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rudukai13
07-29-2008, 04:33 PM
Hi guys, I'm new here. I have been looking around the site for a while, and doing quite a bit of reading in this section. Sounds like it would be a really fun and challenging task to build a Mech to compete. So I had a question concerning a design idea I had-If I built a robot with two "legs" and two "arms", and designed it so that it would not only be able to walk on two feet (bipedal) but also then bend down and walk alternately on its hands and feet (quadruped), would that still count as two legs, or would it be tacked with the additional targets due to the use of the hands to walk? I was thinking the way you would get it to work would be like how a monkey sometimes walks-plants its hands, lifts its feet and swings its whole body forward through the arms, plants its feet, moves the arms forward, plants its hands and then repeats the process to move forward. Has anyone done this yet? What problems do you see with the design? Would there be a good kit to start as a base? Any and all input is highly appreciated, but please use simple words or explain complicated things-I am but 16 and just being introduced to robots of this complexity :(

darkback2
07-29-2008, 04:39 PM
Welcome to the forum.

Here is a thought...what if your robot walks on two feet, but then plants itself on four...2 arms, 2 feet for targeting and shooting. Then I think it would count as a biped. But...if your robot actively walks on all fours, then quad. Thats just my opinion though, and you'll have to ask tyberious what he thinks because its his event.

Have you seen the new robobuilder kits? They look like they would be perfect for a beginner who wants to get into this sort of thing, and The biped is really stable and fast.

Just a thought.

DB

Adrenalynn
07-29-2008, 04:42 PM
Look out! Here comes ShivaMech! :)

DresnerRobotics
07-29-2008, 04:42 PM
Welcome to the TRC! If a bot is using 4 limbs at any point to move around, I would consider it a quadrapod in terms of the contest rules.

I personally haven't seen a bot with an 'ape walk' gait but that certainly sounds very interesting! I would say keeping balance and swinging the limbs might be difficult, hard to say without having ever tried it myself though. If this is your first bot you might consider a more 'tried and true' type of bot, and expand later.

If you're a beginner to robotics, the best way to decide on kit or set of parts to use would be to look at what is used to control the servos. The Lynxmotion Servo Erector set can be easily controlled using a Basic Atom, which uses a form of Basic for programming- a very easy language to pick up and learn.

Ultimately the programming of these Mechs will be the most complicated part of the project.

rudukai13
07-29-2008, 04:52 PM
Yeah I knew balance would be an issue, but I assume as long as I can get a relatively flat surface for the hand that can be put on the ground it should be fine. I am deffinitely not sure about programming, I have never really worked with any programming language or code. I think a robot like this would do better in the wrestling matches where stability/agility is key. Thanks for your help guys!

DresnerRobotics
07-29-2008, 04:56 PM
Yeah I knew balance would be an issue, but I assume as long as I can get a relatively flat surface for the hand that can be put on the ground it should be fine. I am deffinitely not sure about programming, I have never really worked with any programming language or code. I think a robot like this would do better in the wrestling matches where stability/agility is key. Thanks for your help guys!

I would recommend you start looking around at various programming languages and see what you feel comfortable with learning. It's all going to be Greek at first... but some languages are much easier to learn than others. Like I said, the type of basic that is used on the Basic Stamps and Atom microcontrollers is fairly simple and straight forward. You could look at building a custom bot using the Lynxmotion SES, servos, a SSC-32 (serial servo controller) and a Basic Atom Bot board.

Another option would be to use the Robonova platform. Dave Calkins is building his first bot for Mech Wars based on this robot.

rudukai13
07-29-2008, 05:00 PM
I don't want to start from scratch since this would be my first Biped (I've had the Lynxmotion hexapod before and had a great deal of fun with that although somebody else did the vast majority of the programming). I've looked at the Robonova and have to say I don't really like it-it's small, slow, clumsy and doesn't look very appealing to me. Money is not really a problem here, so I was thinking that whatever kit I get I will be upgrading all of the arm servos (at least) for more torque to be able to support the weight of the robot, and then go from there. Now I just need to look for a robot that looks like it would be a good base to start off with. Does anyone know of a bot that has a hand upgrade? Like one that can move the fingers to open and close the hand? Links are much appreciated!

DresnerRobotics
07-29-2008, 05:10 PM
Well I would suggest the Bioloid, but programming one to do what you would need in Robogames is no easy task. Other than that, I'd suggest looking around at various humanoid kits. Trossen Robotics has the largest selection in the US.

Dont know of any bots that come with multijointed hands/fingers, probably would have to be something you would build yourself.

rudukai13
07-29-2008, 05:23 PM
Thanks for your help! I was looking around the net looking for a kit to start with and think I may have found something: http://www.roboporium.com/roboviem_v2.html Relative to the other kits out there this one has better proportions (longer arms) that would help with walking on the hands, looks the part (nice and chunky), and I could easily modify the hands to provide a stable walking surface. Obviously it's a litte pricey but as I said money is not a problem for this project. Does anyone have any experience with this kit?

DresnerRobotics
07-29-2008, 05:26 PM
Way overpriced in my opinion. You could easily build a Lynxmotion SES based biped (they have build docs on it, so its not really custom) with all 5990TGs (best hitec style servos available) for a decent amount less.

Something like this for example:

http://www.lynxmotion.com/images/jpg/ironmanl.jpg

Or this:

http://www.lynxmotion.com/images/jpg/l20901.jpg

rudukai13
07-29-2008, 06:19 PM
Hmm...I'll look into the kits from Lynxmotion, they look like they could be promising.

4mem8
07-29-2008, 07:27 PM
rudukai13: These SES parts are great to use I have quite a number of different parts and you can just about anything you want if you are so inclined.

rudukai13
07-29-2008, 07:57 PM
What's the programming like? Is it like lines of code or is there a digital representation of the robot?

darkback2
07-29-2008, 09:15 PM
I think we should start a list of robot kits and parts that we think will work well for mechwars. So far I have seen a few bioloid kits, and a robonova. I have also read posts of people talking about using the lynxmotion robo erector set.

I know its a competition, but it seams like it would be a shame for someone to go down a road that just wouldn't end up working in the end. Besides...I need some ideas.

DB

DresnerRobotics
07-29-2008, 09:20 PM
I actually started one on the Mech Wars site, just need to add more to it.

rudukai13
07-29-2008, 09:39 PM
I was thinking that I could just take a kit and swap the arms and the legs-that would put the right distances between things and put the right DOF on the supporting limbs. After that it's a simply matter of reprogramming the robot to use the right servos for the right actions...Or am I way off?

darkback2
07-29-2008, 09:41 PM
I would say it would depend on the kit. You may also run into some balancing issues. Also, I'm not sure that arms and legs are interchangeable in that way...

DB

rudukai13
07-29-2008, 09:46 PM
If all the servos on the bots are the same size I don't see any reason why it couldn't work...If there is a really nice person out there with a Biped who would be willing to try to switch the arms and legs-just to see if it would work-that would be really awesome of that really nice person!