A space station mechanical arm motion interference state real-time detection method

Abstract

The application provides a space station mechanical arm motion interference state real-time detection method, which utilizes Pro / E and 3Dmax software, adopts a layered processing method to decompose a fine geometry model, and then utilizes a fast layered recursion algorithm to process mechanical arm self-detection and scene interference detection, so as to obtain an overall interference state and a safety distance. The application can obtain a space station and a mechanical arm accurate calculation model completely consistent with an actual geometry state based on the layered processing method, and the model is simple and easy to construct, and can cope with space station configuration change processes; the fast layered recursion algorithm can accurately calculate the interference state and the safety distance on the basis of the accurate model, and provides a guarantee for motion safety and path planning feasibility; the layered recursion algorithm has high calculation speed and stability, and can provide real-time interference state detection for the mechanical arm in-orbit motion.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, and specifically relates to a method for real-time detection of motion interference state of a space station robotic arm. Background Technology

[0002] Safety is the primary constraint in mission planning and path planning for the space station's robotic arm, which performs operational tasks in orbit, especially assisting astronauts with extravehicular activities. As the space station's on-orbit construction progresses, the status of installed equipment and modules becomes increasingly complex. The movement of the large robotic arm is greatly affected by the module body, solar panels, and onboard equipment. Furthermore, the space station's robotic arm itself lacks pre-emptive interference inspection sensors and distance measurement capabilities. Therefore, it is essential to utilize other interference state detection methods to achieve accurate prediction of real-time collision detection and precise calculation of safe distances.

[0003] Currently, there are no academic achievements in the domestic and international literature specifically addressing the interference state detection of large and complex space station robotic arms. Existing results are mostly simple geometric and envelope analyses under simple environments. Chinese Patent (CN201711125091.1), "A Creo Dynamic and Static Interference Inspection Result Fast Feedback System and Method," introduces a geometric model interference inspection method based on Creo software. This method maintains high model accuracy but has a long computation time, cannot perform real-time dynamic detection, and is only applicable to known, simple working environments. Chinese Patent (CN201710775981.0), "A Robotic Arm Path Planning Method and Device Based on a Spatial Coordinate System," discloses a robotic arm path planning method based on a spatial coordinate system and time-sharing segmented planning. This method is highly flexible and can perform obstacle avoidance operations, but it can only handle fixed base conditions and has no planning capability for robotic arm crawling states, with poor planning safety and reliability.

[0004] Therefore, the current real-time detection of motion interference states of the space station robotic arm has the following problems:

[0005] (1) During the construction of the space station, the configuration of the main body changes greatly (from a single module to three modules or even more modules), the status of the external equipment is complex, and the movement of the robotic arm faces the problem of large changes in the detection environment.

[0006] (2) Space station operation has high safety requirements and extravehicular missions are complex. The movement of the robotic arm requires accurate safety distance information as a guarantee for movement safety and path planning feasibility.

[0007] (3) The space station robotic arm is a large robotic arm with a fast end-effector speed, and the real-time problem of interference state detection needs to be solved. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a real-time detection method for the motion interference state of a space station robotic arm, which solves the problem of dynamic and real-time interference state inspection of the space station robotic arm under complex spatial constraints, and provides reliable interference state and accurate safety distance information.

[0009] To overcome the shortcomings of existing technologies, the inventors have conducted intensive research and provided a real-time detection method for the motion interference state of a space station robotic arm. Using Pro / E and 3Dmax software, a layered processing method is employed to decompose a fine geometric model. Then, a fast layered recursive algorithm is used to process the robotic arm's self-check and scene interference detection to obtain the overall interference state and safe distance, thus completing this invention.

[0010] The technical solution provided by this invention is as follows:

[0011] A method for real-time detection of motion interference state of a space station robotic arm, comprising:

[0012] The task profile is determined by combining environmental constraints and task requirements, and the motion state of the robotic arm related to the task profile is established.

[0013] Based on the geometric models of the space station robotic arm and various environmental structures, the required robotic arm model and environmental structure model are divided into blocks, and the point, line, and surface data required for model calculation are output.

