Point-to-point planning: methodologies for underactuated space robots

In free-floating mode, space manipulator systems have their actuators turned off, and exhibit nonholonomic behavior due to angular momentum conservation. The system is underactuated and a challenging problem is to control both the location of the end effector and the attitude of the base, using manipulator actuators only. Physical limitations, imposed by system´s dynamic parameters, are examined. Lower and upper bounds for base rotation, due to manipulator motions, are estimated. An analytical path planning method is briefly presented and appended by a technique which extends drastically the accessibility of final configurations and simplifies the free parameters selection. Based on this extension, a numerical approach is also derived and examples are given. The presented methodologies avoid the need for many small cyclical motions, and use smooth functions in the planning scheme, leading to smooth configuration changes in finite and prescribed time