Calling bike physics/tech experts!

[bogan]

I'm a bit pissed, but steppers can do a lot more than position things with some processor behind them. Yes you will have to think in advance what will happen - theres no way you will be able to just fire some step commands at a corner, but I think in the end there is a lot more that can be accomplished.

You will have to hydraulic-damp any pneumatics or other force-based systems or bumps are going to be hell. Maybe at high speed it will be smooth, but at low speed it will flop around like a bitch.

With displacement servos you will need to measure steering system torque and follow the front wheel around with the stepper to set torque to the desired amount. So the steering input will be that torque you measured rather than the steering input you created. Clear as mud? So you don't talk to the stepper directly - the torque feedback loop does, and you just input what steering torque you want and the stepper ramps it up.


Steve

Ok, will add steppers to the shortlist.

I'll see what the damping is like in the chosen steering system before adding another one, the voice-coil may have enough control to do it, will ask my flatmate as he knows more about that sort of thing than I.

Hmmm, not overly sure what you mean with using both...

[bogan]

I'd be keen to help out, obviously we'd need to set this up on a gsxr-1000 and make it do a lap of pukekohe or something.

I think you could avoid using a stepper motor by using a pulley system with to control the steering with a gyro and Ping-type sensors on either side of the body to figure out lean angle. It would work similar to the typical 'balancing bot' project that you see guys doing as basic microcontroller programming projects.

Then you could get hardout with a forward-facing laser scanner to map upcoming contours and such to anticipate bumps and dips or just make sure it doesn't run into anything.

It's not just the alcomohol talking, I'm keen.

yip, that'd be the final goal of the project, dunno if anyone would give me a gixxer atm though. Hmmm, interesting idea with the mechanical control, but I'd want more direct computer control over things than that, the sensors and equipment i plan on using would be able to simulate such a system anyway if needed. Lidar is sooo last decade, machine vision is the way. But yeh, thanks for the offer and chances are I'll take you up on it once the project gets started.

[bogan]

They do use contra-rotating flywheels. I’d say the aim is to eliminate precession issues (the 90deg deviation to external inputs) but retain the stability function.




A gyro is the easiest way to get attitude data, an accelerometer won’t work. Yup, get an old laptop for a donor. In fact you could build a tolerably good gyro from the hard drive…

Be much easier if you don’t mind recycling existing systems. Go see New Age Materials on Gracefield Rd and rummage through their stuff. Or Casa Modular Systems in Petone.

hmmm, I though the two were linked, back to physics school for me!

An accelerometer will work (test rig bout a year ago), but is susceptible to bumps and fast orientation changes, I'm thinking a gyro is the way to go this time.

I have access to a CNC mill so probably will make a really accurate usb gyro module, as it will be the main measurement device. Will salvage the bits for throttle, clutch, brakes, shifter, fold up trainer wheels, etc where possible, but wont skimp on quality for the important stuff, as I've learnt you will only have to redo it later anyway.

Will keep the pneumatic actuator off in mind, thanks.

[bogan]

Perhaps I've missed the point here, but wouldn't it be easier to just ride it yourself.

yup, missed it by a mile

[bogan]

Ok, I'm pretty sure I was right about the contra-rotating discs see bottom of this page perhaps you are refering to the triple gyro set up (one for each axis)?

[Ocean1]

Those flywheels aren't rotating on the same axis, they're both on an independantly mounted fulcrum.

[Redstar]

effort was made into the creation of a gyroscopic regenerative motor for Train propoltion it worked ,but required a dead straight track as when the gyro was effected laterally in a off line direction the reaction gyro set the train in the oposite direction and that created an wobble that grew into a catatropic situation, its critical to have a compensation drive stabiliser that consists of a conical belt componation drive stabiliser two horizontally opposed conical drives with a soft rubber belt as it gyros it will automatically create a reverse bias that will as least maintain the bike in a straight direction. when the bike is turned there will need to be a fluid gravity pump that sends weight from the down side to the up side the fluid is pumped hydracaccally using the turn solenoids it needs to be a high pressure systems using DOT 3 oil and a high pressure capacity pump. retractable stabalisation minor tractor wheels may be advisable? owing to the relative delay in solenoid activation a pre primed pressure release secondary solenoid is advisable. Gravity plays a big part in stabilisation so keeping the weight low and having the pump that conical inverter lower in the frame is a must. Usually Eddie currents and electromagnetic induction in the electrial system will need a sink earth capacitor say 200 micro farads accross all solonoids or other inductive loads is always a good idea. The unwanted flux measured in Henry.s should not exceed 1.3 Joules thats a watt / per second for the uninitiated otherwise your bike is sound well done.

[bogan]

Those flywheels aren't rotating on the same axis, they're both on an independantly mounted fulcrum.

yeh, they ain't contra-rotating in the pic either, its once of the sentences lower down

Many other arrangements are possible - two contra-rotating flywheels close to each other on the same axis will do the trick; the gyroscopic moments cancel out but the angular moments add

edit: fuck it, 2moro i'm gonna tape some angle grinders together and see what the go is, If i don't post again, it all went horribly wrong

[Ocean1]

Bolt propellers to 'em.

And for fuck's sake don't turn them over, you'll dissappear up yer own woirmhole.

[marty]

can't be fucked reading all the above, but at low speed steering is all good, but even my C90 scooter steers via countersteering above about 30km/h.

[bogan]

Bolt propellers to 'em.

And for fuck's sake don't turn them over, you'll dissappear up yer own woirmhole.

That doesn't sound pleasant at all! So ended up bolting them together (using their handles and a bit of plate), really wanna find something that needs grinding like that now. Anyway, no noticeable difference between having none on or both on for moving them round, one on is harder as well as precession being noticeable; so guess they do cancel out.