3. Mechatronics system
A system can be thought of as a box or a bounded whole which has input and output elements, and a set of relationships between these elements. Figure 1.1.4 shows a typical spring system. It has ‘force' as an input which produces an ‘extension'. The input and output of this system follows the Hooke's law F = - kx, where F is force in N, x is distance in m and k is stiffness of the spring.
Figure 1.1.4 A spring-force system
Figure 1.1.5 Constituents of a mechatronics system
A Mechatronics system integrates various technologies involving sensors, measurement systems, drives, actuation systems, microprocessor systems and software engineering. Figure 1.1.5 shows the basic elements of a mechatronics system. Consider the example of a simple spring-mass system as shown in figure 1.1.4. To replace the mechanics of this mechanical system with an equivalent mechatronics based system, we need to have the basic controlling element, a microprocessor. Microprocessor processes or utilizes the information gathered from the sensor system and generates the signals of appropriate level and suitable kind (current or voltage) which will be used to actuate the required actuator viz. a hydraulic piston-cylinder device for extension of piston rod in this case. The microprocessor is programmed on the basis of the principle of Hooks' Law. The schematic of microprocessor based equivalent spring mass system is shown in figure 1.1.6.
Figure 1.1.6 Microprocessor based equivalent spring mass system
The input to the system is a force which can be sensed by suitable electro-mechanical sensors viz. piezo-electric device or strain gauges. These sensors generate either digital signals (0 or 1) or analogue signals (milli-volts or milli-amperes). These signals are then converted into right form and are attenuated to a right level which can properly be used by the microprocessor to take generate the actuation signals. Various electronics based auxiliary devices viz. Analogue-to-Digital Converter (ADC), Digital-to-Analogue Converter (DAC), Op-amps, Modulators, Linearization circuits, etc. are used to condition the signals which are either received by the microprocessor from the sensors or are sent to the actuators from the microprocessor. This mechatronics based spring-mass system has the input signals in the digital form which are received from the ADC and Piezo-electric sensor. The digital actuation signals generated by the microprocessors are converted into appropriate analogues signals. These analogue signals operate the hydraulic pump and control valves to achieve the desired displacement of the piston-rod.
In this course we will be studying in detail the various elements of a Mechtronics system (shown in figure 1.1.5) and their applications to manufacturing automation.
In the next lecture we will study the applications of Mechatronics in manufacturing engineering and in the subsequent lectures; above-mentioned elements will be discussed in detail.