Effects of knee locking and passive joint stiffness on energy consumption of a seven-link planar biped

Abstract

Abstract-Energetic efficiency and stability are the fundamental criteria which can improve the autonomy and task performance capabilities of humanoid robots. The scope of this paper is to investigate the energetic effects of knee locking and addition of torsional springs to different joints of a sevenlink fully actuated planar bipedal robot. The focus is on the reduction of energy consumption during walking. The energetic cost of walking is determined without joint stiffness and knee locking as a baseline for the comparison of results. In the first approach, the gait trajectory is optimized by adding springs to different joints and energetic cost of walk is then calculated at different walking speeds. The second approach presented in this paper is to mechanically lock the support knee and then optimize the gait and calculate the walking cost. The energetic cost of walking determined for the above two cases is then compared to the baseline cost. It is observed that addition of torsional springs at both hips reduce the walking cost up to 50%, support hip up to 85% with spring stiffness as an optimization variable for both cases while mechanically locking the support knee reduces the cost of walking up to 25% with gait and knee locking angle optimized.

Robust stabilization of a fully actuated 3D bipedal locomotion via nonlinear H<inf>∞</inf>-control under unilateral constraints

“…To illustrate the performance issues of the developed stable bipedal gait synthesis numerical simulations were performed for a laboratory prototype whose parameters were drawn from the Aldebaran's ROMEO documentation. The contact constraints (no-take off, no rotation, and no sliding during the single support phase) are verified on-line to confirm the validity of (17), (18). The well-known constraint (complementarity)-based approach [21], [22], [23] is utilized to simulate the biped contact with the ground.…”

“…After an impact, the right foot (previous stance foot) takes off the ground, so the vertical component of the velocity of the taking-off foot just after an impact must be directed upwards and the impulsive ground reaction in this foot equals zeros. Thus, the impact dynamic model can be represented in the form ( [18]):q…”

“…The unilateral constraint can be defined as F(q), which represents the height of swing foot, as a function of the generalized coordinates of the implicit-contact model (17). In the next section, a specific trajectory invoked to generate a cyclic motion of the undisturbed model (17)- (18), is designed so it can be used in our tracking problem as a reference trajectory.…”

Compliance analysis of human leg joints in level ground walking with an optimal control approach

“…These studies are mainly directed to find possible parameters to design active or passive mechanisms that are able to reproduce human-like gaits, such as prostheses, exoskeletons and walking robots [1], [2], [3].…”

Finite time tracking of a fully actuated biped robot with pre-specified settling time: A second order sliding mode synthesis

“…satisfying the conditions of contact using an offline optimization [19]. Each step is composed of a single support phase on the stance foot which ends with an impact of the foot of the swing leg on the ground, without rebound.…”