the field of view of the visual measurement equipment as little as possible. The capture object of the non-cooperative target is a ring with a radius of R2. The distance between the ring and the reference coordinate system of the space robot is L2. The target position of the manipulator is T mb Describe the position and posture of the target position relative to the robot arm installation coordinate system, through the target position relative to the space robot reference coordinate system T fb , the manipulator installation coordinate system relative to the space robot reference coordinate system T fm Obtained by conversion.

[0023] Furthermore, in step 2, the target position of the manipulator is designed according to the task constraints, wherein:

[0024] Before the arrest:

[0025] The rotation matrix of the target position relative to the reference point coordinate system of the visual measurement equipment is expressed as T sb =(T fs ) -1 T fb , does not satisfy the equation: That is, the constraints are met; where T sb (i,j) represents the matrix T sb The data in row i and column j,

[0026] The rotation matrix of the target position relative to the solar panel reference point coordinate system is expressed as T tb =(T ft ) -1 T fb , satisfying the constraints: T tb (1,4) 2 +T tb (3,4) 2 >T tb (2,4) 2 ,0≤T tb (2,4)≤L;

[0027] The rotation matrix of the target position relative to the data transmission antenna reference point coordinate system is expressed as T cb =(T fc T cc ) -1 T fb , satisfying the constraints: T cb (1,4) 2 +T cb (3,4) 2 >T cb (2,4) 2 ;

[0028] The rotation matrix of the target position relative to the thruster reference point coordinate system is expressed as T yb =(T fy ) -1 T fb , satisfying the constraints:

[0029] When preparing to capture, the target position meets the constraints

[0030] Furthermore, in step 3, the inverse solution of the robotic arm is obtained based on the position and posture of the target position relative to the robotic arm installation coordinate system, and a configuration that meets the constraints is selected. Finally, the robotic arm joint angle is imported into the spatial machine geometric model for verification to determine the configuration of the robotic arm.

[0031] Furthermore, in step 3, the configuration that satisfies the constraint conditions indicates that the structure of the robotic arm does not block the field of view of the visual measurement equipment and the data transmission equipment, the motion envelope of the solar cell wing, and does not enter the thruster plume field before capture, and the position to be captured is within the visual range during capture.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] The present invention avoids contact, collision or interference between the robotic arm and the base or target through the on-orbit configuration design of the robotic arm, thereby ensuring the safety of the space robot in performing tasks under multiple constraints.

[0034] This paper addresses the design challenges of manipulator arm configurations for complex space robot missions and proposes a design method for a space manipulator arm capable of capturing non-cooperative targets. Through motion simulation, this method reduces obstruction of the visual measurement equipment's field of view, interference from thruster plumes, and avoids the motion envelope of rotatable accessories, thereby improving mission safety. This method is low-cost, convenient, and offers realistic simulation results. Through multidisciplinary collaborative simulation, it can be widely applied to manipulator arm configuration design for space missions (such as retrieving tools or payloads, inspecting, manipulating, and repairing targets, and docking payloads), and can also be extended to ground-based test design. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of a space robot in an embodiment of the present invention.

[0036] Figure 2 It is a flow chart of an embodiment of a configuration design method for a space manipulator to capture a non-cooperative target according to the present invention.

[0037] Figure 3 It is the relative position relationship in the task of capturing a non-cooperative target in an embodiment of the present invention.

[0038] Figure 4 This is the configuration of the robotic arm before capturing a non-cooperative target in an embodiment of the present invention.

[0039] Figure 5 This is the configuration of the robotic arm for preparing to capture a non-cooperative target in the task of capturing a non-cooperative target in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The above description is intended only to illustrate the technical concept of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications based on the technical concept of the present invention and any modifications made to the technical solution are within the scope of protection of the present invention. Any matters not described in detail in this specification constitute common knowledge to those skilled in the art.

[0041] To more clearly illustrate the technical solution of the present invention, the following examples illustrate the technical solution of the present invention. This invention addresses the design of manipulator arm configurations for space robots performing complex tasks. A design method for a space manipulator arm to capture non-cooperative targets is proposed. Through motion simulation, this method reduces obstruction of the visual measurement equipment's field of view, interference from thruster plumes, and avoids the motion envelope of rotatable accessories, thereby improving the safety of space robot missions.

