14 Nov 08 The Robot: A body, Sensors and Good Progress

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Progress is going really well and I’m happy so far. Unfortunately I didn’t want to show the body yet as it is so far from finished but as I haven’t posted an update in a while I decided to just go with it.

Front

Head

The body is ever so slightly lop sided by a few mm here and there which is a shame however from a short distance you wouldn’t notice, it stands up straight and weight distribution is equal throughout the base plate so I’m happy with it. Ok, ‘professionally’ the body’s a mess however for my zero experience in that kind of work, I’m reasonably happy.

This is the front of it, top is a mounted webcam, to the left of that is a phidgets temperature sensor and top right is a phidgets light sensor. I am waiting to add 8 colored status LEDs around a small flat panel 5v stereo speaker as a ‘mouth’ (I got it from a Nokia phone bundle).

Front

Two very small stereo mics will be added to the left and right side of the top back plate. At the far top is a phdgets distance sensor, and the same on the back side. Above is also the head in a little more detail - remember it’s waiting for LEDs, mics and a flat panel speaker to be added! As the plastic plate was likely to fall off at some point I reinforced it with two of those right angle thingys.

It doesn’t weight too much at this point, so I’m not concerned about that. Unfortunately by my own design, I’ve pretty much ruled out heavy lead acid batteries, however I’m pretty much settled on a NiMH 12V/10Ah battery pack anyway. I don’t anticipate it using more than 1A in full operation but without wheel movement. Seeing as it will move slowly and infrequently, I’m pleased with the battery choice.

Next level down

The next level down holds the main board, and antennae. It will also house another USB phidgets sensor kit (as I’ve run out of sensor space), and probably some MAX232 serial chips.

Incidentally, the rods are all separate from each other and do not follow straight down from the top to bottom. With that in mind, looking at the picture, it’s actually the rods that aren’t straight, not the body. It’s no big deal and it’s also not fixable at this point as they are fixed firm with polycarbonate glue. Bad idea? Probably.

There’s still a lot to do, but I’m making good progress. I’ve put on order a picoPSU to power the 12v and 5v parts without much hassle. They will be hooked up to the battery and it’s power level will be monitored with the phidgets voltage sensor that’s also on order. I need to fit the motors and brackets next and I have omni directional wheels on the way. The motor controllers will connect directly to the battery as they will happily accept 14.4v to about 9v so there’s no need to drag 60W+ jerks through the PSU unnecessarily.

Here’s some more pictures:

Eyes in the back of his head	Back	Back
Back as a whole	Front	Back

As I say the body is far from complete and expect a much more exciting update in a week or so. Other than the bits above, I need to affix the motor controllers and write some serial port comms tools. I changed from the Devantech MD23 set to 2x Sabertooth 5A dual motor controller. It’s cheaper, easier to use, works with tried and tested linux standard serial drivers and also does the job just fine.

Robot currently weighs in at 2.6kg (5.5lb) and is 52cm (20.5in) tall which is actually pretty short - the up close pictures make it look at lot taller.

The head is is 12cm (5in wide), the middle is 26cm (10in wide) and the base plate soon to house the motor controllers and wheels is 34cm (13.5in) wide. Although not much larger than the center parts, 90% of the weight is going to be distributed along the base plate, including the motors, motor controllers and a battery.

I’m hoping that in a post or two’s time, I’ll be on a final hardware change list. I also have a PicoLCD sitting on top of my ‘APNIC Box‘ which I no longer use or have any use for, so I’ll happily add it here. It also has an IrDA input and with the multitude of cheap IR all in one remotes available, it could open up some more interesting features. I’m also wondering when I can start referring to it as a ‘him’ (or her)