Small wonder

Small wonder

Keyword Motors

EMS Limited has just launched the smallest production volume motor and planetary gearhead ever. The remarkable Minimotor device measures just 1.9mm in diameter, small enough to fit on a postage stamp, 24 times over (Plate 4)!

Designed to offer a solution to growing demand in extremely high precision activities such as laser tools, medical instruments and lens positioning, the new Microdrive System incorporates a brushless DC micromotor, a planetary micro gearhead and a speed controller. Creating a planetary gearhead of this size is in itself a feat of modern day cutting technology.

The innovative motor system, combined with an external electronic drive, creates a torque capability considerably higher than the motor's own moment of friction. During operation,the motor's drive provides a three-phase sinusoidal signal to the DC micromotor to assure constant speed, even at low frequencies.

Plate 4 The remarkable Minimotor device measures just 1.9mm in diameter ­ small enough to fit on a postage stamp, 24 times over

In order to give adequate power cover for the whole of the range of speeds, from 0 to 100,000 rev/min, two potentiometers are provided to set coarse and fine speed. Frequency and amplitude can be adjusted via external potentiometers.

To avoid loss of synchronisation during start-up, the motor speed undergoes standard asymptotic ramp-up, the ramp rate being set by the potentiometer.

The Microdrive System was initially developed by Dr Fritz Faulhaber of Stuttgart, using unique skew winding and brushless technology, to meet the needs of medical procedures conducted inside the body's major blood vessels.

For further information contact Jeff Mead, Electro Mechanical Systems Limited, Eros House, Calleva Industrial Park, Aldermaston, Reading RG7 4QW, UK. Tel: +44 (0)1189 817391; Fax:+44 (0)1189 817613.