Point-to-point motion planning of a parallel 3-dof underactuated cable-suspended robot

Abstract

This paper presents a planar parallel threedegree-of-freedom underactuated cable-driven robot. The mechanism is first described and a dynamic model is derived. The proposed mechanism does not require any mechanical (e.g. pulleys) or electrical (e.g. actuators) hardware to be mounted on the end-effector. A trajectory planning approach is developed, which is based on the natural frequency of the pendulumlike free motion (unconstrained degree of freedom). Sine-like excitation functions are used and their frequency and phase delay are determined using simulation results. A prototype is then described and experimental results are provided together with a video clip of an example trajectory. The results confirm that the mechanism can be effectively used to perform pointto-point trajectories.

Fundamental dynamics based adaptive energy control for cooperative swinging of complex pendulum-like objects

“…Existing approaches for cooperative suspended load manipulation either focus on oscillation damping [8], [9] or use one centralized controller [10]. In [11] and [12] a robot helps a human with sustaining a rope turning motion.…”

Human-robot cooperative object swinging

“…Brachiating robots [7] and underactuated cable-suspended robots [8] are example applications for swing motion. A twolink robot is controlled to brachiate in a pendulum fashion like an ape by controlling it to a desired target dynamic in [7].…”

Adaptive simple pendulum swing-up controller based on the closed-loop fundamental dynamics

“…The initial value of the natural frequency estimate isω(t = 0) = 1 rad /s. The lossless simple pendulum is actuated with a constant amplitude factor a = 0.04 m. Despite the constant amplitude, the pendulum swing-up is slightly affected by the adaptation process, as the estimated natural frequency defines the cut-off frequency of the second-order low-pass filter (11). The constant actuation increases the system energy over time with the effect of a decreasing natural frequency ω (see Fig.…”

“…Application of swing motion in robotics is motivated by an increased workspace [11] as well as extended locomotion [2] and manipulation capabilities [3]. Ape-like brachiation is achieved in [2] by controlling a two-link robot to follow certain target dynamics.…”