Page 39 - Electric Drives and Electromechanical Systems
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Chapter 1 Electromechanical systems 31
FIG. 1.18 Block diagram of a motion-control system typically used in robots and machine tools.
The encoders and transducers required to provide feedback of the load’s position
and speed to the controller.
The motor controller, and motor. In most cases, these can be considered to be an
integral package, as the operation and characteristics of the motor being totally
dependent on its control package. Depending on the motor type, position and
current feedback may be required.
The transmission system. This takes the motor output and undertakes the required
speed changes and, if required, a rotary-to-linear translation.
The load. The driven elements greatly influence the operation of the complete sys-
tem. It should be noted that a number of parameters, including inertia, external
loads, and friction, may vary as a function of time, and need to be fully determined
at the start of the design process.
The key to successful implementation of a drive system is full identification of the
applications needs and hence its requirements; these are summarised in Table 1.2.In
order to select the correct system elements for an application, a number of activities,
ranging over all aspects of the application, have to be undertaken. The key stages of the
process can be identified as follows:
Collection of the data. The key to satisfactory selection and commissioning of a
motor drive system is the collection of all the relevant data before starting the
sizing and selection process. The information obtained will mostly relate to the
system’s operation but may also include commercial considerations.
Sizing of the system. The size of the various drive components can be determined
from the data collected earlier.
Identification of the system to be used. Once the size of the various elements and
the application requirements are known, the identity of the various elements can
be indicated. At this stage, the types of the motor, feedback transducer, and
controller required can be finalised.
Selection of the components. Using the acquired knowledge, the selection process
can be started. If the items cannot be supplied and the selection revised, or the
