Looking to get more information on the speed reaction of voicecoil vs. a piezo stage under load. I know that piezo is faster in no load. however how does it react under load? does it loose speed?

 

Voicecoils and piezo drives are vastly different technologies with different applications. Here is a breakdown of devices I know of:

- Piezo stacks can be bought that when actuated produce a fair amount of force (dozens of pounds) but only move a very short distance (under 0.001" or 25 microns...). They are good for short work or where you can use mechanical distance multiplication (within reason). Their speed is limited by the input capacitance charge time and the mass of the load (F=MA).

- Piezo linear and rotary stages with "walking fingers". These devices use two points of contact to alternate and effectively walk the load over fairly long distances (an inch or more). They tend to be slow because the increment of motion is small for each step and the frequency is limited by the capacitance of the piezo (which can operate at kilohertz speed, but the step size is very small....). I've heard one advantage is the they are not effected by magnetic fields and as such are useful in MRI applications among other things.

- Voice coils can move distances up to an inch (or maybe slightly more) and can have extremely high accelerations if they are paired to the load properly. I've seen these packaged with bearings and a linear encoder. You can drive them with a DC servo motor drive. The forces per unit size will be smaller than piezos, but the motion range is much greater.

KEJR