26 Unit One Principles of Robotics
Controller
The controller is the part of a robot that coordinates all movements of
the mechanical system, Figure 2-4. It also receives input from the immediate
environment through various sensors. The heart of the robot’s controller is
generally a microprocessor linked to input/output and monitoring devices.
The commands issued by the controller activate the motion control mech-
anism, consisting of various controllers, amplifiers, and actuators. An
actuator is a motor or valve that converts power into robot movement. This
movement is initiated by a series of instructions, called a program, stored
in the controller’s memory.
The controller has three levels of hierarchical control.Hierarchicalcontrol
assigns levels of organization to the controllers within a robotic system. Each
level sends control signals to the level below and feedback signals to the level
above. The levels become more elemental as they progress toward the actu-
ator. Each level is dependent on the level above it for instructions, Figure 2-5.
Figure 2-4. A controller/power supply with a teach pendant. (Motoman)