Flexible multi-degree-of-freedom docking mechanism based on force feedback

Abstract

The utility model provides a compliant multi-degree-of-freedom docking mechanism based on force feedback, which comprises a measured surface, a movable platform and a static platform, the movable platform is connected with the static platform through a plurality of high-precision hooke joints, and an electromagnetic locking device and a guide groove are arranged on the outer surface of the movable platform. An electromagnetic interface connected with the electromagnetic locking device in a matched mode and a positioning groove matched with the guide groove are formed in the measured face, the high-precision hooke joints are distributed around the circumference of the static platform at equal intervals, and a collision force collecting device is arranged between each high-precision hooke joint and the static platform; the guide groove on the outer surface of the movable platform is provided with a macro proximity switch, and the macro proximity switch detects the distance between the detected surface and the movable platform in real time. The flexible butt joint of the modules can be achieved, the mechanism posture can be changed according to requirements after the butt joint is completed, the configuration of the ultra-large combined spacecraft can be changed, and then different functions can be achieved in the space.

Description

Technical Field

[0001] The utility model relates to the technical field of aerospace module docking, in particular to a compliant multi-degree-of-freedom docking mechanism based on force feedback. Background Art

[0002] With the development of aerospace technology, the in-orbit splicing technology of micro-nano spacecraft has gradually become a research hotspot in the aerospace field. Since micro-nano spacecraft adopt a large number of high-tech technologies, they have the advantages of high functional density and technical performance, low investment and operation costs, strong flexibility, short development cycle, and low risk. Inspired by computer network technology, the concept of "space flight cluster" composed of multiple micro-nano spacecraft flying in formation has been widely accepted. Micro-nano spacecraft can usually be combined and spliced ​​into large spacecraft during the mission, and this process involves related technical issues of spacecraft docking.

[0003] Modular micro-nano satellite technology is different from traditional satellites. It splits satellites into multiple modules according to mission requirements and connects them together through interfaces to form a complete satellite. Micro-nano module satellites can be repaired by replacing faulty modules to prevent the waste of effective components and reduce mission costs. On the other hand, each individual satellite can also be used as a module and connected through a docking interface to form a large on-orbit mission executor, such as a large-aperture space telescope mirror, which greatly reduces the difficulty of the mission.

[0004] Large multi-assembly spacecraft refers to spacecraft that is assembled and spliced ​​on-orbit by small modular spacecraft. The autonomous docking of modular spacecraft clusters during the on-orbit assembly process is the main technical difficulty. Due to the small size of the small docking mechanism and the precision of the attitude adjustment mechanism, this docking mechanism cannot withstand the collision force generated when the celestial body collides and docks. The traditional passive buffer mechanism is flexible as a whole and cannot meet the requirements of high-precision movement of the docking mechanism. It is not suitable for small modular spacecraft. However, the docking process of small spacecraft has not been simplified due to the reduction of volume and mass. It still requires capture, buffering, locking, separation and other links. Therefore, the docking technology of small spacecraft is extremely complex. In addition, for large-scale assembly spacecraft with variable configuration requirements, if it is spliced ​​by modular spacecraft, the adjustment of the overall configuration is also related to the position and posture of the docking mechanism between each module. This requires that after the module is docked, the locking mechanism must maintain good rigidity and have a certain attitude adjustment capability. Utility Model Content

[0005] In order to solve the problems of the prior art, the utility model provides a flexible multi-degree-of-freedom docking mechanism based on force feedback, which is combined with a high-precision collision force acquisition system, a docking locking judgment device based on a macro proximity switch, and a flexible control method of a docking mechanism based on model prediction. In the scenario of splicing and transformation of a large multi-module assembly spacecraft, flexible docking between modules is achieved. The electromagnetic locking device provides a locking force of 300N, the high-sensitivity proximity switch has a detection distance of 0.8mm, and a response time of <0.5ms, which meets the docking requirements of small spacecraft. In addition, the high-precision force sensor combined with the flexible control method of the docking mechanism based on model prediction can also achieve adjustment of the relative posture between modules, with an accuracy of up to ±0.02mm and ±0.002°.

