Satellite capture simulation system and control method thereof

Abstract

The invention belongs to the field of aerospace and mechanical automation, and particularly relates to a satellite capture simulation system and a control method thereof. The system comprises a general control unit, a microgravity simulation module, a mechanical arm module and a tail end execution module. The master control unit is connected with the mechanical arm module, the microgravity simulation module and the tail end execution module, and the mechanical arm module is connected with the microgravity simulation module and the tail end execution module; the microgravity simulation module is used for providing a microgravity environment for capturing a target satellite; the device has the advantages that the microgravity environment of the space is simulated, the satellite is captured by the mechanical arm, a ground verification platform is established to test the satellite recycling effect, and the satellite capturing success rate of the space mechanical arm in the real space is increased.

Description

Technical Field

[0001] The present invention belongs to the fields of aerospace and mechanical automation, and particularly relates to a satellite capture simulation system and a control method thereof. Background Art

[0002] Currently, space mission simulations mainly rely on robotic arm technology and space environment simulation technology, but often lack an accurate simulation of the microgravity environment; existing simulation systems may not be able to fully simulate the dynamic conditions in space, especially the influence of microgravity on the movement of objects. Existing methods for controlling the attitude adjustment of aerospace robotic arms generally use deep learning combined with 3D cameras. This method has a high hardware cost and requires a large amount of data for training, which is not suitable for systems with high experimental costs.

[0003] For example, a Chinese patent with an application number of 201511027890.6, a filing date of December 30, 2015, and a patent title of "Device and Method for Simulating the Ground Three-Dimensional Space Microgravity of a Space Robotic Arm Capturing a Target Satellite". The technical solution of this invention is as follows: The device includes two industrial robotic arms; a space robotic arm, an eye camera, a capture sub-claw, and an interface, a service and target satellite body simulator, and a six-axis force / torque sensor. The method is achieved through steps such as simulating the movement of the target satellite; determining the position and attitude of the target satellite and the movement information of each joint of the space robotic arm; calculating the movement information of the base of the service satellite body simulator and the industrial robotic arm; the capture interface capturing the target satellite body simulator within the capture sub-claw area; and simulating the actual movement state of the target satellite to achieve the movement state of the service satellite body simulator. This patent can achieve the simulation of microgravity in the ground three-dimensional space, thereby verifying the operations of the space robotic arm capturing and repairing the target satellite in the real three-dimensional space, and testing relevant control algorithms and hardware.

[0004] However, the above patent lacks a good microgravity simulation device. Directly implementing microgravity simulation through a robotic arm will produce certain errors, thereby affecting the testing of subsequent relevant control algorithms and hardware. Summary of the Invention

[0005] The present invention provides a satellite capture simulation system and a control method thereof that can simulate the microgravity environment in space, use a robotic arm to capture a satellite, and improve the success rate of a space robotic arm capturing a satellite in real space.

[0006] To achieve the above technical effects, the technical solution of the present invention is as follows:

[0007] In a first aspect, a satellite capture simulation system is provided, including a master control unit, a microgravity simulation module, a robotic arm module, and an end effector module; the master control unit is connected to the robotic arm module, the microgravity simulation module, and the end effector module, and the robotic arm module is connected to the microgravity simulation module and the end effector module; the microgravity simulation module is used to provide a microgravity environment for capturing a target satellite.

[0008] Further, the master control unit includes a PLC control cabinet, a master control computer, and a switch installed thereon, and the master control computer, the PLC control cabinet, and the switch are connected to each other.

[0009] Further, the microgravity simulation module includes an air-bearing platform, a gravity compensation device, and a laser range finder; the laser range finder is disposed on the gravity compensation device, and the gravity compensation device is placed on the air-bearing platform; the robotic arm module includes a robotic arm body, an X-axis guide rail driver, and a robotic arm control cabinet; the robotic arm control cabinet is connected to the X-axis guide rail driver and the robotic arm body; the robotic arm body includes three sections of robotic arm structures, and each section of the robotic arm is connected by a joint; the joints include a first joint, a second joint, a third joint, and a fourth joint, and gravity compensation devices are installed at the bottoms of the second joint, the third joint, and the fourth joint; the end effector module includes a vision device and a pneumatic gripper, and the vision device is installed above the pneumatic gripper.

