In robotic systems, reduction of inertia is a key concern. One way to reduce the system inertia is to replace counterbalance masses with an equilibrator, which is a force element like a spring. Although there has been much research on equilibrated mechanisms, there has not much research on the control of these mechanisms. This thesis explores the PID control of equilibrated systems, and compares the results to the PID control of a common method of equilibration, the mass counterweight. Through modeling, simulating, and testing of the two systems, the equilibrated system response was found to be superior to the mass counterweight in measures of settling time and peak overshoot. / Master of Science