The development of a man-machine interface for space manipulator displacement tasks

A space manipulator is a lightweight robotic arm mounted on a space station or a spacecraft. If the manipulator is manually controlled from a remote location (teleoperation), the human operator can only see its movements in the pictures from the cameras mounted on the manipulator and the pictures from the cameras installed in the neighbourhood of the manipulator. Typical tasks of space manipulators are transportation tasks and inspection tasks. During the execution of these displacement tasks, the human operator has to be alert not to cause a collision between the manipulator limbs and objects in the environment. This is not an easy job, because the distances between the manipulator and the objects can hardly be estimated from the available camera pictures.
Recently, at our laboratory, a conceptual man-machine interface has been developed for space manipulator displacement tasks. The new anthropomorphic European Robot Arm (ERA) served as a reference in this project. At the control-side of the interface, a force-activated control device with six degrees-of-freedom (the Spaceball) is applied to control the movements of the ERA end-effector (the hand of the manipulator). At the display-side of the interface, a single camera picture is shown: the picture from the camera, that is mounted near the ERA elbow joint. To assist the operator in deriving spatial information from the elbow camera picture, a graphical camera overlay is added: the Raindrop Overlay. In this graphical overlay, the actual distances between the manipulator and the objects in the environment are visualised by means of raindrop-shaped distance lines.