[0010] Further, the PLC control cabinet includes a PLC controller, an IO module, a wireless communication module, a power supply, and a solenoid valve; the PLC controller is connected to the wireless communication module, the power supply, the IO module, the master control computer, and the switch, and the IO module is connected to the solenoid valve.

[0011] Further, the gravity compensation device includes an air-bearing device, an adjustment screw, an air-bearing mounting seat, a pneumatic component, and an air source treatment component; the adjustment screw is installed on the air-bearing device, and a pneumatic component is installed on one side of the air-bearing device; the pneumatic component and the adjustment screw are both connected to the air-bearing mounting seat; the air-bearing mounting seat is connected to the air source treatment component for filtering gas through an air pipe.

[0012] Even further, the air source treatment component includes a primary filter for filtering particles, a secondary filter, and a tertiary filter for filtering water vapor; the primary filter, the secondary filter, and the tertiary filter are sequentially connected to each other through an air pipe, and the tertiary filter is connected to the air-bearing mounting seat through an air pipe.

[0013] Further, the switch is connected to the laser range finder and the end effector module.

[0014] In a second aspect, a control method for a satellite capture simulation system is provided, specifically including the following steps:

[0015] Step 1: After the master control unit receives the position of the target satellite, it sends a position command to the robotic arm control cabinet through the PLC control cabinet.

[0016] Step 2: After the robotic arm control cabinet receives the position command, it controls the robotic arm to move towards the target position. During the movement, a microgravity simulation module is used to simulate the microgravity environment in space.

[0017] Step 3: The end effector module of the robotic arm moves near the target satellite, and an autonomous posture adjustment of the end effector module is achieved by using a template matching method.

[0018] Step 4: The pneumatic gripper of the end effector module is controlled by a solenoid valve to open and close to capture the target satellite.

[0019] Further, the microgravity simulation module in Step 2 simulates the microgravity environment in space. By controlling the on / off and air pressure values of each air floating air path in the air floating platform of the microgravity simulation module, the floating height of the robotic arm joints is controlled for dynamic adjustment of the floating height of the robotic arm joints. The specific control steps are as follows:

[0020] Step a: The first joint of the robotic arm is fixed on the platform, and the second, third, and fourth joints of the robotic arm float on the air floating platform.

[0021] Step b: The five air floating device distribution points under each joint are respectively marked as A, B, C, D, and E, and a laser range finder of each air floating device is used to feedback the floating height of this point.

[0022] Step c: Consider setting the floating height of the i-th joint as h i , then the floating height of each air floating device in this joint can be respectively set as h iA , h iB , h iC , h iD , and h iE ;

[0023] Step d: The dynamic equation at each joint is: In the formula, h i is the floating height of the i-th joint, m i is the mass that each joint needs to overcome, g is the acceleration due to gravity, and F 浮 is the resultant force of the buoyancy of all air floating devices at this joint; Among them, A 浮 is the buoyancy area of each air floating device, and P i，j is the air pressure of the j-th air floating device on the i-th joint;

[0024] Step e: The PID algorithm is used to adjust the air pressure of a single air-floating device, thereby adjusting the floating height. The output of the PID controller can be expressed as:

[0025]

[0026] Among them, K P , K i , K d represent the proportional gain, integral gain, and derivative gain respectively. e i (t) is the error of the floating height, e i (t) = h 目标 - h i (t), h 目标 is the target floating height, h i (t) is the actual floating height, and t represents time;

