Interactions between feet and environment influence the stability and mobility of legged robot. This paper proposes a model to indirectly identify 3 degrees of freedom feet reaction forces for a quadruped robot with parallel-serial legs. The research platform is called Baby-Elephant: a heavy-duty four-legged robot designed for nuclear plant maintenance and disaster relief purposes. Each leg has three hydraulic actuators. With the pressure data from pump and hydraulic actuators, a double-chamber model with experimental derived friction is used to obtain the actuated force. The reaction forces model, including joint and foot forces, is simplified into an explicit function. Comparison between CAD simulation and analytical results shows the effectiveness of the model. A walking experiment with load cells proves the model is validate in practical application. The proposed model is used to identify the foot contact phase and the zero momentum point during crawling gait walking.
SeminiCTsagarakisNGGuglielminoE. Design of HyQ – a hydraulically and electrically actuated quadruped robot. Proc IMechE, Part I: J Systems and Control Engineering2011; 225: 831–849.
2.
SicilianoBKhatibO. Springer handbook of robotics, Berlin Heidelberg: Springer, 2008.
3.
Raibert M, Blankespoor K, Nelson G, et al. Bigdog, the rough-terrain quadruped robot. In: Proceedings of the 17th World Congress, International Federation of Automation Control, 2008, pp.10823–10825. Amsterdam, Netherlands: Elsevier.
4.
Li Y, Li B, Ruan J, et al. Research of mammal bionic quadruped robots: a review. In: 2011 IEEE conference on robotics, automation and mechatronics (RAM). Piscataway, USA: IEEE, 2011, pp.166–171.
5.
Grieco JC, Prieto M, Armada M, et al. A six-legged climbing robot for high payloads. In: Proceedings of the 1998 IEEE international conference on control applications. Trieste, Italy: IEEE, 1998, pp.446–450.
6.
FukuokaYKimuraHCohenAH. Adaptive dynamic walking of a quadruped robot on irregular terrain based on biological concepts. Int J Robot Res2003; 22: 187–202.
ErnstMOBanksMS. Humans integrate visual and haptic information in a statistically optimal fashion. Nature2002; 415: 429–433.
9.
GilletteRLAngleTC. Recent developments in canine locomotor analysis: a review. Vet J2008; 178: 165–176.
10.
ZumwaltACHamrickMSchmittD. Force plate for measuring the ground reaction forces in small animal locomotion. J Biomech2006; 39: 2877–2881.
11.
KirpensteijnJVan Den BosRVan Den BromW. Ground reaction force analysis of large breed dogs when walking after the amputation of a limb. Vet Rec2000; 146: 155–159.
12.
SwaimSFMarghituDBRumphPF. Effects of bandage configuration on paw pad pressure in dogs: a preliminary study. J Am Anim Hosp Assoc2003; 39: 209–216.
13.
Van der TolPMetzJNoordhuizen-StassenE. The vertical ground reaction force and the pressure distribution on the claws of dairy cows while walking on a flat substrate. J Dairy Sci2003; 86: 2875–2883.
14.
AoyagiSMatsudaTKongT-W. Proposal and development of arrayed sole sensor for legged robot and contact force detection using neural networks. Sens J IEEE2011; 11: 2048–2056.
15.
DaleyMAUsherwoodJRFelixG. Running over rough terrain: guinea fowl maintain dynamic stability despite a large unexpected change in substrate height. J Exp Biol2006; 209: 171–187.
16.
SpagnaJCGoldmanDILinP-C. Distributed mechanical feedback in arthropods and robots simplifies control of rapid running on challenging terrain. Bioinspiration Biomimetics2007; 2: 9–9.
17.
Hurst JW, Chestnutt JE and Rizzi AA. An actuator with physically variable stiffness for highly dynamic legged locomotion. In: Proceedings of ICR’04 2004 IEEE international conference on robotics and automation. New Orleans, LA: IEEE, 2004, pp.4662–4667.
18.
Playter R, Buehler M and Raibert M. BigDog. In: Defense and security symposium: international society for optics and photonics, 9 May 2006, p. 62302O-O-6. Orlando, FL: SPIE.
19.
Gienger M, Loffler K and Pfeiffer F. Towards the design of a biped jogging robot. In: Proceedings of 2001 ICRA IEEE international conference on robotics and automation. Seoul, Korea: IEEE, 2001, pp.4140–4145.
20.
KepplinVBernsKA. concept for walking behaviour in rough terrain. In: Climbing and walking robots and the support technologies for mobile machines (CLAWAR99), United Kingdom: Springer, 1999, pp. 509–516.
