I.I. Za’balawi,∗ L.C. Kiong,∗ W.E. Kiong,∗ and S.M.N.A. Senanayake∗∗
Global entrainment, biped robot, PD controller, central pattern generator, response surface methodology, van der pol oscillators, rhythmic movements
In recent years, many researchers have studied the generation of rhythmic movement emerge as a stable limit cycle from global entrainment between biological neural networks that include central pattern generators (CPGs) and physical systems (i.e. robot arm) interacting with external environment. However, the effect of global entrainment on biped locomotion energy has yet to be addressed. This paper delineates an approach to minimize biped’s locomotion energy by means of global entrainment. The rhythmic movements for biped locomotion such as walking and running are generated by CPG using coupled nonlinear oscillators of Van Der Pol (VDP). Tuning VDP oscillator parameters to meet certain criteria (i.e. minimum energy) is a difficult task to accomplish. This is due to the nonlinearity and the coupling of the oscillators. To overcome these difficulties, response surface methodology (RSM) has been proposed to characterize VDP parameters to achieve efficient energy for biped locomotion. Then, global entrainment has been implemented between five-link biped robot and the constructed CPG. As a result, the sensory information modulates VDP oscillators’ frequencies and tuned them to the resonance frequencies of the biped link lengths. The obtained results show an evidence of the importance of global entrainment in achieving lower energy for biped locomotion while maintaining the same or even higher forward velocity.
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