Hexapod Posture Control for Navigation Across Complex Environments

Abstract

Hexapod locomotion in unstructured environments relies on an efficient posture adjustment with the terrain topology. This paper presents a strategy to adapt the hexapod torso orientation through ground plane estimation. With an Inertial Measurement Unit (IMU) and the robot kinematic model, the current supporting feet coordinates are calculated, and the relative inclination between the ground and the torso angular position can be obtained. This information is used to adjust the novel foothold positions, in order to ensure the hexapod posture remains stable. The torso height is also controlled to avoid collisions with the ground asperities and decrease its deviation during motion. The proposed method is evaluated in a complex terrain made of 0.1×0.1 m blocks with variable height, causing different slopes across the field. Through result analysis, a significant behavior improvement is observed, due to the reduction of the torso posture oscillation and the increase of its locomotion efficiency.

Development and implementation of a new approach for posture control of a hexapod robot to walk in irregular terrains

“…Considering the models presented in refs. [37, 51], the torso’s center of mass is defined as the reference for all calculations. The kinematic model of one limb is depicted in Fig.…”

“…In the foothold planning scientific approach, the control posture is obtained by developing gait planning methods to adapt the foothold position according to the ground discontinuities [29][30][31][32][33]. The presented method can be implemented by using the data provided by a gyroscope or an Inertial Measurement Unit (IMU) as input of a kinematic-based control for the limbs' actuation [32,[34][35][36][37]. Instead of calculating the torso orientation, the robot's relative height can be obtained through the estimation of the plane formed by the supporting limbs [38,39].…”