PILine® Ultrasonic Piezomotors

Compact Drives, Fast and Self-Locking

  • Linear and rotary motion
  • Basically unlimited travel ranges
  • Easy mechanical integration
  • Holding force up to 15 N, holding torque up to 0.3 Nm
  • Velocity to 500 mm/s, resolution to 2 nm

Motor-spindle combinations convert the rotary motion of the motor into linear motion, whereby the response times are delayed due to the backlash between the mechanical components. Drives such as PILine® however generate linear motion directly, with greater stability and less inertia.

PILine Motor-leadscrew combination
Motor-leadscrew combinations (above) transform the rotational motion of the motor into linear motion. Due to play in the mechanical components responsiveness is limited. Linear motors such as PILine® generate linear motion directly and provide much faster response and better stability

PILine® drives dispense with the mechanical complexity of classical rotary motor/gear/spindle combinations in favor of costs and reliability. These components can be very susceptible to wear, especially in miniaturized systems.

Operating Principle

Operating Principle of PILine®

An integral part of the ultrasonic piezomotor is a piezo actuator that is pretensioned against a movably guided runner via a coupling element coupling element. The piezoceramic actuator is excited to ultrasonic vibrations with a high-frequency AC voltage between 100 and 200 kHz. Deformation of the actuator leads to a periodic diagonal motion of the coupling element, relative to the runner. The created feed is a few nanometers per cycle; the high frequencies lead to the high velocities.

Inducing a Rotary Motion

PILine® motors can induce a rotary motion in one of two ways:
Analog to linear motion the piezo-ceramic actuators act laterally on a ring-shaped runner thus creating a fast rotary motion. The holding torque generated is approximately 0.3 Nm.

Implementation of Rotary Motion
A ring-shaped runner induces a rotary motion

Small rotary stages with a diameter of 20 mm or 30 mm use a ring-shaped actuator. This type of drive achieves very high speeds of more than two revolutions per second. The holding torque is approximately 30 mNm.


Features of PILine® Piezo Motors

Preloading the piezoceramic actuators against the runner ensures self-locking of the drive when at rest and powered down. As a result, it does not consume any power, does not heat up, and keeps the position mechanically stable. Applications with a low duty cycle that are battery-operated or heat-sensitive benefit from these characteristics.

Service Life and Reliability

The motion of the piezoceramic actuator is based on crystalline effects and is not subject to any wear The coupling to the runner, on the other hand, is subject to friction effects. Depending on the operating mode, travel distances over 2,000 km or a MTBF of 20.000 hours are achieved.

Piezo Motors for All Applications

Piezomotors from PI are vacuum-compatible in principle and suitable for operation under strong magnetic fields. Special versions of the drives are available for this purpose.

Low Profile Height

The benefits of the small design height of the PILine® drives becomes apparent with positioning systems such as the M-687 microscope cross table (25 mm height): a consistently flat design without spindle channels or flanged motors.

PI M-660 M-686K
PILine® Products: M‑660 rotary stage and M-686K microscope cross table
PI PILine Maximum Duty Cycle
Maximum duty cycle depending on the ambient temperature with a control signal level of 100 %
PI PILine Force Velocity
Force / velocity motor characteristic of a PILine® motor 6 N holding force. The percentages refer to the control signal level, which denotes the coupling of the electric power of the actuator

Dynamics in Use

The direct-driven, robust design and fast response times of the piezo ceramics allows for very fast start / stop behavior and velocities to several 100 mm/s.

PILine Acceleration
PILine® ultrasonic linear motors are extremely dynamic and provide acceleration to several g. They can step and settle within a few 10 microseconds for small distances

Slow Travel with PILine®

The demand for faster scanning speeds or greater throughputs characterizes only some of the applications in microscopy. Others demand high-resolution motion at low, constant speeds.

Stages with PILine® drives can be equipped with PIOne sensors and can achieve resolution in the range of single nanometers. Special control and regulation processes then provide constant speeds in the range of single encoder counts per second.

Integration Levels

Different Integration Levels Offer Flexibility

PILine® drives allow the design of positioning systems with higher dynamics and smaller dimensions. PI offers various integration levels of PILine® drives for easier integration into customer designs:

  • Positioning Tables with integrated PILine® drives, adapted to OEM requirements.
  • Linear Actuators move the load via a guided rod. Position feedback is available as an option.
Examples for PILine® integration stages: OEM motor, integrated OEM motor and linear drive
  • RodDrives are unguided and non-regulated linear driveswhich replace motor spindle combinations in integration. They can easily be coupled to a guided positioning platform.
  • The integration of piezo-ceramic actuators as OEM motors is relatively complex as the optimal preload between runner and actuator has to be set up by the customer.



PILine® ultrasonic piezomotors are small, high-speed and cost-efficient. Ideally suitable for applications with low operating cycles, they can also be integrated as drives into mobile measuring and medical devices. Due to their self-locking, the target position does not have to be held via additional brakes or electrical currents as in the case of magnetic drives.

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PI U-521


Technology PILine® Ultrasonic Piezomotors
Compact Drives, Fast and Self-Locking
Pdf 386 K 12/03/14.0
Brochure: PILine Ultrasonic Piezomotors
Small, High-Speed and Cost-Efficient
Pdf 1.3 M BRO47E 06/2015

Patented Technology

PI owns the following patents or patent applications for the technology field Ultrasonic Piezo Motors (PILine®):

  • Germany
    DE102004024656A1, DE102004044184B4, DE102004059429B4, DE102005010073A1, DE102005039357B4, DE102005039358A1, DE102006041017B4, DE102008012992A1, DE102008023478A1, DE102008058484A1, DE102010022812A1, DE102010047280A1, DE102010055848, DE102011075985A1, DE102011082200A1, DE102011087542B3, DE102011087542B3, DE102011087801B4, DE102011108175, DE102012201863B3, DE19522072C1, DE19938954A1: 
  • Europe
    EP0789937B1 EP1210759B1, EP1267425B1, EP1581992B1, EP1656705B1, EP1747594B1, EP1812975B1, EP1861740B1, EP1915787B2, EP1938397B1, EP2095441B1, EP2130236B1, EP2153476B1, EP2164120B1, EP2258004B1, EP2608286A2
  • USA
    US2010/0013353A1, US5872418A, US6765335B2, US6806620B1, US6806620B1, US7218031B2, US7598656B2, US7737605B2, US7795782B2, US7834518B2, US7973451B2, US8253304B2, US8344592B2, US8482185B2 
  • Japan
    JP2011514131, JP2011522506, JP3804973B2, JP4377956, JP4435695, JP4477069, JP4598128, JP4617359, JP4620115, JP4648391, JP4860862, JP4914895, JP2013539346 
  • China
    ZL200380108542.0, ZL200580015994.3, ZL200580029560.9, ZL200580036995.6, ZL200680007223.4, ZL200680030007.1, ZL200680042853.5
  • International patent applications
    WO2009059939A2, WO2010121594A1, WO2012048691A2, WO2012113394A1, WO2012155903A1, WO2013034146A3, WO2013117189A2

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