[0014] Based on point, line, and surface data, a model reconstruction method is used to reconstruct the computational model of the space station robotic arm and related environmental structures in an interferometric inspection simulation environment;

[0015] Set the traversal strategy for detecting the current state and interference state of the robotic arm and the space station;

[0016] Conduct self-inspection and detection of robotic arms and scene interference status detection;

[0017] Input the joint angle data of the robotic arm motion sequence at a set time interval into the calculation model, and repeatedly carry out the robotic arm self-check and scene interference state detection to obtain the interference dynamic detection data of the robotic arm motion state.

[0018] The method for real-time detection of motion interference state of a space station robotic arm provided by the present invention has the following beneficial effects:

[0019] Based on the hierarchical processing method, an accurate calculation model of the space station and robotic arm that is completely consistent with the actual geometric state can be obtained. The model is simple to build and easy to obtain, and can cope with the process of space station configuration changes. Using a fast hierarchical recursive algorithm, the interference state and safety distance can be accurately calculated based on the accurate model, which can guarantee the motion safety and path planning feasibility. The hierarchical recursive algorithm has a fast calculation speed and strong stability, and can provide real-time interference state detection for the robotic arm's on-orbit motion. Attached Figure Description

[0020] Figure 1 Flowchart of a method for real-time detection of motion interference state of a robotic arm on a space station;

[0021] Figure 2 A schematic diagram of a geometric model constructed using basic geometric shapes;

[0022] Figure 3 A schematic diagram of the constructed computational model. Detailed Implementation

[0023] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0024] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0025] This invention provides a method for real-time detection of motion interference state of a space station robotic arm, such as... Figure 1 As shown, it includes the following steps:

[0026] Step (1): Combine environmental constraints and mission requirements to determine the mission profile and establish the robotic arm motion state related to the mission profile, including the robotic arm joint angles, base position markings, and environmental structure attitudes or positions (such as solar array rotation angles, manned spacecraft and cargo spacecraft position markings, and astronaut markings) at each time point under the mission profile.

[0027] For example, in a mission supporting the astronaut's extravehicular activity (EVA) and lifting of the panoramic camera, the robotic arm needs to perform the astronaut transfer maneuver. In this mission state, the manned spacecraft is located at the forward docking port, the cargo spacecraft is located at the rear docking port, and the core module's solar panels are in a vertical zero-position state. Based on the current environmental constraints and mission requirements, the robotic arm base needs to be located at the HA adapter and, through typical posture movements such as foot limiter configuration, astronaut upper arm point configuration, equipment connection configuration, intermediate point configuration, and work point configuration, reach the work point position and complete the path planning of the robotic arm under the time sequence.

[0028] For example, in a cargo spacecraft transposition test, the robotic arm needs to perform the actions of pushing out and transpositioning the cargo spacecraft. In this mission state, the manned spacecraft is located at the radial docking port, the cargo spacecraft is located at the forward docking port, and the core module solar panels are in a horizontal zero-position state. According to the current environmental constraints and mission requirements, the robotic arm base needs to be located at the HB adapter, and meet the transposition test requirements through typical actions such as linear push-out, multi-joint motion, and circular transposition, and complete the path planning under the time sequence of the robotic arm.

[0029] Step (2) involves processing the layered representation of the precise geometric model.

[0030] Based on the precise geometric models of the space station's robotic arm and various environmental structures, such as the space station's modules and solar panels, the Pro / E models are exported as igs or step files and imported into the 3ds Max platform. The required robotic arm models and environmental structure models (such as solar panel models and models of various space station modules) are then processed into blocks and exported sequentially as obj format model files, which are then processed into the point, line, and surface data required for model calculation.

[0031] In this step, the geometric model is constructed using basic geometric shapes, including proto-cones, cylinders, spheres, etc. Arbitrary shapes are obtained through combinations of these basic geometric shapes. Specifically, for example... Figure 2 As shown, for the robotic arm model, the joints are represented by a combination of cylinders and spheres, the arm is represented by a combination of cylinders and spheres, the camera and gimbal are represented by a combination of cones and cylinders, and the end effector is represented by a combination of cylinders and spheres.

[0032] For the solar array model, the truss structure is represented by a combination of cylinders; the fan-shaped structure is represented by a combination of rectangular surfaces.

[0033] For the models of the various modules of the space station, the node modules are represented by spheres; the cylindrical sections are represented by cylinders; and the complex external equipment is represented by a combination of cones, cylinders and spheres.

