Conveyor Sorting System
A mechatronic system to sort blocks of aluminium, steel and 2 types of plastic
Group Members: Nicholas Whyte and Keira Lane
Mechatronics Test
The Problem
For the mechatronics design project, my partner and I designed, created and implemented a system that could identify and sort cylinders of four different material types. The four types of material were classified as steel, aluminium, white plastic, and black plastic. The final grade assigned for the project was an A.
The Design
An apparatus was provided that consisted of a DC motor powered conveyor belt, and a unipolar stepper motor connected to a four-section tray; one section for each different material type. Additionally, three sensors (ferromagnetic, reflective and optical) were used to identify material type and position of the pieces along the belt. A hall effect sensor was used to set the stepper to the home position. The following diagram shows the system's high level block diagram:
The team was responsible for connecting an appropriate circuit to the provided apparatus and for implementing an efficient algorithm to control the apparatus and sort in a timely and accurate manner. The desired outcome was to use the apparatus to move the cylinders along the DC motor driven belt, use the sensors to identify the type of cylinder present, and adjust the stepper motor so that each cylinder fell into its corresponding bucket.
Objectives
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Write code that incorporates all sensors and identifies the ranges of sensor values (high/low or analogue range) required to differentiate between cylinder material types.
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Sort an unknown quantity of cylinders of different material types into the correct bin in the fastest time possible, by optimizing the use of the stepper motor to drive the tray and the DC motor to drive the conveyer belt.
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Include a ‘pause’ functionality that, when a button is pressed, the system pauses sorting and displays, using LEDs, items that were fully or partially processed when button was activated.
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Include a ‘system ramp down’ functionality that, when a button is pressed, the system finishes sorting items on the belt and then displays using LEDs the items that were sorted.
System Algorithm
Conclusions
Through the design and testing phases, the maximum and recommended operating parameters of the system were identified. Parameters were optimized for both speed and accuracy.
There were various system limitations and trade-offs identified during the design and testing process. The DC motor created a lot of noise that would sometimes disrupt correct function of the sensors. The tray size and position would allow pieces to become jammed between the tray and the DC motor belt. Also, the acceleration profile created for the stepper would fail when heavy weights were applied to the stepper.
Overall, the system that was implemented was successful and could sort cylinders into their correct bin consistently.