Enhancing learning of advanced topics in hydraulic controls.
Fluid power students encounter increasingly complex and sophisticated principles and applications in course and curriculum content. Mastery of detailed and comprehensive subject matter such as control systems is dictated by the expanding demands of the fluid power industry. Unfortunately, fluid power educators encounter many obstacles and constraints. State-of-the-art examples of electrohydraulic systems and controls are very expensive. Bench-type trainers are often perceived to be too abstract to students. Training equipment can quickly shift from state-of-the-art to obsolete technology in a very short period of time.
In contrast, well-designed, durable, and affordable training components and equipment are readily available for basic level hydraulic training. Traditionally, these devices are used in lab settings to construct specific hydraulic circuits. Students are expected to observe and report on the characteristics of these varied circuits. Lab reports are generally included in these exercises to promote in-depth learning and analysis. However, creativity and imagination are not strongly encouraged or rewarded. The goal is to have students integrate basic concepts of flow, pressure, and energy within operating systems.
The challenge to fluid power educators is to provide meaningful and effective laboratory activities involving higher level fluid power concepts without relying solely on bench-type training equipment. Students need to have access to and work on integrated systems which include electrohydraulic components such as proportional valves, servo valves, variable pumps, and actuators as well as controllers and sensors. Sensors are typically used to measure important parameters including displacement, position, pressure, temperature, speed, flow, and fluid level. Though essential, these types of applied laboratories must be conducted within the restraints of limited departmental budgets.
Educators in other technical fields have encountered similar problems providing cost effective and practical experiences for students in laboratory settings. As an example, Mooney (2006) discussed constraints such as costly equipment demands and effective student-to-faculty ratios in soil science laboratories. He also identified grants as potential sources of funding for equipment. Industries are often willing to provide direct donations of equipment. As an example, all of the equipment for the student team project discussed later in this paper was donated by two industry partners.
Individual or team assignments consisting of design and application projects in a real world setting are one way to help students learn advanced principles and applications involving instrumentation and control of fluid power systems. Advantages of such projects include encouraging independent learning, integrating knowledge, applying creative and critical thinking, enhancing diagnostics skills, developing teamwork, and improving interpersonal skills. Design and application projects also create the opportunity for increased and more nurturing interactions between students and industry technical personnel. These projects make learning fluid power concepts a more personal and focused experience for students. They also help increase students' interest in instrumentation and controls, which is very important to the fluid power industry. This article discusses the implementation and results of design and application projects in a capstone fluid power course.
Fluid Power Program
The fluid power major at The Ohio State University, Wooster Campus is an Associate of Applied Science degree program titled Hydraulic Power and Motion Control. The curriculum and its accompanying coursework are designed to prepare graduates to succeed in the following career areas in the fluid power industry:
* Systems design
* Installation of systems
* Maintenance and repairs
Employers of fluid power graduates include original equipment manufacturing companies, distributors, component suppliers, rebuilders, and manufacturing industries. Several personnel from these industry groups serve on the Hydraulic Power and Motion Control Advisory Committee. These individuals provide important and valuable feedback and direction on the content and focus of the program and specific coursework. The committee communicated the importance of increasing the emphasis on advanced training in instrumentation and controls. In response, additional projects involving analysis and design were incorporated in advanced fluid power coursework.
The capstone course in the Hydraulic Power and Motion Control program is titled Instrumentation and Control Systems and is designed to integrate knowledge of advanced elements of instrumentations and controls with real world applications. It is a three credit-hour course consisting of two hours of lecture/discussion and three hours of applied learning in a laboratory setting. Starting with the Winter Quarter 2005 course offering, design and application projects have been emphasized as a major applied learning activity. In order to be approved, projects selected by the students are required to have the appropriate technical content, level of difficulty, and timeline. The degree of student interest in the project is also an important factor in terms of value and success. Team projects are encouraged but not required.
Because of generous industry support, the department has a good selection of machines and equipment available for student use. These include industrial units and agricultural and construction equipment. The equipment controls range from programmable logic controllers (PLC's) to microprocessor monitored and controlled diesel engine and vehicle systems. Students are encouraged to interact with industry personnel concerning questions about the technology and help with the design and programming of controllers. Engine diagnostics, vehicle system diagnostics, and system optimization on mobile equipment have been found to be especially alluring to students in the program. Therefore, individuals or teams often select the readily available mobile equipment for their projects.
Design and Application Project
The major goal of the design and application project is for students to apply basic and advanced principles of instrumentation and controls to a real world hydraulic system application. Students are permitted to self-select a project; however, instructor approval is required. In order for a project to qualify and be approved, the following criteria have to be met:
* Appropriate level of complexity
* Satisfactory amount of time and effort required
* Inclusion of system design and application involving instrumentation and controls
* Completion with successful implementation and testing of the project
* Written report including discussion of results and recommendations concerning future projects
* High level of interest on the part of the student
Smaller or less complex projects have typically been appropriate for individuals. Examples include instrumentation of diesel engine systems and PLC control of a proportional motor drive. The individual approach works fine as long as the project complexity matches the student's capabilities and time constraints. The decision to tackle projects as a team or individually has been an interactive process between the students and instructor.
