DLR-robot arm proof of stiffness. An important result of SENSOPAC was the transfer of the neuroscience and haptic results to robotic systems. To this end, a novel, variable-impedance robotic hand-arm-hand system was developed for integration within the project. This DLR Hand-Arm System is a robotic system mimicking the kinematic, dynamic and force properties of the human arm using modern mechatronic technologies. It is based on a variable stiffness drive concept with joint structures as close to the biological counterpart as possible.