This paper presents a controller for a robotic manipulator for spacecraft docking operations oriented to on-orbit servicing. The proposed controller combines visual and force/torque feedback in order to complete the approach and contact phases of the docking. Visual servoing is used not only for guiding the end-effector during the approach phase, but also to maintain the end-effector probe correctly aligned during the contact phase. During the contact phase, an impedance controller generates the compliant behavior needed to minimize the peak forces that could result in a failed docking. The proposed controller has been tested experimentally in a hardware-in-the-loop robotic test-bench showing that in this ground-testing environment docking can be completed successfully for a set of initial conditions (relative speed of the spacecraft).

On-orbit satellite servicing is a technology that is expected to transform the space sector in the coming years. Space robotics is a promising approach to refuel, repair, update, and transport satellites on orbit. However, safe and reliable docking with the client satellite, needed as part of most servicing operations, is still considered a challenge. This paper presents an autonomous robot-based approach for this purpose. An impedance control strategy is added to the controller of a conventional robotic manipulator to allow compliant and safe manipulation of a spacecraft docking mechanism. This setup is expected to facilitate autonomous docking and manipulation operations with cooperative and non-cooperative on-orbit serviced satellites. Platform-art©, a dynamic test bench for hardware-in-the-loop validation of space GNC technologies is used to test the proposed approach.

Walking-robot technology has reached an advanced stage of development, as has already been demonstrated by a number of real applications. However, further improvement is still needed if walking robots are to compete with traditional vehicles. Some potential improvements could be gained through optimization. Thus, this paper presents a method for distributing the legs around the robot’s body such as to reduce the forces the legs must exert to support and propel the robot. The method finds through non-linear optimization techniques the middle leg displacement that nulls the difference between foot forces in a middle leg and a corner leg. A walking robot has been built to assess the theoretical results.

This paper presents a method for generating free gaits for quadruped robots capable of performing statically stable, omnidirectional locomotion on irregular terrain containing forbidden areas. The rule-based deliberative algorithm can generate flexible sequences of leg transferences while maintaining constant vehicle speed. The foothold planning method is compatible with the use of these flexible leg sequences, and is designed to maintain a minimum absolute stability margin despite the terrain height uncertainty. The integration of exteroceptive terrain profile data has been considered to improve adaptability. Experimental results are presented to show the gait's efficiency in adapting to an irregular terrain containing forbidden areas.