An adaptive locomotion controller for a hexapod robot: CPG, kinematics and force feedback

Abstract

Insects can perform versatile locomotion behaviors such as multiple gaits, adapting to different terrains, fast escaping, etc. However, most of the existing bio-inspired legged robots do not possess such walking ability, especially when they walk on irregular terrains. To tackle this challenge, a central pattern generator (CPG)-based locomotion control methodology is proposed, integrated with a contact force feedback function. In this approach, multiple gaits are produced by the CPG module. After passing through a post-processing circuit and a delay-line, the control signal is fed into six trajectory generators to generate predefined feet trajectories for the six legs. Then, force feedback is employed to adjust these trajectories so as to adapt the robot to rough terrains. Finally the regulated trajectories are sent to inverse kinematics modules such that the position control instructions are generated to control the actuators. In both simulations and real robot experiments, we consistently show that the robot can perform sophisticated walking patterns. What is more, the robot can use the force feedback mechanism to deal with the irregularity in rough terrain. With this mechanism, the stability and adaptability of the robot are enhanced. In conclusion, the CPG-base control is an effective approach for legged robots and the force feedback approach is able to improve walking ability of the robots, especially when they walk on irregular terrains.

A hybrid tactile sensor-based obstacle overcoming method for hexapod walking robots

“…For acquisition of data required for obstacle detection and environment recognition, different types of sensors could be used [64][65][66]. Ultrasonic and the infrared (IR) sensors can be used to overcome obstacles when a robot moves sideward-forward direction [67]. Although the most sophisticated sensory system to observe the robot surroundings are vision-based systems (stereo cameras, etc.)…”

Motion Simulation of Ionic Liquid Gel Soft Actuators Based on CPG Control

“…The application of a bioinspired control method based on the central pattern generator (CPG) of neural oscillators to generate rhythmic motion has attracted the attention of some researchers [ 10 – 12 ]. The rhythmic movement of animals is achieved by the interaction between the rhythm signal generated from the CPG and the dynamics of the musculoskeletal system [ 13 – 15 ].…”

Trajectory Correction and Locomotion Analysis of a Hexapod Walking Robot with Semi-Round Rigid Feet

“…Because multi-legged robots have a parallel closed chain structure in the standing state, the nonconformity of body trajectory error caused by the semi-round foot of each leg will eventually lead to sliding between the foot and the ground, and affect the stability of the robot. To address the problem above, Chen et al proposed a trajectory correction method [23], where the predefined trajectory of the robotic foot tip is modified according to the information from force feedback. In this way, the robot can adapt to the current terrain at any time and it can relieve the running deviation.…”