[0006] The utility model provides a compliant multi-degree-of-freedom docking mechanism based on force feedback, comprising a measured surface, a moving platform and a static platform, wherein the moving platform and the static platform are connected via a plurality of high-precision Hooke's hinges, an electromagnetic locking device and a guide groove are installed on the outer surface of the moving platform, an electromagnetic interface connected with the electromagnetic locking device and a positioning groove matched with the guide groove are installed on the measured surface, the high-precision Hooke's hinges are equidistantly distributed around the circumference of the static platform, a collision force collection device is arranged between each high-precision Hooke's hinge and the static platform; a macro proximity switch is arranged at the guide groove on the outer surface of the moving platform, the macro proximity switch detects the distance between the measured surface and the moving platform in real time, and when the moving plane approaches the measured surface, the macro proximity switch detects whether they are close and controls the electromagnetic locking device to work.

[0007] Further improvement, the static platform is a regular hexagonal structure, and high-precision Hooke's joints are distributed on the six corners of the regular hexagonal structure. The collision force acquisition device is a high-precision force sensor. The high-precision force sensor has a range of ±29.4N, a full-range accuracy of 0.0294N, and a frequency response of 0~1000Hz; the high-sensitivity macro proximity switch has a detection distance of 0~0.8mm, a response time of <0.5ms, and a switching frequency of 0~2000Hz. The high-precision force sensors together perform multi-dimensional force feedback monitoring on the docking mechanism, and the motor is controlled by the docking mechanism compliant control method based on model prediction to adjust the posture of the moving plane, so that it can dock with the measured surface more flexibly and reduce docking collision losses, so that the docking mechanism can cope with docking tasks with more special conditions and higher precision requirements.

[0008] As a further improvement, the electromagnetic locking mechanism comprises three sets of power-off type electromagnets, and a single magnetic suction device generates a suction force of 150N.

[0009] As a further improvement, the macro proximity switch is a highly sensitive metal sensor installed on the moving plane. When it detects the approach of the measured surface, it returns a signal value so that the main control system receives a docking signal.

[0010] As a further improvement, when the measured surface of the docking mechanism is separated from the moving plane, the internal relay will receive a signal from the control system, causing the internal magnet of the relay to be attracted, thereby acting on the electromagnetic locking device to separate the measured surface from the moving plane.

[0011] The beneficial effects of the utility model are:

[0012] 1. The collision force acquisition system uses a high-precision force sensor to monitor the force conditions of the docking process in real time, and converts the measured force into an acquisition signal. It adopts a docking mechanism compliance control method based on model prediction to achieve flexible docking between modules based on the acquisition signal.

[0013] 2. The docking lock determination device based on the micro proximity switch uses a high-sensitivity proximity switch located at the dynamic plane positioning pin to detect the distance of the measured surface at a higher frequency. When the two docking mechanisms are docked with each other, the macro proximity switch detects the approach of the measured surfaces and returns a docking completion signal. After receiving the signal, the main control system controls the electromagnetic locking device to work, and the active docking surface and the passive docking surface are attracted together to complete the docking.

[0014] 3. The measurement accuracy of the high-precision force sensor is 0.0294N. Six high-precision force sensors monitor the force on the docking mechanism at the same time, and use a compliant control method of the docking mechanism based on model prediction to control the motor to adjust the posture of the moving plane, so that it can dock with the measured surface more flexibly and reduce docking collision losses. This allows the docking mechanism to have a stronger ability to adapt to the docking environment while maintaining the accuracy of posture control. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some examples of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a schematic diagram of the structure of the utility model;

[0017] Figure 2 It is a schematic diagram of the moving platform of the utility model;

[0018] Figure 3 This is a schematic diagram of the installation of the high-precision force sensor in the utility model;

[0019] Figure 4 It is a schematic diagram of the hardware communication framework in the utility model;

[0020] Figure 5It is a schematic diagram of the control program framework of the docking mechanism in the utility model.

[0021] In the figure: dynamic platform 1, static platform 2, positioning pin 3, electromagnetic locking device 4, guide groove 5, DC motor 6, high-precision Hooke's hinge 7, macro proximity switch 8, high-precision force sensor 9, measured surface 10, positioning groove 11, electromagnetic interface 12. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] The utility model designs a compliant multi-degree-of-freedom docking mechanism based on force feedback, and its three-dimensional effect diagram is as follows Figure 1 As shown, the utility model realizes smooth docking between modules. The high-precision force sensor monitors the force in the docking process in real time and adjusts the dynamic plane posture, so that the docking mechanism has stronger adaptability to the docking environment while maintaining the posture control accuracy. In addition, the six-degree-of-freedom parallel platform can realize the adjustment of the relative posture between modules while realizing collision buffering.

