The Winch-Bot: A cable-suspended, under-actuated robot utilizing parametric self-excitation

Abstract

A simple, compact, yet powerful robotic winch, called "Winch-Bot," is presented in this thesis. The Winch-Bot is an underactuated robot having only one controllable axis. Although hanging a load with merely one cable, it is capable of moving it in a large workspace by swinging the load dynamically based on parametric self-excitation. The generated trajectories can be used for a variety of tasks, from moving material to cyclic inspection of surfaces. The basic principle and design concept of the Winch-Bot are first described, followed by dynamic modeling and analysis. Two trajectory generation problems are solved. One is point-to-point transfer of a load, and the other is the tracking of a continuous path. It will be shown that the system can track a given geometric trajectory, although the tracking velocity cannot be determined arbitrarily due to the underactuated nature of dynamics. A prototype Winch-Bot is designed and built, and point-to-point, continuous path, and parametric excitation control are implemented.

Dynamic trajectory planning of a two-DOF cable-suspended parallel robot

“…In [7], [8] and [9], dynamically controlled (pendulum-like) cablesuspended robots were proposed. By dynamically controlling the robots, their workspace can be extended beyond the static workspace and the notion of dynamic workspace [10] arises.…”

Development of the Acroboter Service Robot Platform

“…A tethered aerial robot presented in (McKerrow and Ratner 2007), of which the working unit is suspended on a single cable and equipped with two ducted fan actuators. A similar but simplified concept is the Winch-Bot that is presented in (Cunningham and Asada 2009). Here the cable winch is the only actuator on the robot, which can perform pick-and-place tasks.…”

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

“…In [1] and [2], results obtained by [6], [7] and [8] on the dynamic analysis of swings were used to produce point to point motions. In [9], control algorithms were studied while [10] and [5] mainly analyzed trajectories. Finally, [6], [11], [12] and [13] show the need to use periodic excitations based on the natural frequency of the mechanism.…”

“…A two-degree-of-freedom (2-dof) cable-driven pendulumlike robot referred to as Winch-Bot was presented in [5]. However, the control algorithm of Winch-Bot is based on an off-line trajectory planning, which requires specific initial conditions.…”