A lift apparatus includes a lift assembly and a servo-control system. The lift assembly includes at least one pneumatic actuator including a movable member to provide a load to transfer a substrate between a support and a transfer plane. The lift assembly further includes at least one proportional pneumatic valve to control fluid flow between the actuator and a pressurized fluid supply or a vent, a plurality of pressure sensors each to measure pressure in a respective supply line to the actuator, and at least one position sensor to measure a position of the movable member. The servo-control system includes a controller to determine an output force based on a commanded force and an estimated force, generate a control signal based on the output force, and apply the control signal to the proportional valve to move the movable member.