In the Product Design & Development Brainstorm we talk with industry leaders to get their perspective on issues critical to the design engineering marketplace. In this issue, we ask:
What new encoder technologies are helping ease-of-use and cut costs in industrial applications, such as wind turbines, steel plants, or loading cranes? What helps protect equipment from damage due to loss of control, or personnel who might be in proximity to such equipment and where such a failure could cause injury?
In the past, two main encoder technologies have been available for absolute position measurement.
Optical encoders offered superior accuracy and dynamic response, but were expensive and potentially vulnerable to harsh environmental conditions. Magnetic encoders were compact and rugged, but with lower performance specs.
Recently, a new generation of magnetic encoders has emerged that offer the best of both worlds, fast and accurate enough to meet the requirements of high performance motion control systems, but sufficiently tough to operate reliably in the roughest industrial settings.
With this new technology, systems designers and integrators can build what they need, without compromise.
Absolute encoders offer a safety advantage since they provide the control system with a complete picture of the position of all mechanical components, even during the critical period when the system is recovering from a power outage.
Motion control systems built around incremental encoders can ‘lose track’ of the location of mechanical components when system power is lost and the controller’s memory is wiped out.
System designers have historically relied on redundancy using multiple sensors to increase safety. However, this presented its own challenges and complexity as control systems had to be programmed to compare position data and create appropriate alarms.
Recently a new generation of sensors has emerged, combining redundant measurement, data verification, and alarms all in one unit. Furthermore, certifications, such as safety integrity level (SIL) help designers to select appropriate sensors based on safety needs.
As regulations such as the machinery directive in Europe become more common, these sensors are reducing the development time for new machines and make it easier to add redundant sensing to existing systems.
This article originally appeared in the October 2014 print edition of PD&D.
