Piezo motors
During the 1980s, the founders of PiezoMotor AB, Professor Stefan Johansson and Dr Mats Bexell started their research on micro motion systems. After almost ten years of research, they were awarded the Swedish Innovation Cup and the ”Entrepreneurs of Tomorrow” prize for their new rotating piezoelectric motor. The motor was the world’s smallest and strongest motor built to date. A Piezo LEGS motor is precise down to the nanometer range, has instant response time and does not suffer from backlash problems.
PiezoMotor AB developed the basis of the linear piezo motor that eventually led to the first product – Piezo LEGS. In 2002, the first shipments to customers were launched and growth continues across markets .
In 2007, PiezoMotor AB started a collaboration agreement with the FAULHABER GROUP making the FAULHABER GROUP a shareholder in the company.
Piezo motors are available as linear version or as rotary version:
Piezo LEGS Linear motors
This linear Piezo LEGS motor is ideally suited for move and hold applications where precision, minimal space, low energy consumption and simple construction are required.
Piezo LEGS Rotary motors
This Piezo LEGS rotary motor is intended for a large range of applications where high speed dynamics and positioning with precision is crucial. High torque output in a small package is also beneficial.
Speed - max: 24 mm/s Resolution: 1 nm Maximum voltage: 48 V Stall force: 6,5 N 
Speed - max: 265 °/s Resolution: 0,1 µrad Maximum voltage: 48 V 
Speed - max: 24 mm/s Resolution: 1 nm Maximum voltage: 48 V Stall force: 20 N 
Speed - max: 0,3 mm/s Resolution: 1 nm Maximum voltage: 48 V Stall force: 300 N 
Speed - max: 12 mm/s Resolution: 1 nm Maximum voltage: 48 V Stall force: 40 N 
Speed - max: 0,3 mm/s Resolution: 1 nm Maximum voltage: 48 V Stall force: 450 N
Piezo LEGS motor takes steps to create motion
Piezo LEGS motors can be used in different ways depending on the requirements of the particular application. Required resolution is always the key question. As its name implies, a Piezo LEGS motor takes steps to create motion and, just as in humans, it can walk in different ways. It can move fast or slow, take long steps, short steps or partial steps, and stop at any point. All accomplished by different movement patterns and frequencies of the legs.
If we study one of the piezoceramic legs in detail, the actuator is built like a bimorph (Figure 1). Left and right side of the leg can be independently activated (0-48V). When energized, the leg can extend and bend a few microns. The tip of the leg (i.e. the friction drive pad) can move to any point within the rhombic area as illustrated in Figure 1. When the leg is not energized, the tip of the leg will be at point a. When only activating one side of the leg, it will bend to the left or to the right (b or d respectively). With both sides of the leg fully activated, it will extend to its maximum height (at point c). A Piezo LEGS motor will have several actuator legs working together. The motion of the motor will be dependent of the input electrical waveform signals. To achieve motion, two legs (or more) are driven in parallel. In total, each motor will need four separate control signals. Each leg, however, is controlled with two voltages. In Figure 2 two different waveforms are depicted. Rhomb is a rudimentary waveform which will make the tip of the leg move in a rhombic pattern. A more advanced waveform is called Delta. The Delta waveform is optimized for smoothest walking, and is best for high precision positioning.
Element movement of a piezo motor
Voltage plots of a piezo motor
Voltage plots; waveform Rhomb (left), and waveform Delta (right). The two input signals (U1 and U2) will control each separate half of the bimorph leg. Resulting plots describe the motion of the tip of the leg for given waveform type.
Features and benefits
- Small size
- High force output
- Direct drive
- Backlash free
- Nanometer resolution
- Energy efficient
Key Features - Linear piezo motors
- Force 0,1 ... 450 N
- Resolution < 1 nm
- Speed nm/s ... mm/s
KEY FEATURES - Rotary piezo motors
- Torque 0,1 ... 80 mNm
- Resolution < 1 μrad
- Speed μrad/s ... rad/s