Moving onto High Steps for a Fourlimbed Robot with Torso Contact* In this paper, we describe approaches to enable a fourlimbed robot to get over a step higher than its leg with torso contact. The higher the step becomes, the more difficult it is for legged robots to get over from the viewpoint of stability and kinematic reachability. Torso landing contributes to improving stability and robustness of motion for moving onto high step because of lower center of mass (CoM) and larger support polygon, which is seldomly utilized by previous humansized legged robots. The approaches in this paper consist of the following two components. As for hardware, spikes are arranged on the bottom of robotxe2x80x99 s body for stable torso landing on a high step. As for motion generation, Sequential Quadratic Programming (SQP) is utilized to generate motion with torso landing to guarantee stability of robots during getting over the high step. From experiments, it is confirmed that the fourlimbed robot WARECI succeeded in moving onto a step with the height of 865mm.

WholeBody Motion and Landing Force Control for Quadrupedal Stair Climbing In this paper, we present a novel framework for quadrupedal stair climbing, which considers force interaction with stairs. For stable and robust climbing, a key issue is to avoid falling down on the stairs. From this point of view, control to minimize rate of change of angular momentum about Center of Mass (CoM) which is produced by ground reaction force (GRF) at contact of robotxe2x80x98s foot is necessary. Using this approach, direct forcebased Zero Moment Point (ZMP) for motion planning of the CoM and landing force control are implemented. The direct forcebased ZMP method allows the robot to lift its foot with reduced possibility of tilting on the stairs, and the landing force control prevents instant increase of the moment by impact of the GRFs. In addition, terrain recognition to estimate parameters of the stairs and find proper footholds by vision system mounted on the robot is presented. Proposed framework is implemented to quadruped robot, AiDINVI, that has torque sensor at each joint, through experiments, capability of ascending several stairs including 3step stairs which have 21cm height (31% of its maximum leg length) and 26.5xc2xb0 inclination is validated.