[0042] Figure 1 Schematic diagram of a space robot in an embodiment of the present invention. Figure 1 The space robot consists of a base 1 and two sets of seven-degree-of-freedom robotic arms 2, which complete the robotic arm configuration design under the task of capturing non-cooperative targets.

[0043] Figure 2 This is a flow chart of an embodiment of the method for designing a configuration of a space manipulator to capture a non-cooperative target according to the present invention. Figure 2 The present invention provides a method for designing a configuration for a space manipulator to capture a non-cooperative target, comprising the following steps:

[0044] Step 1: Establish a space robot simulation model and a robotic arm motion constraint library;

[0045] Step 2: Design the target position of the robot arm based on the task constraints;

[0046] Step 3: Find the inverse solution of the robotic arm and select the configuration that meets the task constraints.

[0047] In step 1, refer to Figure 1 The space robot consists of a base 1, a robotic arm 2, and an end-use tool. The top (+X plane) of the base 1 houses a visual measurement device 4 (including a short-range optoelectronic system, a laser imaging radar, and three binocular cameras), tools, and a first thruster 31. The sides (±Z planes) are equipped with a data transmission antenna 6, the robotic arm 2, and a second thruster 32. The sides (±Y planes) of the base are equipped with solar panels 5. The robotic arm 2, located on the side of the base, consists of a series of rigid bodies (connecting rods) connected by revolute joints, typically with no more than seven degrees of freedom. The end-use tool is equipped with a hand-eye camera and a tool.

[0048] In step 1, the robotic arm motion constraint library includes the field of view of the visual measurement equipment, the motion envelope and field of view of the data transmission antenna, the motion envelope of the solar cell wing and the plume field of the thruster, the non-cooperative target capture position, etc.

[0049] In step 1, the manipulator space robot simulation model includes the space robot geometric model, the manipulator motion model, the visual measurement equipment and data transmission antenna field of view model, the solar cell wing motion envelope model, and the thruster plume field model.

[0050] The above-mentioned robot arm motion model includes a robot arm inverse solution model and a robot arm geometric model.

[0051] The above-mentioned geometric model of the space robot can be expressed in two ways: mathematical model and visual model.

[0052] The space robot simulation models are all in the space robot reference coordinate system o f -x f y f z f The following means:

[0053] Transformation matrix T of the reference point of the visual measurement equipment relative to the reference coordinate system fs , field of view angle θ, the coordinates of the four corner points of the field of view relative to the reference point of the visual measurement equipment are (x 0i y 0i 0)(i=1,2,3,4), the Z direction is the field of view direction, and the field of view cross section is a rectangle, then the distance from the reference point z i The four points in the field of view section can be represented as:

[0054] z=z i

[0055]

[0056]

[0057] Let P = [x i y i z i ] T , E is a 3×3 matrix, then the transformation matrix of the corner point relative to the reference point coordinate system of the visual measurement equipment is The transformation matrix of the corner point relative to the reference point coordinate system of the space robot is T fs =T fs T si .

[0058] Transformation matrix T of the solar panel reference point relative to the reference coordinate system ft The Y direction of the solar cell wing is the rotation axis direction, the rotation radius is R, the Y direction length is L, and the point on the rotation axis is in the solar cell wing reference coordinate system. The transformation matrix of the point on the rotation axis relative to the reference coordinate system of the space robot is T fc =T ft T tc .

[0059] Transformation matrix T of the data transmission antenna reference point relative to the reference coordinate system fc , the universal joint's rotation axis θ1, θ2, the field of view reference point relative to the data transmission antenna reference point coordinate system transformation matrix T cc =RotX(θ1)·RotY(θ2), the field of view is a cylindrical surface with a radius of R1. The field of view model of the digital antenna in the field of view reference point coordinate system can be expressed as P p =[0 y p 0] T , The transformation matrix of the point on the rotation axis relative to the reference coordinate system of the space robot is T fc =T fc T cc T cp .

[0060] The thruster plume field model is a cone model, and the thruster reference point relative to the reference coordinate system transformation matrix T fy , plume angle α, Z is the plume direction of the thruster, and the plume field equation can be expressed in the thruster reference point coordinate system as The point on the thruster center axis is in the thruster reference point coordinate system The transformation matrix of the point on the central axis relative to the reference coordinate system of the space robot is T fy =T fy T yy .