Unfortunately, individual projects have not included any significant industry involvement in terms of equipment donations, technology sharing or personal interaction. The reasons for this lack of involvement and support on the part of industrial partners include 1) the involvement of only one student in the project and 2) simple projects are not as attractive as bigger, more complex projects.
Students are encouraged to form teams because of the many educational benefits associated with group work. Advantages commonly cited include increased learning, longer retention, more active involvement, and greater satisfaction on the part of students (Davis, 1993). Davis also provides practical and helpful recommendations for successful group activities in such areas as strategy, organization, assignments, and evaluation.
Usually, students choose to participate in the team format with team sizes ranging from two to five members. Students appreciate the opportunity to divide the workload among the team members and the chance to select a particular area of project responsibility. This allows team members to take ownership of one or more parts of the project while also contributing to the overall group effort. Major challenges to team success have included timely communication of concerns, equitable distribution of the workload, and keeping updated on the status of the project. Good teams find ways to address issues, resolve problems, and achieve success.
A Representative Team Project
One specific team project involved a small remotely controlled mobile vehicle. This unit had recently been donated, and its technology and features attracted the interest of a student team. The vehicle characteristics included:
* Diesel power
* 4-wheel drive
* Electro-hydraulic independent 4-wheel steer
* Hydrostatic drive
* Radio remote control capability
Initially, the students were not in complete agreement on the project objectives. Intentionally, they were given liberal latitude by the instructor and were content with simply investigating the controls and systems of the vehicle. The technical documentation available for the machine was minimal, thus compelling students to apply their knowledge of control systems while they made measurements and developed schematics. A perceived lack of direction and cohesion prevailed until the students began to work as an effective team--gathering information, asking questions, sharing duties, and seeking help.
The second phase of the project began when the instructor and the team narrowed the focus of the project to include only the steering system with specific objectives of adding more features and modes. The team was confident the goals could be met by installing a new controller with reconfigured controls.
In the third phase of the project, the instructor and team members solicited industry assistance. Christy, Lima and Ward (2000) discuss in detail the value of student project teams interacting with real-world industry contacts. In this case, the industry partner volunteered expertise, hardware, and software to support the newly established goals of the project. The instructor, students and industry partners together addressed the problems and chose the appropriate approaches to finding solutions.
The students became an effective team and made appropriate progress throughout the duration of the project. With proper planning, there was sufficient time available to do the necessary optimization and fine tuning of control parameters. The new control design was successfully implemented and tested. Students increased their understanding of the purpose and relevance of control functions. Additionally, they gained an appreciation for the realities of problem solving and troubleshooting in control development and diagnostics. Industry support proved to be invaluable in the programming and fine tuning phases. Students benefited from interaction with skilled and capable engineering technicians who were trained and experienced in the field of controls. A positive, experimental learning environment was achieved in a manner relevant to the career paths of graduates of fluid power programs.
Another very important part of a laboratory learning experience is documentation and reporting. Zimmerman (1992) described three of the most common laboratory writing formats and discussed the merits of each. For this project, students were required to keep records of activities and progress in journals. Students were allowed to choose the format and structure of the final lab report. This "student-directed format/notebook" approach allowed for greater flexibility of the complex project. Involvement of both students and industry contributors was well documented in the process.
Students were very satisfied with the results of the project. The performance of the vehicle controls was impressive and the system was easily tuned to meet different operator preferences. This perceived level of success greatly reinforced the technical training as well as enhanced communication and business skills. Another encouraging result was that several students offered suggestions for plausible future projects involving the vehicle control systems.
Design and application projects are valuable in advanced fluid power courses to augment classroom content and laboratory experiences. The use of appropriate equipment to engage individual students and student teams in meaningful and challenging projects is critical to stimulating students and preparing them for a future in the fluid power industry.
The exposure to industry components, software, and trained technicians is an especially valuable part of the learning experience of the projects. The interaction with industry personnel also demonstrates to students the need for professionalism in documentation and communications. In addition, industry support of the design and application projects provides an excellent example to students of the importance management places on a well-prepared and professional workforce.
Christy, A. D., Lima, M., & Ward, A. D. (2000). Implementing real-world problem solving projects in a team setting. NACTA Journal, 44 (3), 72-77.
Davis, G. L. (1993). Collaborative learning: Group work and study teams. In B. G. Davis (Ed.), Tools for teaching (pp. 147-158). San Francisco, CA: Jossey-Bass Publishers.
Mooney, S. J. (2006). A simple group work approach for effective field work: A soil sciences case study. Journal of Geoscience Education, 54 (1), 74-79.
Zimmerman, A. P. (1992). Laboratory assignments in writing-across-the-curriculum. NACTA Journal, 36(1), 7-10.
John W. Arnold is Assistant Professor of Engineering Technologies and Allen P. Zimmerman is Professor of Engineering Technology and Technical Physics at Ohio State University, Wooster, Ohio.
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|Author:||Arnold, John W.; Zimmerman, Allen P.|
|Date:||Sep 22, 2009|
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