Hybrid modeling and analysis method for dynamic coupling of space robots

Resolving linear and angular momentum conservation equations in different ways, a hybrid method was proposed to model and analyze the dynamic coupling of a space robotic system. This method dealt with the coupling problems for the base's centroid position at the position level and attitude at the velocity level. Based on the base centroid virtual manipulator concept, the coupled space was addressed to represent the base's centroid position coupling. For different cases, the reachable coupled space, attitude-constrained coupled space, and free coupled space were defined. However, the coupling for the base's velocities was decomposed into joint-to-base rotation, joint-to-base translation, end-to-base rotation, and end-to-base translation coupling types. The dependence of the rotation and translation coupling was revealed, and the coupling factors were determined to measure the coupling degree. Then, the coupling effect for different loads, installation positions, and joint configurations was analyzed. Coupled maps were established to plan the trajectory for minimizing disturbance. Compared with previous works, dynamic coupling at the position level avoids the singularity problem for solving differential equations; at the velocity level, each type of coupling motion was separately modeled and analyzed for different requirements. The proposed method is useful for practical applications, such as designing a new manipulator or using an existing robotic system.