Chapter 2 Fundamentals of Robotics 45
control valves, and a hydraulic actuator. Hydraulic drive systems provide both
linear and rotary motion using a much simpler arrangement than conventional
electric-drive systems, Figure 2-26. The storage tank supplies a large amount
of instant power, which is not available from electric-drive systems.
Hydraulic actuator drives have several advantages. They provide
precise motion control over a wide range of speeds. They can handle heavy
loads on the end of the manipulator arm, can be used around highly explo-
sive materials, and are not easily damaged when quickly stopped while
carrying a heavy load. However, they are expensive to purchase and main-
tain and are not energy efficient. Hydraulic actuator drivers are also noisier
than electric-drive actuators and are not recommended for clean-room
environments due to the possibility of hydraulic fluid leaks.
Pneumatic Drive
Pneumatic drive systems make use of air-driven actuators. Since air is
also a fluid, many of the same principles that apply to hydraulic systems
are applicable to pneumatic systems. Pneumatic and hydraulic motors and
cylinders are very similar. Since most industrial plants have a compressed
Figure 2-25. Note the simplifi ed mechanical design of this direct-drive robot as compared to the
conventional electric-drive robot shown in Figure 2-22. (Adept Technology, Inc.)