[0027] Apply the output U i (t) of the PID controller to each air-floating device respectively. The specific formula is: U i (t) = P i，j (t), where P i，j (t) is the air pressure of the j-th air-floating device on the i-th joint at time t; By adjusting the PID parameters K p , K i , K d , the output of the controller is used to make the joint stably reach the desired floating height; K P , K i , K d represent the proportional gain, integral gain, and derivative gain respectively; e i (τ) is the floating height error of the i-th joint at time τ;

[0028] Step f: When the robotic arm joint runs to the platform splicing place, let the step difference height at the splicing place be h 阶差 . When h 目标 > h 阶差 , the system can still adjust the joint height through the above method to pass through the splicing place; When h 目标 < h 阶差 , the joint will get stuck at the splicing place. At this time, the running speed of the motor at this joint is zero, used to judge the serial number of this joint and send an abnormal feedback to the master control unit. At this time, the master control unit controls the air-floating pressure at this joint through the PLC control cabinet to increase the floating height of this joint.

[0029] Furthermore, for the autonomous posture adjustment of the end effector of the robotic arm in step three, the specific steps are as follows:

[0030] Step a1: Establish a template library, wherein the template library includes an image library and a posture adjustment program library, the image library is images of the target in different postures, and the posture adjustment program library is the robot arm posture adjustment program corresponding to different postures;

[0031] Step b1: The visual device at the end of the robotic arm collects the image of the current target satellite;

[0032] Step c1: Using a template matching method based on the NCC algorithm to search for a template image with the highest matching degree;

[0033] Step d1: The matching result searches for the corresponding posture adjustment program number in the database, and sends the program number to the robot arm controller, and the robot arm executes the posture adjustment program corresponding to the program number.

[0034] Furthermore, in step a1, the number of template images to be collected is determined, and the attitude of the target satellite rotating along the Z axis, assuming that the interval angle between adjacent attitudes is β, the number of template images to be collected is N=360 / β; collect template images, save all template images in the same folder, and number the template image set as {1, 2, 3, ..., N}; establish a posture adjustment program library, teach the robot arm for each attitude, and generate the corresponding teaching program, and the teaching program number is {P1, P2, P3, ..., P N}.

[0035] Furthermore, in step c1, the specific steps of template matching are as follows:

[0036] Step a2: Seamlessly stitch the images in the template library into a template master image, read all template images, create an empty stitched image, then stitch the images together, and finally output and save the stitched image, named S;

[0037] Step b2: The current image T is placed in the upper left corner of the template image S. The template image area directly below the current image T is S i , j, then T and S i , the similarity between j is:

[0038]

[0039] In the formula, S and T are two image regions, where S is the template image; T is the current image; (i, j) is the coordinate of the upper left corner of the overlapping area of ​​S and T; (m, n) is the position of the current image placed in the template image; (M, N) is the size of the current image T;

[0040] Step c2: According to step b2, calculate the similarity R(i, j) of each region template;

[0041] Step d2: Obtain the maximum value of R(i, j). The template image corresponding to this region is the template image corresponding to the current pose, and output the number n corresponding to the template image.

[0042] Further, for the output image number n, search for the corresponding pose adjustment program number P in the database n , and then send P n to the robotic arm controller and start the operation of the robotic arm. The robotic arm executes the pose adjustment trajectory corresponding to the program number to complete the pose adjustment task.

[0043] According to the above technical solution, the beneficial effects of the present invention are as follows:

[0044] 1. The present invention adopts a satellite capture system, which realizes the simulation of the microgravity environment in space through the master control unit, microgravity simulation module, robotic arm module and end effector module, and uses the robotic arm to capture the satellite, and establishes a ground verification platform to test the satellite recovery effect, improving the success rate of satellite capture by the space robotic arm in real space.