[0024] The structure of a specific embodiment of the utility model includes:

[0025] 1. The compliant multi-degree-of-freedom docking mechanism based on force feedback has the following specific structure:

[0026] The improved docking mechanism is a variable configuration assembly spacecraft docking attitude adjustment mechanism based on the Stewart configuration. It adopts a symmetrical structure and is composed of a base, a docking surface, a servo motor, etc. The base is the supporting foundation of the entire mechanism and is made of aluminum alloy to ensure stability and safety. The mechanism includes a measured surface 10, a moving platform 1 and a static platform 2, wherein an infrared sensor is installed on the moving platform, and the moving platform and the static platform are connected by a number of DC electric push rod mechanisms, which include a DC motor 6, a high-precision Hooke hinge 7, and are connected to a number of high-precision force sensor units 9. The moving platform and the measured surface are docked through a docking lock judgment device based on a micro proximity switch. The moving platform and the static platform are connected by several DC electric push rod mechanisms, whose data lines are connected to the signal transmission chip embedded in the base of the static platform. The signal transmission chip transmits all the collected data to the main control board, and then uses the model-predicted flexible control method of the docking mechanism to analyze and process the collected data. The moving platform can be magnetically docked through several magnetic suction and positioning mechanisms; the magnetic suction and positioning mechanism includes a positioning groove 11, an electromagnetic locking device 4 and an electromagnetic interface 12 located on the measured surface, and a positioning pin 3, an electromagnetic locking device 4 and a guide groove 5 located on the moving platform. The two electromagnetic locking devices are connected in coordination, the positioning groove and the positioning pin are connected in coordination, and the electromagnetic interface 12 and the guide groove 5 are connected in coordination. The electromagnetic locking mechanism is three sets of power-off type electromagnets. A single magnetic suction device generates a suction force of 150N. When the mechanism is ready to separate and execute the separation program, the main control sends a signal to control the electromagnetic relay to energize, thereby controlling the electromagnetic locking device to work and lock and separate the moving plane from the measured surface. The high-precision force sensor 9 of the utility model monitors the force conditions during the docking process in real time, so as to better monitor the force conditions during the docking process and adjust the position of the moving platform for better docking.

[0027] 2. The collision force collection system for receiving force monitoring includes a high-precision force sensor 9, etc. The dynamic platform and the static platform are connected by a number of DC electric push rod mechanisms. The high-precision force sensor is installed at the motor base between the dynamic platform and the static platform. Its data line is connected to the signal transmission chip embedded in the base of the static platform. The signal transmission chip transmits all the collected data to the main control board, and then uses the compliant control algorithm to analyze and process the collected data. The differential signal data received by the high-precision force sensor is transmitted to the computer via the SPI protocol. The collected data is put into the compliant control method of the docking mechanism based on model prediction to derive the dynamic platform posture adjustment plan, and then adjust the dynamic plane posture to dock with the measured surface more accurately. The high-precision force sensor realizes real-time collection of the force conditions of the docking surface, and then controls the motor by the compliant control method of the docking mechanism based on model prediction, so that the docking mechanism has a stronger ability to adapt to the docking environment while maintaining the accuracy of posture control. The high-precision force sensor has a measuring range of ±29.4N, a full-range accuracy of 0.0294N, and a frequency response of 1000Hz, which can meet the accuracy requirements of the docking process in this docking scenario.

[0028] 3. The docking lock determination device based on the macro proximity switch is as follows: Figure 1 As shown, the device includes a macro proximity switch 8, an electromagnetic locking device 4, etc. During the docking process, when the moving plane approaches the measured surface, the macro proximity switch detects whether they are close. When the macro proximity switch detects that the measured surface is close, the macro proximity switch will send a signal to allow the control system to receive information that the docking is successful. When the measured surface of the docking mechanism is separated from the moving plane, the control system sends a signal to act on the internal relay, and the magnet inside the relay is attracted, and then acts on the electromagnetic locking device to separate the measured surface from the moving plane. In order to achieve precise control of the docking process of the docking spacecraft, the detection distance of the macro proximity switch used is 0.8mm, the response time is less than 0.5ms, the switching frequency is 2000Hz, and the electromagnetic locking device is three sets of power-off electromagnets. A single magnetic suction device generates a suction force of 150N, which can meet the docking process accuracy requirements in this docking scenario.

