I don't know if anyone has mentioned this yet, there is video of the device in use - http://www.segway.com
Reese ---------------
It is petty and stupid of me to be annoyed by Kamen. But there is something about him that pisses me off. He reminds me of Gates---billionair slime, pseudo-mysterious, tech-savy wonder-boy-cool manufactured as personae: jeans, worn boots fetish, youngish, makes it all sound like altruism. Gotta be scum. Probably has a little dick.
[Let's go to full techo-babble alert, Scotty. The wing-nuts and propeller beanies are loose in the quadrant. Attention Ian and Les are you all still out there?]
After looking around at Kamen's two-wheel power scooter I have to admit, even if (or probably because) it is irrelevant, there is still, something very neat about it. (Damn. I hate it, when it turns out like that.) The idea of using a stirling engine is also very neat. So the scooter is different since the power is supplied by a hydrogen engine (heat exchange?), which uses pistons in a perpendicular configuration turning on an eccentric crank, for zero angular momentum. Here's the design patent (wait for it to fully load and go down to the bottom to see the illustrations):
http://www.stirlingengine.com/kamen/dean_kamen_patent.html
I have to guess the scooter uses an inertial gyroscope somehow coupled to the joystick/controller. It might not, but that would be one approach. This would make sense if the IBOT used a similar joystick/gyro/controller arrangement---which I suspect it might.
Guessing at it, the core wheelchair control idea depends on processing and integrating the resistance changes in an inductive joystick, the voltage changes in dc motors and the motion sensor data of an inertial gyroscope.
The standard underlying power stage of the controller driving the motors, uses power transistors in a bridge driven by a pulse width modulated switching circuit. Microprocessors were introduced to monitor both the joystick input signal, and the battery, motor current, in order to protect the power transistor bridge. The reason all that is needed is the bridge is driven at a high oscillating frequency (above hearing range) to a close tolerance to keep the transistors from burning out, and in case of a closed short, to turn off the system to keep the chair from driving full speed locked on via a dead short.
Getting back to gyros, motors and controllers, the military use related principles in everything from nuclear missiles and jets to the latest smart bombs and killer drones blitzing Afghanistan.
One of the more interesting problems is designing an approach (chaos theory) to filtering and measuring meaningful information (signal) out of multiple and inter-related but constantly changing feed-back loops (potential noise) and calibrating all this to desired tolerances.
Motion in the joystick alters (via processors/switching circuits) voltage in the motors (alias motion) which change the inertial state of the gyro, which in turn feeds back to the processors/switching circuits which control the motors.
For a robotic example see:
http://www.egr.msu.edu/microrobot/
The other interesting part is miniturization of the controller/gyro system. The part of the system that I am not at all familiar with are the inertial gyroscopes and how they are integrated into the joystick/controller system. Some very low grade microchip accelerometers are used in auto electronics to trigger air bags.
At the other end of the spectrum are some very sophisticated devices, right up there at the top of the techie robotic food-chain (DARPA, defense advanced research projects agency, MEMs, micro electro-mechanical systems, SOI, silicone on insulator).
As far as I understand it the top end of micro inertial gyroscopes and accelerometers use micro rotors, and micro combs that respond (electrostatic excitation) to changes of motion, registered as coriolis forces on the microrotors or translation forces on microcombs:
http://www.imi-mems.com/pastproj.htm
http://buffy.eecs.berkeley.edu/IRO/Summary/98abstracts/aseshia.1.html
http://mae.eng.uci.edu/mems/inertial_mems.htm
A lot of the software monitoring and driving this shit is written in GNUs C++. Remote controlled killer drones run FreeBSD or Linux? Must use picoBSD in an embedded controller, booted from flash or eeproms. How depressing.
For the less thrilling, crappy local police-state and terrorist grade applications see:
http://www.xbow.com/html/gyros/gyro_ov.htm
The software claims to monitor wireless vehicle telemetry and data acquistion. The illustration shows a truck being monitored (range 20miles) presumably by the dispatcher/control freak (not shown) at a PC. Perfect for remote car bombing. Works only on NT and Win95 naturally.
Chuck Grimes