[0034] Step (3): Construct an accurate calculation model.

[0035] Based on point, line, and surface data, a model reconstruction method was used to reconstruct an accurate computational model of the space station's robotic arm and related environmental structures, such as the various modules and solar panels, within an interferometric inspection simulation environment. The computational model still uses point, line, and surface data; therefore, the computational model is essentially identical to the actual geometric model. Figure 3 As shown.

[0036] In this step, a computational model of the relevant environmental structures that may interfere with the robotic arm along the robotic arm's motion path is established for the mission profile, without having to build a computational model of the entire space station.

[0037] Step (4): Set the traversal strategy for detecting the current state and interference state of the robotic arm and the space station.

[0038] Based on the updated information of the robotic arm joint angles, base position markings, and environmental structure attitude or position (such as solar array rotation angles, manned and cargo spacecraft position markings, astronaut markings, etc.), the current state of the robotic arm and space station is set.

[0039] The design traversal strategy is as follows: if the interference state detection (collision detection) only requires logical results, the traversal can stop when interference exists. This early termination strategy is not applicable to distance calculation. If the interference state detection requires outputting the distance or penetration depth between the robotic arm and the environmental structure, then based on the logical results, the distance calculation of points, lines, and surfaces is completed, and the location of the nearest distance or maximum depth is stored.

[0040] Step (5): Conduct self-inspection of the robotic arm.

[0041] Using a fast hierarchical recursive algorithm, the interference state and safe distance of each pair of links in the robotic arm are detected sequentially. Links are selected starting from the base, ignoring adjacent links. First, surface-to-surface distances are determined, then line-to-line distances, and finally point-to-point distances are checked, until the end link is selected. Based on the set traversal strategy, the corresponding interference state detection results are output.

[0042] 1) Determine the distance between the surfaces of each pair of links in the robotic arm. Calculate whether each pair of links in the robotic arm model is a cylinder, sphere, or cone structure, and determine the distance between the surfaces representing each pair of links:

[0043] a) The distance between the cylindrical surface and other surfaces can be simplified to the distance between the cylinder axis and other surfaces. This distance minus the cylinder radius is the required distance.

[0044] b) The distance between the sphere and other surfaces can be simplified to the distance between the center of the sphere and other surfaces. Subtracting the radius of the sphere from this distance gives the required distance.

[0045] c) The distance between the conical surface and other surfaces can be simplified to the distance between the axis of the cone and other surfaces. This distance minus the intercept of the direction vector of the surface on the cone is the required distance.

[0046] Based on the three calculation strategies above, the face-to-face distance is essentially simplified to the distance between the axis of the cylinder, the center of the sphere, and the axis of the cone (i.e., the line-to-line distance and the point-to-line distance), greatly simplifying the calculation. If there is a negative distance, it indicates that there is contact or collision; otherwise, there is no contact. By iterating through all face-to-face distances, the minimum value can be obtained.

[0047] 2) Determine the line distances between each pair of links of the robotic arm. For the line distances, assume A and B are arbitrary points on two straight lines, and L... AB Let n1 and n2 be the direction vectors of the two lines, respectively, and let n1 and n2 be the distance between the two lines. Then the distance between the two lines is |(n1×n2)·L AB If the distance is zero, it indicates a collision; otherwise, there is no contact. For the point-to-line distance, assuming the direction vector of the line is n, a point A on the line, and a point M outside the line, the point-to-line distance is |AM×n|. If the distance is zero, it indicates a collision; otherwise, there is no contact. By iterating through all line distances, the minimum value can be found.

[0048] 3) Determine the point-to-point distance of each pair of links of the robotic arm. By iterating through the coordinates of two points in space, the minimum point-to-point distance can be obtained.

[0049] Step (6): Conduct scene interference state detection.

[0050] Using a fast hierarchical recursive algorithm, the interference state and safe distance between the robotic arm and relevant environmental structures such as the space station module and solar panels are determined. The detection begins with the first link after the robotic arm base, first determining the surface-to-surface distance, then the line-to-line distance, and finally the point-to-point distance. This process sequentially determines the distance between each link and each relevant environmental structure, such as the space station module and solar panels. The distance calculation method is the same as in step (5), using layered calculations of surface-to-surface distance, line-to-line distance, and point-to-point distance.

