Design and Construction of Hardware Extensions (Add-

Ons) for a Modular Self-Reconfigurable Robot System

Mohamed MareiACS420

Presentation Outline• Introduction (MSR)• Hi-Gen Module• Hardware Extensions (Add-Ons)• Architecture• Design

• Phase 1: Hardware (Electronics)• Phase 2: Hardware (Chassis)• Phase 3: Software Design

• Add-on Testing• Conclusion and Further Work• Questions

Aims and ObjectivesAims• Study, design, and build a hardware add-on for a Modular Self-Reconfigurable

Robot (MSR) system under development (the HiGen Module)Objectives• Research MSR theory and implementations• Research applications of MSR systems• Design and build a hardware add-on (extension) for the HiGen module• Program and test the hardware add-on• Conduct experiments to assess the utility of the add-on

Introduction (MSR)• Modular Self-Reconfigurable Robots (MSR)

• Concept credited to Fukuda (Dynamically Reconfigurable Robot) [1]

• Designed to fit any given task through reconfiguration

• Lattice, Chain, and Hybrid Architectures

• Homogeneous, Heterogeneous

ATRON: Snake and vehicle-like[2]

Thor: Heterogeneous MSR[3]

SuperBot: Bipedal Configuration[4]

HiGen Module• HiGen: High-speed Genderless Mechanical Connection Mechanism for Self-

Reconfigurable Modular Robots• Genderless nature enables single-sided disconnect• HiGen Module: Modular robot with four HiGen connectors

HiGen Module[6]

Standalone HiGen Connector[5]

Hardware Extensions (Add-Ons)• Add functional “tools” to the robot• Increase the utility of the robot• Tool examples: sensors (camera modules); functional (grippers, wheels, etc.)

CKBot with camera module[7]

Add-on Modules of Thor[2]

Architecture• Add-on computer: retrieve data and

transmit it to workstation PC, acting as the robot “brain”; communicate with PC for coordination

• Add-on connects to the Connector Controller via the Tool Expander

• Add-on as a whole connected to another robot via its Connector Controller

The vision add-on connected to the HiGen Robot Workstation

Phase 1: Electronics Design• Research into previous implementations of camera add-ons• Based on Requirements decided with C. Parrott• SBC (Single-board Computer) as the “brain” of the add-on• Research into SBC’s Raspberry Pi Model A+ and NoIR Camera

Raspberry Pi Model A+Raspberry Pi NoIR Camera Teensy 3.2 Board Connector Controller[Parrott]

Phase 1 (Continued): Power Consumption• Assessed the power requirements of the add-on to ensure it could be powered

through other HiGen modules (at completion)• Used a 5V, 2A regulated bench power supply with current measurement

Test Description Average Current Draw (mA)

Pi Minimal boot voltage: only the Pi connected to the Wi-Fi dongle

110

Pi and all electronics (camera, Teensy, servos) connected; idle 350

Pi and all electronics connected and normal activity 950

Phase 1 (Continued): Electronics• Tool Expander: Connects the HiGen

connector (and other robots) to the Pi via UART serial• Connects to the HiGen CAN bus• Communications middleman• Teensy 3.2 + CAN transceiver +

Potentiometer + Resistors• PCB using DesignSpark PCB

Prototype version of the Tool Expander Board

Phase 1 (Continued): Schematic and PCB• Designed the schematic of the add-on using DesignSpark PCB

Schematic Diagram PCB Layout

Phase 2: Hardware (Chassis) DesignPan-Tilt Camera Mechanism (PTM)Enclosure Design

Pan-Tilt Mechanism RangeEnclosure showing hole placement

Phase 2: Full Add-On Construction• Missing: HiGen Connector and Connector Controller (CC)

Phase 3: Software Design• Step 1: Operating System (OS) Selection• Raspbian Wheezy (variant of Linux Debian)• MATLAB and Simulink support package

• Step 2: Networking• Wi-Fi Configuration• Secure Shell (SSH)• MATLAB command window

