Quasi Optimal Gait of a Biped Robot with a Rolling Knee Kinematic

Abstract

In this paper, we address the problem of optimization of trajectories for a new class of biped robot. The knees of this biped are similar as the anthropomorphic one and have a rolling contact between the femur and the tibia. The robot has seven mechanical links and six actuators. The walking gait considered is a succession of single support phase (SSP) and impact of the mobile foot with the ground. Cubic uniform spline functions defined on a time interval express the gait for one step. An energy consumption function and a torques quadratic function are used to compare the new robot with anthropomorphic knees to a conventional robot with revolute joint knees. The minimization of the criteria is made with simplex algorithm. The physical constraints concerning the ZMP and the mobile foot behavior are respectively checked to make a step. Simulation results show that the energy consumption of the new biped with rolling knee contact is less than that of the robot with revolute joint knees

Gait Optimization of a Rolling Knee Biped at Low Walking Speeds

“…The results clearly show the advantages of Bézier functions to express support trajectories at low speed. These results are better than those proposed with spline functions in (Hamon and Aoustin, 2010) and (Hobon et al, 2011) for higher speed range.…”

Influence of frictions on gait optimization of a biped robot with an anthropomorphic knee

“…• The selection of the best kinematic structures of the knee joint [1], [2], [3] • The improvement of gait support trajectories used by some control strategy [4], [5], [6] These two parts contribute to improve the robot energetic efficiency during the gait and also the range of travel of the robot without recharging its battery, named in brief biped autonomy.…”

“…The design of the knee mechanism in the LARP project in [7] is coming from the studies on prosthetic knees and consist of a structure with two cylindrical surfaces in contact. [3] proposes simulations with the same design for the knees. The structure is called rolling knee.…”

“…In the optimization problem, the discussion is about the criteria. In [3], we use the sthenic criterion to compare our robot to a conventional revolute joint robot and this criterion permits the actuator selection. In this work, an energy criterion is used to calculate the energy consumption of two bipeds during the gait.…”

“…The friction influence also more the biped autonomy as the kinematic structure of the knee joint. In [3], the authors have proposed optimal trajectories in regards of a sthenic criterion. These trajectories minimize also the Joule losses in the motor.…”