Robotic legs. Researcher mimicking the posture of a pair of robotic legs. Instead of traditional electric motors, the legs use pneumatic muscle actuator (PMA) technology. PMAs are soft tubes that can be contracted pneumatically to produce force. They have high power-to-weight ratios. They are also efficient and precisely controllable. The properties of PMAs are similar to those of natural muscles. This is part of a project to explore the potential of the technology by building a full humanoid robot. Photographed at the Department of Electronic and Electrical Engineering, University of Salford, UK.