Session: ASME Undergraduate Student Design Expo

Paper Number: 176163

A Lab Introducing the Components of a Mechatronic System 

A mechatronic system consists of four major components namely mechanism, actuator, sensor and control algorithm. A mechanism can be a linkage, gear-train or cam-follower system while an actuator can be one of several types of motors or linear actuator. There are several types of sensors such as a hall-effect sensor, encoder, inertial measurement unit (IMU), etc. that can be integrated into a system. The data from the sensors are collected, analyzed and used in a control algorithm that will be used to actuate the input to the mechanism. In addition to these standard components, there are a lot of electrical and electronic components including microcontrollers, motor drivers and others that are used in conjunction with the four components to realize a mechatronic system.

In typical engineering courses involving experimentation, students are exposed to a standard actuator (such as stepper motor or servo motor) with a motor driver, a microcontroller board (Arduino Uno) and sensors (IMU and ultrasonic sensor). These components can directly interface with the microcontroller board and are made operational through a straightforward program and circuitry. But a typical mechatronic system has a lot more components and it is important to introduce those to students to make them industry ready.

At Worcester Polytechnic Institute, a system for eddy current braking was developed for a research project and it included several mechanisms, actuators and sensors along with a control algorithm. The system essentially involved a flywheel that was spun to a certain speed and was brought to a complete stop using eddy current braking. The flywheel is spun to the required speed using a friction wheel arrangement. The friction wheel is controlled by a brushless DC motor with encoder. A linear actuator is used to move the friction wheel so that it can contact the flywheel. There is also an emergency brake that utilizes a servo motor and a caliper brake to stop the spinning wheel. The whole system is controlled using an Arduino Mega microcontroller along with several motor drivers, relays, regulators along with sensors such as an encoder and a hall effect sensor.

The experiment in the course involved students spinning the friction wheel to 1000rpm. Once the speed is attained, which is verified using a handheld tachometer, the linear actuator is engaged so that the friction wheel and the flywheel can make contact. This would enable the flywheel to rotate at around 500 rpm, which is also verified using the tachometer and a custom encoder. During the first trial, the students measure the time taken for the flywheel to come to a stop (the data is automatically saved as a comma separated value file) without the use of eddy current braking. During the second trial, the electromagnet is engaged and the time for the flywheel to come to a stop is measured. The difference between the two trials would display the eddy current braking effect. As part of the report, the students were required to provide a description of all the electronics used in the construction of this system. This lab provided a good exposure to students on various components of a typical mechatronic system along with experience trying to use handheld measurement tools like the tachometer and a vernier caliper.

The poster will detail the machine, lab activity and the experiences of the teaching team and the students.

Presenting Author: Caleb Cotoia Worcester Polytechnic Institute

Presenting Author Biography: BS student in both Mechanical and Robotics Engineering at Worcester Polytechnic Institute.

Authors:

Samuel Gervasi Worcester Polytechnic Institute
Caleb Cotoia Worcester Polytechnic Institute
Pradeep Radhakrishnan Worcester Polytechnic Institute
Cam Tu Le Worcester Polytechnic Institute