Robotic mobility assistant exoskeleton with frame members, which are attached adjacent to biological joints, supplements relative movement between skeletal members. Mechanical joint defines a center of relative rotation of frame members about three mutually perpendicular axes with the center of relative rotation of frame members being displaced from the outer surfaces of skeletal members to correspond in position with the center of biological joint. Actuation devices including powered cable springs rotate frame members. Control system executes calibrated user specific posture sequences and activates power. Mechanical joint exhibits cylindrical guide surfaces defining a slidable or rotatable connection of frame members and has a radius intersecting the center of the biological joint. Node control network distributes computing load and reduces communications overhead. Map unit has object recognition system for monitoring environment. Standard posture data derived from rules of ambulation and posture provide positioning control, optimized by energy-timed margins for balance maintenance.
