[chbot] ESCs for RC models

[Stephen Irons]

The Roboclaw devices from Ion Motion Control (http://www.ionmc.com/) do 
not meet your cost and avaiability requirements, but might be of 
interest to some. I am using the Roboclaw 2x7A. They also have

* brushed DC motors
* dual 7 A continuous, 15 A peak
* up to 34 V DC input
* BEC output
* optional separate controller supply input (or use BEC)
* control via RC inputs, ADC input, or serial commands
* configurable RC input parameters
* over-voltage, over-current, over-temperature detection and cut-off
* optional limit-switch inputs
* optional quadrature shaft-encoder inputs
* speed and position control with separate PID loops for speed and 
position with configurable parameters
* can read many parameters (voltage, current, temperature, position, 
speed, etc) via serial port
* can configure the most useful parameters via button-LED user 
interface, but must use serial port for most

But

* more expensive than you wanted (US$ 70)
* not available locally


This device does what we want (controlled acceleration, speed and 
deceleration to move to a sequence of positions), and seem robust. We 
have found a few issues which we can accept or work around:

* Strange behaviour if we send a new target position too soon after a 
previous target position. Waiting a bit longer (how much longer?) 
between target positions seems to work.

* With separate control and motor power supplies, if the motor power 
supply is off (eg. emergency stop) and it receives a command that needs 
to turn on the motor, it enters an error state. The only way out of the 
error state is to reset the device by cycling the control power supply.

* Grotesque Python library to talk to it via the serial interface

Stephen


On Fri, 23 Feb, 2018 at 8:53 AM, Andrew Errington 
<erringtona at gmail.com> wrote:
> Hi all,
> 
> Apropos of nothing in particular, I am looking for advice on what ESC 
> to buy to run a couple of motors on a skid-steer robot platform.
> 
> I know there are several to choose from, and ones for boats are 
> different to ones for cars. I will need two of them.
> 
> If anyone is into this and can recommend a specific module I'd be 
> happy to hear about it.
> 
> Specifications:
> Handle up to 24V at around 10A.
> Variable speed forward and reverse across the typical servo timing 
> pulse range, with a stop band in the middle.
> Probably non-braking.
> Not expensive (between NZ$10 and NZ$20 each).
> Available in Christchurch or NZ from a store or TradeMe.
> BEC output not necessary.
> 
> Any tips or pointers welcome.
> 
> Thanks,
> 
> Andrew
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ourshack.com/pipermail/chchrobotics/attachments/20180226/d9b4a232/attachment.html>