Question

I have a robot that I’m controlling via a browser. A page with buttons to go forward, reverse, etc is written in PHP hosted on an onboard computer. The PHP is just sending ASCII characters over a serial connection to a microcontroller. Anyway, I need to implement a failsafe so that when the person driving it gets disconnected, the robot will stop. The only thing I can think to do is to ping the person on the web page or something, but I’m sure there is a better way than that. The robot is connected either via an ad hoc network or a regular wireless network that is connected to the internet. Obviously if I go with the ping method then there will have to be a delay between the actual time disconnected and when it realizes it’s been disconnected. I’d like this delay to be a small as possible, whatever the method used. I’d appreciate any ideas on how to do this.

Answer 1

May I suggest you use a simple flash object embedded in the web browser to open a socket connection to a server on the robot? The server can be written in any suitable language – even PHP (cough).

Then it is a simple matter to detect immediately when the connection goes down, and implement your fail-safe approach.

HTTP is not a ideal protocol for robot control.

Good luck!