PAW: a hybrid wheeled-leg robot

Abstract

This paper discusses current wheeled mobility work on a hybrid wheeled-leg robot called PAW. In addition to providing design details, controllers are proposed for inclined turning and sprawled braking which take advantage of the hybrid nature of the platform and improve stability. Power consumption values for a number of its basic behaviours are given, as is the range of the robot.

Zero-moment point based balance control of leg-wheel hybrid structures with inequality constraints of dynamic behavior

“…In the ZMP-FB-BC, the desired balancing motions are generated from the ZMP-feedback equation (9). In the ZMP-FF-BC, the equality constraint equation (10) is inserted into the DDM to form the ZMP-feedforward system model which is underactuated.…”

“…where x d is a desired trajectory which includes the ZMPfeedback equation (9), e x d − x is a tracking error, K D diag(2ζ i ω n,i ) and K P diag(ω 2 n,i ) are error gains, andB is a constant gain matrix determined from the Time-Delay Control (TDC) [18]. The reason we used the TDC is that it is simple but powerful for estimating the uncertainties.…”

“…Accordingly, various methods of implementing the stable quasi-static locomotion have been suggested, such as introducing compliances in the design of legs [2], optimizing contact forces [3], utilizing variable mechanisms [4], estimating wheel-terrain contact angles [5], decoupling a control procedure for the posture and trajectory [6], calculating balancing wheel torques [7], and adopting walking algorithm of legs [8], to name a few. However, for all its importance, only a few studies have been conducted for the second part of problems except for considering turning and breaking motions [9] and realizing bounding gates [10].…”

An evolved climbing SAWR: From simulation to realization with 3D printing

“…Hybrid mobile robot is more suitable in operating in unstructured terrain in comparing to traditional wheeled or legged robots. Various successful hybrid mobile robots platform had been developed; for example, Sojourner and Rocky 7 Rover by NASA [1] [2], bounding gait robot PAW by McGill University [3] [4], Shrimp by Swiss Federal Institute of Technology Lausanne [5], Wheeleg by University of Catania [6], and etc.…”

Mobile Platform with Leg-Wheel Mechanism for Practical Use

“…Work Partner (Halme et al 2003), Roller Walker (Endo and Hirose 2000), Zero Carrier (Yuan and Hirose 2004), Hylos (Grand et al 2004), and PAW (J.A. Smith et al 2006) are equipped with wheels placed at the ends of their legs; the Chariot series (Nakajima andNakano 2008a,b, 2009a-c, Fig. 1), RoboTrac (Six and Kecskem'ethy 1999), and a wheel chair robot (Morales et al2006) have separate wheels and legs; Whegs (Quinn et al 2003;Daltorio et al 2009) and Epi.q-1 (Quaglia et al2010) have four wheels composed of rotating legs or wheels; and Wheeleg (Lacagnina et al 2003) has two front legs and two rear wheels.…”