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16 Commercial Robot Manipulators

Sensor Data Processing

Before any sensor can be used in a robotic workcell, it must be calibrated.
Depending on the sensor, this could involve significant effort in
experimentation, computation, and tuning after installation. Manufacturers
often provide calibration procedures though in some cases, including vision,
such procedures may not be obvious, requiring reference to the published
scientific literature. Time-consuming recalibration may be needed after any
modifications to the system.

Figure 1.4.2: Signal Processing using FSM for Optical Encoders (a) Phase relations in
incremental optical encoder output, (b) Finite state machine to decode encoder output
into angular position. (Snyder 1985).

Figure 1.4.3: Hardware design from FSM. (a) FSM for sonar transducer control on a
mobile robot, (b) Sonar driver control system from FSM.

Particularly for more complex sensors such as optical encoders, significant
sensor signal conditioning and processing is required. This might include
amplification of signals, noise rejection, conversion of data from analog to
digital or from digital to analog, and so on. Hardware is usually provided
for such purposes by the manufacturer and should be considered as part of
the sensor package for robot workcell design. The sensor, along with its
signal processing hardware and software algorithms may be considered as a
data abstraction and is called the ‘virtual sensor’.

Copyright © 2004 by Marcel Dekker, Inc.