Macropede studies

[jmccartney]

Very impressive! Let me know if there is anything I can do!!

[steamboat]

(05-28-2014 06:14 AM)jmccartney Wrote:  Very impressive!

Thank you.
I printed all gears and the base already. Today I will print the 32 legs. Will take about 4 hours after quitting time - so maybe no running legs tonight.

In the moment there is no help necessary. We could think about which hall sensors we want to integrate into all the leg modules. Are hall sensors a good choice - maybe yes!

In Germany everybody can get from Reichelt the TLE 4905L (for 59 €ct) and the TLE 4935L (for 73 €ct) with this English data sheet:

https://cdn-reichelt.de/documents/datenb...%23SIE.pdf

I think al other kind of sensors will have a similar price? What about a simple Reed relais?

[jmccartney]

(05-28-2014 06:50 PM)steamboat Wrote:  In Germany everybody can get from Reichelt the TLE 4905L (for 59 €ct) and the TLE 4935L (for 73 €ct) with this English data sheet:

https://cdn-reichelt.de/documents/datenb...%23SIE.pdf

I think al other kind of sensors will have a similar price? What about a simple Reed relais?

I would think deciding on a package really for design integration is all we need for now. I would prefer TO-92-3 package for this sensor I think.

[steamboat]

(05-29-2014 02:08 AM)jmccartney Wrote:  I would prefer TO-92-3 package for this sensor I think.

The piece in my link is TO-92-3 but with a flat side where it should be round - do you know other forms or types?

[steamboat]

Status 2014-05-28 21:55



Last 8 legs are in print. Arm hurts - no more final assembly for today...

---

22:13
OK, I mounted the motor at one side for a test run. 5 Volt and 160-170 mA without load and no legs - but no run in also...

[steamboat]

2014-05-29 - 17:15 MESZ

Video at Youtube -> all gears in mesh

[steamboat]

It is running with 7.2 Volt. But the motors become really hot with this so the plastic becomes weak and the main gear comes off of the others.

I have to cancel the gear motor idea and change to the servos. The chassis design is already prepared for this alternative.

[jmccartney]

(05-30-2014 03:48 AM)steamboat Wrote:  It is running with 7.2 Volt. But the motors become really hot with this so the plastic becomes weak and the main gear comes off of the others.

I have to cancel the gear motor idea and change to the servos. The chassis design is already prepared for this alternative.

Can you explain a little more whats going on? Why would servos work here and not the gear motors? I think I may have missed something you have implied maybe?

[steamboat]

Look at the picture above. Because of the geometry I have to use a big gear wheel to couple the motor to the drive train. This means high speed but low torque. I started here with 20 teeth, went to 16 and ended up with 14 teeth as shown in the photo above. 14 is the smallest wheel I can place here but with this the legs running to fast with to low torque.

The servos have a slower turning disk. That's why RepWalker is slower with servos than with gear motors. Because of this they have higher torque using the same wattage as the gear motors - because demand = force x path.

The only way to use the gear motors would be to place an additional step down gear between motor and drive train - possible but even less efficient and more complicate.

[jmccartney]

(05-30-2014 10:59 AM)steamboat Wrote:  Look at the picture above. Because of the geometry I have to use a big gear wheel to couple the motor to the drive train. This means high speed but low torque. I started here with 20 teeth, went to 16 and ended up with 14 teeth as shown in the photo above. 14 is the smallest wheel I can place here but with this the legs running to fast with to low torque.

The servos have a slower turning disk. That's why RepWalker is slower with servos than with gear motors. Because of this they have higher torque using the same wattage as the gear motors - because demand = force x path.

Ah. That makes perfect sense explained that way. These things are not that obvious to the non-engineers