[0051] In steps (5) and (6), for continuous collision calculation, it is necessary to store the object configuration and shape representation of the calculation model of the previous time node (frame); while for discrete collision calculation, only the object configuration and shape representation of the calculation model of the current time node (frame) are needed.

[0052] Step (7) inputs the joint angle data of the robotic arm motion sequence at a set time interval, such as 50ms or 1s, into the calculation model (the desired angle can be directly input into the calculation model while in orbit), and repeats the self-check detection of the robotic arm and the scene interference state detection to obtain the interference dynamic detection data of the robotic arm motion state.

[0053] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0054] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for real-time detection of motion interference state of a space station robotic arm, characterized in that, include: The task profile is determined by combining environmental constraints and task requirements, and the motion state of the robotic arm related to the task profile is established. Based on the geometric models of the space station robotic arm and various environmental structures, the required robotic arm model and environmental structure model are divided into blocks, and the point, line, and surface data required for model calculation are output. Based on point, line, and surface data, a model reconstruction method is used to reconstruct the computational model of the space station robotic arm and related environmental structures in an interferometric inspection simulation environment; Set the traversal strategy for detecting the current state and interference state of the robotic arm and the space station; Conduct self-inspection and detection of robotic arms and scene interference status detection; Input the joint angle data of the robotic arm motion sequence at a set time interval into the calculation model, and repeatedly carry out the robotic arm self-inspection and scene interference state detection to obtain the dynamic interference detection data of the robotic arm motion state. The steps for conducting self-inspection of the robotic arm include: sequentially detecting the interference state and safety distance of each pair of links of the robotic arm; selecting links starting from the base, without detecting adjacent links; first determining the surface distance, then the line distance, and finally completing the point-to-point determination until the end link is selected; and outputting the corresponding interference state detection results according to the set traversal strategy. The steps for conducting scene interference state detection include: determining the interference state and safe distance between the robotic arm and the environmental structure, starting the detection from the first link after the robotic arm base, first determining the surface distance, then the line distance, and finally completing the point-to-point judgment, and sequentially determining the distance between each link and each relevant environmental structure.

2. The method for real-time detection of motion interference state of a space station robotic arm according to claim 1, characterized in that, The step of establishing the motion state of the robotic arm related to the mission profile includes: establishing the joint angles of the robotic arm, the base position markings, and the attitude or position of the environmental structure at each time point under the mission profile, wherein the attitude or position of the environmental structure includes the solar array rotation angle, the position markings of the manned spacecraft and cargo spacecraft, and the astronaut markings.

3. The method for real-time detection of motion interference state of a space station robotic arm according to claim 1, characterized in that, The geometric model is constructed using basic geometric shapes, and arbitrary shapes are obtained by combining these basic geometric shapes.

4. The method for real-time detection of motion interference state of a space station robotic arm according to claim 1, characterized in that, In the step of reconstructing the computational model of the space station robotic arm and various modules and solar panels in the interference inspection simulation environment, a computational model of the relevant environmental structures that may interfere with the robotic arm on the movement path is established for the mission profile, without having to construct a computational model of the entire space station.

5. The method for real-time detection of motion interference state of a space station robotic arm according to claim 1, characterized in that, The steps for setting the current state of the robotic arm and the space station include: setting the current state of the robotic arm and the space station based on the updated information of the robotic arm joint angle, base position markings, and the attitude or position of the environmental structure.

6. The method for real-time detection of motion interference state of a space station robotic arm according to claim 1, characterized in that, The steps of setting the traversal strategy for interference state detection include: if interference state detection only requires logical results, the traversal can be stopped when interference exists; if interference state detection requires outputting the distance or penetration depth between the robotic arm and the environmental structure, then based on the logical results, the distance calculations for points, lines, and surfaces are completed, and the location where the nearest distance or maximum depth occurs is stored.

7. The method for real-time detection of motion interference state of a space station robotic arm according to claim 1, characterized in that, In the steps of performing self-inspection and scene interference state detection of the robotic arm, for continuous collision calculation, it is necessary to store the object configuration and shape representation of the calculation model at the previous time node; while for discrete collision calculation, only the object configuration and shape representation of the calculation model at the current time node are needed.

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