Towards dynamic trot gait locomotion: Design, control, and experiments with Cheetah-cub, a compliant quadruped robot. (July 2013)

• Record Type: Journal Article
• Authors: Spröwitz, Alexander; Tuleu, Alexandre; Vespignani, Massimo; Ajallooeian, Mostafa; Badri, Emilie; Ijspeert, Auke Jan
• Is Part Of: International journal of robotics research. Volume 32:Number 8(2013)
• Page Start: 932
• Page End: 950
• Publication Date: 2013-07
• Subjects: self-stabilizing quadruped locomotion -- three-segment -- pantograph -- robotic leg design -- passive compliance -- robust locomotion -- coupled oscillator -- drive function; Robots -- Periodicals; Robots, Industrial -- Periodicals; 629.89205
• DOI: 10.1177/0278364913489205
• Languages: English
• ISSNs: 0278-3649

Abstract

We present the design of a novel compliant quadruped robot, called Cheetah-cub, and a series of locomotion experiments with fast trotting gaits. The robot's leg configuration is based on a spring-loaded, pantograph mechanism with multiple segments. A dedicated open-loop locomotion controller was derived and implemented. Experiments were run in simulation and in hardware on flat terrain and with a step down, demonstrating the robot's self-stabilizing properties. The robot reached a running trot with short flight phases with a maximum Froude number of FR = 1.30, or 6.9 body lengths per second. Morphological parameters such as the leg design also played a role. By adding distal in-series elasticity, self-stability and maximum robot speed improved. Our robot has several advantages, especially when compared with larger and stiffer quadruped robot designs. (1) It is, to the best of the authors' knowledge, the fastest of all quadruped robots below 30kg (in terms of Froude number and body lengths per second). (2) It shows self-stabilizing behavior over a large range of speeds with open-loop control. (3) It is lightweight, compact, and electrically powered. (4) It is cheap, easy to reproduce, robust, and safe to handle. This makes it an excellent tool for research of multi-segment legs in quadruped robots.