Quadruped Robot Locomotion Research Articles

An experimental study for 3D dynamic control of quadruped locomotion robot with point-support feet.

Dynamic walking is often required in a quadruped robot for the purpose of quick locomotion. It is generally known that the walking pattern of animals is changed to the trot or the pace in middle speed locomotion. Trot walking was recently studied by several groups because of its stability. In the trot, diagonal legs form pairs. While one pair of legs provides support, the other pair of legs swings forward in preparation for the next step. In the trot of the quadruped robot with point-support feet, a rotation around a diagonal line formed by the supporting leg can't be controlled directly by using torques at the articular joints. In this paper, the 3D behavior in trot walking is analyzed from the viewpoint of foot force, duty factor and the roll angle of the body. The effects of the stance and the center of gravity of the body are also examined experimentally using our quadruped robot 'COLT-2.'

Dynamic control for a quadruped locomotion robot in consideration of the leg-support-exchange phenomenon.

This paper proposes a new control method for quadruped walking robots in which the leg-support-exchange is lithely implemented. First, the authors formulate the leg-support-exchange phenomenon in 'Trot' using Lagrange's collision equation. Then the continuous walking can be numerically analyzed. Secondly, we propose a new control algorithm for leg-support-exchange. The conventional high gain local feedback causes many problems such as slip and excessive high torque in the leg-support-exchange phase of dynamic walking since it is impossible in this phase to prepare the proper reference values beforehand. In this algorithm, the control law is changed to 'free mode' or 'constant current mode' in order to adjust to the exvironment. The effectiveness of the proposed control strategy is confirmed by computer simulation and experiments using the walking robot 'COLT-1'.