Embedded control for a three-tube concentric tube robot: an Arduino Mega driving seven stepper motors with limit-switch protection, and a MATLAB GUI that visualises the robot and sends inverse-kinematic commands over serial.
Built during a research visit to IIT Madras in 2018, modelled on the concentric tube robot at QUT.
Status: archived. Complete as of the 2018 visit and not maintained.
A concentric tube robot is steered by rotating and translating pre-curved tubes relative to one another, so the control problem is coordinating every tube axis at once to hit a commanded tip pose.
Three tubes, seven motors. Each tube gets two — one to rotate it, one to translate it — for six axes of shape control, plus a seventh driving the gripper.
- On the Arduino: stepper coordination and the inverse kinematics, solved on-device using matrix arithmetic.
- On the host: a MATLAB GUI that renders the robot's configuration and sends target poses over the serial link.
- Limit switches on interrupts. Concentric tubes can collide with themselves when the axes run past one another. The switches are wired to hardware interrupts so motion halts immediately rather than at the end of the current control cycle — a software poll is not fast enough to protect the mechanism.
Two Arduino libraries, neither vendored here:
#include <AccelStepper.h> // https://github.com/waspinator/AccelStepper
#include <MatrixMath.h> // https://github.com/eecharlie/MatrixMathPlus MATLAB on the host for the GUI.
Flash the Arduino:
SnakeRobotIITMadrasSerialInterface.ino
Then start the GUI in MATLAB:
SnakeRobotIITMadrasGUI.mThe steppers need their own power supply — the Arduino cannot drive them from board power.
A photograph of the actual wiring rather than a schematic. It is what exists.
The concentric tube robot at QUT that this one is modelled on, teleoperated by hand gesture: hand_gesture_control_snakebot — Razjigaev et al., ROBIO 2017.
MIT — see LICENSE.
Written by Andrew Razjigaev. Questions: andrew_razjigaev@outlook.com