Computer Controlled Instrumentation Projects By Sophomore Level Eet Students

This paper presents student-initiated projects as part of an instrumentation and data acquisition course for sophomore-level electronics engineering technology students. Project objectives and associated assessment methodologies as well as general project management concepts are discussed. Two sample instrumentation projects reported in this paper are an automated street parking system and a computer-controlled bowling game system. Both projects focused on instrumentation system development integrating multiple sensors and actuators, data acquisition hardware, interface electronics, control logic implementation in LabVIEW software, and wood/metal work for prototype development. These end-of-semester course projects were carried out during the final four weeks of the semester after eleven weeks of lecture/laboratory session. Introduction The ability to conduct and design experiments is rated as one of the most desirable technical skills of engineering and engineering technology graduates. Specifically, the referenced survey indicates that employers want graduates with a working knowledge of data acquisition, analysis and interpretation; and an ability to formulate a range of alternative problem solutions. Additionally, potential employers of our EET graduates are in the automated manufacturing and testing sector of the industry providing additional motivation for an instrumentation and data acquisition course at the sophomore level of a four-year EET program. This course consists of two hours of lecture and three hours of laboratory per week. Students have had courses in electrical circuit analysis, electrical machines, and analog and digital electronics before taking this course. The first three weeks of the fifteen-week semester are devoted primarily to LabVIEW programming. During the next eight weeks, the concepts and integration of sensors and actuators, interface electronics, and data acquisition and instrument control hardware /software are covered. The final four weeks are dedicated to student-initiated laboratory design projects. This paper focuses on general approach to implementing end-of-semester course projects and associated assessment tools used to assess the project objectives. Technical details of two sample instrumentation projects, an automated street parking system and a computerized bowling game system, implemented during the spring-2007 semester are also presented. Course project objectives and the associated assessment method The learning and teaching objectives for the project experience are listed in the next page. A list of questions was prepared based on the stated objectives, and the survey was conducted at the end of second and fourth week of the four-week project experience as an indirect assessment tool. The results of the first survey was used to improve the project experience during the second half, and the results of the second survey is to be used to improve the next offering of the instrumentation project experience in spring-2008. Students are also assessed using direct assessment tools for teamwork, oral presentation, final report, successful operation and demonstration of the completed project, and design review meetings. Example rubrics used to assess teamwork and oral presentation are shown in Appendices A and B, respectively. Results of direct and indirect assessment instruments are archived for use as an input to the course P ge 13322.2 continuous improvement process and also as part of display materials for program accreditation visits. Project Learning Objectives Project Teaching Objectives ‚ Gain experience in interpreting technical specifications and selecting sensors and transducers for a given application ‚ Foster discovery, self-teaching, and encourage desire and ability for life-long learning ‚ Understand terminologies associated with instrumentation systems ‚ Provide experience in designing instrumentation system based on specifications ‚ Gain experience in developing computerized instrumentation systems for industrial processes using multiple sensors, interface electronics, data acquisition hardware, and GPIB and serial instruments ‚ Develop soft skills including teamwork, openended problem solving, formal report writing and oral presentation Project management Early in the semester students start developing potential project topics with appropriate feedback and guidance from the instructor leading to a required pre-proposal submission by the fifth week of the semester. Upon approval of the pre-proposal, students are required to submit a formal proposal for a specific project topic by the ninth week of the fifteen-week semester. Use of a minimum of four sensors/transducers and four actuators is required as part of any project. The required proposal is quite detailed as it includes project implementation ideas supported by major outcomes and specifications, I/O interface drawing, circuit schematics, parts list with vendor and price information, LabVIEW program flow chart, and project completion schedule including a Gantt chart. An example student-generated Gantt chart is shown in Appendix C, prepared using Vision Professional. For implementation of the project, students are in charge of selecting the necessary sensors and actuators and are required to use the well-equipped departmental shop for fabrication and metal/wood work. Each group of two students is allocated a nominal budget of $200 for purchasing project-specific parts not normally available in the laboratory. Project deliverables include pre-proposal, proposal, preliminary design review, critical design review, final report, and a formal presentation. Student presentations and final reports are archived for use as part of the display materials for future accreditation visits. Laboratory setup Each station is equipped with a PC, and GPIB/RS-232 interfaced instruments such as digital multimeter, triple output laboratory power supply, arbitrary function generator, and two-channel color digital oscilloscope. The instrumentation and data acquisition specific software and hardware are briefly described below. Software: LabVIEW 8.5 from National Instruments Data acquisition (DAQ) board: Model 6024E from National Instruments ‚ 16 single-ended or 8 differential analog input channels, 12 bit resolution, 200 kS/s ‚ 2 analog voltage output channels, 12 bit resolution, 10 kHz update rate ‚ 8 digital I/O channels with TTL/CMOS compatibility; and Timing I/O GPIB controller board: ‚ IEEE 488.2 compatible architecture (eight-bit parallel, byte-serial, asynchronous data transfer) ‚ Maximum data transfer rate of 1 MB/sec within the worst-case transmission line specifications Signal conditioning accessory: ‚ Model SC-2075 from National Instruments ‚ Desktop signal breakout board with built-in power supplies, connects directly to 6024E DAQ board P ge 13322.3 Sample Project: Automated street parking system The objective of the automated street parking system was to implement a prioritized parking system with prepayment and post payment options including a boot system for parking violators. For this street parking management system, three categories of cars are considered: resident, frequent, and visitor. A resident car can be parked for an unlimited amount of time without accruing any fines, a frequent car can be parked on a daily basis for a limited number of hours to be billed for parking fees on a biweekly basis, and a visitor car would need to pay upfront for parking. Additionally, activation of a boot system from under the street upon expiration of parking credit and/or other violations was an integral part of the system. A block diagram representation of the I/O interface for the street parking system is shown in Figure 1 and a pictorial view of the system is shown in Figure 2. This prototype system consisted of three parking spots along a street. A total of eight analog inputs were used in implementing the system: three inputs for detecting the type of car, three inputs for parking spot availability status, one input for spot selection for prepayment, and an additional input for coin collection system. The coin collection system was based on an inductive proximity sensor while the other seven input signals were based on simple voltage divider networks and/or photoresistors. An example voltage-divider based interface for prepayment spot selection is shown in Figure 3. Figure 1: A block diagram representation of the I/O interface for the automated street parking system. P ge 13322.4 Figure 2: A pictorial view of the automated street parking system. Figure 3: Implementation of the spot selection logic for prepayment. The parking system used a total of nine outputs: six digital outputs for various parking status indicators and three analog (but used as digital) outputs for driving the solenoids for the boot system. In case of malfunctioning of the car type detection system for a given spot, the status light will turn red and draw attention of the police via the end of street display lights. This end of street display and the boot system get activated in case of an unpaid visitor car in a spot. For an activated boot deployment system, only the police personnel can release the boot system. After the car is removed from the spot, the system resets itself for the next car to be parked. The control logic for this system was implemented in LabVIEW software. A typical front panel display for the automated street parking system is shown in Figure 4 and it includes status monitoring of the following subsystems: parking spot, boot activation, prepayment, coin collection, and prepaid parking timer. The corresponding block diagram for implementing the Figure 4: A typical front panel display of the automated street parking system. P ge 13322.5 parking spot logic functions are shown in Figure 5. The major LabVIEW function blocks used are case structure, sequence structure, for loop, subVIs, local variable, various array and string f