Cable transmissions are commonly used in robotics for remote force transmission, offering a lightweight, compact, and efficient solution for transmitting high forces between input and output. However, cables in flexible compression housings (Bowden cables), exhibit high static friction, which increases exponentially with total bend angle. Alternatively, internally routed ball-bearing supported cable capstan transmissions are low friction, but complex and present challenges in routing multiple sets of cables. In this paper, we propose motion-decoupled cable transmission modules that address these challenges, occupying the middle ground, functioning as discrete-joint ball-bearing supported Bowden cables. Our rolling-plus-twist joint design decouples pairs of routed cables from changing significantly in tension, length, or friction during large angle motion of the linked transmission. Using sub-1 mm diameter high-strength synthetic cable, the transmission exhibits a maximum coupling motion of only 0.15 mm over the full range of motion of the cable-transmission mechanism, approximately 10% of pretension in combined hysteresis and friction, a transmission stiffness of 10 N/mm, weighing just 9 g per rolling joint and 5 g per twist joint. Two applications are demonstrated: cable routing alongside a robot arm for, say, gripper remote actuation, and remote needle advancement for an MRI-safe needle biopsy robot.

We present an efficient algorithm which computes, for a kinematic point mass moving in the plane, a time-optimal path that visits a sequence of target sets while conservatively avoiding collision with moving obstacles, also modelled as kinematic point masses, but whose trajectories are unknown. The problem is formulated as a pursuit-evasion differential game, and the underlying construction is based on optimal control. The algorithm, which is a variant of the fast marching method for shortest path problems, can handle general dynamical constraints on the players and arbitrary domain geometry (e.g. obstacles, non-polygonal boundaries). Applications to a two-stage game, capture-the-flag, is presented.