• Step 3: Motor Control• Teensy 3.2 Microcontroller• Microcontroller programming to control servos

Phase 3 (Continued): MATLAB• Data acquisition• Lightweight image processing (as opposed to using e.g. OpenCV [8])• Simulink support package for hardware: Raspberry Pi and ARM

Microcontrollers• Control design made easier through Simulink• Integration of the steps in software design (Step 1, Step 2, and Step 3)• Internet of Things support using ThingSpeak (later)

Add-on Testing (Task Execution)• Combine the image processing functionality from the Pi with motor

control• Locating and tracking a stationary green object

Add-On Testing (Task Execution)• Attempted to integrate tracking functionality with servo control to

track a moving object• Serial communication pathway from Pi Tool Expander: problem• Instrument Control Toolbox: successful communication with Tool

Expander• Explored alternative: design communication system in Simulink• Integration still failed• Third alternative: PC-in-the-loop• Successful communication between Pi, Tool Expander and PC

Add-On Testing (Control and Data Acquisition)• Pan-tilt tracking: modelling using framework outlined by Chen et al. [9]• Experiment: Object fixed distance and position away from add-on• Constant position constant tracking angles• Not the case

Conclusion and Further WorkAchievements• Hardware design of the add-on• Successful programming and testing independent functions• Attempted to combine functionality but faced problems• Demonstrated the add-on’s ability to execute application-relevant tasks and acquire data• Attempted to model and simulate the pan-tilt auto-tracking problem to develop a controllerFurther Work• Finalize integration and test with Connector Controller and HiGen connector• Verify tracking model and implement on the Raspberry Pi• Exploit the Raspberry Pi to enable Internet of Things (IoT) access through ThingSpeak [10]

Questions?Thank You

References• [1] Fukuda, T., & Nakagawa, S. (1987, October). A dynamically reconfigurable robotic system (concept of a system and optimal

configurations). In Robotics and IECON'87 Conferences (pp. 588-595). International Society for Optics and Photonics.• [2] Østergaard, E. H., Kassow, K., Beck, R., & Lund, H. H. (2006). Design of the ATRON lattice-based self-reconfigurable robot.

Autonomous Robots, 21(2), 165-183.

• [3] Salemi, B., Moll, M., & Shen, W. M. (2006, October). SUPERBOT: A deployable, multi-functional, and modular self-reconfigurable robotic system. In Intelligent Robots and Systems, 2006 IEEE/RSJ International Conference on (pp. 3636-3641). IEEE.

• [4] Lyder, A., Garcia, R. F. M., & Stoy, K. (2010). Genderless connection mechanism for modular robots introducing torque transmission between modules. In Proceedings of the ICRA Workshop on Modular Robots, State of the Art (pp. 77-81).

• [5] Parrott, C., Dodd, T. J., & Gross, R. (2014, September). HiGen: A high-speed genderless mechanical connection mechanism with single-sided disconnect for self-reconfigurable modular robots. In Intelligent Robots and Systems (IROS 2014), 2014 IEEE/RSJ International Conference on (pp. 3926-3932). IEEE.

• [6] Parrott, C., Dodd, T. J., & Gross, R. (2014) Towards a 3-DOF mobile and self-reconfigurable modular robot.

• [7] Shirmohammadi, B., Taylor, C. J., Yim, M., Sastra, J., & Park, M. (2007, September). Using smart cameras to localize self-assembling modular robots. In Distributed Smart Cameras, 2007. ICDSC'07. First ACM/IEEE International Conference on (pp. 76-80). IEEE.

• [8] Open-Source Computer Vision Library (OpenCV). URL: http://opencv.org/

• [9] Chen, G., St-Charles, P. L., Bouachir, W., Bilodeau, G. A., & Bergevin, R. (2015, September). Reproducible Evaluation of Pan-Tilt-Zoom Tracking. In Image Processing (ICIP), 2015 IEEE International Conference on (pp. 2055-2059). IEEE.

• [10] The Internet of Things: ThingSpeak. URL: https://thingspeak.com