Real-Time Physics Simulation Forum

Re: Six legged robot

2013-06-17T23:06:12+00:00

Added little bit of modularity:
http://www.youtube.com/watch?v=ycQaosevyN8

Statistics: Posted by lukasdurica — Mon Jun 17, 2013 11:06 pm

Re: Six legged robot

2013-04-27T19:51:50+00:00

Control applied to a real hardware:

http://www.youtube.com/watch?v=LY_UHcEO1Yw

Statistics: Posted by lukasdurica — Sat Apr 27, 2013 7:51 pm

Re: Six legged robot

2013-03-27T19:36:09+00:00

Yes

Statistics: Posted by lukasdurica — Wed Mar 27, 2013 7:36 pm

Re: Six legged robot

2013-03-26T17:28:35+00:00

I just wanna double check this: so you are basically setting the high and low limits both to your target angle to control the joint, rather than computing the torques?

Thanks man, you are so helpful!

Statistics: Posted by Dr.Shepherd — Tue Mar 26, 2013 5:28 pm

Re: Six legged robot

2013-03-25T20:46:10+00:00

I'm glad I helped. Is there anything else you want to know?

Statistics: Posted by lukasdurica — Mon Mar 25, 2013 8:46 pm

Re: Six legged robot

2013-03-25T17:40:16+00:00

But if you think, that 64-bit processor can work with 2 32-bit-long words and when you swtich it to 64-bit,and you are expecting it will be 2*slower, that is not correct. Speed of simulation is not affected by 64-bit precision in this way.

Hi Lukas,

Thanks for the explanation, I did think that 64-bit processor can cope with two single float simultaneously, which will speed up the computation. I may need to read some posts on google and improve my fundamental knowledge on computers!

Cheers.

Statistics: Posted by Dr.Shepherd — Mon Mar 25, 2013 5:40 pm

Re: Six legged robot

2013-03-23T23:32:20+00:00

Well, no, there is not such a thing. I´ll try to explain how it works.
There are 32-bit processors and 64-bit processors in ..hm.. modern computers.
32-bit processors can work with 32-bit-long word and 64 -bit processors can work with 64-bit-long word (so it means that 64 -bit processors can technically work with two 32-bit-long words, but this is not a point).
Example (just principle):
32-bit processor: 8,2456
64-bit processor: 8,24567859
So double precision means double precision, and if you have got 64bit processor - you can enjoy this advantage.
But if you think, that 64-bit processor can work with 2 32-bit-long words and when you swtich it to 64-bit,and you are expecting it will be 2*slower, that is not correct. Speed of simulation is not affected by 64-bit precision in this way.

Statistics: Posted by lukasdurica — Sat Mar 23, 2013 11:32 pm

Re: Six legged robot

2013-03-23T21:32:04+00:00

Hi Shepherd,

What do you mean with "the speed doesn't slow down too much"?
Speed of what?
What do you expect to see? And what do you really see?

The way, I have realized double precision has affect to quality of simulation, that my Hexapod was shaking/jittering after I have reinstalled BulletPhysics, with the same simulation values as before, and I knew that simulation was more stable last time. I forgot to turn on double precision. So I did it. Quality of simulation was back.
So try to build some chain of constraints, fix it in the space, set some of my values (above) and you should see different type of behavior.

God, I have to do something with my english.
Hope this helps.

Don't worry too much about your English, you have expressed yourself perfectly well.

Then you discovered this by practice. What I mean is that by using double precision, the speed is expected to be about 2x slower than single float mode. So there should be something, like simulation steps, CPU usage etc to see this difference.

Cheers.

Statistics: Posted by Dr.Shepherd — Sat Mar 23, 2013 9:32 pm

Re: Six legged robot

2013-03-23T19:19:10+00:00

Hi Shepherd,

What do you mean with "the speed doesn't slow down too much"?
Speed of what?
What do you expect to see? And what do you really see?

The way, I have realized double precision has affect to quality of simulation, that my Hexapod was shaking/jittering after I have reinstalled BulletPhysics, with the same simulation values as before, and I knew that simulation was more stable last time. I forgot to turn on double precision. So I did it. Quality of simulation was back.
So try to build some chain of constraints, fix it in the space, set some of my values (above) and you should see different type of behavior.

God, I have to do something with my english.
Hope this helps.

Statistics: Posted by lukasdurica — Sat Mar 23, 2013 7:19 pm

Re: Six legged robot

2013-03-23T16:44:51+00:00

Hi Lucas,

One more thing, I have switched to Double-precision, and there is no problem with compiling and running, which assumes I have done correctly.

But since I only got two objects in the space, the speed doesn't slow down too much. Is there any way that could prove the double-precision mode is running slower than single-float mode? Not sure which number I should look into.

Cheers.

Statistics: Posted by Dr.Shepherd — Sat Mar 23, 2013 4:44 pm