MDRobot
The original and longest-running project — a robotic platform that tows a metal detector coil array across an open area and scans it automatically or under teleoperation. Towing the coil keeps the detector away from the robot’s own metal so it doesn’t trigger on itself.
Scan patterns include back-and-forth lawnmower and circular spirals. The platform doubles as a general-purpose robotics development rig.
Major subsystems
Power. Dual 12V 35 Ah batteries, 600W sinewave inverter. The batteries drive a Sabertooth 2×25 amplifier directly. The inverter feeds the control rails: 5V for SBCs, 12V for the WiFi router, 24V for contactors and brakes, ±15V for current sensors and the detector circuitry.
Supervisory control. A high-level Windows PC running an Azure-based GUI with a SQL Server historian, plus several Raspberry Pi SBCs running Codesys SoftPLC runtimes. The main Pi interfaces to a custom baseboard hosting a Teensy 3.1, a 10-DOF IMU, and a 4-channel I²C DAC that drives the Sabertooth.
Positioning. Adafruit Ultimate GPS Hat on the robot, IMU, wheel encoders for dead reckoning, plus a three-corner beacon system — each beacon a Pi with its own GPS hat, exposing readings over a Modbus server. The supervisor polls the beacons via Modbus client and fuses the data for scan-area position.
Metal detecting subsystem. Multiple pulse-induction detection circuits driving a large PI coil and smaller coils mounted on a PVC frame. The frame lifts on a linear actuator for turning or obstacle clearance. Each coil is fired in sequence to avoid interference, with detections routed back to the supervisor over WiFi and logged with GPS + dead-reckoning + beacon-triangulated coordinates.
Operator interfaces. A hand pendant (ESP8266 + Teensy, dual-axis joystick, LCD, E-stop) for basic driving and emergency stop, plus a base station laptop connecting via VNC to the Windows PC’s Azure GUI. Eventually a 3D virtual-environment client.
Heritage
This is where the project started. The Blogspot archive (see blog) documents the build log going back to 2012.