Research On Multi-function Tool And Docking Strategy Of Space Robotic Arm

In the past half a century, space exploration have been executed continually anda large number of spacecrafts in different functions have been sent into space. Wit hthe progress of space technology, now our major challenges have moved beyondsimply launching huge and complex spacecraft systems, but how to more fullyexploit the flight systems already launched, to ensure a more permanent and morestable operation in space orbit, so the On-Orbit Servicing technology come intobeing. Compared with the high risk and low economy of EVA, the space robotics getthe favor of many countries owing to the advantages of low cost and high reliability.And the development of various automatic operation tools for spacecraftcomponents have become one of the key technologies. By analyzing and researchingon the demand and results of similar projects in recent years, this paper develops aMulti-Function Tool (MFT) for co-operative as well as non-cooperative targets inspace.Firstly, the paper proposes the overall design scheme of MFT, which can expandthe rotation of robotic end-effector as well as connect different tool adapters. Thefunctional requirements and the implementation structure are discussed in fourdifferent sections: tool adapters module, axial servo module, rotation clutch moduleand electrical control module, of which the strength is checked to ensure the designreliability. Considering the temperature rise and magnetic force of MFT, theelectromagnetic coil is especially optimized on the Genetic Algorithm, while thebrake is simulated through Maxwell software.Secondly, the Screw Removal Adapter (SRT) is especially proposed andanalyzed, which is one of the five tool adapters. Considering the positioncompensation and size adaptability of SRT, propose an overall design schemefocusing on cross slipper and arch flat spring, in which the motion and efficiencycharacteristic of cross slipper, the structural parameter and dynamic responseperformance of arch flat spring, as well as the force and capture performance ofclamping jaws have been analyzed and designed. So the SRT with fast dynamicresponse and smooth motion character is obtained.Then, considering the requirements of dock&capture tolerance between theMFT and tool adapters, the paper establishes the reference coordinate fixed on thetwo docking ends and deduces the friction and geometry conditions for successfullydocking. The range of tolerance is obtained theoretically. Through the ADAMSsoftware and the6-DOF manipulator platform, the range of interface tolerance andthe correctness of the docking theory are verified in simulation and in experiment respectively.Finally, the compliance control strategy of the interface docking is proposed anddiscussed, both in overall mission planning level and specific implement level. Inthe specific implement level, the impedance control method is proposed, while thecompliance characteristic of desired impedance parameters is discussed in theory.The co-simulation results between ADAMS and Simulink verify the proposedmethod.