Washington, District of Columbia
June 23, 1996
June 23, 1996
June 26, 1996
1.288.1 - 1.288.7
Introduction to Hydraulic and Logic Systems in a Controls Course
Joey K. Parker, Dale Schinstock Department of Mechanical Engineering The University of Alabama, Tuscaloosa, AL
Abstract A four week long module on industrial hydraulics and logic control systems is described. This module is taught in an otherwise conventional senior level controls course that emphasizes feedback control systems. Students are introduced to hydraulic system components and circuit design considerations. Logic control systems, including programmable logic controllers (PLC’s), are introduced next. Pneumatic systems are introduced as a special form of hydraulics. Some tutorial introduction to the material is given along with several specific design guidelines for the students. A representative student design project is also described.
Introduction Many mechanical and electrical engineering programs include a required or elective course in control systems. The topical outlines for these courses typically follow the approaches used in the numerous textbooks available. Closed loop, feedback control system analysis is greatly emphasized, both from the transfer function and state space points of view. Little or no mention is made of another broad class of topics, logic control systems, which are very commonly found in industrial applications.
Logic control systems are used with sensors and actuators that operate in a simple “on/off“ mode (for example a light switch). A great deal of simple automation can be accomplished with inexpensive pneumatic cylinders and a few solenoid valves. Unfortunately, many students are never exposed to even the most basic concepts of this powerful and widely used control system technique. Additionally, many students are simply unaware of the wide variety of actuators and sensors that are available for use in control systems. One reason for this is the faculty's lack of familiarity with these subjects. Another is the perception that there is not enough “room” in the course for adding this material. A third reason is that texts and other supporting materials are not as readily available for logic control as for feedback control systems.
The purpose of this paper is to attempt to address some of these concerns by providing a description of the relative simple, but very practical, material that we use. We have successfully incorporated a four week long hydraulics and logic control systems component into our required senior level control systems course (outline given in Table 1). Our focus is on hydraulic and logic control system design, not the selection of specific components, i.e. we work at a “schematic” level. We introduce hydraulic system components first for three reasons. 1. Students learn the available components and can quickly create a schematic of systems to be controlled. 2. Most mechanical engineering students have a better “feel” and appreciation for hydraulic actuators than electric motors. 3. The incompressible nature of hydraulic fluid system makes them somewhat easier to understand than compressible fluid systems (pneumatics), although the much lower cost of pneumatics makes them very attractive in many applications.
1996 ASEE Annual Conference Proceedings
Parker, J. K., & Schinstock, D. (1996, June), Introduction To Hydraulic & Logic Systems In A Controls Course Paper presented at 1996 Annual Conference, Washington, District of Columbia. https://peer.asee.org/6150
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