October 21, 2010 by admin
Filed under Featured Mechatronic Articles, Motion Control, Technology
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Here’s what happened in a multi-year collaboration among engineers and scientists at New Scale Technologies, austriamicrosystems and TDK-EPC tosimultaneously develop the motor, mechanics, electronics and control systems for the M3 piezoelectric micro motor.
Larger-scale mechatronic systems include this integrated size 17 stepper motor and IDEA drive from Haydon Kerk.
Piezoelectric micro motors satisfy the need for linear motion in miniature products. These millimeter-scale motors are less than half the size of solenoids or traditionalelectromagnetic micro motors. They are more efficient at small sizes, and produce direct linear motion without gears or drive trains. They also offer longer travel, higher precision and higher force than solenoids or shape memory alloys (SMAs). These features make them suitable for use in portable battery-powered devices, such as miniature focus systems for cameras in phones or industrial laptops, orany application requiring small size and high precision. These include machine vision, optical fiber and RF tuning devices, medical devices, and military systems for vision, targeting and control.
Since 2006, SQUIGGLE piezo motor systems have shrunk in size from (at right) a 12 mm diameter motor with 51 x 76 x 14 mm drive card, to (at left) a 2 x 2 x 5 mm motor with a flip-chip drive ASIC (shownon the dime). This enabled the creation of integrated micro-mechatronics modules such as the M3-L module (center) – complete closed-loop motion systems in housings of less than 7 x 12 x 30 mm.
Designing with piezoelectric (piezo) motors requires a different mindset than that used with traditional servo or stepmotors. The traditional approach of specifying the motor and then buying or designing thecontrol system works for servo and stepmotors because there is a vast body of “cookbook motor” control solutions and experienced drive teams available for traditional motor implementation. This is not the case for piezo motors, which require special drive circuits to create and maintain ultrasonic resonant vibrations in the motor.
In addition, piezo motors are most effective when the mechanics,electronics, control system, software – and even the motor design itself – are developed in concert. In this way the piezoelectric ceramics, the silicon, and the system can be tuned to work together for optimal performance. It is a perfect illustration of the benefits of a mechatronic design process.
Miniaturization meets mechatronics
The last five years have seen impressive miniaturization ofpiezo motors. One example is our SQUIGGLE motor. Recent innovations have yielded dramatic reductions in the size of the drive electronics. Such reductions were possible in part through collaboration with TDK-EPC to develop new, lower-voltage piezo actuators and eliminate the need for voltage boost circuits; and in part by work with analog IC experts at austriamicrosystems to incorporate moreintelligence into the piezo drive ASIC.
These advances enabled new integrated micro-mechatronic modules: small closed-loop actuators that serve as simple “drop in” subsystems in OEM product designs. The system designer provides high-level commands to the module through a standard serial interface. A 3.3 Vdc battery provides power. The mechanical coupling is customized to the application: to move alens, adjust a grating, push a valve, and so on.
Such micro-mechatronic modules typically provide as much as 50 grams force with precision of one-half micron and closed-loop accuracy measured in tens of microns.
Mechatronics compared to micro-mechatronics
In some ways these micro-mechatronic modules are analogous to larger versions. However, there are important differences. For example, Haydon...