Originally Published July 2000
Motors and Motion Control
A manufacturer has added a family of motor controls for use with its line of linear motors and stage products. These controls are part the manufacturer's Matched Performance drive package featuring brushless linear servomotors. The controls possess the high-current-loop, rate-loop, and position-loop bandwidths required to direct drive linear motion applications where smooth, low-speed performance and settling times are important. The controls use an IGBT power base for cool running and enhanced reliability. Baldor Electric Co., P.O. Box 2400, Fort Smith, AR 72902.
Custom induction motors are suitable for a variety of medical applications. The motors deliver high performance in a small package. They feature high-energy magnetic laminations, Class H insulation, and squirrel-cage rotors using various materials. ARC Systems Inc., 2090 Joshuas Path, Hauppauge, NY 11788.
Brushless dc motors
A line of brushless dc motors includes integral controllers. They can be used as direct, two-wire replacements for brush-type motors. Available in 1.7- or 3-in. diam, these motors provide high performance in a package that is more compact than designs with external controllers. They feature a high torque-to-inertia ratio for good start/stop characteristics. Single- or dual-shaft designs are available with torque up to 100 oz-in. and speeds up to 23,000 rpm. Ametek, Rotron Technical Products, 627 Lake St., Kent, OH 44240.
Specifically designed for medical applications, a line of brushless dc motors can survive as many as 1000 autoclave cycles. The motors are available in sizes 5, 8, and 10, with operating voltages of 12 to 48 V dc and speeds of 3000 to 100,000 rpm. Gearheads come in sizes 5, 8, and 10, with ratios of 3:1 to 256:1. The motors can be customized extensively, and control electronics are available for all motors. Transicoil, 2560 General Armistead Ave., Norristown, PA 19403.
MicroLynx is a complete motion control solution in a compact, panel-mounted assembly. It incorporates a bipolar stepper-motor microstepping drive and a versatile, programmable indexer with expandable I/O and multiple communication ports all running off a single supply. The robust design of the MicroLynx makes it suitable for medical product applications. Intelligent Motion Systems Inc., P.O. Box 457, Marlborough, CT 06447.
According to their manufacturer, 58-mm brushless dc motors are 30% more efficient and 33% smaller than industry-standard packages. They feature a three-phase MOSFET pulse-width-modulation drive with surface-mounted components that eliminates the need for external controllers. Available in 14- and 17-W outputs with motor lengths of 46 and 55 mm, these brushless motors have a peak power capability of up to 100 W, encoder pulses per revolution of 45 or 50, and operating speeds of 505000 rpm without dynamic balancing and up to 10,000 rpm with dynamic balancing. Thomson Industries Inc., 2 Channel Dr., Port Washington, NY 11050.
Motion control packages
A broad line of servo motion control products is specially designed to deliver precise control for medical instrumentation. The MedMaster product line consists of brush and brushless servomotors, encoders, and PWM amplifiers, which can be supplied as motion control packages or components. To provide reliable performance, rare-earth, ring-magnet technology is used in the brushless motors. The high torque-to-inertia ratios within the motors allow medical instrumentation to operate with precision at high speeds. Cleveland Motion Controls, 829A Middlesex Tpke., Billerica, MA 01821.
A size-17 hybrid linear actuator incorporates engineering thermoplastics in the rotor drive nut and a stainless-steel acme leadscrew. This makes the motor more efficient and durable than the commonly used v-thread and bronze-nut configurations. An additional feature is a bearing-preload adjustment that does not protrude from the motor as in many other designs. The motor is available in a wide variety of resolutionsfrom 0.00012 to 0.00192 in./step, delivering thrust up to 50 lb. The linear actuator is suitable for applications requiring a combination of precise positioning, rapid motion, and long life. Haydon Switch & Instrument Inc., 1500 Meriden Rd., Waterbury, CT 06705.
Digital servo controller
A four-quadrant PWM digital servo amplifier is designed to control position, velocity, or torque. Compatible with brush and brushless motors up to 250 W, the Model MIP-50 can supply 5 A continuously, 11 A for 5 seconds, and 13 A for 200 milliseconds. The compact controller may be used in Eurocard systems or individually. Several different operating modes are configurable including stand-alone via external switches. Low-jerk acceleration and deceleration profiles may be selected, as well as autotuning functions. Target position, velocity, acceleration, and deceleration can all be modified on the fly. Maxon Precision Motors Inc., 838 Mitten Rd., Burlingame, CA 94010.
Ac synchronous motor
Using the latest magnetic technologies, an ac synchronous motor is able to produce twice the torque of the manufacturer's previous model. The Slo-Syn motor is available in six sizes with torque ratings from 80 to 700 oz-in., and in NEMA 23 and 34 frame sizes. The motor also features a phase-shifting network that provides smooth, quiet operation. Superior Electric, 383 Middle St., Bristol, CT 06010.
Five-phase motors with a 0.72° full-step angle are available in frame sizes of 24 and 42 mm. Ultrasmall and lightweight motor/driver packages offer holding torque from 2.5 to 33.4 oz-in. and phase current of 0.35 and 0.75 A. Both sizes are designed for high speed and high torque. The manufacturer also offers a wide range of driver/amplifiers for full, half, and microstepping along with larger five-phase motors. Daido Corp., 615 Pierce St., Somerset, NJ 08875.
Synchronous step motor
A low-speed, permanent-magnet step motor can be used for timing applications. The PTM-series motor has a shaded-pole permanent-magnet design that allows automatic self-starting and dynamic braking without an external brake. The motor contains internal impedance protection so that the shaft can be stalled continuously without the danger of burning coils. Plastic and metal gearheads are available for most applications. Kollmorgen, 201 Rock Rd., Radford, VA 24141.
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