A human’s ability to perform physical tasks is limited by physical strength, not by intelligence. We coined the word «extenders» as a class of robot manipulators worn by humans to augment human mechanical strength, while the wearer’s intellect remains the central control system for manipulating the extender. Our research objective is to determine the ground rules for the control of robotic systems worn by humans through the design, construction, and control of several prototype experimental direct-drive/non-direct-drive multi-degree-of-freedom hydraulic/electric extenders. The design of extenders is different from the design of conventional robots because the extender interfaces with the human on a physical level. The work discussed in this article involves the dynamics and control of a prototype hydraulic six-degree-of-freedom extender. This extender’s architecture is a direct drive system with all revalue joints. Its linkage consists of two identical subsystems, the arm and the hand, each having three degrees of freedom. Two sets of force sensors measure the forces imposed on the extender by the human and by the environment. The extender’s compliances in response to such contact forces were designed by selecting appropriate force compensators. The stability of the system of human, extender, and object being manipulated was analyzed. A mathematical expression for the extender performance was determined to quantify the force augmentation. Experimental studies on the control and performance of the experimental extender were conducted to verify the theoretical predictions.

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This report describes the MBAssociates Exoskeleton/Merlin Robot Interface used in th Human Sensory Feedback Lab Testbed for studies of human performance in coarse positioning tasks. The dual-armed, seven-degree-of-freedom (DOF) exoskeleton, worn by an operator, serves as a master device to control the end-effector position/orientation of a six-DOF Merlin slave robot. Kinematic position transformation matrices are detailed for both master and slave devices, as is the approach used for operator control of a six-DOF robot using a seven- DOF exoskeleton. The use of a desktop 386-33MHz type personal computer as a central system controller, user interface, and software development platform is described.

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