Servo pneumatics (not an oxymoron)

Pneumatic cylinders and actuators are commonly known as “bang-bang” devices, making quick moves from one end of their stroke to the other, with limited regulation of the force or the move profile. On the other hand, electromechanical actuators with servo controls offer high levels of refinement in positioning, force/torque, and accuracy. Generally speaking, pneumatics are a cost-effective solution for rather crude, point-to-point moves, while electromechanical actuators provide high precision, at a higher cost.

There’s a spot between these two solutions where a relatively high level of control is needed, but without the complexity and cost of electromechanical servo driven systems. Bridging this gap are pneumatics that operate in a closed-loop system—in other words, servo pneumatics.

Servo pneumatics vs traditional pneumatics

A servo system is one that uses a feedback device and a controller to monitor and correct the system’s error (in position, speed, or torque/force). Hence, integrating a pneumatic cylinder or actuator with a feedback system and a controller that can issue commands based on that feedback, gives us a servo pneumatic device. Another key component of a servo pneumatic system is a proportional valve, which precisely regulates air delivery to ensure that the commanded position and/or force is achieved.

The key components of a servo pneumatic system are an actuator with feedback, a proportional valve, and a servo controller. Image credit: Festo

Traditional pneumatics enable rapid, high-force, point-to-point motion. Servo pneumatics provide the same speed and force capabilities, with the advantage of higher accuracy positioning, not only at the ends of the stroke, but also at intermediate points along the travel. In addition to obtaining feedback on position, servo pneumatics also monitor and regulate air pressure, which enables precise control of the force that’s produced.

Continue reading to learn why and when you should consider servo pneumatics over traditional electromechanical actuators.