Bounding With Active Wheels and Liftoff Angle Velocity Adjustment James Andrew Smith † , Ioannis Poulakakis ‡ , Michael Trentini ⊳ , and Inna Sharf ⋄ May 12, 2009 † Dept. of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada(jasmith@ ee.ryerson.ca) ‡ Dept. of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, USA(poulakas@princeton.edu) ⊳ Defence R&D Canada – Suffield, Medicine Hat, Alberta, Canada (Mike.Trentini@drdc-rddc. gc.ca) ⋄ Centre for Intelligent Machines, McGill University, Montreal, Quebec, Canada (inna.sharf@ mcgill.ca) Abstract The bounding gait for the Platform for Ambulating Wheels (PAW), a new and unique hybrid wheeled-leg system is presented here. Two hypotheses are tested and discussed: first, that the robot’s forward speed can be increased by increasing the leg liftoff angles and, second, that addition of distally-mounted actuated wheels can be used in running gaits such as the bound. Both hypotheses were tested experimentally and found to be valid. Keywords: bounding gait, legged locomotion, wheeled locomotion, autonomous robot, wheeled- leg robot, quadruped, running, gallop 1 Introduction 1.1 Legged and Hybrid Wheeled-Leg Systems As an alternative to traditional wheeled and tracked ground vehicles, biologically-inspired legged systems are becoming increasingly common. This work examines a particular form of legged loco- motion, the bounding gait, which is common in the animal world, making it a reasonable locomotion mode to better understand the design and implementation of artificial quadrupeds. However, given that the dominant method for ground-based mobile robot locomotion is wheeled or tracked, fu- ture deployment of legged systems may be preceded by hybrid wheeled-leg technology. This is the primary motivation behind the development of the robot presented here. James Andrew Smith, Ioannis Poulakakis, Michael Trentini, and Inna Sharf. Bounding with active wheels and liftoff angle velocity adjustment. The International Journal of Robotics Research, 29(4):414 – 427, April 2010. Pre-print version. Final version is available from IJRR: http://ijr.sagepub.com/content/29/4/414