Harmonic Drive has developed what it believes is the world’s smallest servo actuator, as part of a range of miniature hollow-shaft actuators. The device, which measures 50 x 50 x 50mm and weighs 400g, combines an AC servo motor, gearbox and encoder and delivers 1.8Nm of torque.

The FHA-C mini family of actuators also includes a device with a 30:1 reduction ratio – claimed to be a first for hollow-shaft actuators. The backlash-free actuators are said to deliver smooth torque curves at output speeds from 60–200 rpm.

Specially developed cross-roller output bearings resist axial and radial loads as well as high tilting moments. A TTL encoder mounted on the motor shaft provides feedback accurate to within 1.6 arc-seconds.

The actuators will interface directly will any standard servo controller. They are aimed at applications, especially in the medical sector, where accurate motion control and high torque capacities are required, or where the operating space or weight are restricted.