Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: gadis on January 06, 2011, 12:13:56 AM

Title: how to do simple walking robot
Post by: gadis on January 06, 2011, 12:13:56 AM
Actually i need help to do walking robot for my project in my engineering course.
anyone know how to do it?help me please.
Title: Re: how to do simple walking robot
Post by: Soeren on January 06, 2011, 01:06:38 AM
What have you done yourself so far?
Title: Re: how to do simple walking robot
Post by: gadis on January 06, 2011, 03:44:01 AM
i do not do anything yet.still looking for the specification
Title: Re: how to do simple walking robot
Post by: Ro-Bot-X on January 06, 2011, 06:32:19 AM
Here is a very simple biped I made just for fun. It is not walking nice yet, I have to play more with the code and at this moment it can't turn. More work needs to be done, but I had fun with it.
Wobbly, a MiniBiped robot (http://seriousrobotics.wordpress.com/2011/01/06/wobbly-a-minibiped-robot/).
Title: Re: how to do simple walking robot
Post by: Joker94 on January 06, 2011, 06:44:14 AM
tell us a few basics.

how many legs do you want, 2, 4, 6, 8. a 'walking robot can have any number of legs'

second is what size do you want to make it? do you want it the be the size of the robot Ro-Bot-x posted or do you want it to be 1' tall, 2' tall etc.

why are you making the robot and what do you  have to focus on. e.g. come up with a new/smarter control software, come up with a better designed set of electronics for optimal operation, or increase the efficiency of the mechanical components?

give us a few parameters and we will be able to help!
Title: Re: how to do simple walking robot
Post by: blackbeard on January 06, 2011, 06:57:17 AM
by far the simplest "walking" robot is the hexapod. you need only 2 motors of continuous rotation. this one here uses 2 servos and a bunch of protoboard

Simple hexapod robot with two servos (part 8) (http://www.youtube.com/watch?v=B9pcZaeAtc8&feature=related#)
Title: Re: how to do simple walking robot
Post by: Joker94 on January 06, 2011, 07:05:48 AM
I agree with blackbeard. due to the tri-gate walking sequence either applied mechanically like the example blackbeard gave or through software like on hexapods with 12 or 18 Degrees of freedom they are more stable in principle.

It also gives you a easy opportunity to pic levels of complexity by increasing or reducing the degrees of freedom in the robot has. e.g. 2 motors like given in the example from Blackbeard giving essentially 2 DOF, 1 servos per leg giving 6 DOF, 4 DOF in each legs as one of the Trossen Robotics Hexapods has giving 24 DOF.
Title: Re: how to do simple walking robot
Post by: blackbeard on January 06, 2011, 07:16:51 AM
in fact the only change you would need to make for the $50 robot tutorial is to the chassis. you'll still need to get a bit creative but i doubt that the software would need any changing
Title: Re: how to do simple walking robot
Post by: gadis on January 08, 2011, 02:26:03 AM
ok actually i want to make 2 leg only.why i do the robot are the lecturer ask me to synchronize the leg just like human walk.
i really dont have any idea.he said if i do more leg,there are lots of problem.
it is about 15 cm.come up with a better designed set of electronics for optimal operation and good enough to walk like human.

i really need the details abou the circuit also.
Title: Re: how to do simple walking robot
Post by: Joker94 on January 08, 2011, 03:35:52 AM
well if you want to go for a 2 legged robot hen i would use Admins Axon controller for the electronics as there is already an 'engine' for it. the SOR biped engine.

the SOR biped engine can be found here

http://www.societyofrobots.com/sor_biped_engine.shtml (http://www.societyofrobots.com/sor_biped_engine.shtml)

and the Axon  can be found here

http://www.societyofrobots.com/axon/ (http://www.societyofrobots.com/axon/)

using these two in combination and you can get it to work well as proven at the approximate size you stated.

unless you are required to build and design this your self there is no re-engineering the wheel.

as for the mechanical parts you can get sets of brackets for the structure from places like Trossen robotics or the robot shop.

hope this helps

Title: Re: how to do simple walking robot
Post by: gadis on January 08, 2011, 03:44:46 AM
what types of servo are used and where can i get it?
Title: Re: how to do simple walking robot
Post by: Elijah5647 on January 08, 2011, 06:45:23 PM
You can get pretty much any type of servo from servo city. www.servocity.com (http://www.servocity.com)
 
Title: Re: how to do simple walking robot
Post by: Joker94 on January 08, 2011, 07:18:16 PM
most standard servos will fit the kits that are sold for this sort of thing. but be careful that you don't get some cheap Chinese servos as some can be really noisy(loud and jitter a lot) which is not at all suitable for this sort of platform.

