LURCH - The autonomous wheelchair
L.U.R.C.H. is the acronym of "Let Unleashed Robots Crawl the House".
LURCH is an extended version of an commercial electric wheelchair (Rabbit by OttoBock) equipped with:
- An interface circuit for digital drive via a radio serial link (XBee modules)
- Two on-board computers (PCBricks), powered by wheelchair batteries
- A 7-inch touchscreen monitor (Xenarc 700TSW), 800x480 resolution (16:10 AR)
- Two laser scanners Hokuyo URG 04LX
- A colour camera FireI400 (resolution 640×480)
- An odometry system based on encoders applied to the rear wheels
Main goals of the LURCH project are:
- Add sensors and robotic functionalities to the powered wheelchair.
- Add various command interfaces, such as Joypad wireless, speech command, brain-computer interface.
- Semi-autonomous navigation with collision and obstacle avoidance.
- Autonomous navigation by path planning and localization.
Functions currently provided by LURCH:
- Driving by the original joystick or a Logitech RumblePad2 wireless joypad.
- Obstacle sensing using planar scanner lasers.
- Basic collision and obstacle avoidance behaviours.
- Indoor localization by a fiducial marker system
- Path planning and basic autonomous navigation.
- Documentation on the interface circuit between the wheelchair joystick and computer: Media:LurchCircuitDocument.pdf.
- WARNING: the circuit was modified and the documentation above is upgraded by this new file: Media:LurchXBee.pdf.
- How to modify the wheelchair joystick to connect to the interface circuit: Media:LurchCircuitJoystick.pdf.
- Brief discussion about the interface circuit between the wheelchair joystick and computer: Media:LurchCircuitJoystickBrief.pdf.
- Brief description of the LURCH project: Media:LurchBriefDesc.pdf.
- Brief description of the communication between the wheelchair interface circuit and a PC via RS232 port: Media:LurchProtocol.pdf.
- Source code for PIC 18F452 microprocessor and Eagle project (schematic and board): Media:LurchCircuitProject.zip.
- Thesis by Simone Ceriani, titled Sviluppo di una carrozzina autonoma d'ausilio ai disabili motori (Development of an autonomous wheelchair to help motor-disabled persons): Media:LurchThesisCeriani.pdf (in Italian)
- Thesis presentation by Simone Ceriani (note: Videos don't work, you can found similar videos below): Media:LurchPresentazioneThesisCeriani.zip
PCBrick-03 and PCBrick-05 feature Xubuntu Linux 7.10, Xfce Window Manager, Openchrome graphics drivers and eGalax touchscreen drivers v1.08.1227 (Drivers here). The touchscreen is configured and calibrated on both machines, hence it can be used with either one or the other indifferently.
A universal interface to connect various models of joysticks to the wheelchair onboard systems is currently under design. The interface should be programmable in order to accept absolute or differential analog voltage inputs and generate a coherent output, while transferring the values read to the PC via serial port.
LURCH YouTube Videos
Marco Dalli (Tesista)
Simone Ceriani (Assegnista di ricerca)
Matteo Rossi (Tesista)
Laboratory work and risk analysis
Laboratory work for this project is mainly performed at AIRLab/Lambrate. It includes some mechanical work and electrical and electronic activity. Potentially risky activities are the following:
- Use of mechanical tools. Standard safety measures described in Safety norms will be followed.
- Use of soldering iron. Standard safety measures described in Safety norms will be followed.
- Transportation of heavy loads (e.g. robots). Standard safety measures described in Safety norms will be followed.
- Robot testing. Standard safety measures described in Safety norms will be followed.