Hydraulic-actuation joystick use: A torque,range of motion and electromyographic description

The purpose of this work was to quantify upper limb and joystick kinematics, muscle activation of the prime movers and stabilizers of the shoulder (anterior deltoid, posterior deltoid and upper trapezius) as well as torque exerted by operators of hydraulic-actuation joystick controllers. Dynamic and impact torques were captured through the use of an instrumented joystick. Results indicate that the impact torque (5.36 ± 1.75 N·m for forward motion) sustained as the joystick reaches the end range of motion is substantial and is more than twice that of the operator exerted torque prior to reaching the hard endpoint. EMG data confirm that the upper trapezius is in a state of constant but low level activation, which may be largely attributable to postural demands forced upon the operator by the armrest.