Let's Make Robots!

Guard II

Waits, listens, looks and shoots

21 January 2009

Guard II is now up and running. I'll try to make a video in the next few days but it's time consuming.

This is a stationary bot that listens and "looks" for targets. When it finds one it shoots a ball at them.

Overall, this has worked well for me. It came together quickly, and unlike Guard, the design of both the bot and its program are my own. The ultrasonic problem was a simple fix in the end, but the nxt-g interface made it hard to spot. I hadn't created a control link between the sensor block and the fire/don't fire decision block.

I am finding that the ultrasonic module only gives a reasonable reading off a hard surface that's pretty much at 90 degrees to the sensor, and along a very narrow beam. Soft or angled surfaces won't register.

With a stationary bot, the range of its "weapon" is now more obvious, and it's not as good as I hoped. I'll need to see if this can be improved with higher gearing or another design change.

31 January 2009

Finally got some video up. I'm entering Guard into the Cat-Splat Challenge (someone has to enter), I think it meets the criteria. I had to lower the ultrasonic sensor so that it could see its "victim"! The higher gearing didn't work - the motor doesn't have the torque todrive the gear-train.

I could also enter the video for "show your feet on LMR".

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Got fed up with Guard's tangled legs, so built a stationary version with extra sensors.

Ultrasonics aren't working reliably yet. Pic and video to come.