Product Development · Mechatronics · Systems Integration

Automated Powder Dispenser

A precision dispenser that automates powdered supplements with ±1 g accuracy. I led the end-to-end product development—from user research and PRD to architecture, controls, and validation—integrating mechanical design, embedded software, and electronics.

Product Vision & Execution Strategy

Goal: Define a precise, automated dispenser that eliminates the mess and inconsistency of manual scooping while maintaining simplicity and reliability for fitness enthusiasts and health-conscious users.

Outcome: A functional MVP that won "Best Entrepreneurship Award" for execution and market validation, delivering ±1g accuracy with 98% success rate and 3-second average cycle time.

My Role: Product lead and systems engineer across the full development cycle. Performing user research and PRD development. Concept selection using weighted decision matrix. Mechanical design: transmission, bearings, and alignment systems. Embedded software: state machine, PWM control, interrupt handling. Creating timelines and iterative improvements based on performance.

Requirements & Scoped Features

Precision & Reliability

±1g accuracy target with real-time feedback control via load cell and HX711 amplifier. Robust state machine prevents operational errors and ensures consistent performance.

User Experience Focus

Simple 3-step process: select weight, confirm tare, dispense. LCD guidance reduces setup errors while debounced interrupts prevent false triggers during operation.

Mechanical Integration

Helical auger with 4:1 transmission for smooth flow control. Modular hopper design enables easy cleaning and refilling while maintaining food safety standards.

Scalable Architecture

Single-powder MVP to de-risk flow variability and contamination. Modular design supports future multi-compartment expansion with anti-cross-contamination features.

System Performance

±1 g

Accuracy

98%

Success Rate

3 s

Avg Cycle

250 g/min

Flow Rate

Execution Plan & Milestones

User Insights & PRD

Interviews surfaced accuracy and simplicity as must-haves. PRD fixed an MVP scope: single powder, ±1 g accuracy, hands-off operation.

Concept Selection & Validation

Weighted matrix favored auger + feedback. Early breadboards validated signal quality from HX711 and UI latency with debounced interrupts.

Mechanical Design & CAD

4:1 gearing improved effective resolution and torque margin. Bearings/collars constrained shafts; coupler handled minor misalignment.

Control Software & States

Finite state machine with timeouts and proportional slowdown near target. LCD prompts guided setup, reducing misuse.

Testing & Iteration

Addressed gear wear, improved shaft support, added motor timeout when weight stalls; refined funnel and cup recess for repeatability.

System Components

ESP32 Controller

Main processing unit with PWM motor control and interrupt handling

HX711 Load Cell Amp

High-precision weight measurement with real-time feedback

Helical Auger System

4:1 geared mechanism for controlled powder flow

LCD Display

User guidance and weight selection interface

State Machine Control

Robust software architecture with safety interlocks

Modular Housing

Food-safe components with easy cleaning access

Control Software Architecture

// State machine core (ESP32)
#define SETTING 0
#define SETWAIT 1
#define CONFIRMGO 2
#define REACHED 3

volatile bool buttonIsPressed = false;
int state = SETTING;
int desiredWeight = 0;     // from POT
long currentWeight = 0;    // from HX711
int threshold = 0;

void loop(){
  switch(state){
    case SETTING:
      checkPot();                   // map POT → grams
      if(CheckForButtonPress()) state = SETWAIT;
      break;
    case SETWAIT:
      if(CheckForButtonPress()){
        scale.tare();               // zero scale
        state = CONFIRMGO;
      }
      break;
    case CONFIRMGO:
      currentWeight = scale.get_units();
      runMotorUntilWeight(153, currentWeight, threshold); // PWM control
      state = REACHED;
      break;
    case REACHED:
      stopMotor(); delay(7000);     // show result, then reset
      state = SETTING;
      break;
  }
}

Build Photos & Development

Technical Challenges & Solutions

Precision Control: Achieving ±1g accuracy required implementing proportional PWM control near the target weight to prevent overshoot. The 4:1 gear reduction provided both the necessary torque and finer control resolution.

Mechanical Reliability: Initial gear wear issues were addressed through material selection and improved shaft support with bearings and collars. Added flexible coupling to handle minor misalignments without binding.

User Experience: Debounced interrupt handling prevented false button triggers, while the structured state machine with LCD prompts guided users through the proper tare and dispense sequence, significantly reducing operational errors.

System Integration: Careful wiring layout isolated sensitive analog measurements from motor noise. Real-time tare functionality and drift compensation maintained accuracy across extended use sessions.

Product Management Takeaways

User-Driven Requirements

Direct user interviews revealed that accuracy and simplicity trumped feature complexity, leading to a focused MVP scope that delivered core value effectively.

Systematic Decision Making

Weighted decision matrix for concept selection provided clear rationale for technical choices and enabled stakeholder alignment on architecture decisions.

Risk-Based Development

Single-powder MVP de-risked contamination and calibration challenges while establishing a scalable foundation for multi-compartment expansion.

Iterative Validation

Continuous testing and feedback integration improved mechanical reliability and user experience, resulting in 98% success rate in final validation.