Posture control for legged robots has been widely developed on custom-designed robotic platforms, with little work being done on commercially-available robots despite their potential as low-cost research platforms. This paper presents the implementation of a Walking Posture Control system on a commercially-available hexapod robot which utilizes low-cost joint actuators without torque control capabilities. The hierarchical control system employs Virtual Model Control with simple foot force distribution and a novel, position-based Foot Force Controller that enables direct force control during the leg's stance phase and active compliance control during the swing phase. Ground truth measurements in experimental tests, obtained with a Vicon motion capture system, demonstrate the improvement to posture made by the control system on uneven terrain, with the results comparing favorably to those obtained in similar tests on more sophisticated, custom-designed platforms.

Posture control is one of the fundamental requirements for legged robots to achieve mobility on uneven terrain. Most of the research on posture control is conducted on custom designed robot platforms, which are much more expensive than their commercially available counterparts. This paper presents the implementation of a standing posture control system on a low-cost, commercially available hexapod robot platform. The Virtual Model Control (VMC) strategy is implemented, along with a simple method for foot force distribution and a direct force control method that can be used with position control of low-cost joint actuators. The controller was experimentally tested on level and uneven terrain, as well as on a dynamic balance board. Ground truth measurements of the tests revealed that the results compared favorably to those obtained on more expensive, custom designed platforms.