Sunday, February 16, 2014
SENSORS USED IN ROBOTICS
There are a vast number of different sensors being used in robotics, applying different measurement techniques, and using different inter- faces to a controller. This, unfortunately, makes sensors a difficult subject to cover. We will, however, select a number of typical sensor systems and discuss their details in hardware and software. The scope of this chapter is more on interfacing sensors to controllers than on understanding the internal construction of sensors themselves. What is important is to find the right sensor for a particular application. This involves the right measurement technique, the right size and weight, the right operating temperature range and power consumption, and of course the right price range. Data transfer from the sensor to the CPU can be either CPU-initiated (polling) or sensor-initiated (via interrupt). In case it is CPU-initiated, the CPU has to keep checking whether the sensor is ready by reading a status line in a loop. This is much more time consuming than the alternative of a sensor-initiated data transfer, which requires the availability of an interrupt line. The sensor signals via an interrupt that data is ready, and the CPU can react immediately to this request.
· Binary signal (0 or 1) - Tactile sensor
· Analog signal (e.g. 0..5V) - Inclinometer
· Timing signal (e.g. PWM) - Gyroscope
· Serial link (RS232 or USB) - GPS module
· Parallel link - Digital camera