A Low-Cost Control System Experiment for Engineering Technology Students

Curtis Cohenour

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Conference: 2017 ASEE Annual Conference & Exposition
Location: Columbus, Ohio
Publication Date: June 24, 2017
Start Date: June 24, 2017
End Date: June 28, 2017
Conference Session: EET Papers 2
Tagged Division: Engineering Technology
Page Count: 19
DOI: 10.18260/1-2--27474
Permanent URL: https://peer.asee.org/27474
Download Count: 3291

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Curtis Cohenour P.E. Ohio University

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Dr. Cohenour is an Assistant Professor in the Ohio University Engineering Technology and Management Department, in Athens, Ohio. He received a Bachelor of Science degree from West Virginia Institute of Technology in 1980, a Master of Science degree from Ohio University in 1988, and a Ph. D. in Electrical Engineering from Ohio University in 2009. He is a registered professional engineer in West Virginia, and Ohio.

Dr. Cohenour has worked in Industry as an electrical engineer and project manager. He joined Ohio University in 2002 as a research engineer working for the Ohio University Avionics Engineering Center. He has worked on projects covering a wide variety of avionics and navigation systems such as, the Instrument Landing System (ILS), Microwave Landing System (MLS), Distance Measuring Equipment (DME), LAAS, WAAS, and GPS.

His recent work has included research with the Air Force Research Laboratory in Dayton, Ohio, aimed at understanding and correcting image geo-registration errors from a number of airborne platforms.

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Abstract

A low-cost control system experiment is presented. The plant for the control system is a modified Radio Control (RC) servo. The servo is modified by removing the controller, then brining the two motor leads, and the three potentiometer (pot) leads outside the servo case. The motor and pot are connected to an Arduino Uno R3. Inputs for auto manual selection, manual inputs, and additional pots are connected for reference and gain adjustments.

This experiment is part of an electronics course in Engineering Technology and Management (ETM). The electronics course uses the Arduino Uno R3 to teach electronics, real time programing, and with this experiment, PID control. There is no time allotted in this course for traditional frequency based or time based control system design, but this simple set up allows the student to experience many of the situations that arise in industrial control systems.

The student learns about input, output, feedback, and control. The first step for the student is to move the servo by hand and observe the feedback from the pot. The student then runs the motor and observes the direction. The student can then determine the sign of the feedback, and implement manual control.

The motor is connected to two Arduino outputs. This creates an H-bridge. Dead-band control is implemented by setting the outputs high and low for one direction, low and high for the reverse, and low and low for stop. The student sets the dead-bands to allow the servo output to follow a reference pot. At this point the student has performed his/her first control system startup and likely experienced many of the challenges of commissioning a control system.

The Arduino outputs connected to the motor are capable of Pulse Width Modulation (PWM). Proportional output is achieved by setting one output pin low, while the other is controlled using PWM. This allows proportional control of the motor in either direction. The student can now implement proportional only control. The student can turn the pot by hand and feel the control system response. This gives the student a direct kinesthetic learning experience.

Advanced learners can now add integral and derivative control. The addition of integral control forces the student to understand initialization and integral windup. The student writes the Proportional Integral Derivative (PID) control algorithm such that auto/manual transitions and gain changes are bumpless.

The addition of the control system experiment cost less than $5.00 per student, but provides the student with a realistic control system problem complete with all of the vagaries of an in-plant control system commissioning.

Citation
Format

Cohenour, C. (2017, June), A Low-Cost Control System Experiment for Engineering Technology Students Paper presented at 2017 ASEE Annual Conference & Exposition, Columbus, Ohio. 10.18260/1-2--27474

TY - CPAPER
AB - A low-cost control system experiment is presented. The plant for the control system is a modified Radio Control (RC) servo. The servo is modified by removing the controller, then brining the two motor leads, and the three potentiometer (pot) leads outside the servo case. The motor and pot are connected to an Arduino Uno R3. Inputs for auto manual selection, manual inputs, and additional pots are connected for reference and gain adjustments.

This experiment is part of an electronics course in Engineering Technology and Management (ETM). The electronics course uses the Arduino Uno R3 to teach electronics, real time programing, and with this experiment, PID control. There is no time allotted in this course for traditional frequency based or time based control system design, but this simple set up allows the student to experience many of the situations that arise in industrial control systems.

The student learns about input, output, feedback, and control. The first step for the student is to move the servo by hand and observe the feedback from the pot. The student then runs the motor and observes the direction. The student can then determine the sign of the feedback, and implement manual control.

The motor is connected to two Arduino outputs. This creates an H-bridge. Dead-band control is implemented by setting the outputs high and low for one direction, low and high for the reverse, and low and low for stop. The student sets the dead-bands to allow the servo output to follow a reference pot. At this point the student has performed his/her first control system startup and likely experienced many of the challenges of commissioning a control system.

The Arduino outputs connected to the motor are capable of Pulse Width Modulation (PWM). Proportional output is achieved by setting one output pin low, while the other is controlled using PWM. This allows proportional control of the motor in either direction. The student can now implement proportional only control. The student can turn the pot by hand and feel the control system response. This gives the student a direct kinesthetic learning experience.

Advanced learners can now add integral and derivative control. The addition of integral control forces the student to understand initialization and integral windup. The student writes the Proportional Integral Derivative (PID) control algorithm such that auto/manual transitions and gain changes are bumpless.

The addition of the control system experiment cost less than $5.00 per student, but provides the student with a realistic control system problem complete with all of the vagaries of an in-plant control system commissioning.

AU - Curtis Cohenour P.E.
CY - Columbus, Ohio
DA - 2017/06/24
PB - ASEE Conferences
TI - A Low-Cost Control System Experiment for Engineering Technology Students
UR - https://peer.asee.org/27474
DO - 10.18260/1-2--27474
ER -