AcroMonk: A Minimalist Underactuated Brachiating Robot

Abstract

Brachiation is a dynamic, coordinated swinging maneuver of body and arms used by monkeys and apes to move between branches. As a unique underactuated mode of locomotion, it is interesting to study from a robotics perspective since it can broaden the deployment scenarios for humanoids and animaloids. While several brachiating robots of varying complexity have been proposed in the past, this paper presents the simplest possible prototype of a brachiation robot, using only a single actuator and unactuated grippers. The novel passive gripper design allows it to snap on and release from monkey bars, while guaranteeing well defined start and end poses of the swing. The brachiation behavior is realized in three different ways, using trajectory optimization via direct collocation and stabilization by a model-based time-varying linear quadratic regulator (TVLQR) or model-free proportional derivative (PD) control, as well as by a reinforcement learning (RL) based control policy. The three control schemes are compared in terms of robustness to disturbances, mass uncertainty, and energy consumption. The system design and controllers have been open-sourced 1 . Due to its minimal and open design, the system can serve as a canonical underactuated platform for education and research.

Bibliometric analysis and visualization of research and development trends in humanoid robotics

“…Human-like motion gives the most direct solution. Mahdi Javadi uses a bionic approach, the humerus robot utilizes a unique underdriven motion pattern to broaden the deployment scenarios for humanoid and animal robots [70]. Zhehao Jin controls the motion through a mathematical approach, the Gaussian process movement primitive (GP-MP) is a novel non-parametric movement primitive that allows the movement to be completely data-driven [71].…”