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Massive mesh wanderer

Introduction

An autonomous wifi device that roams the experimental mesh to research protocol behaviour under dynamic conditions.

Subsystems

Wifi card for experiment

Mother board

Soekris

Power supply

- 7Ah 12v lead-acid alarm battery weighs +-2,5kg.
- Ten 2,3Ah NiMH (12v) with holder weighs only 0,25kg.
- Lead-acid charge 8 to 14hr, NiMH charge 1-4hr.
- Lightweight 2,3Ah batteries would probably give the same range as heavy 7Ah Lead-acid battry.
- NiMH charger a bit more sophisticated.
- Seperate batteries for WiFi & Robot traction recommended (GvdB)
Charging station for recharching battery

Drive chain

options: motors, gears/pullies, tracs/tyres ..
- Tracs not recommended for carpets. (GvdB)
- Nice motorised & gearde wheels at http://www.tecel.com/gearwheel/. At ~ 40cm/second these might be too fast :-( (acdc) http://www.tecel.com/pics/gmw01.jpg

sensors (proximity/touch/visual?)

- First just some machanical touch sensors, later we could try IR and Ultrasonic distance sensors.

guidance computer ..

- Very simple with mainly crash avoidance and some local command execution (assist straight line movement, forward/backward x cm., turn X deg, move x cm in an arc of y cm radius).
- Suggests major movement directives are controlled by remote computer via camera in ceiling. This will allow high-level programming .. even make inter-active click and go commands on screen possible. Dynamic changes to environment could be accommodated without sophisticated on-board guidance computer. Video from camera could be used to record and correlate tests results, can also have huge WEB (read marketing) impact. Camera could be B&W but should provide reasonable resolution +-1000 pixels (GvdB)

communication for controlling

- a) Bluetooth, but it might interfere with WiFi.
- b) 802.11a as Mesh test management, control and status link but also as Wanderer command, control and feedback link. This 5GHz link should not interfere with the 802.11b Mesh network and should allow fast enough feedback for remote control of Wanderer robot. Interface to Wanderer control computer could be via serial port. (GvdB)

Options

We can collaborate with UP's soccerbot team.
- Do they only work on university-term intervals? That would require us to catch them when the new year starts...
We can collaborate with M+Mtek. I have invited Riaan Coetzee of M+Mtek to participate (acdc).
We can purchase a ready-made kit for the mechanics and assemble it ourselves

Lego Mindstorms

Use our Lego Mindstorms set to do initial concept demonsration
Interface to the brick using David's IR module.

Specs

size

Needs to fit through the experimental mesh without touching. Possibly a high 'Turtle' type shape to prevent snagging wires (GvdB)

weight

< 50kg - no < 5kg .. We must be able to pick it up ;-) (GvdB)

dimensions .. Max dimension 25cm - to fit between boxes (GvdB)
turning radius .. must be able to turn in it's own size
minimum running time without visiting recharge station

0.5 hr .. If it could do 8 hours with 10% movement duty cycle, it would be super (GvdB)

minimum speed

1 cm/second

maximum speed

10 cm/second

load carrying abilities

1 kg

- load dimensions
- load weight
- load power requirements (A Soekris would require +-1/2Ah so that is 4Ah for 8hrs)(GvdB)
form factor (round/square) .. Round to turn in its own space and not snag wires (GvdB)
mechanical noise levels

< 80 dB at 1m