[0045] 2. The present invention adopts a control method for a satellite capture system, using the PID algorithm and the end effector autonomous pose adjustment method based on NCC template matching, obtaining a more accurate simulated microgravity environment, and improving the operation accuracy and efficiency of the robotic arm. Brief Description of the Drawings

[0046] Figure 1 It is a schematic diagram of the satellite capture simulation system of the present invention.

[0047] Figure 2 It is a schematic diagram of the system control method flow.

[0048] Figure 3 It is a schematic diagram of the principle of the air floating device.

[0049] Figure 4 It is a schematic diagram of the five-point distribution of the air floating device.

[0050] Figure 5 It is a flowchart of the end effector autonomous pose adjustment of the robotic arm.

[0051] Figure 6 It is a flowchart of template splicing during the end effector autonomous pose adjustment of the robotic arm.

[0052] Figure 7 It is a connection diagram of the components of the system.

[0053] Figure 8 It is a three-dimensional structure diagram of the air floating device.

[0054] Figure 9 It is a front view structure diagram of the air floating device.

[0055] Figure 10 It is a top - view structural schematic diagram of the air - floating device. Specific embodiments

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments.

[0057] Embodiment 1

[0058] As Figure 1 shown, a satellite capture simulation system includes a master control unit, a microgravity simulation module, a robotic arm module, and an end - effector module; the master control unit is connected to the robotic arm module, the microgravity simulation module, and the end - effector module, and the robotic arm module is connected to the microgravity simulation module and the end - effector module; the microgravity simulation module is used to provide a microgravity environment for capturing a target satellite.

[0059] The master control unit includes a master control PLC installed in the PLC control cabinet (also Figure 7 in), a master control computer, and a switch, and the master control computer, the PLC control cabinet, and the switch are connected to each other; the switch is connected to a laser range - finder sensor and the end - effector module; the master control computer uses the EVOC W15, and the PLC control cabinet uses the Beckhoff CX8090 model.

[0060] The microgravity simulation module includes an air - floating platform, a gravity compensation device, and a laser range - finder sensor; the air - floating platform has a length and width of 20m×20m and is composed of 4 marble platforms of 10m×10m spliced together; the gravity compensation device includes an air - floating device, an adjusting screw, an air - floating mounting seat, a pneumatic component, and an air source treatment component; as Figure 8 , Figure 9 and Figure 10 shown, an adjusting screw is installed on the air - floating device, and a pneumatic component is installed on one side of the air - floating device; the pneumatic component and the adjusting screw are both connected to the air - floating mounting seat; the air - floating mounting seat is connected to an air source treatment component for filtering gas through an air pipe; the air source treatment component includes a primary filter for filtering particles, a secondary filter, and a tertiary filter for filtering water vapor; the primary filter, the secondary filter, and the tertiary filter are connected to each other in sequence through air pipes, and the tertiary filter is connected to the air - floating mounting seat through an air pipe; as Figure 9 shown, the filtered gas enters from port A of the air - floating device and exits from port B, thereby forming the air pressure with the air - floating platform to achieve the floating action; as Figure 3The figure shows a schematic diagram of the principle of the air-floating device. The working air pressure refers to the air pressure input into the air-floating device through the air pipe, and the ambient air pressure refers to the air pressure of the external environment. A pressure difference is formed to achieve floating. The laser ranging sensor is set on the gravity compensation device, and the gravity compensation device is placed on the air-floating platform. The laser ranging sensor adopts the OSM40 model of Xuanke Electronics and can real-time feedback the floating height of the robotic arm joint. The robotic arm module includes a robotic arm body, an X-axis rail driver, and a robotic arm control cabinet. The robotic arm control cabinet is connected to the X-axis rail driver and the robotic arm body. The robotic arm body includes three sections of robotic arm structures, and each section of the robotic arm is connected by a joint. The joints include the first joint, the second joint, the third joint, and the fourth joint, and gravity compensation devices are installed at the bottoms of the second joint, the third joint, and the fourth joint. The robotic arm module can reach the specified position according to the coordinates input by the master control unit.

