Dalek project - multiple sensors

Hi all,

I am building a full sized Dalek, but I am not interested in sitting inside and walking it around saying "exterminate" and scaring kids. Of course I want it to be completely autonomous, artificial intelligence and all that... dream on. So, remote control using electric wheelchair drive, and some semi automation is reality. I have some logic in mind as follows:

Head to zero position - Angle sensor referenced to main body. 8 PIR sensors around the neck (practical = number of struts). Constantly sense all sensors (like a coarse radar) Upon sensing movement, move head to centre of the detected sensor segment. Wait ?? seconds before checking other sensors for further movement. 3 (ultrasonic?) sensors in head. When head is turned to a sector, switch to head sensors to centre on closest target. Read head compass heading as a reference. Rotate body to zero head position while holding head on target (Compass hold?), Ultrasound targeting? Lock head and body and then track target. Trundle to within 1.5 metres of target. If target is still for 30 seconds, rotate head 45 degrees left and right (for show), then reinstate neck scan for another target.

Possible issues: Multiple PIR targets - inputs?. 360 dived by eight is large sector. How to zero in with U/S sensor?

I sort of have in mind an Arduino for the PIR "radar", another to control the head, and another for the main drive motors. I am an absolute beginner with code, but have been in electronics and computers for 30 years. Obviously I will have to start very simple, but thought I would put the whole dream project up there for comments and any help that may be offered. I am after practical advice like just how much of this I can reasonably expect an Arduino Uno R3 to handle with crappy beginner code, as well as anybody who may have done this before. I thought I might start with the PIR ring and even thought maybe make a little radar display with an LCD of some sort, more for fault finding than practical use.

Thanks, Glenn.

Now THAT sounds like a fun project.

Eminently doable I should think, although personally I'd go for lurking inside and going round frightening the kids, but that's just me.

The great thing about that is, you can say with some level of certainty right now that it's doable, while expecting to get stuck every now and then and engineer your way round the problems.

I can't wait to see it turn its head, then keep the head still while the body catces up.

I'd go for something bigger than a Uno right off: I haven't counted but I suspect you'll be short of i/o pins before you can say "bidi bidi beep" or have I got the wrong show?

Embrace BlinkWithoutDelay right from the start: you'll want lots of things to (seem to) happen at the same time.

Thanks Jimbo.

I was thinking of using a board for each single "function" (one for PIR's, one for head motion, one for main motion, maybe one for Ultrasound sensors) and another to tie it all together. 8 inputs is probably maximum in terms of sensors, do you think the Uno will do that? Bear in mind I am completely new at this so such integration is way off, but I am here asking for experienced opinions I guess, just to head me in the right direction.

I doubt if you need so many boards.

A Uno has 20 i/o pins, but you'll need to do some sums to see how many you need. Depending on the make of ultrasonic sensor, for example, you will need 1 or 2 pins: some trigger and echo on the same pin, others use 2 separate ones.

The head motion depends also on what motor you end up with: a servo for example only needs 1 control wire, dc motors need more.

But you in any case won't go wrong buying a Uno to learn: you'll either end up installing it in the project and you'll need another to play, or it'll be too small for the project and you'll buy more or bigger anyway.

Also should add: the i2c protocol is a bus which uses only 2 wires plus power/ground is supported by loads of sensors and lcd/oled screens. It's worth looking to see which of the sensors you need are available as i2c:lots of sensors, but 2 wires in total.