Minimalistic control of a compass gait robot in rough terrain

Abstract

Abstract-Although there has been an increasing interest in dynamic bipedal locomotion for significant improvement of energy efficiency and dexterity of mobile robots in the real world, their locomotion capabilities are still mostly restricted on flat surfaces. The difficulty of dynamic locomotion in rough terrain is mainly originated in the stability and controllability of gait patterns while exploiting the natural mechanical dynamics of the robots. For a systematic investigation of the challenging problem, this paper presents the simplest control architecture for the compass gait model which can be used for locomotion in rough terrain. Locomotion of the model is mainly achieved by an open-loop oscillator which induces self-stabilizing gait patterns, and we test the proposed control architecture in a real-world robotic platform. In addition, we also found that this controller is capable of varying stride length with a minimum change of control parameters, which enables locomotion in rough terrains. By using these basic principles of self-stability and gait variability, we extended the proposed controller with a simple sensory feedback about the location in the environment, which makes the robot possible to control gait patterns autonomously for traversing a rough terrain. We describe a set of experimental results and discuss how the proposed minimalistic control architecture can be enhanced for dynamic locomotion control in more complex environment.

Using efference copy and a forward internal model for adaptive biped walking

“…Ogino et al (2008) developed a walking controller that enables a robot to walk on rough terrain by changing the compliance of the joints without sensing the state of the surface of the ground. Iida and Tedrake (2009) presented a minimalistic control architecture with a minimum sensory feedback of a compass gait model for dynamic bipedal walking on the different inclinations of slope.…”

Stable dynamic walking over uneven terrain

“…In Yang et al (2009), stability of aperiodic walking motions was studied via the virtual-constraints and hybrid zero dynamics approach which achieves stability via high-gain feedback (Grizzle et al, 2001;Westervelt et al, 2003Westervelt et al, , 2007. The problem of footstep planning has been approached using computational optimal control (Byl and Tedrake, 2009) and experimental studies have shown that a minimalistic open-loop control can achieve stability for the compassgait walker (Iida and Tedrake, 2009). Recently, more complete planning and control systems have been developed for quadruped walkers -see e.g.…”

Reactive Planning and Control of Planar Spring–Mass Running on Rough Terrain

“…Initial intuitive controllers for complex terrain [15] were followed by more careful consideration of walking dynamics [38], leading to optimal control methods for rough terrain traversal [7], [27]. Recent results in this area recognize that trajectory stability on rough terrain is difficult to define [8] but exploit reduced dimension projections of walking dynamics to coordinate frames to which desired trajectories are transversal to achieve formally established stability properties [18], [31].…”

“…whose solution for θ, in conjunction with (27), yields the solution for k through the identity tan 2 θ + 1 = 1/ cos 2 θ as…”