Spotlight on Motion Control Devices

Machine Builders Look to Simplify Their Products With New Hardware, Software and Standalone Devices

By Rich Merritt

Although motion control markets took a beating in 2001 and 2002, the ARC Advisory Group says sales picked up in 2003, passed the $4 billion mark, and are expected to grow at an annual rate of 6.3% over the next five years. The tide has turned, says ARC.

Several factors are driving this market growth. The semiconductor and electronics industries, which were the impetus behind the very fast market growth up to 2000, have been in a slump lately, but finally appear to be reawakening. The food & beverage industry, which was one of the stars of motion control during these bleak years, is expected to continue its formidable strides as investment in consumer goods manufacturing continues.

Machine builders are expected to begin using more advanced motion controls, says ARC. "Mechatronic solutions with drives and motors will encourage machine builders to replace maintenance-ridden and inflexible mechanical linkages," says ARC senior analyst Himanshu Shah, author of the latest study, "General Motion Control Outlook." "As a result, an increasing number of machines will have more servo or stepper controlled motion axes."

Although we looked everywhere for other opinions on the future of motion control, ARC seems to be the only market research firm that has paid attention to the industry since 9/11. We don't refer to any market studies published prior to 9/11, because the world changed so significantly at that time, all those old studies are useless. 

We can find some clues into the future by looking at the products in this round-up. Like most product categories, some motion control vendors have stagnated over the past several years, choosing to make only minor changes in their products, such as adding an Ethernet interface or making improvements that don't require much R&D funding.

Prices, which dropped like a stone for several years in a row, appear to have stabilized under $1,000 per axis. We found one controller that sells for $200 per axis.

Motion controllers are slowly but surely emerging as standalone devices, which barely need the services of a supervisory or host computer or even a PLC. Today's motion controllers are sometimes complete systems that embody everything you need, including a motor, drive amplifier, encoder, controller, logic control, networking and a Windows-based software development system that runs on a PC.

Motion control software also is getting very sophisticated and easy to use. If machine builders want to turn to motion control to simplify their products, as predicted by ARC above, then the hardware and software is making it possible.

Servo Drive Fits in Small Space
Acopos mini servo drive measures 2.3x8.1x8.7 in., and includes a braking resistor, line filter, restart inhibit and motor-holding brake control. The device is compatible with existing models in the series and applications include CNC, point-to-point positioning and coordinated movements. Single-axis and complex multi-axis applications can be created using Ethernet Powerlink. 

Fast Screw Travels at 3 mph
The RGS Rapid Guide Screw travels at speeds of more than 60 in./sec. (3 mph) over distances to eight ft. It has an aluminum guide and carriage, stainless steel lead screw and a wear-compensating, anti-backlash driven carriage. Applications include high-speed printing, scanning and engraving, actuation and positioning in transportation -applications, pick-and-place mechanisms and most automated equipment. 

Smart Motor Packs It All in
ServoStep integrated motion control system includes a high-torque, 50-pole NEMA 34 frame step motor, motion controller, drive amplifier and encoder. Torque is 650 oz-in at a nominal speed of 2,200 rpm. It has an RS-485 port, 14 I/O, 4 kHz PID filter, software current limit, limit-switch inputs and thermal protection. The system can operate in position, velocity, torque, and step and direction modes. 

Controllers Priced to Sell
RMC70 Series motion controllers for one and two-axis applications are priced under $1,000 per axis, depending on quantity. The RMC75S-MA1 is for linear motion control and includes RS232/485 Serial communications and interfaces to magnetostrictive displacement and synchronous serial interface absolute position transducers. The RMC70 Series is for hydraulic, pneumatic and electric servo motion control applications with position, velocity and position/pressure control capabilities. 

All the World's a Stage
The Pico Series ball screw-driven miniature linear stage for high-precision pick-and-place positioning applications is available in 60 mm and 80mm sizes in five standard stroke lengths, has travel speeds to 500 mm/sec., and provides the same load-carrying capacity as drive screws. It has an extruded aluminum base, stainless steel cover, and limit switche with plug attachment. Options include stepper motor package, linear measurement system and variable multi-axis assembly. 

Optical Encoders
The EH and ES series of incremental encoders are available in resolutions 100-5,000 ppr with quadrature and index pulses. Both are available in servo mount with either solid or hollow-shaft configurations that provide a footprint of 37 mm or 50 mm outside diameter. Input voltage, output signal and lead length can be varied. 

