The M10A minimotor from Elliptec AG (Dortmund, Germany) is said to offer engineers highly dynamic and precise movement in a small package. Designed for rotary as well as linear applications, the motor can be installed in gearless drives without the need for a transmission of any kind.
According to Christian Stromberg, technical support, the core element of the M10A motor is the low-voltage piezoactuator. “By optimizing the vibrancy behavior of aluminum frames, a new shape with reduced size was developed for the piezoactuator to be operated in resonance,” he explains. “This allows for novel designs that couldn’t be realized before due to size or precision limitations of conventional motors.”
Measuring approximately 13 × 12 × 2.5 mm, the motor has a flat surface. While conventional motors usually have nearly equal dimensions in height and width, Stromberg says the depth of the typical motor is usually “a multiple of these dimensions.” He adds, “The orientation of the oscillation has been rotated by 90 degrees. As a result, the M10A features a flat form factor and requires no lever arm.”
Stromberg says one of the motor’s key features is precision. “The engine is driven by a signal with a frequency between 128 and 155 kHz, while its typical average speed is about 500 mm/sec, resulting in a calculative single step width of about 3 to 5 μm,” he says. “By usage of pulse-width modulation (PWM), the step width can be reduced even further. In addition to that, the motor does steps with a width of below 1 μm in the beginning of acceleration, which can be used in conjunction with small signal pulses to address submicron steps.”
Also, because the motor’s maximum speed can be adjusted by software, there is no need for a gearbox, eliminating gearbox wear and noise generation.
The motor is controlled by a simple electrical circuit that Stromberg says can be easily integrated into existing microcontroller environments. “Even basic controllers can generate frequencies with the minimally required resolution of 1 kHz (preferably 300 Hz),” he says. “Many even include a timer or a PWM unit so that the computation power is barely affected. Alternatively, analog circuits may be used as well.”
The new motor is said to be ideal for high-precision applications such as portable medical and consumer electronics products. One possible application is an electronic-controlled aperture used in professional tilt-shift lenses for perspective eye correction. “Due to the nature of these lenses, a mechanical linked solution is usually not practical because of the otherwise necessary high complexity to allow aperture operation during tilt and shift,” Stromberg says. “The small size of the M10A allows driving the aperture from within the lens. Its electronics remain in the camera body, using the electronic contacts of the camera mount for communication instead of a mechanical link. As exact light exposure depends on accurate aperture opening, the M10A provides the needed high-precision positioning and offers high-dynamic movement to allow for short blackout times while stopping the aperture down and back open.”