Piezo actuators challenge steppers

A small Harlow company has developed a piezoelectric-based actuator technology which it claims has many advantages over traditional actuators such as stepper motors and solenoids. PBT says that its solid-state Servocell technology is more reliable and durable, uses less power, and generates less heat than conventional devices. It describes Servocell as "the world`s first ready-to-install range of smart material proportional actuators for the mainstream OEM".

PBT originally developed the technology as an alternative to electromagnetic actuation for residual current circuit-breakers, but it envisages a wide range of other potential applications, including stepper motors, proportional pneumatic valves, robot grippers, sorting machines, trip releases, and locking mechanisms.

The "planar bimorph" piezo-ceramic actuators are said to deliver unprecedented levels of movement and force. The movement, which is governed by the input voltage, is accurate to within microns and can be stepped, proportional, binary - or a combination of all three.

The devices are available either as bare-bone actuators, capable of providing 4mm of movement and forces of up to 0.5N, or as enclosed packages delivering 8mm of movement and forces of 0.35N.

As well as simple voltage driver control board, there is the option of a microcontroller that can deliver five pre-programmed operating modes including closed-loop, open-loop and direct control.

PBT is continuing to develop its patented technology and is working on flat piezo motors as well as new versions of the actuator which will provide two axes of motion.