Rotary Encoder Fits PLCs
The SCS10 Series single-turn parallel-output absolute rotary encoder is available with Gray, Gray-Excess, Binary and BCD output codes, plus serial code outputs for interfacing with PLCs. Maximum shaft speed is 6,000 rpm, and it can handle axial/radial shaft loads to 40 lbs. The encoder is housed in an aluminum casing, has IP-65 protection, provides 13-bit resolution, and has inputs for latching, preset, selection of counting direction. A preset function allows the encoder to be set to zero at any time.

Drive On
Revised VLT 5000 Flux drives are 35% smaller than previous versions, but use the same software. The 90-200 kW units are available in ranges 125-300 hp, with ambient temperature ratings of 40-45? C in VT mode and 50? C with changes in switching pattern. Other enhancements include built-in RFI performance to EN 55011 class B, integral disconnect with option of available fuses, power terminations that accept single box lug or dual-cable legs, and 98% operating efficiency. 

Servomotor Mounts in 30 minutes
Kollmorgen Cartridge DDR direct-drive rotary servo motor combines the performance advantages of a frameless direct-drive motor with the ease of installation of a full-frame motor. Because it eliminates all mechanical transmission parts, installation takes less than 30 min. Motors are available in two frame sizes, with three stack lengths per frame. Voltage ratings are available in 230, 400, and 480 V and provide 50-510 N-m continuous torque, peak torque to 1100 N-m, and speeds to 1,200 rpm. 

Linear Motor Doesn't Backlash
The HyCore linear motor has zero backlash, unlimited travel, velocity to 60 in./sec and up to 3-g acceleration. It provides continuous force up to 750 lb.-in. a 5x4x14-in. package. The continuous force capability can be extended an additional 20% with optional air cooling. Controls for the motor include the company's MicroFlex/FlexDriveII motor drive or Mint II motion controller. 

Sensorless Drive Makes Sense
The Durapulse Series of sensorless vector AC drives are available 1-100 hp with vector and closed-loop control, autotuning, 175% starting torque, 150% rated current for one minute, automatic torque and slip compensation, an internal dynamic-braking circuit for models under 20 hp and programmable jog speed. The drives have 0-10 V, +/-10 VDC or 4-20 mA analog inputs, 16 preset speeds, 11 programmable digital inputs, four programmable outputs, and one analog output. 

Drives Takes Input Well
Available in both 230 VAC and 460 VAC systems, MMC Smart Drives interface to feedback devices including resolver, incremental encoder and single-turn or multi-turn absolute encoders. They provide 0.5-24kW continuous output power, and operate on a voltage supply range of 100-528 VAC, single and three phase. Drive configuration is via the company's IEC61131 PiCPro for Windows software, which supports ladder logic, function block and structured text programs. 

Ethernet-Based Motion Controllers Coordinate
DMC-31x3 Flexible-Distributed controllers use Ethernet for communications between various controllers, I/O, cameras and similar devices, freeing the host computer from the task of motion coordination. Each controller handles positioning, jogging, linear and circular interpolation, gearing and ECAM, is configurable for stepper or servo control on any axis, provides non-volatile program memory with multitasking, and handles up to eight axes.

Motion Control Is in the Cards
The ACR1505 half-slot PCI card motion controller can operate four axes of servo or stepper motion with four encoder inputs at up to 30 MHz, post-quadrature. It provides 120 million 32-bit floating point operations per second (MFLOPS), has dual-port RAM, and can be equipped with eight analog inputs using 12 or 16-bit analog-to-digital converters for general-purpose inputs or for closing a servo loop. Options include a communications module with two serial and one parallel port. 

Adaptive Software Does Motion Control
The Model-Free Adaptive (MFA) Control Toolset for LabView version 1.1 provides high-speed adaptive control for motion control loops. When PID is insufficient or to avoid building models, a user can select an appropriate MFA controller from the toolset. No process model is required to launch a controller, and no controller tuning is required once installed. Free demos are available on the web site. 

Motion Controller Module Fits PacSystem
The DSM314 module for the PacSystems RX3i programmable automation controller can control up to four analog servos or two Fanuc digital servos plus one analog servo. It supports high-speed local logic, so it can perform limited logical decisions and math synchronous with the position loop update rate, and provide high-speed digital output control synchronous to axis motion. Two high-speed strobe position capture inputs per axis are suitable for applications that require registration control.