Robotic arms. Time exposure image of a researcher mimicking the movements of a pair of robotic arms. Instead of traditional electric motors, the arms 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.