Humanoid robot moving its arms. This robot is modelled on a gorilla. Instead of traditional electric motors, it uses 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 robot is part of a project to explore the potential of the technology to mimic biological structures. Photographed at the Department of Electronic and Electrical Engineering, University of Salford, UK. Time exposure image.