[0061] The end effector module includes a vision device and a pneumatic gripper, and the vision device is installed above the pneumatic gripper. The end effector module is responsible for the identification, positioning, and grasping of the target satellite. The target satellite adopts a customized simulated cube satellite, which is a prior art. The vision device adopts the ME2P-1230-9M of Daheng Technology. The pneumatic gripper adopts the form of a flexible gripper, and the grasping force is provided by the linear motion of the cylinder piston. A DSNU-10-20-P-A circular cylinder is used, and its pushing thrust can reach 47N, and the return pulling force can reach 40N.

[0062] The PLC control cabinet includes a PLC controller, an IO module, a wireless communication module, a power supply, and a solenoid valve. The PLC controller is connected to the wireless communication module, the power supply, the IO module, the master control computer, and the switch, and the IO module is connected to the solenoid valve. The IO module adopts the Beckhoff EL1008 model or the Beckhoff EL2008 model.

[0063] Embodiment 2

[0064] As Figure 2 shown, a control method for a satellite capture simulation system specifically includes the following steps:

[0065] Step 1: After the master control unit receives the position of the target satellite, it sends a position command to the robotic arm control cabinet through the PLC control cabinet;

[0066] Step 2: After the robotic arm control cabinet receives the position command, it controls the robotic arm to move towards the target position. During the movement, a microgravity simulation module is used to simulate the microgravity environment in space;

[0067] Step 3: The end effector module of the robotic arm moves near the target satellite, and an autonomous posture adjustment of the end effector module is realized by using a method based on template matching;

[0068] Step 4: Control the pneumatic gripper at the end effector module to open and close through a solenoid valve to capture the target satellite.

[0069] The above steps are configured and programmed by using Visual Studio 2015 for compilation and the TwinCat3 software dedicated to Inovance Beckhoff PLC.

[0070] The microgravity simulation module in Step 2 simulates the microgravity environment in space. By controlling the on / off and air pressure values of each air floating air path in the air floating platform of the microgravity simulation module, the floating height of the robotic arm joints is controlled for dynamic adjustment of the floating height of the robotic arm joints. The specific control steps are as follows:

[0071] Step a: The first joint of the robotic arm is fixed on the platform, and the second, third, and fourth joints of the robotic arm float on the air floating platform.

[0072] Step b: As Figure 4 shown, the 5 air floating device distribution points under each joint are respectively marked as A, B, C, D, and E, and the laser ranging sensor of each air floating device is used to feedback the floating height of this point.

[0073] Step c: Considering that the floating height of the i-th joint is set as h i , then the floating height of each air floating device in this joint can be respectively set as h iA , h iB , h iC , h iD and h iE ;

[0074] Step d: The dynamic equation at each joint is: In the formula, h i is the floating height of the i-th joint, m i is the mass that each joint needs to overcome, g is the acceleration due to gravity, and F 浮 is the resultant force of the buoyancy of all air floating devices at this joint; Among them, A 浮 is the buoyancy area of each air floating device, and P i，j is the air pressure of the j-th air floating device on the i-th joint;

[0075] Step e: The PID algorithm is used to adjust the air pressure of a single air floating device, thereby adjusting the floating height. The output of the PID controller can be expressed as:

[0076]

[0077] Among them, K P , K i , K d respectively represent the proportional gain, integral gain, and derivative gain, and ei (t) is the error of the floating height, e i (t) = h 目标 -h i (t), h 目标 is the target floating height, h i (t) is the actual floating height, and t represents time; The PID controller is a PLC that writes the PID control logic, specifically the master PLC in the master control unit part of this system.

