Assistive Feeding Robot Product

Overview

An assistive feeding robot is a tabletop arm bringing independence and dignity to individuals with severe motor disabilities who cannot self-feed. Users with advanced ALS (amyotrophic lateral sclerosis), spinal cord injury (SCI), severe cerebral palsy, or post-stroke paralysis retain cognitive ability but lack the motor control to lift utensils or maneuver food. The robot addresses this functional gap: the user selects which course to eat (via a sip-puff switch, large button, joystick, or eye-gaze interface), the [[assistive-feeding-robot-face-camera|camera]] identifies the user's mouth location, and the [[assistive-feeding-robot-arm|four-axis arm]] autonomously approaches with the [[assistive-feeding-robot-spoon|spoon]], delivers a bite, and retracts. The [[assistive-feeding-robot-bowl-carousel|carousel]] cycles through multiple dishes, allowing normal meal progression without external help.

The user retains autonomy over what, when, and how much to eat—critical to psychological well-being. The arm is safe (force-limited, collision-detecting) and unobtrusive (sits beside the table, powder-coated aluminum frame).

Arm design and kinematics

The [[assistive-feeding-robot-arm|four-axis arm]] is lightweight and compliant:

• [[assistive-feeding-robot-base-joint|Base joint]]: rotating shoulder, 360° swing around the user.
• [[assistive-feeding-robot-shoulder-lift|Shoulder lift]]: vertical reach 0–60 cm, accommodating sitting heights 80–120 cm.
• [[assistive-feeding-robot-elbow|Elbow]]: extension 0–90°, bringing spoon to face.
• [[assistive-feeding-robot-wrist|Wrist]]: rotation ±45°, orienting spoon for scooping or level delivery.

Each joint is driven by a [[assistive-feeding-robot-joint-motor|low-torque BLDC servo]] (max 5 N-m) capped at 5 N peak force at the spoon tip—safer than hand-fed bites from a caregiver. The [[assistive-feeding-robot-controller|SoC]] solves inverse kinematics in real time, accepting high-level commands ("next course", "open carousel", "feed me") and translating them into smooth joint trajectories. An [[encoder|encoder]] on each joint provides closed-loop feedback, ensuring repeatable positioning within ±20 mm—good enough to reliably find the mouth even if the user shifts position slightly.

Spoon and carousel system

The [[assistive-feeding-robot-spoon|spoon utensil]] is stainless steel with a rounded 8 cm bowl, sized for comfortable bite-sized portions (~50 mL). A [[assistive-feeding-robot-load-sensor|strain gauge]] under the bowl detects how much food is loaded; the [[assistive-feeding-robot-controller|controller]] uses this to calibrate approach speed and angle—a full spoon approaches slower than an empty one, preventing spills. A [[assistive-feeding-robot-spoon-quick-couple|bayonet quick-change]] lets the user swap the spoon for a [[assistive-feeding-robot-spoon-bowl|fork]] (for solids like meat or vegetables), or a cup with straw (for liquids or smooth textures).

The [[assistive-feeding-robot-bowl-carousel|carousel]] holds 3–4 bowls on a rotating platform. A [[assistive-feeding-robot-carousel-motor|stepper motor]] indexes to the next bowl; the user's input (button press or switch) triggers a sequence: arm retracts, carousel rotates, arm re-approaches the new bowl, ready to scoop. This enables a normal meal flow: starter, main course, dessert—without manual intervention or disassembly.

Face tracking and autonomous feeding

The [[assistive-feeding-robot-face-camera|overhead camera]] runs a trained neural model identifying the user's face and mouth in real time. During a normal feeding cycle:

1. User activates a control input (sip, button, etc.) indicating readiness.
2. Arm retracts from last position, dips spoon into the carousel bowl, and scoops.
3. Camera detects mouth opening (or the user's preferred "ready" signal).
4. Arm approaches at 5 cm/s, positioning the spoon at the mouth center.
5. User pulls food into mouth and swallows.
6. Arm waits ~3 seconds (user chewing time), then retracts.
7. Cycle repeats or pauses based on user control.

If the user shifts position (head movement), the camera re-detects the new mouth position and the controller adjusts the approach trajectory mid-motion—real-time guidance ensuring the spoon stays on target. If the user coughs or turns away unexpectedly, a [[assistive-feeding-robot-safety|safety coprocessor]] detects the change in sensor data and immediately halts the arm, preventing accidents.

Control interfaces and accessibility

The [[assistive-feeding-robot-switch-interface|input interface]] is modular, matching the user's capabilities:

• Sip-puff switch: A sensitive air-pressure sensor detecting breath. Single sip = "feed me", double sip = "next course", puff = "pause/stop". Zero hand strength required, works for locked-in patients.
• Button array: Large (5 cm) soft-touch buttons labeled with photos of food. Finger or hand movement required. Easy to use for users with residual upper-limb control.
• Joystick: Proportional low-force analog stick commanding arm speed and direction. For users with enough hand dexterity to steer.
• Eye-gaze tracking (optional): Infrared eye-tracker letting the user point at a food photo on-screen, selecting it by dwelling the gaze. Enables feeding for individuals who cannot move hands, head, or speak.

All inputs feed into the same [[assistive-feeding-robot-controller|SoC]], which interprets commands in the context of the meal state—if the user is mid-chew, a second "feed" command is ignored; if the carousel is empty, a "next course" command prompts verbal feedback ("Bowl is empty, please refill").

Safety and collision detection

The [[assistive-feeding-robot-safety|safety system]] monitors [[assistive-feeding-robot-joint-current-sensor|motor current]] on each joint in real time. If the arm contacts the user's face unexpectedly (e.g., user turns toward the arm), the sudden motor stall is detected within 50 ms, the current cut, and the arm backs away under gentle spring force. All joints are mechanically limited with [[assistive-feeding-robot-elbow|soft end-stops]] preventing over-extension.

A large red [[assistive-feeding-robot-estop-button|e-stop button]] is placed within reach of the user's caregiver or reachable by cheek/chin movement if the user has any facial control. Pressing it instantly halts all motion, and requires manual reset—a critical safeguard for unexpected situations.

Daily use and care

The robot sits on a wheeled [[assistive-feeding-robot-base|base pedestal]] (25 kg weighted, preventing tipping) that can be repositioned around the table to accommodate different seating. The [[assistive-feeding-robot-battery|integrated Li-ion battery]] powers 8–10 hours per charge (roughly three meals per day with snacks), and overnight charging from standard wall power restores full capacity.

A caregiver loads the [[assistive-feeding-robot-bowl-carousel|carousel bowls]] before the meal (normal caregiver task) and monitors the feeding session from a distance. The user controls pace and portion size, dramatically reducing caregiver burden compared to hand-feeding. Studies show that users report restored autonomy, improved appetite (eating at their own pace improves digestion), and reduced caregiver stress—making this device one of the highest-impact assistive robots for quality-of-life outcomes.

Cleaning is straightforward: the [[assistive-feeding-robot-spoon-quick-couple|quick-change spoon]] detaches for dishwashing, and the arm frame wipes clean with a damp cloth.