Bipedal Chair Progress - NOT FINISHED YET!

echorobotics · February 21, 2009, 11:02pm

VIDEO!!!

Well, video is up. I dont show anyone sitting on it because I'm the only person who knows how to controll it and I had to shoot the video, so I just let it walk solo. Enjoy :]

BTW at the end one of the neighbors is like "whats that?" so I, (almost startled) say "um...robot" and the video ends...

June 5, 2009 Update:

Well I never could get a video...yet. I'm doing some repairs and upgrades today, and rebuilding the control box. WITH ANY LUCK it'll stop raining here and I can shoot a video on our new, flat, and level driveway ( hehe :] ). I must say however that I am disapointed at how ugly it truly is...especially compaired to this: http://basicrobotics.net/mech.html

WOW I need that thing... I'm seeing an expensive new project coming in the next few months.....

But I'm not done yet. These actuators are AMAZING. I'm going to figure out how to build a more efficient, better looking frame with whatever money I can save up. Then just transfer the actuators, and bam, WIN.

QuickUpdate:

OK the brand new batteries already died. I put a 10 amp car fuse to regulate the amps, too. I have an 18 volt drill battery on it (6 volts more than supposed to) and it still walks frustratingly slow. You can't even tell its walking on video. But on the good side, I made an brilliantly designed way of controlling it without anything more than tape, wires, tin foil, glue, and a box.

Here it is (It has 1 big switch for back and forth motion, two for independent side control to recalibrate, and one master cut-off switch): I know its hard to make it out, its very complex and immaturely built, plus lighting is bad.

UPDATE3:

It walks! I am sooooooo happy! My actuators came today, and I've been pondering forever on how to get it all together safely... And it all paid off. Test 1 was a 50% sucess, because the wheels gave in to the twisting motion of the legs. Tests 2 and 3 were 90% sucess, because it walks, but it walks backwards (although technically I never even defined a front or back yet, seemg how its a square...)

It held my weight, and walked flawlessly. I will post a video tomarrow! Thanks for sticking with me!

UPDATE2

Ok, sooo close. I have the money. I finished the frame. Now I just need the actuator. I found a pair of cheap, 250 lbs actuators, 85 lbs stronger than the last one I chose. In less than two weeks I'll have it done and walking...

I also updated specs. Instead of a rechargable battery, I chose alkaline. It's cheaper, as my budget is shrinking. The new actuators are 250 lbs now, not 165. There are also no sensors like I had planned. And my idea to put 10 amp fuses on it probably won't happen, because the actuators only can go up to 5 amps. So that's it, stay tuned for more...!

That's my dog Abby on the latest frame.

The new actuator model, capable of 250 lbs.

OLD:

Side View

Front View

Extended View

This is the first side of my "Mech"

It's hard to make out the shape chair yet because I only have 1/4 the parts so far... this project will be completed probably early May, but I'll update in the meantime.

This chair dubbed TP (or TS) is a walking chair, as in you sit i it and it walks (bipedal). Here's the CAD model of the final design:

Neat, huh?

Bipedal Human Transport

Actuators / output devices: 2 Linear Actuators Rated 250 lbs each
Control method: Controlled
CPU: none
Operating system: none
Power source: 2 Alkaline 6 Volt Batteries
Programming language: none
Sensors / input devices: none
Target environment: outdoor

This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/bipedal-chair-progress-not-finished-yet

ezekiel181 · February 22, 2009, 12:21am

How will you lift the feet
How will you lift the feet off the floor? Or will there be rollers underneath to slide? Where are the linear actuators going to be mounted?

echorobotics · February 22, 2009, 12:32pm

yes, rollers
i origionally had a plan for it to have feet curved up so that it could tip slightly and balance on one foot, but after some testing it was too dangerous, not because it could tip too far, but because it would have changed the distance between the feet, which compromised structural integrity. and because it is supposed to carry a 150lb person, it needed a sturdier design, and i can’t afford that much metal.