[0078] Apply the output U i (t) of the PID controller to each air-floating device respectively, and its specific formula is: U i (t) = P i，j (t), where P i，j (t) is the air pressure of the jth air-floating device on the ith joint at time t; By adjusting the PID parameters K p , K i , K d , the output of the controller is used to make the joint stably reach the desired floating height; K P , K i , K d represent the proportional gain, integral gain and derivative gain respectively; e i (τ) is the floating height error of the ith joint at time τ;

[0079] Step f: When the robotic arm joint runs to the platform splicing place, let the step difference height at the splicing place be h 阶差 , when h 目标 > h 阶差 , the system can still adjust the joint height through the above method to pass through the splicing place; When h 目标 < h 阶差 , the joint will get stuck at the splicing place. At this time, the running speed of the motor at this joint is zero, so as to judge the serial number of this joint and send an abnormal feedback to the master control unit. At this time, the master control unit controls the air-floating pressure at this joint through the PLC control cabinet to increase the floating height of this joint.

[0080] The autonomous pose adjustment of the end effector of the robotic arm in step three is as follows:

[0081] Step a1: As Figure 5 shown, establish a template library, where the template library includes an image library and a pose adjustment program library. The image library is the images of the target object in different poses, and the pose adjustment program library is the robotic arm pose adjustment programs corresponding to different poses;

[0082] Step b1: The vision device at the end of the robotic arm collects the image of the current target satellite;

[0083] Step c1: Using a template matching method based on the NCC algorithm to search for a template image with the highest matching degree;

[0084] Step d1: The matching result searches for the corresponding posture adjustment program number in the database, and sends the program number to the robot arm controller, and the robot arm executes the posture adjustment program corresponding to the program number.

[0085] In step a1, determine the number of template images to be collected, the attitude of the target satellite rotating along the Z axis, assuming that the interval angle between adjacent attitudes is D, then the number of template images to be collected is N = 360 / D; wherein adjacent attitudes refer to the current attitude of the target object and its attitude when it rotates around the Z axis β, which are adjacent attitudes to each other; collect template images, save all template images in the same folder, and number the template image set as {1, 2, 3, ..., N}; establish a posture adjustment program library, perform robot arm teaching for each attitude, generate the corresponding teaching program, and the teaching program number is {P1, P2, P3, ..., P N}.

[0086] In step c1, the specific steps of template matching are as follows:

[0087] Step a2: Seamlessly stitch the images in the template library into a template master image, read all template images, create an empty stitched image, stitch the images again, and finally save the stitched image output, named S; the process of stitching images is shown as follows Figure 6 As shown;

[0088] Step b2: The current image T is placed in the upper left corner of the template image S. The template image area directly below the current image T is S i，j , then T and S i，j The similarity between them is:

[0089]

[0090] In the formula, S and T are two image regions, where S is the template image; T is the current image; (i, j) is the coordinate of the upper left corner of the overlapping area of ​​S and T; (m, n) is the position of the current image placed in the template image; (M, N) is the size of the current image T;

[0091] Step c2: According to step b2, calculate the similarity R(i, j) of each region template;

[0092] Step d2: Get the maximum value of R(i, j). The template image corresponding to this area is the template image corresponding to the current posture. Output the number n corresponding to the template image.

[0093] Output image number n, find the corresponding posture adjustment program number P in the database n , and then Pn Send it to the robotic arm controller and start the operation of the robotic arm. The robotic arm executes the posture adjustment trajectory corresponding to the program number to complete the posture adjustment task.

[0094] The above description is a detailed description of the preferred and feasible embodiments of the present application. However, the embodiments are not intended to limit the scope of the patent application of the present application. Any equivalent changes or modifications completed under the technical spirit disclosed in the present application shall fall within the scope of the patent covered by the present application.

Claims

1. A satellite capture simulation system, characterized in that: It includes a main control unit, a microgravity simulation module, a mechanical arm module and an end execution module; the main control unit is connected with the mechanical arm module, the microgravity simulation module and the end execution module, and the mechanical arm module is connected with the microgravity simulation module and the end execution module; the microgravity simulation module is used to provide a microgravity environment for capturing a target satellite.

