Older blog entries for Trilithon (starting at number 3)

Just got my motors mounted, and the tail-wheel. They all turn freely, and it is a great design for a mobile base. I tried stepping the motors a bit, and found they contained plenty of power to move the base on a level surface. I did not incline the plane, though.

I also completed my MCU programmer, now I just need to make a cable for it to interface, and then I can start programming! I have drawn a few flow-charts which are very condensed and I think I know how I shall aproach the mammoth task.

I am building my stepper controllers tomorrow, and think the robot will INITIALLY use steps for navigation, just as an experiment. But that will not be acceptable in the end product.

29 Sep 2006 (updated 29 Sep 2006 at 06:25 UTC) »

I finished my platform today. It is more crude than I had wanted, but better than I expected. It is a simple plywood thing with cutouts for my recessed wheels, which happen to be 3.5" in Diameter. Tomorrow I drill the platform for the tail wheel, and too accept the stepper mounts. Circuit board mounts have not yet been determined, but the battery carrier is also to be mounted after drilling. Rear docking sensor mounts will also be installed.

I think I will complete my peogrammer tomorrow. I would have this evening, had it not been for losing a couple of 3906 signal transistors which I needed. This is no big problem, but wanted to work on some programming tonight. I am using a Pic 16F877 for my primary controller, and a couple of 16x648's as slaves. I think this arrangement will give me all the power I need for this particular robot, and give me ample room to adapt and modify as needs arise.

This is turning into a very challenging and amusing project, and has been amusing so far. lots of details which I love. And it is fascinating how the more I learn of this field, the more questions come up. Having always been a person who likes multi-disciplinary works, this is really my cup of tea.

I am now considering a triangulation method of having the robot locate itself. Using three small RF transmitters. I am sure someone here has tried this before, and I would love to hear your results.

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27 Sep 2006 (updated 27 Sep 2006 at 02:46 UTC) »

I am very new to this so please be patient with me. I am pretty familiar with most electronics, and am in the process of designing a robot which will serve a few household funtions.

I am currently building a PIC programmer, a bastardized version of one of Bojan's. I am going to us a 16F877 for my main controller, and one more to control a few peripherals, addressed by the primary controller as master.

This robot is self charging, self righting, and must navigate complex room interiors. This robot also must utilize voice recognition, though it will be limited to very few commands.

For locomotion, I am using 2 small TEAC steppers, which I canabalized from some very archaic floppy drives. I like to do things cheaply. I also like the fact that if one of my brakes fail, my MCU can sense this and revert to motor braking. Safety is job one. This is one of my largest questions, though... what are the disadvantages to these compared to DC's or servos? I am only using them for locomotion, and not braking, which will be handled differently. But are there any advantages to steppers in this application? Since the steppers are driving the wheels directly, the friction environment will negate the advantage of stepping, in my opinion.

All opinions are considered and appreciated. Thanx. Matt

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