40 Unit One Principles of Robotics
actual locations. The brain sends signals to the arms to make necessary
adjustments. This process is repeated as the operator follows the scribed
line during the sawing operation.
The diagram in Figure 2-20 details one of the axes used in a hydraulic
robot and helps to explain its operation.
1. When the cycle begins, the controller searches the robot’s
programming for the desired locations along each axis.
2. Using the feedback signals, the controller determines the actual
locations on the various axes of the manipulator.
3. The desired locations and actual locations are compared.
4. When these locations do not match, an error signal is generated and
fed back to the servo amplifier. The greater the error, the higher the
intensity of the signal.
5. These error signals are increased by the servo amplifier and applied to
the control valve on the appropriate axis.
6. The valve opens in proportion to the intensity of the signal received.
The opened valve admits fluid to the proper actuator to move the
various segments of the manipulator.
7. New signals are generated as the manipulator moves.
Band saw
Cutting edge
of blade
Scribed
line
Figure 2-19. Human beings make use of the servomechanism principle for many tasks, such as
cutting a circle on a bandsaw.