Roller skating with passive wheels on a quadrupedal robot is more efficient than traditional walking. However, the typical mammalian quadruped robot with 3-DoFs legs can only perform one dynamic roller skating gait and has difficulty achieving turning motion. To address this limitation, we designed a novel quadrupedal robot with each leg having 4-DoFs to enable various roller skating locomotion including Swizzling, Stroking, and trot-like gaits while easily achieving turning motions. We considered the geometrical characteristics of the passive wheel and used the Levenberg-Marquardt method in robot kinematics to improve precision for both roller skating kinematics and contact point position for the dynamics controller. The position of the robot foot and the yaw angle of the passive wheel are decoupled for motion planning of all proposed gaits. Our proposed kinematics with wheeled geometry was verified through experiments to have higher precision, while the feasibility of all proposed roller-skating gaits was confirmed during straight motion and turning motion with a small radius on our prototype robot. Finally, we discussed the mobility efficiency of different roller skating gaits which were found to be more efficient than walking.

The solar array wing deployment of orbiting satellites cannot be performed due to power failure of the connector caused by uncertain loads such as high temperature or vibration in the launching process of the spacecraft. There is currently a lack of suitable unlocking solutions for solar wing re-unfolding. This paper proposes a solution in which an extensible continuum robot (ECR) carrying the unlocking device enters the gap between the satellite and the solar wing, re-unlocking the solar wing. This solution effectively leverages the advantages of ECR collision buffering and adaptable maneuverability within confined space. In response to the proposed solution, the designed ECR with two segments helical spring structure features scalability, hollowness, lightweight, and a big length-diameter ratio. To perform the critical unlocking task, an end effector with the function of loosening and unplugging the aerospace connector for communication is designed based on the drive device away from itself to reduce the inertia of the manipulator. The information from the cameras and force sensors is used to estimate the extent of task execution. We establish an experimental setup to simulate the process of unlocking. The results validate that the ECR successfully accesses the gap (65mm) and accomplishes the unlocking task. The ECR has great application potential for on-orbit service.