2. Learning Outcomes:
Upon completion this chapter, student should be
able:-
1. Explain of concept pneumatic, hydraulic and
motor devices
2. Compare the three actuating systems
4. Basic pneumatic system
Pneumatic drive: are generally used for smaller
robots. These robots, with fewer degrees of
freedom, carry out simple pick-and-place material
handling operations.
5.
6. Advantages and disadvantages of
Pneumatic Actuators.
Advantages:
low cost;
high speed of moving;
ease at reversion
movements;
high reliability of work;
explosion and fire safety;
ecological purity
Disadvantages:
compressibility of the air ;
impossibility to receive
uniform and constant
speed of the working
bodies movement
difficulties in performance
at slow speed
limited conditions - use of
compressed air is
beneficial up to the definite
values of pressure
compressed air requires
good preparation.
7. Basic hydraulic system
Hydraulic drive: gives a robot great speed and
strength. These systems can be designed to actuate
linear or rotational joints.
The main disadvantage of a hydraulic system is that it
occupies floor space in addition to that required by the
robot.
8. Types of hydraulic actuator
Linear actuator (hydraulic cylinder)
Provides motion in straight line
Linear displacement depends on stroke length (length of
actuator)
Usually referred to as cylinders, rams (single acting
cylinders) or jacks (cylinder used for lifting)
Rotary actuators (Hydraulic motors)
Produces continuous rotational motion
Pump shaft is rotated to generate flow, a motor shaft is
caused to rotate by fluid being forced into the driving
chambers
9. Semi rotary actuators
Produces non-continuous rotational motion
Limited to less than one revolution (<360°)
Used to produce oscillatory motions in mechanisms.
25. Basic electrical motor system
Electric drive: compared with a hydraulic system, an
electric system provides a robot with less speed and
strength.
more accurate, exhibit better repeatability, and are
cleaner to use.