[0061] In step 2, the task constraints for capturing non-cooperative targets are: before capture, the robotic arm and tool do not interfere with the motion envelope of the solar array and data transmission antenna, and do not enter the field of view of the visual measurement equipment and data transmission antenna or the thruster plume field; when preparing to capture, the target's to-be-captured part is within the field of view of the hand-eye camera at the end of the robotic arm and a position ΔL ahead of the tool capture, and obstructs the field of view of the visual measurement equipment as little as possible.

[0062] The part of the target to be captured is a circular ring with a radius of R2, and the distance between the circular ring and the reference coordinate system of the space robot is L2.

[0063] The target position of the above-mentioned robot arm is T mb Describe the position and posture of the target position relative to the robot arm installation coordinate system, through the target position relative to the space robot reference coordinate system T fb , the manipulator installation coordinate system relative to the space robot reference coordinate system T fm Obtained by conversion.

[0064] In step 2, the target position of the manipulator is designed according to the task constraints, where:

[0065] Before the arrest:

[0066] The rotation matrix of the target position relative to the reference point coordinate system of the visual measurement equipment is expressed as T sb =(T fs ) -1 T fb , does not satisfy the equation: That is, the constraints are met; where T sb (i,j) represents the matrix T sb The data in row i and column j.

[0067] The rotation matrix of the target position relative to the solar panel reference point coordinate system is expressed as T tb =(T ft ) -1 T fb , satisfying the constraints: T tb (1,4) 2 +T tb (3,4) 2 >T tb (2,4) 2 ,0≤T tb (2,4)≤L;

[0068] The rotation matrix of the target position relative to the data transmission antenna reference point coordinate system is expressed as T cb =(T fc T cc ) -1 T fb , satisfying the constraints: T cb (1,4) 2 +T cb (3,4) 2 >T cb (2,4) 2 ;

[0069] The rotation matrix of the target position relative to the thruster reference point coordinate system is expressed as T yb =(T fy ) -1 T fb , satisfying the constraints:

[0070] When preparing to capture, the target position meets the constraints

[0071] Figure 3 is the relative position relationship in the task of capturing non-cooperative targets in the embodiment of the present invention. Figure 3, is a schematic diagram of the target position, reference coordinate system, and manipulator installation coordinate system during the capture of a non-cooperative target task, before capture and during capture preparation. The space robot reference coordinate system 51, manipulator installation position 10, manipulator installation position 20, manipulator pre-capture target position 11, manipulator pre-capture target position 21, manipulator capture preparation position 12, and manipulator capture preparation position 22 are shown in FIG. Figure 3 When preparing to capture, the distance between the target and the capture front end, that is, the non-cooperative target 30, is ΔL. The motion envelope 52 of the data transmission antenna and the field of view envelope 53 of the visual measurement device are as follows: Figure 3 shown.

[0072] In step 3, the inverse solution for the manipulator is calculated based on the position and attitude of the target position relative to the manipulator's mounting coordinate system. A configuration that satisfies the constraints is selected. Finally, the manipulator's joint angles are imported into the spatial machine geometry model for verification, confirming the manipulator's configuration. This configuration satisfies the constraints in step 2: The structure of the manipulator (including the arm and its tool) does not obstruct the field of view of the visual measurement and data transmission equipment before capture, does not obstruct the motion envelope of the solar panel, does not enter the thruster plume, and the position to be captured is within visual range during capture.

[0073] Figure 4 This is the configuration of the robotic arm before capturing a non-cooperative target in an embodiment of the present invention. Figure 5 This is the configuration of the manipulator arm for capturing the non-cooperative target task in the embodiment of the present invention. This example is for the task of capturing the non-cooperative target. The design result of the manipulator arm configuration before capturing is referenced. Figure 4 The capture front manipulator configuration 60, the capture front manipulator configuration 61, the thruster plume field 54 are as follows Figure 4 As shown. The design results of the manipulator configuration when preparing to capture refer to Figure 5 , the manipulator arm is in configuration 63 when ready to capture, and the manipulator arm is in configuration 64 when ready to capture. Figure 5 As shown.

[0074] The above is only a specific embodiment of the present invention, which is only used to more clearly illustrate the present invention, and is not intended to limit the present invention. Any changes that can be conceived by those skilled in the art should fall within the scope of protection.

