January 2025 - February 2025

Header Image: Adapted from [1]

💭 Problem Definition

TARGET DEMOGRAPHIC

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When it comes to using common cooking utensils in a kitchen environment, the level of risk associated with such a task is greatly magnified for individuals with limited hand mobility, such as those with arthritis or Parkinson's disease. This can ultimately affect their level of independence and quality of life. As such, it is necessary for technological advancements regarding kitchen appliances to improve the accessibility of cooking.

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NEED STATEMENT

Design an assistive device for individuals with motor deficits that improves their ability to cut food without risk of injury. The device should be able to determine the length of food and accept inputs for the size of cuts chosen by the user, using this information to determine how many cuts to make.

TRANSFERABLE AND TECHNICAL SKILLS

✔️ Computing (Python) and Output Device Initialization (Raspberry Pi)

✔️ Breadboard/Input and Output Device Wiring

✔️ Effective Note Taking

✔️ Professional Documentation and Academic Writing

✔️ Teamwork and Collaboration

Figure 1: A rocker knife is used by individuals with limited ranges of motion/hand mobility to cut food easily. However, it is still difficult for most users as it requires significant vertical force and stability, potentially causing strain or fatigue after extended use [2].

CONSTRAINTS & OBJECTIVES

The assistive device must:

1. Include a sensor and continuously input data from that sensor.
2. Have a moving mechanism that is controlled by an actuator.
3. Inform the user when the length of the cut is inconsistent with their set length.
4. Record the state of input and output devices and relay information to the user.

The assistive device should:

1. Be user-friendly for those with fine motor deficits and limited dexterity.
2. Withstand daily use and accidental impacts.
3. Function consistently without failures.
4. Allow the user to select the thickness of each cut.
5. Retract back to its initial position once food is removed.

🏅 Finalized Prototype

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The Steady Slicer features:

• Automated Food Length Detection
• Adjustable Cut Length
• Precise Mechanical Cutting Motion
• Interactive Feedback (LED alert) </aside>

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Application of the Steady Slicer: A piece of food is placed in front of the slider rack. The user selects the length of cut they require, then the slider pushes the food towards the slicer, which cuts the food. Once the food has been cut, the slider retracts back to it’s initial position.

Application of the Steady Slicer: A piece of food is placed in front of the slider rack. The user selects the length of cut they require, then the slider pushes the food towards the slicer, which cuts the food. Once the food has been cut, the slider retracts back to it’s initial position.

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📈 The Design Process

Whole Team Contributions

BRAINSTORMING

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Before arriving at our final design, the Steady Slicer, we shared multiple different ideas including a pill dispenser, Jackson Pratt drain modifications and automatic eyedroppers. Though each of these concepts had its benefits, they posed certain challenges when it came to fabrication. As such, we settled on a tabletop slicing device with the following components:

Cutting Arm Linkage

• Instead of a straight drop, we wanted to mimic how people usually angle knives. Therefore, we opted for a multi-bar linkage system attached to a motor, which recreated the pivot and downward slicing motion while keeping the user’s hands safely away.

Rack and Pinion Feeding Mechanism

• Although we initially planned on using a linear servo motor to push the food forward, it was hard to customize. As such, we decided to use a rack and pinion powered by a DC motor to support the consistent forward movement needed for each slice.

Slider Rail

• Adding a slider rail helped guide the blade in a straight, controlled path, which helped us achieve our goal of replicating human slicing behaviour by maintaining the blade at just the right angle to cut the food. </aside>

Figure 2: A storyboard highlighting each of the states of our mechanism starting from the moment food is placed on the cutting board.

DESIGN ITERATIONS

Figure 3: CAD model of the sliding rack and pinion mechanism.

Figure 4: CAD model of cutting arm linkage mechanism.

SOLID MODELLING SUBTEAM

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3D Modelling and Printing

1. We first calculated the gear ratio for the rotary DC motors and confirmed their dimensions. We then used Autodesk Inventor 3D modelling software to create our design. We started by making simple 2D drawings of all the parts - the cutting arm linkage and the gear system that moves the food (the rack and pinion).

After making sure everything would fit together properly and the motors were properly constrained to the gears, we used PrusaSlicer 3D printers to make all the parts.

Laser Cutting

1. While most parts were 3D-printed, the knife and guardrails needed to be laser cut. The edges of these components were sanded down after fabrication.

Assembly

1. Once all the pieces had been created, we began the final assembly of the Steady Slicer. Stationary components like the guardrails, motor shelves, and sensor holder were marked down and secured to the cutting board or cardboard base with super glue after confirming the slicing motion of the blade. The DC motors were friction-fit to the gears. </aside>