RoboSavvy Forum

Video of dynamic standing

2008-07-02T06:29:16+01:00

i'm pleased i've made some small progress in my attempts to understand
my robot, i look forward to learning more.
bye for now and be well from Will.

Statistics: Posted by Will — Wed Jul 02, 2008 6:29 am

Video of dynamic standing

2008-07-01T18:30:00+01:00

Will wrote:
Hi from Will,
well done, i have not got to try my gyro thing yet, i'm still trying to understand my rx64 feet.
i've writen a behavior control which i've yet to try it is similar to
start
loop
load print id 120:25
if id 120:25 > 1658 then play motion page 50"lean forward"
else if id 120:25 < 1656 then play motion page 51"lean backward"
jump loop
end

does this sound like its going to stop my robot falling backwatds, or do i need to master programming in
C ?
i thought it might be as easy as "print ID 120:25" and then some if and then call. ?

again i say well done,
bye for now and be well from Will.

Yes Will, that will work up until a point. My Bioloid Cartwheel does just that. While it does not let precise control, it will help.

--Scotty

Statistics: Posted by srobot — Tue Jul 01, 2008 6:30 pm

Video of dynamic standing

2008-06-28T21:59:07+01:00

Can you please share the code with us. I just bought the IMU and am having a hard time getting it to work. Looks like you got it in video 2. Any help or code you can share would be greatly appreciated.

Statistics: Posted by Droid Works — Sat Jun 28, 2008 9:59 pm

Video of dynamic standing

2008-06-25T11:22:39+01:00

I have found that the torso and arms are a fraction too heavy for the leg servos.

I now tend to oscilate between 2 configurations (and sets of moves) depending upon the challenge. The first configuration is the standard Bioloid build, and the other configuration is without the torso (i.e. legs and hips only).

I found that with the second 'topless' configuration the servos perform much, much better and seldom overheat. This is especially noticeable on the stair climb where the Bioloid needs to balance on one foot.

Statistics: Posted by BillB — Wed Jun 25, 2008 11:22 am

Video of dynamic standing

2008-06-25T09:57:41+01:00

Ah cool. I didn't notice before, but you stretched him too. I stretched my guy awhile back but I never got around to actually doing anything with him after the surgery. Are you having any problems with the servos not being powerful enough?

Nothing yet, no... but...

I notice that the upper thigh and the ankle servos are positioned 180 degrees from the standard humanoid build. I imagine that this gives you a much broader range of leg motions, but raises the COG even higher. Would you recomend this configuration to other Bioloid owners?

It's a bit early to make recommendations. I specifically modified him because I wasn't happy with the range of motion (specifically the step climbing ability) of the standard layout. As it's turned out while the longer legs and reversed ankle orientation his stance is (obviously) much higher and the CoG is much higher, but this actually reduces the frequency of the pendulum swing when he's balancing, which is helpful. As the CoG is higher, though, he has further to fall when it goes wrong

Right now he hasn't done anything than stand and take a few (badly executed and useless) steps. Therefore I can't really say what his servo load etc is likely to be like. The legs do feel agile enough but the servos are overheating reasonably quickly, perhaps partially due to the LiPo power.

Statistics: Posted by StuartL — Wed Jun 25, 2008 9:57 am

Video of dynamic standing

2008-06-25T09:33:45+01:00

Very nice, much Qudos.

I notice that the upper thigh and the ankle servos are positioned 180 degrees from the standard humanoid build. I imagine that this gives you a much broader range of leg motions, but raises the COG even higher. Would you recomend this configuration to other Bioloid owners?

Statistics: Posted by BillB — Wed Jun 25, 2008 9:33 am

Video of dynamic standing

2008-06-25T03:05:02+01:00

Ah cool. I didn't notice before, but you stretched him too. I stretched my guy awhile back but I never got around to actually doing anything with him after the surgery. Are you having any problems with the servos not being powerful enough?

Statistics: Posted by billyzelsnack — Wed Jun 25, 2008 3:05 am

Video of dynamic standing

2008-06-25T00:40:38+01:00

Wow, thats cool.
and the spring effect of the book cover is an interesting test. well done.
My mom said my hoverbike was fantastic but man your robot seems pritty fantastic to me.
The yellow thing i got from tribotix a while ago in Data's chest might be one of those, man! i hope i get to learn about it.
i just watched your vid again, i'm trying to work out how to say "co o ol"
Bye for now and be well from Will.