Claims

1. A method for designing a configuration for a space manipulator to capture a non-cooperative target, characterized in that: The following steps are involved: Step 1: establishing a space robot simulation model and a robotic arm motion constraint condition library, wherein the space robot comprises a base (1) and a robotic arm (2); Step 2: Design the target position of the manipulator according to the task constraints of capturing the non-cooperative target; Step 3: Find the inverse solution of the manipulator and select the configuration that meets the task constraints. The top of the base (1) is provided with a visual measurement device (4) and a first thruster (31); the side is provided with a data transmission antenna (6), a solar cell wing (5), a mechanical arm (2), and a second thruster (32); the mechanical arm (2) is arranged on the side of the base (1), and is connected by a series of rigid connecting rods through a rotating joint, with no more than seven degrees of freedom, and a hand-eye camera and a tool are configured at the end. In step 2, the task constraints are: the robotic arm and the tool do not interfere with the motion envelope of the solar panel and the data transmission antenna before the capture, and do not enter the field of view of the visual measurement equipment and the data transmission antenna and the thruster plume field; When preparing to capture, the part of the non-cooperative target to be captured is within the field of view of the hand-eye camera at the end of the manipulator and the position △L in front of the tool capture, and the field of view of the visual measurement equipment is blocked as little as possible. The capture object of the non-cooperative target is a ring with a radius of R2. The distance between the ring and the reference coordinate system of the space robot is L2. The target position of the manipulator is T mb Describes the position and posture of the target position relative to the robot arm installation coordinate system, through the target position relative to the space robot reference coordinate system T fb , the manipulator installation coordinate system relative to the space robot reference coordinate system T fm Convert to obtain; In step 2, the target position of the manipulator is designed according to the task constraints, wherein: Before the arrest: The rotation matrix of the target position relative to the reference point coordinate system of the visual measurement equipment is expressed as T sb =(T fs ) -1 T fb , does not satisfy the equation: That is, the constraints are met; where T sb (i,j) represents the matrix T sb The data in row i and column j, The rotation matrix of the target position relative to the solar panel reference point coordinate system is expressed as T tb =(T ft ) -1 T fb , satisfying the constraints: T tb (1,4) 2 +T tb (3,4) 2 >T tb (2,4) 2 ,0≤T tb (2,4)≤L; The rotation matrix of the target position relative to the data transmission antenna reference point coordinate system is expressed as T cb =(T fc T cc ) -1 T fb , satisfying the constraints: T cb (1,4) 2 +T cb (3,4) 2 >T cb (2,4) 2 ; The rotation matrix of the target position relative to the thruster reference point coordinate system is expressed as T yb =(T fy ) -1 T fb , satisfying the constraints: When preparing to capture, the target position meets the constraints:

2. The method for designing a configuration for a space manipulator to capture a non-cooperative target according to claim 1, characterized in that: In step 1, the robotic arm motion constraint library includes the field of view of the visual measurement device, the motion envelope and field of view of the data transmission antenna, the motion envelope of the solar cell wing and the plume field of the thruster, and the non-cooperative target capture position.

3. The method for designing a configuration for a space manipulator to capture a non-cooperative target according to claim 1 or 2, characterized in that: In step 1, the space robot simulation model includes a space robot geometric model, a robotic arm motion model, a visual measurement equipment model, a data transmission antenna field of view model, a solar cell wing motion envelope model, and a thruster plume field model.

4. The method for designing a configuration for a space manipulator to capture a non-cooperative target according to claim 3, characterized in that: The robot arm motion model includes a robot arm inverse solution model and a robot arm geometric model.

5. The method for designing a configuration for a space manipulator to capture a non-cooperative target according to claim 4, characterized in that: In step 3, the inverse solution of the robotic arm is obtained based on the position and posture of the target position relative to the robotic arm installation coordinate system, and a configuration that meets the task constraints is selected. Finally, the robotic arm joint angles are imported into the space robot simulation model for verification to determine the configuration of the robotic arm.

6. The method for designing a configuration for a space manipulator to capture a non-cooperative target according to claim 5, characterized in that: In step 3, the configuration that meets the task constraints means that the structure of the robotic arm does not block the field of view of the visual measurement equipment and the data transmission antenna before capture, does not interfere with the motion envelope of the solar panel, and does not enter the thruster plume field, and the position to be captured is within the visual range during capture.

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