Author Topic: beginner robot  (Read 3650 times)

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Offline robonova1Topic starter

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beginner robot
« on: March 14, 2013, 03:01:46 PM »
 i am new on the site society of robots. i am very thankful that there was this site and i have a question about robots. what is a good "beginner humanoid robot"? please do not suggest the lego mindstorms kit i already have and have built alpha rex. please don't ask me to rebuild it and post pictures because i have a robot built for a robot firefighting competetion and have my robot built and would not like to rebuild it.

Offline jwatte

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Re: beginner robot
« Reply #1 on: March 14, 2013, 08:10:01 PM »
The best beginning humanoid robot I know if is the Bioloid by Robotis. It uses Dynamixel AX-12 servos. It also uses a Robotis microcontroller and software that can be programmed from your PC, but you can also program it yourself. There's also the Arbotix which is a replacement controller that works a lot like an Arduino board, yet can control the Bioloid.

Note that you really should get the "premium" version of the kit -- the starter kit only has a few servos and isn't very humanoid-like.

I don't have experience with the smaller AX-12 servos myself, but I've been impressed by the bigger MX line of servos, which is the step up from AX.

Offline robonova1Topic starter

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Re: beginner robot
« Reply #2 on: March 17, 2013, 10:22:49 AM »
thank you, do you have any suggestions how to save up? i have noticed it is way over $800 USD. but i do like how the premium looks and i have heard dynamixels are very strong.

Offline jwatte

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Re: beginner robot
« Reply #3 on: March 17, 2013, 03:54:58 PM »
To save money: Make sure you have a job. Spend less than you make. Wait :-)
The trick really is to spend *way* less than you make. Even if you could afford your own apartment, live with room-mates in a shared flat, banking the difference. Even if you could afford to lease a new car, buy an old junker for cash and fix it yourself if it breaks. Etc.

Offline SushiKitten

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Re: beginner robot
« Reply #4 on: March 18, 2013, 07:36:35 AM »
I was not expecting such a drool inducing robot. This is exactly what I was looking for. I wish the price tag didn't break the bank though. I need my money for tuition still.

And it's programmable in C... This thing was made for me.

Offline robonova1Topic starter

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Re: beginner robot
« Reply #5 on: March 18, 2013, 04:17:10 PM »
not to be a constant complainer but i'm not old enough to get a job. as i said i am entering in a robot firefight competition. i'm only in fifth grade and i have heard some people say that some servos would be dangerous for me because of how fast they are.

Offline robonova1Topic starter

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Re: beginner robot
« Reply #6 on: March 18, 2013, 06:56:13 PM »
also i was looking at robobuilder 5710k. is this good for robot soccer?

Offline idee17

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Re: beginner robot
« Reply #7 on: March 26, 2013, 07:47:35 PM »
Working for family members is a good way to save up and asking parents to help pay robot parts will work if you can prove that you will learn a lot (which you will, if you stick with it). Also joining Science Olympiad when in 6th grade is also a good thing to do. There are events where robotics (general robotics) skills are mandatory or helpful. Also your school could pay for the of the parts (if the school offers Science Olympiad), which is always good  :)
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Offline robonova1Topic starter

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Re: beginner robot
« Reply #8 on: April 18, 2013, 01:06:11 AM »
i decided im going to make a humanoid robot from scratch. it will be small,about 8 inches. does anyone know of some good servos and a nice microcontroller? my budget is coming in around 1100$. remember, small fast servos.

Offline jwatte

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Re: beginner robot
« Reply #9 on: April 22, 2013, 03:02:31 PM »
In a humanoid, torque is a lot more important than speed. Very few joints need to move faster than 0.2 seconds for 60 degrees, which is not a "fast" servo, but all the leg joints will need a lot of torque to keep the body upright.

For $1100, I'd still recommend the Bioloid, or perhaps the Hovis (a similar robot from competitor Dongbu Robot.)

If you want to do a humanoid with hobby servos, try a Pololu Maestro as your controller, and the Hitec servo brackets from lynxmotion. It's probably still going to be taller than 8", though.

The 5710K looks like another option, although I have no experience with the wCK servos/actuators, so I couldn't say whether this is a good deal or not.



Offline robonova1Topic starter

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Re: beginner robot
« Reply #10 on: April 23, 2013, 06:09:46 PM »
i looked at the HOVIS lite and it comes in at 750 USD. i may choose this but i also looked at the robovie nano. it is a small robot by Vstone and is pretty cool looking and comes in at 815 USD.
Heres the link to robovie nano: http://www.roboteshop.com/robot-catalogue/vstone/robots/robovie-nano.html

Offline robonova1Topic starter

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Re: beginner robot
« Reply #11 on: April 23, 2013, 07:05:52 PM »
robovie nano is 500 usd here! :http://www.rt-shop.jp/index.php?main_page=index&cPath=1000_1015
i have found my robot!
thank you all for your help i am sorry about spelling errors i am very happy right now.

