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hmartiro / project-thesis

xJüs, the hexapodal robot with a passive-backbone to improve behavior over harsh terrain.
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Install new legs with stiffer steel #55

Closed PayneTrain closed 11 years ago

PayneTrain commented 11 years ago
hmartiro commented 11 years ago

A lot of the horizontal leg movement was probably due to the fact that the left leg's motor screws came loose, allowing the leg to move side to side. After tightening, both legs look about the same in terms of horizontal motion.

However, I agree that the current legs are not very usable. Not just because they are too compliant, but also because they get bent out of shape easily. Looking just now, one leg was extended out a full inch more than the other, when both are in the air. I was able to bend it back with my hands, so it really is not ideal because when our robot is running the legs are just going to get permanently bent out of the semicircle shape. We should try the next thickness steel first, but maybe this is why all the RHex designs have used composites. Tom, you should order metal for the next thickness today or tomorrow.

towlett commented 11 years ago

Alright 2 things here:

  1. The new spring steel should be here. I slipped it in Greg's last order.
  2. I also looked on the McMaster site and they suggest heat treating the steel after bending it into our desired shape. I definitely think that this is the play here. If we increase the hardness after bending, the steel should hold its shape better. I can ask Glenn about heat treating our new spring steel legs.

We can also look at changing the alloy from 1075 to 1095. I think that the thicker steel and hardening will suffice though. Also I'll be a lot more careful when bending the new legs so that the legs are perfectly straight.

hmartiro commented 11 years ago

sounds good - how soon do you think we can make the new legs? the cart really can't walk with these ones, they just splay outward and deform too much

towlett commented 11 years ago

Realistically, I can probably bend them late tomorrow afternoon but I may not be able to heat treat them until Friday. I gotta do the fluids final tomorrow, but I don't have practice until 5.

hmartiro commented 11 years ago

Sounds good, and think of something for the leg rubber too. We need to cover about half the length of the leg with some thin grippy material for the legs to really work well.