26 Dec 08 The Linux Robot – Progress, Software & a Video

Over the past week I’ve made a couple of hardware improvements, as well as building the majority of the software library, a TCP server and making a good start on a client.

The camera draws over 350mA@12V and there’s no reason why I need it permenantly on. I’ve connected one of the Phidget Kit’s outputs to a simple transistor/resistor/LED circuit, with a 12V supply passing into the transistor’s collector pin, through the transistor, relay input and resistor. Then I’ve connected the camera’s power over the relay’s output. The power on and off for the camera/LED are now through setting the board’s digital output 0 to 1 and 0 respectively. Power consumption with no movement has now dropped from 1.25A to just under 0.90A. I’ve also put all essential USB hardware on one usb hub and all optional hardware on another (USB to TTL adapters, sound adapter) on the other. The optional hub is also on a relay now on the opposite side of the robot, and this now reduces idle power consumption from 0.90A to about 0.50A which I’m happy with.

I’ve spent a while working on the software site of things. I’ve written a ‘library’ in C which interfaces with the various hardware that we’re interested in. The library provides a number of functions, I’ve listed the useful ones here, and they’re hopefully pretty self explainatory: (more…)

Tags: 12v, beej, C, camera, collector, cvoiceengine, digital output, LED, Linux robot, phidgets, phidgets sensor, port settings, power consumption, relay, resistor, software library, speech to text, struct, tcp server, termios, transistor, usb hub, usb to ttl

26 Nov 08 The Robot: Hardware working and ready to go, a few minor glitches

Progress has as always been good lately. The robot boots up quickly and appears on the wireless LAN, with openssh running. The internal Atheros miniPCI wasn’t doing the trick and wireless performance was shaky at best. I’m using an Alfa Networks USB adapter (r8187) and an 8dBi gain antenna now, so this has some distance now!

I was also getting frustrated with the laggyness of the board while VLC was running for streaming audio and video and so I decided on an IP Camera (Edimax), which is connected directly to the LAN port on the Alix board (I don’t have any reason to use it for anything else).

The motor control script works well and the device is responsive. At this point I can drive the device around

relatively easily and accurately, stream video and audio back to my laptop, which again is connected wirelessly.

Using ‘espeak’ you can easily generate a synthesized voice to provide easy text to voice:

Everything is working great and I’m pleased so far. The only reason why there isn’t a video up yet is because I haven’t had the time! There will be one up shortly.
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Tags: 8dbi, alfa networks, alix, antnna, atheros, cf card, distance sensor, edimax, espeak, gain, hardware sensors, ip camera, Linux, motor control, phidgets, picolcd, power consumption, r8187, SD card, serial, usb, usb to ttl, vlc