2. The satellite capture simulation system according to claim 1, characterized in that: The master control unit includes a PLC control cabinet, a master control computer and a switch, and the master control computer, the PLC control cabinet and the switch are connected to each other.

3. The satellite capture simulation system according to claim 1, characterized in that: The microgravity simulation module includes an air floating platform, a gravity compensation device and a laser ranging sensor; the laser ranging sensor is arranged on the gravity compensation device, and the gravity compensation device is placed on the air floating platform; the robotic arm module includes a robotic arm body, an X-axis guide rail driver and a robotic arm control cabinet; the robotic arm control cabinet is connected to the X-axis guide rail driver and the robotic arm body; the robotic arm body includes a three-section robotic arm structure, and each section of the robotic arm is connected through a joint; the joint includes a first joint, a second joint, a third joint and a fourth joint, and a gravity compensation device is installed at the bottom of the second joint, the third joint and the fourth joint; the end execution module includes a visual device and a pneumatic gripper, and the visual device is installed above the pneumatic gripper.

4. The satellite capture simulation system according to claim 2, characterized in that: The PLC control cabinet includes a PLC controller, an I0 module, a wireless communication module, a power supply and a solenoid valve; the PLC controller is connected to the wireless communication module, the power supply, the I0 module, the master control computer and the switch, and the I0 module is connected to the solenoid valve.

5. The satellite capture simulation system according to claim 3, characterized in that: The gravity compensation device includes an air flotation device, an adjusting screw, an air flotation mounting seat, a pneumatic component and an air source processing assembly; the air flotation device is installed with an adjusting screw, and a pneumatic component is installed on one side of the air flotation device; the pneumatic component and the adjusting screw are both connected to the air flotation mounting seat; the air flotation mounting seat is connected to the air source processing assembly for filtering gas through an air pipe.

6. The satellite capture simulation system according to claim 5, characterized in that: The air source processing component includes a primary filter and a secondary filter for filtering particles, and a tertiary filter for filtering water vapor; the primary filter, the secondary filter and the tertiary filter are connected to each other in sequence through air pipes, and the tertiary filter is connected to the air floating mounting seat through the air pipe.

7. The satellite capture simulation system according to claim 2 or 3, characterized in that: The switch is connected to the laser ranging sensor and the end execution module.

8. A control method for a satellite capture simulation system, characterized in that: The specific steps include: Step 1: After receiving the position of the target satellite, the master control unit sends a position command to the robotic arm control cabinet through the PLC control cabinet; Step 2: After receiving the position command, the robot arm control cabinet controls the robot arm to move to the target position. During the movement, the microgravity simulation module is used to simulate the microgravity environment in space; Step 3: The end effector module of the robotic arm moves to the vicinity of the target satellite, and the template matching-based method is used to achieve autonomous attitude adjustment of the end effector module; Step 4: Capture the target satellite by controlling the opening and closing of the pneumatic gripper of the end-effector module through the solenoid valve.