If i was you i would look into the hitec servos as they are generally good quality and suitable for such a platform. a servo like the 'hitec HS-311' would work well for what you have planned. and they are relatively well priced in the US you can get them for app $8.90. but they go  upwards form there. $8.90 is a really goo price for such a servo.

http://www.hitecrcd.com/products/analog/standard-sport/hs-311.html (http://www.hitecrcd.com/products/analog/standard-sport/hs-311.html)

here thay are on servo city.com

http://www.servocity.com/html/hs-311_standard.html (http://www.servocity.com/html/hs-311_standard.html)

hope this helps.
Title: Re: how to do simple walking robot
Post by: Ro-Bot-X on January 08, 2011, 07:28:18 PM
I used cheap chinese servos and on Wobbly I used these (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8499) because they work as good as the hitec ones. They have less torque than the hitec equivalent, but that's the only con. They also fit perfectly the Lynxmotion micro servo brackets.
Title: Re: how to do simple walking robot
Post by: paulstreats on January 09, 2011, 03:20:22 AM
Another factor with cheap servos is that they tend to weigh considerably more(larger cheaper motor, less gears), so on a platform that uses lots of servo's you are going to have difficulties in the long run.
Title: Re: how to do simple walking robot
Post by: Joker94 on January 09, 2011, 03:30:25 AM
I have not yet used a cheap Chinese servo that i am happy with and use on my current robotic platform but if it was for a small ,not as important job they might suit.

and considering you sound as if you want 3 or 4 degrees of freedom per leg poor quality and jitter servos will be inconsistent and make the biped hard to program.
Title: Re: how to do simple walking robot
Post by: gadis on January 09, 2011, 08:24:21 AM
thank u for ur help.i really appreciate it.what are the specification that i should consider during making this robot?then how about if we want use remote control to control the movement of the robot?
Title: Re: how to do simple walking robot
Post by: Joker94 on January 09, 2011, 06:42:17 PM
well the first specification to decide on would be degrees of freedom in each leg. this leads to what sort of frame you need, how many servos you need, what controller you want to use that can handle six servos etc. 3 is probably a good number as it provides enough control whilst staying small as the size you mentioned. the picture on the SoR biped engine page looks to be a 3DOF biped.

As for making it remote control, that should be simple. there are many ways that you can do that e.g. blue-tooth through the computer, interface an RC transmitter, over a RF module between two micro controllers.

there are many ways but it depends on how you want to interact with the robot. from my experience blue-tooth would be the easiest.
Title: Re: how to do simple walking robot
Post by: gadis on January 10, 2011, 06:57:31 AM
Actually i'm not really sure about the controller.What i should use if i use 6 servo motor that power <12V?

If i want to use blueetooth what are specification and how about the circuit.
Title: Re: how to do simple walking robot
Post by: Joker94 on January 10, 2011, 07:11:09 AM
well depending on what micro controller you choose to be the main brains they have Blue-tooth modules that simply plug into a UART of the micro controller board. very simple to use. the main part of integrating blue tooth is in the programming.

like the following blue tooth module

http://www.sparkfun.com/products/158 (http://www.sparkfun.com/products/158)

if you go with the axon micro controller all you need to do is plug it directly into one of the UART ports provided and program it. there are numerous examples of using the blue smirf module with the axon that are available.

All you need to power the biped is a 6v battery with a higher mAh rating. i would say 1800 mAh or higher for your application.

the reason i keep suggesting the axon is that the majority of the electronics is 'plug and play' and as for the code much of the structure is there you just have to add the code to get the biped to do  what you want it to.