Neuromechanical control for hexapedal robot walking on challenging surfaces and surface classification

• We present an adaptive six-legged walking robot based on neuromechanical control.
• We apply a proximo-distal gradient to neuromechanical control of robot legs.
• We develop a muscle model enabling variable compliant leg motions.
• We show that such a controller allows the robot to achieve energy-efficient walking.
• We demonstrate that the controller makes the robot accurately classify the surfaces.

The neuromechanical control principles of animal locomotion provide good insights for the development of bio-inspired legged robots for walking on challenging surfaces. Based on such principles, we developed a neuromechanical controller consisting of a modular neural network (MNN) and of virtual agonist–antagonist muscle mechanisms (VAAMs). The controller allows for variable compliant leg motions of a hexapod robot, thereby leading to energy-efficient walking on different surfaces. Without any passive mechanisms or torque and position feedback at each joint, the variable compliant leg motions are achieved by only changing the stiffness parameters of the VAAMs. In addition, six surfaces can be also classified by observing the motor signals generated by the controller. The performance of the controller is tested on a physical hexapod robot. Experimental results show that it can effectively walk on six different surfaces with the specific resistances between 9.1 and 25.0, and also classify them with high accuracy.