Industrial Motion Control Sensors

Outside of the industrial marketplace, microelectromechanical (MEMS) sensors based on semiconductor technology have advanced rapidly. However, industrial applications, especially in the motion control area, continue to rely on more traditional technologies. Still, many of the sensor goals are similar: reduce the size, make the sensor easier to use, and of course, lower the cost. The functionality required for industrial applications and the need for ruggedness provide unique challenges. Industrial ruggedness not only addresses the environment and the need to meet standards and have approval from one or more standards organizations but also the need to operate 24/7 and be easy to replace. Three examples demonstrate some of these unique requirements.

Smart sensor standards were developed in the late 1990s with the primary goal of easing the application of sensors in industrial applications. The IEEE 1451 smart sensor standard defines new terminology for sensors, including a Transducer Electronic Data Sheet (TEDS), a Network Capable Application Processor (NCAP) and the Smart Transducer Interface Module (STIM). By adding a TEDS to a traditional two-wire, constant-current sensor and requiring only a small amount of memory, IEEE 1451.4 has garnered support from several companies including National Instruments, Honeywell Sensotec and others. IEEE 1451.4 meets many of the goals, which have created the industrial sensor trends of simplifying sensor setup, use and maintenance, and, in general, making plug and play a reality for industrial applications.

When a Sensor is Not a Sensor

In some motion control applications detecting position can be more appropriately handled with a switch than a sensor no matter how easy the sensor is to use. Newer limit switches, such as Honeywell's GLL products come in a small size, meet the new requirements for RoHS and address the lower cost trend by costing up to 40 percent less than comparable products. With a double-insulated housing that does not require grounding, the units are also easier to install.

Predicting the Future

While providing one of the smallest laser barcode readers in its class, Keyence BL-600 is the first barcode reader with a built-in Preventive Maintenance Information (PMI) function. During operation, the PMI function provides real-time monitoring and reading performance reporting. The PMI data allows users to easily detect potential reading error problems and provides a convenient tool for acquiring maintenance information and investigating the causes of reading errors.

The other sensors in this section address quite different applications, but all meet one or more of the identified trends.