Skip to comments
5.5 foot tall humanoid robot that walks and talks.
56 servos controlled by 3 ezbv4 boards working together over wifi.
On board power supply lasts 1-2.5 hours depending on activity: 7.4v 5a lithium battery for logic and smaller servos and 11.1v 10.5a battery for everything else.
DOFs? all of them
Been out of the ez-robot loop for awhile, and I have to say I like were things are going with synthiam. Plan on taking full advantage of having an onboard pc, and will be converting to arduino in near future.
Very interested in bipedal gyro control and scripting if anyone has advise on the matter.
here is a link to my project design on grabcad: https://grabcad.com/library/hal-the-robot-1
By cliffordkoperski
— Last update
Other robots from Synthiam community
Joseph4760's Project X-Men
Project X-Men Project X-Men Over the last few months I have accumulated several EZ-Robot candidates. Two of the robots...
Lumpy's Lumpy's Robosapien
I was motivated tonight so I decided to EZ-B my Robosapien. Took about 20min total. He's up and running via Wii remote....
Sudo's Project Shogun
I've started work on my humanoid once again, and this is the thread where I'll share all of my discoveries and such with...
What are the specs (speed, strength and stroke) of the linear actuators you used ?
On the topic of walking:
I am currently not using any gyro sensors, I have decided first to see exactly how far I can get relying on structural rigidity alone.
Test walks with my design so far I have proven that the 1/8 inch aluminum leg construction still has to much flex, which effects the mechanical repeatability of foot placement, my first coarse of action is to remake legs with 1/4 inch aluminum plate.
The static load linear actuators are capable of , in my opinion are the only way to achieve rigidity in the joints a machine of this size.
Here are the specs for the current actuators I am using on the legs
stroke 4.00''
Speed (No Load)* 0.50 per second
Speed (Max Load)* 0.39 per second
Dynamic Thrust* 115 lbs
Static Load 500 lbs
I admittedly cut corners purchasing theses actuators, there main appeal to me at the time was being readily available.
There is no store bought actuator that will fit the bill in my application, and the price of submitting a custom design to an actuator company
I own my own cnc machine shop, so the obvious thing to do is stop being lazy and make some actuators that let me play with the big boys.
I am thinking rolled ball screw and brushless motors, it would be great if ARC supported rotary encoders but I will probably have to use a 10 turn pot.
So things coming soon :
1. thicker legs
2. custom actuators
Gyro stability is of huge interest to me now considering it's inevitable application in my build, question is how and where.
My first thought would be to get a MMA7361 accelerometer and modify a script written for a two wheel balanced robot, you could have the program control two servos in the abdomen instead and use the upper body as a pendulum. This technique could probably be applied to the leg actuators as well, the real trick would be juggling walk commands and balance commands at once.
Another idea is to not completely rely on electrical correction, and instead use a physical spinning mass offset from center of balance and induce the entire body of the robot into gyroscopic effect. I found a cool youtube link that demonstrates this. As always let me know what you all think, we are all here to learn.
Super interesting how Disney copes with instability problems due to highly flexible parts!
Just wanting to share...
But it looks like there is a dynamic layer in top of the desired animation layer, and they invented an algorithm that is matching the dynamic one so it is as close as possible to the desired animation!
I know a company " teknic" which has a product called clearpath servo and provides free auto tuning software which works very much like this.
Actually used there product in a cnc mill I built while back, during the auto tune process the servos literally shake and vibrate the machine like a tuning fork feed back the results to the software and establish optimal performance. I am talking out my back side here
Does anyone know the brand or type of servos Disney typically uses in these applications?
Good catch Jer.
So , what can be done to increase stability and achieve good behavior in a highly oscillating system ?
1) change the parameters (decreasing inertia and elasticity, increasing friction by adequate dampers, reducing loop gain)
2) change the input to the system (no ramp input, but a special oscillatory input conterbalancing the oscillatory output . This special input may be calculated, or produced by an electric circuit having the same characteristics of the mechanical system itself, or may be created by experimentation . This is probably what Disney has done , calling it "retargeting" i.e. change of the "target" (target = system input).
I see we both use metal endoskeletons and a lot of linear actuators. I currently do plastic over the metal. I love everything about your build.
I'd love to get your input on my Ava project if you ever have the time. Mine is about half the size of yours and so the hands are not as functional. I am doing a lot of 3D sensor and AI stuff. I am contemplating designing some linear actuated legs for my bot in the future (using 12V heavy duty ones from Actuonix) Mine would be about 5 feet tall with legs. For now, I am using tracks and a 4-way articulated core/hips. About the only possible advantage I could see with my mechanicals is that my bot can lean over and grab things off the floor without falling over...you can obviously do a lot more with legs...like stairs.
Once again, truly awesome work. I hope to be able to meet you at some point if you ever have time.
Regards,
Martin
Man, what a build!!!!
Have you made some enhancement in robot walking since 2019 ?
Probably need someone smarter than me to figure out gyroscope control when the time comes... But that's were things stand right now, really appreciate your guys enthusiasm and interest in the project and will continue to enjoy seeing what others come up with in future posts:)
I'm awaiting HAL rev.B !...
Will you use your cnc lathe to make your own linear actuators? how will you make the feedback sensors ?
For a large walking robot you will also need high mechanical rigidity and , above all, a gyroscopic stabilization system. In my opinion this is the most important matter to study and experiment.
1) Are the larger ones in the legs the 12V heavy duty line from ServoCity?
2) Do you use their little controller boards (using 1 per actuator) or a regular motor controller?
I found some motor controllers that can drive 4 motors. I have been thinking about trying to use one to drive 4 of the large actuators...I hope this is a valid approach.
If your interested in knowing exactly what I used let me know and I'll let you know later tonight.