Page 252 - Mechatronic Components Roadmap to Design

Case Studies Chapter 16 231

Case 4: Power transmission
Almost all the mechatronic systems have some kind of motion inside them.
There are different ways to generate motion with especially electrically pow-
ered motors (explained in the following case studies). After the motion is gen-
erated, most of the time the speed and torque of the motor should be transferred
to another point inside the machine. There are so many choices available for
power transmission (Chapter 7).
During the design of a snow-blowing robot, a gasoline engine is used for high-
energy output. The energy generated by the gasoline engine is used in two points:
at the blades of the snow blower and at the alternator to generate electricity.
The snow blower robot has mechanical blades and a pump to take the snow
from the front and to throw it out to the side. The transmitting of power from the
engine to the blades and pump was achieved by a chain because of the high tor-
ques. On the other hand, the alternator was powered via a belt system since it is
cheaper than a chain system.
The hybrid system was built by using a gasoline engine and an alternator.
The robot was powered via 4 direct current (DC) motors and the energy to these
motors was supplied by the alternator. By using DC motors, there was no need
for a differential at the back wheels of the robot and a steering mechanism in the
front wheels.

Case 5: Which cables to use?
Any mechatronic application will require cabling. In practice, a cable can be
used for two different purposes, to carry power or signal. At first, the designer
should know the operating voltage and current as well as maximum allowed
voltage and current for the surge duration. Installation conditions also should
be known prior to cable selection. By using the necessary formulas (Chapter 10),
the load on the cable can be calculated. If the calculation is not done, the design
can be either overrated, causing a ticker cable to be used, or because of the use of
too thin cables, the wire will heat up and the insulation over the cable will get
damaged and will cause electrical failure in the system. Circuit breakers and
fuses can be used to decrease the damage of any electrical failure.

Case 6: Actuator selection and motor drivers
Electrical motors are preferred in mechatronics applications because of their
ease of control. A gasoline powered motor, a hydraulic, and a pneumatic actu-
ator have higher inertia compared to electrical motors and nonlinearity charac-
teristic in input to output.
During the selection of the motor (electrical actuator) the task should be
specified. In some applications, like an industrial robotic arm, the position