[0029] 4. The hardware underlying communication framework and docking mechanism control program framework are as follows Figure 4 and Figure 5As shown in the figure, the overall idea of ​​the hardware bottom-layer communication framework is: a communication structure is formed by combining three STM32 development boards with integrated ADS1256, including one main board, two sub-boards and one signal adapter & power board. Among them, the role of the sub-board is to collect the differential signals of the three force sensors (SPI2) respectively, and then transmit the collected data to the main board through SPI communication (SPI1). The role of the main board is: (1) receive the signals from the two sub-boards through SPI communication (SPI1); (2) collect the single-ended signals of the six laser sensors (SPI2); (3) drive the servo motor to extend and retract through the serial port to control the length of each rod of the docking mechanism for docking control; (4) detect the signal from the contact through the GPIO port (indicating that the two docking mechanisms are close enough), control the magnetism of the three magnet blocks by controlling the relay, and finally complete the docking; (5) send the data information of the docking process (such as high-precision force sensor data, macro laser sensor data, micro servo motor rod length, etc.) to the computer host through the serial port. The overall design idea of ​​the docking mechanism control program is as follows: first, each module is self-checked to check whether there is a problem. If so, an error code is returned. If there is no problem, the system will wait to receive instructions. Secondly, the instructions are divided into five types, namely, modifying device parameters, docking mode, attitude adjustment mode, status reading, and separation. The docking mechanism performs different operations in different modes. If a separation instruction is received, it indicates that the docking is completed.

[0030] The utility model designs a compliant multi-degree-of-freedom docking mechanism based on force feedback. The collision force acquisition system of the mechanism can realize the real-time acquisition of the force conditions of the docking surface, and then control the motor by means of the compliant control method of the docking mechanism based on model prediction, so that the docking mechanism has a stronger ability to adapt to the docking environment while maintaining the accuracy of posture control. The docking locking judgment device based on the macro proximity switch is composed of a macro proximity switch and an electromagnetic locking device. The macro proximity switch detects whether it is close. When the macro proximity switch detects that the measured surface is close, the macro proximity switch will send a signal to enable the control system to receive the information of successful docking. When the measured surface of the docking mechanism is separated from the moving plane, the control system sends a signal to act on the internal relay, and the magnet inside the relay is attracted, and then acts on the electromagnetic locking device to separate the measured surface from the moving plane, so that the precise control of the docking process of the docking spacecraft can be realized. At the same time, through the compliant control method of the docking mechanism based on model prediction, the control of the improved compliant multi-degree-of-freedom docking mechanism based on force feedback is designed. The real-time force of the mechanism is collected by a high-precision force sensor, and the extension and contraction amount that the servo motor should make is obtained through the compliant control method of the docking mechanism based on model prediction, thereby realizing the buffering process of docking.

[0031] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, the above is only a preferred implementation of the utility model. Since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited to this. Any technician familiar with the technical field is within the technical scope disclosed by the utility model. For ordinary technicians in the technical field, changes or replacements that can be easily thought of should be included in the protection scope of the utility model without departing from the principle of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A compliant multi-degree-of-freedom docking mechanism based on force feedback, comprising a measured surface, a moving platform and a static platform, wherein the moving platform and the static platform are connected by a plurality of high-precision Hooke's hinges, an electromagnetic locking device and a guide groove are installed on the outer surface of the moving platform, and an electromagnetic interface connected with the electromagnetic locking device and a positioning groove matched with the guide groove are installed on the measured surface, characterized in that: The high-precision Hooke's joints are evenly distributed around the circumference of the static platform, and a collision force collection device is arranged between each high-precision Hooke's joint and the static platform; a macro proximity switch is arranged at the guide groove on the outer surface of the dynamic platform, and the macro proximity switch detects the distance between the measured surface and the dynamic platform in real time.

2. The compliant multi-degree-of-freedom docking mechanism based on force feedback according to claim 1, characterized in that: The collision force acquisition device is a high-precision force sensor.

3. The compliant multi-degree-of-freedom docking mechanism based on force feedback according to claim 1 or 2, characterized in that: The static platform is a regular hexagonal structure, and high-precision Hooke's joints are distributed on the six corners of the regular hexagonal structure.

4. The compliant multi-degree-of-freedom docking mechanism based on force feedback according to claim 2, characterized in that: The high-precision force sensor has a measuring range of ±29.4N, a full-range accuracy of 0.0294N, and a frequency response of 0~1000Hz; the high-sensitivity macro proximity switch has a detection distance of 0~0.8mm, a response time of <0.5ms, and a switching frequency of 0~2000Hz.

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