I've got an RC car that I modified for autonomous control. I've got the PWM control working fine but the method is a bit goofy. Here is the way it works:
When I turn on the main power (7.2V) it sends power through the Duemalinove input jack and to the ESC. Everything works if I: 1) I need to turn on a the ESC power switch after I turn on the main power or 2) I unplug the power to the ESC then plug it back in. If I don't do one of these things the motor won't run.
I am guessing that there is a current surge or some other power up problem when turning on the main power that the ESC doesn't like. I can push the arduino reset button and it all works just fine.
Would a capacitor inline help? If so, any guesses as to what size?
I suppose a relay could be used if I integrated it into the arduino.
I'm no expert on ESC's out of there normal RC enviroment, but have been flying RC helis and planes for several years. Depending on the brand of ESC, some need to be turned on BEFORE the signal transmitting device is switched on, and others need to be turned on AFTER the transmitting device is switched on. Do you get surges to the motor, or just the servos?
It is not uncommon for the servos to twitch when an ESC is first turned on. The motor itself should never engage at all until the ESC has been turned on and has received the required initialization signals. This is a safety feature built into most if not all aircraft ESC's, not sure about car ESC's though. Pushing the Arduino reset tells me that the ESC is one that needs to be turned on BEFORE the Arduino. I have to electric helis that are like that.
Sorry, but this doesn't really help. I want to have one switch that I turn on and not have to turn two switches in the right order and fast enough. I don't care what comes on first but I want one switch to power up everything if it is possible. And really I want to solve this issue because I am just learning electronics and find it very interesting. So thanks for any and all suggestions.
Probably no way around it as ESC's usually require an initialization signal before it will energize the motor (this is so you don't cut your fingers off with the prop when you turn it on or have the car runaway from you before you are ready). You might try a different brand of ESC unless someone has any better ideas.
I am guessing that there is a current surge or some other power up problem when turning on the main power that the ESC doesn't like. I can push the arduino reset button and it all works just fine.
Maybe you need to initialize the ESC after a time delay when the ardiono reboots. You may need to search the old forum for ESC for a lot of previous discussion on these devices.
I've noticed an ESC (that I was driving from a 555 oscillator) would latch up with an error condition if it was started up with the 'throttle' not at minimum. It may be being fussy about the PWM signal it is seeing on start up - an ESC quite rightly plays it safe and doesn't start up if something isn't right, some of these brushless motors are awesomely powerful.
Some ESC's even require that the throttle be at the minimum and then moved to full throttle and back to minimum. Hard to say. I have not tried using an ESC with an Arduino yet, so I would like to see if this problem gets resolved and how it was done.