Older blog entries for ROB.T. (starting at number 0)

Dear diary - ;-)

This is great, a public record to motivate me into working on my robot. Sweet! It's going to take a looonnngggg time to get this project built because this thing called 'life' keeps getting in the way. Hopefully, using this diary, I can make some good gains over the next year or two.

My current project is an 8-legged robot named Predecessor. I've done some modeling and made some initial determinations.

4 motors per leg,8 legs = 32 motors. 4 legs per plate, 2 plates, each plate has an additional 3 motors. Battery pack - pending on design 1 to 3 motors, lets say 3. Extra motor for the top plate brings the total motors to 42.

The motors I'm using are 19 volt - naturally I'm running them at 24VDC - worm gear 24 lbs/in max torque at 1.3 Amps. Batteries are 12V 5A each, I figure I'll start out with 4 and work my way up to 8 batteries. total weight is approximately 30 - 40 lbs. Sounds heavy. Obviously I'm going need to use a few tricks to get the thing to walk properly, this should be a good time.

Each motor will have a potentiometer to signal position, and each leg will have a strain gage or a pressure sensor to determine contact. Groups of motors will be controlled using an Atmel controller. The Atmels will be linked to a parent controller, probably in m-tree fashion. The controllers will talk to each using a SPI interface. I would like to incorporate a small LCD with the base, maybe some LEDs.

Getting the above working will essentially complete the base module. Additional modules such as navigation, ethernet communication, sensing, and action-planning will be added later. One thing at a time!

Alright, my first task is to properly mount the motors. It appears that the best method would be to use the actual motor body as part of the leg-frame since there are mounting screw-holes on each end of the motor. I can't find the channel-stock aluminum I want to use, but I found some straight aluminum stock that will make due though I'll have to bend them. Since I need to make good contact between the gears, I'm going to put in a mounting plate and a slotted gear cradle(?) so I can vary the distance between the gears.

Step 1. - make legs. Construction starts 2/11/02.

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