9. The control method of the satellite capture simulation system according to claim 8, characterized in that: The microgravity simulation module in step 2 simulates the microgravity environment of space, and controls the floating height of the robot arm joint by controlling the on / off and air pressure value of each air flotation gas path in the air flotation platform of the microgravity simulation module, which is used to dynamically adjust the floating height of the robot arm joint. The specific control steps are: Step a: the first joint of the robot arm is fixed on the platform, and the second joint, the third joint and the fourth joint of the robot arm float on the air flotation platform; Step b: Mark the five air flotation device distribution points under each joint as A, B, C, D and E respectively, and the laser ranging sensor of each air flotation device is used to feedback the floating height of the point; Step c: Consider setting the floating height of the i-th joint to h i , then the floating height of each air flotation device in the joint can be set to h iA 、h iB 、h iC 、h iD and h iE ; Step d: The dynamic equation at each joint is: In the formula, h i is the floating height of the i-th joint, m i is the mass that each joint needs to overcome, g is the acceleration due to gravity, and F 浮 is the combined buoyancy of all air flotation devices at the joint; Among them A 浮 is the buoyancy area of ​​each air flotation device, P i，j is the air pressure of the jth air flotation device on the i-th joint; Step e: Use PID algorithm to adjust the air pressure of a single flotation device, thereby adjusting the flotation height. The output of the PID controller can be expressed as: Among them, K P , K i , K d Represents proportional gain, integral gain and differential gain respectively, e i (t) is the error of floating height, e i (t) = h 目标 -h i (t), h 目标 is the target floating height, h i (t) is the actual floating height, t represents the time; The output U of the PID controller i (t) is applied to each air flotation device respectively, and the specific formula is: U i (t) = P i，j (t), where P i，j (t) is the air pressure of the jth air flotation device on the i-th joint at time t; by adjusting the PID parameter K p , K i , K d , used for the output of the controller so that the joint can stably reach the desired floating height; K P , K i , K d Represents proportional gain, integral gain and differential gain respectively; e i (τ) is the floating height error of each i-th joint at time τ; Step f: When the robot arm joint moves to the platform joint, set the step height at the joint to h 阶差 , when h 目标 >h 阶差 When h 目标 <h 阶差 When the joint is stuck at the joint, the running speed of the motor at the joint is zero, which is used to determine the serial number of the joint and send abnormal feedback to the main control unit. At this time, the main control unit controls the air flotation pressure at the joint through the PLC control cabinet to increase the floating height of the joint.

10. The control method of the satellite capture simulation system according to claim 8, characterized in that: In step 3, the autonomous posture adjustment of the end effector of the robot arm is as follows: Step a1: Establish a template library, wherein the template library includes an image library and a posture adjustment program library, the image library is images of the target in different postures, and the posture adjustment program library is the robot arm posture adjustment program corresponding to different postures; Step b1: The visual device at the end of the robotic arm collects the image of the current target satellite; Step c1: Using a template matching method based on the NCC algorithm to search for a template image with the highest matching degree; Step d1: The matching result searches for the corresponding posture adjustment program number in the database, and sends the program number to the robot arm controller, and the robot arm executes the posture adjustment program corresponding to the program number.

11. The control method of the satellite capture simulation system according to claim 10, characterized in that: In step a1, determine the number of template images to be collected, the attitude of the target satellite rotating along the Z axis, and assume that the interval angle between adjacent attitudes is β, then the number of template images to be collected is N = 360 / β; collect template images, save all template images in the same folder, and number the template image set as {1, 2, 3, ..., N}; establish a posture adjustment program library, teach the robot arm for each attitude, and generate the corresponding teaching program, and the teaching program number is {P1, P2, P3, ..., P N }.

12. The control method of the satellite capture simulation system according to claim 10, characterized in that: In step c1, the specific steps of template matching are as follows: Step a2: Seamlessly stitch the images in the template library into a template master image, read all template images, create an empty stitched image, then stitch the images together, and finally output and save the stitched image, named S; Step b2: The current image T is placed in the upper left corner of the template image S. The template image area directly below the current image T is S i，j , then T and S i，j The similarity between them is: In the formula, S and T are two image regions, where S is the template image; T is the current image; (i, j) is the coordinate of the upper left corner of the overlapping area of ​​S and T; (m, n) is the position of the current image placed in the template image; (M, N) is the size of the current image T; Step c2: According to step b2, calculate the similarity R(i, j) of each region template; Step d2: Get the maximum value of R(i, j). The template image corresponding to this area is the template image corresponding to the current posture. Output the number n corresponding to the template image.

13. The control method of the satellite capture simulation system according to claim 12, characterized in that: Output image number n, find the corresponding posture adjustment program number P in the database n , and then P n It is sent to the robot controller and starts the robot. The robot executes the posture adjustment trajectory corresponding to the program number to complete the posture adjustment task.

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