Self-locking, Non-Magnetic and Easy to Integrate: Piezo-Based Linear Drive for Automation Technology

Linear direct drives have advantages over rotating electric motors for rectilinear motions in automation technology because the latter always have to use a spindle to convert the driving force into translational motion.

An often undesirable aspect of conventional linear motors is that they are not self-locking and thus require holding currents which are associated with heat dissipation, high energy consumption and “positional jitter”. Piezo-based linear drives offer a solution here.

Physik Instrumente (PI) of Karlsruhe has paid heed to the requirements of modern automation technology and now offers a versatile, scalable piezo-based linear drive (picture) which has drive forces up to 10 N, velocities up to 0.5 m/s and travel ranges of several tens of 10 mm. A piezo-ceramic actuator oscillating with ultrasonic frequencies is preloaded against a rod with linear guidance. The oscillation profile of the actuator then produces the forward and backward motion of the drive. The ceramic is preloaded against the rod and thus keeps it in its ‘at rest’ position when powered down. Unlike electromagnetic linear motors, the piezo-based drive does not require any energy for this, no heat is dissipated and the position is maintained with a high degree of stability. During positioning operations, the piezo-based linear drive with optical linear encoder achieves an accuracy of around 10 µm. Moreover, in contrast to electromagnetic linear drives, the piezo-ceramic actuator does not generate any interfering magnetic fields when in operation.

The piezo-based linear drive has a matching controller with pre-integrated driver electronics to generate the ultrasonic oscillations; both controller and linear drive are designed for industrial applications. This creates an attractively priced linear drive system which is also easy to integrate into the application. The controller has a 100 mm wide and 160 mm long eurocard which can be controlled via an RS232 interface, CAN or an analog input, as desired, for velocity control or external operation via joystick, for example. The 32-pole multipoint connector can easily be connected up by means of adapter modules or screw terminals when the control cabinet is being installed.