Standing posture maintenance

Postural stability is a requirement for autonomous adaptive legged locomotion.

Neurobiological research leads to independent central systems for posture and locomotion, which interact when required.

In this work we propose a posture control system focused in the standing posture context. We integrate the proposed posture system with a CPG design based on coupled nonlinear oscillators.

The proposed system generates movements for posture correction which are modulated according to sensory information. We integrate of several different responses that individually contribute to the posture equilibrium. This coordination, competition and redundancy among the responses is a key element for adaptive, flexible and fault tolerant motor system.

Postural response Sensory information
Roll compensation Body roll angle
Pitch compensation Body pitch angle
Center of Mass adjustment Encoders and body angle
Load distribution Joints load
Touch control Foot touch
Leg disperser Joint encoders

 The control system is validated through a few experiments, where the robot is subjected to different posture situations ranging from roll and pitch variations to loss of feet support.

We will further extend and improve these results in order to integrate the locomotion propulsion.

People involved in this project: 
Related publications: 
Castro, L., C. P. Santos, M. Oliveira, and A. Ijspeert, "Postural Control on a Quadruped Robot Using Lateral Tilt: A Dynamical System Approach", European Robotics Symposium 2008, vol. 44: Springer Berlin / Heidelberg, pp. 205-214, 2008.  Download: castro_euros_2008.pdf (623.77 KB)
Sousa, J., V. Matos, and C. P. Santos, "A bio-inspired postural control for a quadruped robot: An attractor-based dynamics", Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on, pp. 5329 -5334, oct., 2010.  Download: A bio-inspired postural control for a quadruped robot: an attractor-based dynamics (229.91 KB)
Project status: 
Project in progress