Hey Guys,
I was thinking about building a Motorized Bicycle with 3-Phase Brushless Motor + Arduino. Since this is a very critical application I think that PPM is a way too unsecure way to controll this. Imagine suddenly the controller crashes and the bike goes crazy... I need an ESC that is properly controlled by some data-lane with safe parity and some way to set it to trystate on crash. Any suggestions? (Best would be to directly programm the driver into Arduino in some way)
veecue
I can't see why you'd want PPM, when PWM would be more appropriate.
What's wrong with the Servo library?
Imagine that (for any reason you can imagine), the controller crashes WHILE the pulse is sent. This can create a 1 ms pulse out of a 2 ms second pulse and therefore let's the motor stop instantly. Are there any DRCs with a instant-tristate safety pin? PPM would be a possible way for data transfer, but i need additional saftey. Any ideas how to do this?
But after the controller crashes, you'll get no more pulses produced until the microcontroller reboots.
veecue:
(Best would be to directly programm the driver into Arduino in some way)
I can't see how that would deal with an Arduino crash any better than using a standard Arduino library - it would still be the same Arduino that crashes.
The sort of crash-proof-ness that you are talking about would probably need 3 MCUs each running a different program that produces the same result and another system to compare the results. (I believe that is how an Airbus is controlled).
On a bicycle the standard Servo library and a BIG RED SWITCH for the user might be a more sensible option.
...R
ESCs are probably more robust than you think - they have to cope with RF drop-outs when used on
model planes so missing pulses and random nonsense may be filtered out to some extent and the failsafe
response to throttle down is probably preprogrammed. There are ESCs that can be programmed and
customized too.
The most import safety device is a cutout switch on the power - and easy to add.
The kind of motor intended for bikes have hall sensors and suitable controllers with throttle levers
and all the wiring anyway, so why use an RC ESC?