  This paper presents the design, analysis, and performance evaluation of
RicMonk, a novel three-link brachiation robot equipped with passive hook-shaped
grippers. Brachiation, an agile and energy-efficient mode of locomotion
observed in primates, has inspired the development of RicMonk to explore
versatile locomotion and maneuvers on ladder-like structures. The robot's
anatomical resemblance to gibbons and the integration of a tail mechanism for
energy injection contribute to its unique capabilities. The paper discusses the
use of the Direct Collocation methodology for optimizing trajectories for the
robot's dynamic behaviors and stabilization of these trajectories using a
Time-varying Linear Quadratic Regulator. With RicMonk we demonstrate
bidirectional brachiation, and provide comparative analysis with its
predecessor, AcroMonk - a two-link brachiation robot, to demonstrate that the
presence of a passive tail helps improve energy efficiency. The system design,
controllers, and software implementation are publicly available on GitHub and
the video demonstration of the experiments can be viewed YouTube.
