The methods and devices of the invention include an encoder, an endoscopic robotic instrument, and an encoder/robotic instrument interface. A preferred embodiment of the encoder has a chest/shoulder plate provided with telescoping tubes and joints. Each joint is provided with a direct drive potentiometer to monitor movement and provide a corresponding signal. The chest plate is preferably adaptable to a large range of human chest sizes and the telescopic segments are strapped to the arms of the practitioner at the elbows. A pistol grip is provided at the wrist end of the telescopic segments. According to the presently preferred embodiment, the encoder encodes flexion and rotation at the shoulder, elbow and wrist of each arm in addition to gripping at each hand. The encoding device is coupled to a circuit which operates a servo system. The servo system includes a series of servo motors. A series of pulleys corresponding to the number of servo motors are arranged in a housing. The robotic instrument preferably comprises two arms mounted at the distal end of a multi-lumen tube. Each arm has rotational and flexional joints corresponding to the shoulder, elbow, and wrist of the practitioner. Tendons are coupled to the pulleys of the servo motors and are fed through the multi-lumen tube to the joints of the two arms.