Numerical Simulations of Level-Ground Walking Based on Passive Walk for Planar Biped Robots with Torso by Hip Actuators

Abstract

This study aims at a design technique of energy-efficient biped walking robots on level ground with simple mechanisms. To do this, we focus on the passive dynamic walkers which can walk stably down a shallow slope without actuators and controllers. On level ground, active walking should be studied because the mechanical energy is mainly lost through the swing-leg impacts with the ground. In this paper, numerical simulations show that planar biped robots with torso can walk efficiently on level ground over a wide range of speed by only using hip actuators. The hip actuators are used for a torso and swing-leg control based on passive-dynamic walking. The torso is used to generate active power replacing gravity used in the case of the passive walk. The swing-leg control is introduced to walk stably over a wide range of speed.

Efficient walking with optimization for a planar biped walker with a torso by hip actuators and springs

“…Physical intuitive control methods based on passive dynamics were implemented by Narukawa et al 9 to achieve stable walking on level ground with simple mechanisms. The torso is stabilized by PD control at a desired angle.…”

“…Fortunately, even when the torso is swung back and forth during a step where K T and ζ T are not sufficiently large to stabilize the torso at nearly constant, the biped walks stably over a wide speed range when the swing-leg control parameter is appropriately chosen. 9 When Eqs. (16) and (17) are satisfied, the frequency of the torso is roughly twice that of the swing leg following ref.…”

“…We have investigated that planar biped walkers with a torso on level ground can walk stably and efficiently at various speeds by using the torso and swingleg control with hip actuators. 8,9 Adding a torso to a biped walker needs extra effort because the torso must be stabilized during walking. There are reasons why a torso is added to a biped walker.…”

“…In this paper, a numerical approach is used to find the optimal control trajectories. A comparison between the cost functions of simple feedback control 9 and optimal control is presented. Furthermore, the effect of the springs at the hip joints to attain a greater energy-efficient locomotion is investigated.…”

Parametrically excited inverted double pendulum and efficient bipedal walking with an upper body

“…This approach does not require control inputs for stabilizing the upper body. Narukawa et al 12,13 proposed walking approaches for the bipedal walker with a torso. They verified the effect of PD control, optimal control with/without hip springs for the torso and achieved stable and efficient walking.…”