he Pittman motors i have is unfortunately not prepared for Encoder mounting.

On the ungeared side of the motor there is only about 2mm shaft free.

My solution to this was turning a small aluminium shaft extender and presfitting it on the small shaft and fastening with some lock-tight. The shaft is now about 12 mm and is sufficient for mounting the encoder wheel.

I got 2 pcs. HEDS-5500 F06 encoders from Avego Technologies. They are 2 channel and with 256 counts per revolution i will have 256*38 (gear ratio)= 9728 CPR 9728/37.6 (wheel circumference)= 258 counts per 1cm equals ~ 25.8 counts per 1 mm.

They are very easy to mount , mount the bottomplate with 2 2.5*5mm bolts, click the top part containing the wheel and encoder on and tighten the umbraco and you are ready to test!

The shaft you see below is the homemade 12mm shaft extender the diameter is

6 1/4″ . The bottom plate from the encoder is mounted too.

Just finished mounting the motors on an angle aluminium. The shaft is 8m an is running trough 2 ball bearings and a cardan joint. I had a lot of trouble getting the shaft straight and in center of the motor shaft, but managed to get all alligned at last. Tomorrow i will put the wheels on. Everything has to be custombuild and therefor takes some time to get finished.

I have now connected the driving unit to the body. The body is supported by 4 20lbs gas springs mounted on the driving unit.

I connected the battery and motors together with s switch and took it for a ride down the long hall….Nice fast walking speed and lots of power and traction.

To make stress test and see what kind of power it had i took a hand pallet jack and stood on it and grapped the robot – pushed the button and the robot started to pull me and the pallet jack down the hall !

Thats +120kg pulling force ! And you have to add the weight of the robot too !

The first reason for me to use a gas spring system is for the look and design of the robot.

I wanted the robot to stand tall and not to be so massive looking.

The second reason was to make the robot “soft” without having a soft shell.

I expect that the robot will bump in to many things and if the robot is like a solid rock driving it could accidently break stuff.

The gas spring system works like i wanted, the robot body will bend back 5-10cm when collision occurs. I can also push the body down 10cm.

I just added the 3 aluminium rings you see on the picture, they will be used as base for mounting the shells and giving the shape i have in mind for the robot. The middle ring is mounted on some spacers and the whole assembly is stronger that i expected it to be. The rings will also serve as mounting plate for sensor, light etc.

frame

Im using the Polulu motor driver #755 which can deliver 15A without heatsink at 5.5-30V and its small too. You have to buy 2 because its only a single H-bridge.

I want Hifi sound system in Marvin because i want him to work as ipod speaker when he is not a “robot”. I purchased a 350W carpower amplifier and 2 pcs. 5 1/4 inch fulltone speakers. The sound system is adding a lot extra weight (the carpower amp is 2kg alone!), but i really think that the robot has to have a purpose to live in my family.

Im going to mount the speakers on the upper half body.

I have now decided 1/8-09 to skip the big and bulky 350W amplifier and put a 2* 100W class D amplifier instead from sure-electronics.

Mounted the 12V/26A sealed battery with aluminium angle. 4 pcs. in total one on each side. I can tilt the battery almost 90 degrees. Maybe i will secure it so that it be up side down too, i still don’t know how to transport the robot when its finished

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