Autonomous Robot — Anthony Claudet

project

Autonomous Obstacle-Avoidance Robot

ENGR 122 — Field Sustainable Systems with Sensors · Stevens Institute of Technology · Spring 2026

IN PROGRESS TEAM OF 3

Objective: Design, assemble, and program a tracked autonomous robot to guide visitors on a campus tour, navigating a course, detecting obstacles via ultrasonic sensors, and executing real-time avoidance — all without human input. The robot must safely reach four target locations in sequence using MQTT-provided coordinates.

System Overview

The robot is built on a Pololu Zumo tracked chassis controlled by a WeMos D1 R2 (ESP8266) microcontroller. Three HC-SR04 ultrasonic sensors provide spatial coverage across front-left, center, and front-right fields. A Feetech FT-SMC-2CH motor driver receives PWM signals to independently drive each tracked motor. An SSD1306 OLED display provides real-time sensor readout and system status.

All navigation runs on a single control loop: sensors poll sequentially, distances are evaluated against a 10 cm safety threshold, and the appropriate motion primitive — forward, reverse, turn left, turn right, or full stop — executes with calibrated PWM values. The OLED updates asynchronously every 500 ms using millis()-based scheduling.

Hardware — Build Photos

Robot front view — Early integration — WeMos D1 R2 and motor driver visible; wiring on breadboard.

Robot sensors — Three HC-SR04 sensors on front face — left, center, and right field coverage.

OLED display active — per-sensor distances and navigation status in real time.

Wiring & Pin Mapping

Compact breadboard atop the Zumo chassis. Motor power from onboard 4.8V NiMH battery; logic at 3.3V from the WeMos.

Peripheral	Signal	WeMos Pin	Notes
Motor Driver (FT-SMC-2CH)	Motor L	`D6`	Servo PWM via Servo.h
Motor Driver (FT-SMC-2CH)	Motor R	`D3`	Servo PWM via Servo.h
HC-SR04 (Center)	Trig / Echo	`D4 / D5`	Ultrasonic.h library
HC-SR04 (Left)	Trig / Echo	`RX / D0`	Ultrasonic.h library
HC-SR04 (Right)	Trig / Echo	`D7 / D8`	Ultrasonic.h library
OLED SSD1306	SDA / SCL	`D2 / D1`	I²C bus, address 0x3C

WeMos pinout — WeMos D1 R2 (ESP8266) Wi-Fi development board diagram.

Motor wiring — Wiring of WeMos D1 R2 to Feetech SMC 2CH & DC motors.

Key Code — Obstacle Avoidance Logic

C++, Arduino IDE. The control loop reads all three sensors, evaluates priority from most-blocked to least-blocked. Calibrated PWM values compensate for individual motor variance.

// Sensor thresholds and calibrated PWM constants
const int SAFE_DISTANCE = 10; // cm — triggers avoidance
const int STOP = 90; // neutral PWM
const int L_FWD = 60, R_FWD = 120; // motors mirror mounting
void loop() {
  int dC = sonarCenter.read(CM); delay(30);
  int dL = sonarLeft.read(CM);   delay(30);
  int dR = sonarRight.read(CM);  delay(30);
  if (dC <= SAFE && dL <= SAFE && dR <= SAFE) {
    stopMotors(); delay(200);
    moveReverse(); delay(400);
    turnRight(); delay(800); // U-turn escape
  } else if (dC <= SAFE) {
    (dL > dR) ? turnLeft() : turnRight();
    delay(500);
  } else if (dL <= SAFE) { turnRight(); delay(300); }
  else if (dR <= SAFE) { turnLeft(); delay(300); }
  else { moveForward(); }
  if (millis() - lastUpdate > 500) {
    updateDisplay(dL, dC, dR);
    lastUpdate = millis(); }
}

Competition Course

Obstacle course — Final course layout — robot navigates from SP to T1–T4, avoiding obstacles A–E.

3D Robot Sandbox

Drive the robot with WASD + Space to jump, or toggle autonomous mode. Place blocks to build your own course. Switch to the drone for aerial exploration.

ROBOT · MANUAL\nSPD: 0\nL:-- C:-- R:--

WASD — move · SPACE — jump
DRAG — orbit · SCROLL — zoom
Click terrain — place block

Status & Roadmap

✓ COMPLETED

Full chassis & motor assembly
3-sensor obstacle detection
PWM motor calibration
Real-time OLED display
Sensor-based avoidance logic
Non-blocking display scheduling

→ IN DEVELOPMENT

Waypoint sequencing (T1–T4)
Turn angle calibration
Open-loop path timing
Reduce sensor crosstalk
3D-printed sensor bracket