Assignment #4: Cupcake Decorator
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Goal:
The goal of this project is to design and create a 2.5 degree-of-freedom sub-system that can perform a task. The prototype must include both mechanical and electrical components. A physical prototype must show intent behind the design as well as efficiency. The simulation of the prototype must embody knowledge of the different ways to use various joints (i.e. revolute, prismatic, spherical, and universal)
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Constraints:
The following constraints must be considered when designing the mechanical sub-system:
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The prototype must be light enough and small enough to fit within a backpack.
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The work volume is limited to a size of 2.5 inch by 2.5 inch by 2.5 inch (the volume moved by the end effector).
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The device should be easily assembled and disassembled from components by a single person within 10 minutes.
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The material usage is limited to 2-meters of 8020 Aluminum, 3 stepper motors, 2 motor pulley, 2 idler pulley, and a pulley belt. All other parts must be 3-D printed.
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The Cupcake Decorator Concept:
The concept here is that the two pulley systems would be in perpendicular directions in the x and y-axis here would be powered by the given stepper motors to move two platforms anywhere along its direction. The chassis would be built using 8020 Aluminum. The motor and electrical components would be mounted to the side of the housing using 3-D printed parts. Since, only 2-meters of 8020 is given, the structure must would be conservative of material and therefore the initial design uses a 6-inch by 6-inch by 6-inch dimension. This would later change due to using recycled 8020 given in the classroom. The 3-D printed platform has a hole with a pattern that allows the belt can be inserted through so that the platform can be fixed to the belt. The third DOF comes from the vertical syringe movement which would also be powered by a stepper motor and a fixed screw system that would push and pull the end of the syringe depending on the direction of the motor.
The Simulation Model:
The CAD Components:
The Assembly of the System (SOLIDWORKS)
Front-view
Top-view
Side-view
Physical Prototype of Cupcake Decorator:
Conclusion and Future Work:
In conclusion, the 3-DOF system worked out as demonstrated in the video. The stepper motor was successful in moving the syringe in the X,Y, and Z axis. However, there were problems with the viscosity of the frosting which either prevented the right amount to come out or the fluid became too inviscid which allowed the frosting to freely flow through the tip of the syringe. This meant that fluid was continuously exiting and the desired design was not exactly possible (as demonstrated in the video). If more time was given or if a different syringe was to be used, preferably one which had less friction between the plunger and the liquid casing and one which a smaller syringe tip, the design may have come out more accurately. Additionally, the holes and shaft tolerances became an issue since sometimes the 3-D printed part had holes was inaccurate. This meant that extra measures such as drilling was needed in order to properly fit the shaft.
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Citations:
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BIOVIA, Dassault Systèmes, SOLIDWORKS Education, 2020, San Diego: Dassault Systèmes, Accessed March 23, 2021