The term mechatronics, coined in Japan in 1969, originally referred to electro-mechanical systems. As engineering and information technology have evolved, so has the mechatronics discipline. It now represents the combination of mechanics, electronics, control systems and software computing. This interdisciplinary engineering field provides a means to control advanced hybrid systems. Servo drive, motor manager and magneto-rheological systems are just a few examples of mechatronic systems found in industry today.
Existing mechanical applications can be converted to mechatronic systems through upgrades and add-ons. An example is replacing traditional mechanical drives with modern servo drives that can increase speed while reducing downtime, startup time and changeover time.
The Rexroth IndraDrive Mi is an ultra-compact drive system that integrates motion control electronics with a servo motor. It has built-in predictive maintenance technology, with an integrated programmable logic controller (PLC) that provides advanced monitoring of the drive and its components for machine wear.
The Rexroth drive and motor are combined into a single unit by attaching the drive to the long axis of the motor, saving space in comparison to traditional standalone motor and drive systems. The Rexroth IndraDrive Mi is less than half the size of a conventional servo solution and about one-third the size of other integrated solutions.
A single cable is used for both power and SERCOS communications. As many as 20 drives can be connected together without additional distribution boxes or modifications in the cabinet. Multiple strings of drives can be connected parallel to a single supply unit.
GE Multilin MM300 is a compact, low-voltage motor manager designed to increase equipment life and improve uptime in industrial facilities. This mechatronic system provides motor protection, control automation, communications, metering and advanced diagnostics. The MM300 offers continuous motor health monitoring and diagnostics, and customizable automation and programmable control logic. It can communicate simultaneously using Modbus and either DeviceNet or Profibus DP protocols.
Mechatronics also is breathing new life into existing technologies, such as magneto-rheological (MR) fluids. MR technology combined with computers, sensors and controls provides an alternative to conventional electro-mechanical solutions and electro-rheological (ER) fluids.
When MR fluids respond to a magnetic field, there is a dramatic change in rheological behavior – the fluid instantly changes from a free-flowing liquid to a semi-solid, and the effect is reversed when the magnetic field is removed.
MR fluids typically consist of iron particles suspended in a carrier liquid such as mineral oil, synthetic oil, water or glycol, with proprietary additives to enhance lubricity, modify viscosity and inhibit wear. MR fluids aren’t highly sensitive to moisture or other contaminants, and they can function across broad temperature ranges.
The fluid operating in valve mode, with fixed magnetic poles, might be appropriate for hydraulic controls, servo valves, dampers and shock absorbers, according to LORD Corp., a leading supplier of MR technology. The direct-shear mode with a moving pole would be suitable for clutches and brakes, chucking/locking devices, dampers, breakaway devices and structural composites.
MR-based clutches, for instance, consume less energy than conventional mechanical technology, provide greater controllability and minimize off-state drag. In addition, MR fluids enable the clutch to be smaller than conventional devices and designed with fewer moving parts.
MR-based brakes provide better control and are more responsive. Applying a magnetic field to the MR fluid inside the brake changes the fluid characteristics. This increases torque output precisely in less than 10 milliseconds.
Linde Group worked with LORD to incorporate MR technology into Linde’s R 14 Active – R 20 Active reach trucks. A variable-torque MR rotary damper, position sensor, bearings and steering wheel shaft are packaged together as a compact Tactical Feedback Device. The MR damper allows the torque required to turn the steering wheel to be a function of the truck operation. This provides more instinctive steering control, which improves operator productivity and safety. The patented Linde Rheological Steering (LRS) system, which features individually adjustable steering resistance, is standard equipment in the R 25 S Active reach truck.
Mechatronics Zone within Design News is an online clearing house of mechatronic-related news and announcements. Robert Bishop has written books on the subject, including “Mechatronics: An Introduction” and “The Mechatronics Handbook." Many schools have incorporated mechatronics into their curriculum and some have established mechatronic-specific research laboratories.
E-mail Contributing Editor Sheila Kennedy, managing director of Additive Communications, at [email protected].
Reference Web sites:
www.boschrexroth-us.com
www.geindustrial.com
www.lord.com
www.linde-mh.com
www.designnews.com
www.engnetbase.com