Satellite Docking Parallel Manipulator with Telescopic Arm
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Solution Overview
Problem
Current satellite servicing and de-orbiting technologies face challenges with satellites that are tumbling or have positioning inaccuracies, leading to risks of collision and damage during docking, and existing methods are not effective for satellites with relative rate differences, which can result in force imbalances during capturing.
Innovation Solution
A servicer spacecraft equipped with a deployable 6-degree of freedom parallel manipulator and a telescopic arm with proximity sensors for precise grasping, along with adaptive compliance kinematics to manage force differences and stabilize the satellite, ensuring secure docking and de-orbiting even with significant positioning errors and tumbling motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional docking methods are used for tumbling satellites, then docking can be attempted, but collision risk and damage occur due to positioning inaccuracies and relative rate differences
Solution Approach 1:
The patent employs an adaptive compliance kinematic structure that dynamically adjusts the docking mechanism's stiffness and compliance levels. During approach, the system operates in a compliant mode to accommodate tumbling motion and positioning errors, then transitions to a rigid mode for secure docking. This dynamic adaptation eliminates collision risks by preventing forced contact while maintaining docking reliability.
Solution Approach 2:
The system changes key parameters including the compliance level, stiffness, and control mode during the docking process. By transitioning from a compliant, flexible state during approach to a rigid, stable state for docking, the system handles tumbling satellites safely while maintaining precise positioning and eliminating collision risks.
2Measurement precision
If the docking system uses rigid structures for precision, then positioning accuracy improves, but force imbalances during capturing can damage the docking structures
Solution Approach 1:
The adaptive compliance kinematic structure dynamically adjusts stiffness levels based on the docking phase. During approach and capturing, the system operates with reduced stiffness to accommodate force imbalances from tumbling motion. Only after relative rates are eliminated does the system transition to high stiffness for precision positioning, thus protecting structures from damage while achieving accuracy when needed.
Solution Approach 2:
The compliance mechanism acts as a pre-designed cushioning system that absorbs and attenuates force imbalances before they can damage the docking structure. By incorporating compliant elements and adaptive damping, the system preemptively protects rigid components from impact loads generated during capturing of tumbling satellites.
3Reliability
If the gripper applies high force for secure capturing, then capturing reliability improves, but force development on gripper level can damage structures if not attenuated
Solution Approach 1:
The system incorporates force sensing and feedback control that monitors gripper forces in real-time. When force imbalances are detected during capturing of tumbling satellites, the feedback mechanism automatically adjusts the gripping force to prevent excessive loads while maintaining secure capture. This ensures capturing reliability without subjecting structures to damaging force levels.
Solution Approach 2:
The adaptive compliance mechanism dynamically adjusts the force parameters during capturing. By modulating the stiffness and compliance levels based on detected forces and relative motion, the system achieves reliable capturing while preventing force development that could damage structures. The parameter adaptation ensures forces remain within safe limits throughout the capturing process.
Data Source
AI summary
A service satellite having a body, a controller and a docking unit including a telescopic arm, mounted on a 6-DOF parallel manipulator, and two additional gripping arms. The telescopic arm, deployed from the 6-DOF manipulator, is equipped with a pair of rapid closure digits. The telescopic arm facilitates capturing the launch adaptor ring of a client spacecraft, even during tumbling. The 6-DOF parallel manipulator has force sensors and can accommodate post capturing relative motion through active compliance control and controlled de-tumbling, for avoiding generation of high forces in the telescopic arm. After relative rate annihilation, the telescopic arm retracts and the client ring is secured to the 6-DOF manipulator with the help of a pair of clamps. After the ring is secured, two additional gripping arms secure a rigid connection with the launcher ring so that the docking connection comprises three equally spaced connections.