automatic knife-slicing device

an estimated ten percent of the world lives with dyspraxia, a developmental coordination disorder that makes fine motor tasks difficult. cutting food with a handheld knife is one of the hardest of these, often forcing dependence on others and carrying a real risk of injury. steadyslicer automates that task so that slicing takes only a few button presses instead of precise hand coordination, making a critical step of meal preparation safer and more independent.

the user places food within the guardrails and sets a slice width with three buttons, adjusting up or down from a 5 mm default — buttons were chosen because they need minimal force and precision. a time-of-flight VL53L0X distance sensor reads the change from the empty-board distance to measure the item's length, and if that reading falls within a valid range the mechanism starts.

two DC motors then drive the cut. one turns a rack-and-pinion feed that pushes the food forward by the set distance; the other drives a two-bar linkage that moves the blade in a proper heel-to-toe slicing motion, through a 2:5 gear pair and a 4.7 linkage-to-shaft ratio, with a slider rail constraining the knife to linear travel. the device slices twice at each location to guarantee a complete cut, repeating until the slider reaches the knife or the food passes the sensor's minimum distance, at which point the rack and pinion retract and it resets for the next use. a red LED signals when something is off, such as a cut that missed its length or the feed failing to fully retract. the control system runs on a raspberry pi in python using the gpiozero library, structured modularly with separate inputs.py and outputs.py modules and a main script managing the automation loop.

the two-bar linkage and customizable cut spacing were the design's strengths, but the prototype had clear limits: a single fixed slicing speed, best results only on firm and uniform foods, a DC motor that did not reliably retract the rack to its start position, and components that were not easily removable for cleaning. the strongest candidates for a next version were adjustable slicing speeds, food clamps or holders that adapt to texture for better stability, removable parts for hygiene, and richer interfaces such as voice activation or an app to widen access for users with more severe fine motor deficits.