MaltiK · February 22, 2009, 4:13pm

how will they move forward?
how will they move forward? I only see a side to side motion available. Also what kinda wood you use? I would love to see those actuators capable of 165lbs torque

echorobotics · February 22, 2009, 7:54pm

well, there will be one

well, there will be one actuator on a slant from the foot to the top, like so:

however, after some recent calculations, i found that the leg beams are too long, and the mechanical advantage is lost. I will shorten them and update as soon as i can.

this is the actuator in mind: http://www.firgelliauto.com/product_info.php?cPath=90&products_id=4

its hard to explain how it moves forward... i'll post a video of the prototype when i make it. TPTS is in VERY early stages now. I am still calculating and finding budgets.

by the way the leg wood is a hardwood and the restis either popler or another soft wood. for the chassisi bought the cheapest wood (because that has the least amount of strain) and for the legs a more expensive type.

robologist · February 23, 2009, 12:52am

Interesting leg
Interesting leg parallelogram usage. I’m working through a biped with a similar linked leg, hopefully it’ll work when hooked up.

maneuver · February 23, 2009, 6:11am

Cool idea to use a diagonaly

Cool idea to use a diagonaly mounted actuator.

But how do you intend to lift the foot of the ground? with your current mechanical setup you wont get any forward motion. There mus be some sort of mechanism to move the entire weight over to one foot while the other foot is lifted up and swung forward. -Or am I misunderstanding, again? (it’s not that uncommon)

echorobotics · February 23, 2009, 1:45pm

well, here:hows that?

well, here:

hows that?

echorobotics · February 23, 2009, 1:47pm

yeah, look for a robot on
yeah, look for a robot on the site called “NEON Biped,” it was this robot’s prototype or Proof of Concept. it uses the same paralellogram leg

ezekiel181 · February 23, 2009, 7:58pm

The ankle pivot explains a
The ankle pivot explains a bit, but with that weight on the top where are you going to sit? Unless that weight is actually you and you move from side to side as it walks?

echorobotics · February 23, 2009, 9:28pm

**hows this view? **

hows this view?

you sit right in front of it as it swings moved by a smaller version of that actuator. However, yes, my original plan was to use my body weight to shift from side to side.

rik · February 24, 2009, 6:29am

HID for human actuators

heheheh

I envision a new “Human Interface Device” to control the human’s weight shifting by the micro controller. Two sharp pins rising from the seat. One under each buttock. With each step the sharp pain or (with learning actuators like these), the anticipation thereof will set the body weight in motion. Just get the timing right.

echorobotics · February 24, 2009, 4:28pm

HA!
HA!

maneuver · April 15, 2009, 3:01am

What kind of actuator
What kind of actuator mechanism do you plan to use for the tilting ancles?

electrictape22 · April 15, 2009, 10:23am

Awesome

That thing looks awesome! I hope it works.

echorobotics · April 15, 2009, 3:52pm

thanks! i’ll post a video
thanks! i’ll post a video of my latest progress ASAP!

echorobotics · April 15, 2009, 3:54pm

nope, no tilt anymore

nope, no tilt anymore.

after some thought i fugured a robot this big would have a good chance of breaking if it tilted, because my first attempt (which i never posted) failed totally, and i wanted to be sure that this one works just right

it has wheels on the feet so that they can glide over serfaces more easily as if the foot was off the ground.

i’l be finishing it next month, so I’ll post a video within a few weeks at most.

maneuver · April 17, 2009, 7:02am

toy robots with the same

toy robots with the same kind of “walk” usually has wheels that can only roll forward. This make sure that one leg remains stationary while the other pushes forward. With free running wheels, one foot will roll backwards while the other rolls forward, then they’ll both run back to their starting position before repeating again in opposite order for the other step.

The solution used in the toys I’ve disected are variations of this:

The cogwheel is mounted on the same axle as the wheels underneat the foot. When the cogwheel rotates counter clockwise, the red arm just slides on top og the "teeth". But when you try to turn the cogwheel clockwise the red arm will get stuck against the first cog/tooth it encounters.

K.I.S.S.

rik · April 17, 2009, 2:51pm

techspeak
The technical term for that is ratchet. But you may be describing the function of a freewheel.

echorobotics · April 18, 2009, 11:48am

Yup

Yes, I’ve seen that. in fact, my earliest bipeds used that. This new robot uses a similar technique. a metal bar like below with rubber or something slides along the ground. Then when it backs up, it sticks into the ground, allowing the other leg to move forward. I couldn’y make the “rachet” (that rik said it was called) strong enough for 200 lbs.

I tried to 'Keep It Super Simple" but I think this is pretty good. It is an outdoor targeted robot. And my tests have shown that this would work on coarse surfaces like carpet, cemet, asphalt, etc.