Offline calinezul

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Re: beginner robot
« Reply #12 on: April 24, 2013, 01:53:21 AM »
On the market are available a lot of humanoid robots that can be used in educational of hobby purposes. I create a list for you: Kumotek KT-X, Manoi AT01, Darwin OP, or NAO. The price is high compared with NXT, but it worth if you have in plans to learn something about humanoid robots.
I write articles not just for science or just skill involved, there is also passion for robotics that is present throughout my articles about robots and how they works on www.intorobotics.com

Offline robonova1Topic starter

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Re: beginner robot
« Reply #13 on: April 24, 2013, 02:09:26 PM »
 i am using my robot for competition and the nao, darwin op, and manoi at01 have shells that can be damaged by robot kung fu and such.

Offline Duane Degn

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Re: beginner robot
« Reply #14 on: April 25, 2013, 02:22:22 AM »
The Dynamixel AX-12A servos are really cool. They let you do all sorts of cool stuff when them. The have torque feedback so you can tell how hard your robot is working. You can turn the torque off and then position the robot yourself and have your controller memorize the positions for later play back.

One nice thing about he Bioloid set jwatte mentioned is you don't have to buy the whole set at once. You can purchase just the plastic hardware pieces of the Bioloid without needing to purchase all the servos at the same time. This way you could slowly collect the servos and then once you have enough servos to build a humanoid you could then buy the humanoid set without the servos.

While I really like the AX-12A servos, I also really like being able to get a lot of servos for not much money. HobbyKing has some pretty good prices on servos. I used their cheap HXT900 servos in a hexapod which worked really well (I also used them in a poorly designed hexapod which didn't work well).

Their metal gear HXT-12 servos are pretty strong both in torque and structurally.

Here are some links to the servos:
http://www.hobbyking.com/hobbycity/store/__662__HXT900_9g_1_6kg_12sec_Micro_Servo.html
http://www.hobbyking.com/hobbycity/store/__2__HXT_10kg_Servo_metal_gear_55g_10kg_16sec.html

I used 16 of the small servos and 16 metal gear servos to show how a Propeller can drive 32 servos at once without additional ICs.

http://forums.parallax.com/showthread.php?137597-QuickStart-Driving-32-Servos-(Video)


Offline NERDsoldier

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Re: beginner robot
« Reply #15 on: June 28, 2013, 09:34:19 PM »
What about the RB2000 from V-stone? Its a pretty nifty looking robot for a decent price.
I looked into the dongbu stuff and even though I lived in Korea for so long and love that place, there is just something about a robot that is basically plastic that sort of turns me off.

The nano looks like a cool choice as well, I think that might be what I end up with.
« Last Edit: June 28, 2013, 09:43:11 PM by NERDsoldier »

Offline jwatte

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Re: beginner robot
« Reply #16 on: June 29, 2013, 09:21:04 AM »
The V2000 uses hobby-type servos with plastic gears and single bearings, according to the specs.
You would probably be better off with some Lynxmotion brackets and HobbyKing servos, assuming you found HK servos that fit the Lynxmotion brackets, if you wan to go with hobby servos.
Hobby servos are limited because you can't read back any feedback from them (load, speed, overheat, etc) so it's going to be a limitation if you get deeper into the system.

Offline NERDsoldier

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Re: beginner robot
« Reply #17 on: June 29, 2013, 04:20:54 PM »
Good to know thank you jwatte.

How much would it cost to build a Lynxmotion humanoid then?

Offline idee17

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Re: beginner robot
« Reply #18 on: June 30, 2013, 09:20:32 PM »
There's also the Arbotix which is a replacement controller that works a lot like an Arduino board, yet can control the Bioloid.


You can control the servos with an Arduino directly using this chip:
http://www.alldatasheet.net/datasheet-pdf/pdf/28031/TI/74LS241.html
and this Arduino library:
http://savageelectronics.blogspot.com/2011/08/actualizacion-biblioteca-dynamixel.html
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Offline jwatte

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Re: beginner robot
« Reply #19 on: July 01, 2013, 10:04:53 AM »
You can actually control them directly using an Arduino without an external chip. Doing all servos on a particular port (port B, C and D) at a time will require disabling interrupts for up to 2 milliseconds, but other than that, it will work fine, and have very high accuracy. The way it works is:

0) Set timer 1 to tick four times per microsecond.
1) Calculate the "on time" for each of the pins. Note that pins on/off map to a particular byte value of masked bits you can write to the port register.
2) Build a table from "on time" to "port output value."
3) Sort the table based on "on time."
4) Disable interrupts, check timer 1 baseline, write all port bits to 1
5) while timer 1 minus basline less than next table value time, do nothing
6) set the port to the table value, increment the table pointer
7) if not at the end of the table (port value is not 0 yet) goto 5
8) enable interrupts

This will give you approximately 1/4 microsecond resolution, which maps to 4000 steps between the 1000 and 2000 microsecond approximate end points of a typical hobby servo.

The main challenge is not losing input control data while interrupts are disabled, as the UART in the Atmega CPU only has a single byte of buffering.
One protocol might be to send a "go ahead" byte when coming out of all the disabled interrupt intervals, and immediately receive all the data for the next packet (if any.) Another may be to echo back each byte received, and on the sending side, only send the next byte after seeing the previous byte.

 


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