Statistics: Posted by Will — Wed Jun 25, 2008 12:40 am

Video of dynamic standing

2008-06-25T00:30:37+01:00

StuartL wrote:
I'm assured by my partner in crime (hereby known as RandomMatt) that a Kalman filter is a linear filter and doesn't work (well) for the non-linear space of 3D kinematics.

While that is entirely true of a regular Kalman filter, there are extended Kalman filters that work very well in this space. Look at all the helicopter-based UAVs out there - they all stabilize themselves with a six-axis IMU and an extended Kalman filter.

- Jon

Statistics: Posted by JonHylands — Wed Jun 25, 2008 12:30 am

Video of dynamic standing

2008-06-24T22:38:39+01:00

New video!

Note how the book collapses under his weight and with a short panic he corrects it...

phpBB [media]

However we've now completely broken the software with an attempt to make his feet adopt the angle of the surface he's standing on. Fortunately we have version control.

Statistics: Posted by StuartL — Tue Jun 24, 2008 10:38 pm

Video of dynamic standing

2008-06-24T08:51:03+01:00

JonHylands wrote:
As an interesting aside, one of my friends is going to be implementing a Kalman filter for my IMU this summer, and if it works, we're going to try and shoehorn it into the ATmega168 - if that works out, then the Bioloid IMU will become really useful.

We've got a working exponential smoothing algorithm that goes over the accelerometer and gyro ADC. We use different smoothing parameters for accelerometers to the gyros as the accelerometers are much noisier. The output of the exponential smoothing algorithms goes into a PID filter to control the inverse kinematics for the leg and ankle positions. I'm fairly sure these algorithms are both small enough to squeeze into ATMega8/168.

In fact we plan to rewrite the AX-12 firmware over the summer...

Do you mean put a second kalman filter on top of the IMU sensors' output? It looked more like feedback was the issue and he needs the gain adjusted in his algorithm.

I'm assured by my partner in crime (hereby known as RandomMatt) that a Kalman filter is a linear filter and doesn't work (well) for the non-linear space of 3D kinematics. He's a maths whizz so I trust him on this statement. The exponential smoothing and PID control are all children of his work and are both very compact and exceedingly fast.

You are 100% correct that the gain is a problem. It's slightly more complicated with the two layers of filters (exponential smoothing + PID) with four 'gain's to adjust but that's the core of the problem.

It's looking less and less likely that he's going to be walking by Saturday, which depresses me a little, but you'll certainly be able to see the dynamic standing in action.

Statistics: Posted by StuartL — Tue Jun 24, 2008 8:51 am

Video of dynamic standing

2008-06-24T05:35:49+01:00

Hi from Will,
well done, i have not got to try my gyro thing yet, i'm still trying to understand my rx64 feet.
i've writen a behavior control which i've yet to try it is similar to
start
loop
load print id 120:25
if id 120:25 > 1658 then play motion page 50"lean forward"
else if id 120:25 < 1656 then play motion page 51"lean backward"
jump loop
end

does this sound like its going to stop my robot falling backwatds, or do i need to master programming in
C ?
i thought it might be as easy as "print ID 120:25" and then some if and then call. ?

again i say well done,
bye for now and be well from Will.

Statistics: Posted by Will — Tue Jun 24, 2008 5:35 am

Video of dynamic standing

2008-06-24T04:37:15+01:00

limor wrote:
very nice work!
have you looked at kalman filter to compensate for those oscillations?

Do you mean put a second kalman filter on top of the IMU sensors' output? It looked more like feedback was the issue and he needs the gain adjusted in his algorithm.

Statistics: Posted by billyzelsnack — Tue Jun 24, 2008 4:37 am

Video of dynamic standing

2008-06-24T01:19:28+01:00

As an interesting aside, one of my friends is going to be implementing a Kalman filter for my IMU this summer, and if it works, we're going to try and shoehorn it into the ATmega168 - if that works out, then the Bioloid IMU will become really useful.

- Jon

Statistics: Posted by JonHylands — Tue Jun 24, 2008 1:19 am

Video of dynamic standing

2008-06-23T23:20:47+01:00

It's not quite the amazing videos you see around the world but it's still something of an achievement.

You are too modest...It's a massive leap in biped control,.....one of a select few on robosavvy who has succeeded ..... Congratulations

Statistics: Posted by NovaOne — Mon Jun 23, 2008 11:20 pm