Control and omni-directional locomotion of a crawling quadruped

Traversing unstructured environments, (statically stable) legged robots could be applied effectively but, they face two main problems: the high complexity of the system and the low speed of locomotion. To address the complexity of the controller, we apply a control layer that abstracts the legged robot to an omni-directional moving mass. In this control scheme, we apply the gait generator as proposed by Estremera and de Santos. We present theory to determine the theoretically maximum achievable velocity of a quadruped and compare the (omni-directional) maximum velocity of the selected gait generator with this optimum to validate its performance. For our use case the theoretically maximum achievable velocity is 1 ms − 1; in simulations we achieve a velocity for straight movement of maximum 0.75 ms − 1. Normal turns with a radius larger than 0.45 m are possible at a velocity of at least 0.1 ms − 1; the performance of crab turns is too unpredictable to be useful. The gait generator as proposed by Estremera and de Santos is partially capable of supporting omni-directional movement at satisfactory velocities.