Well, I have finally decided that I am going to buy a robot kit. I’ve been drooling over LM products for years now…I found this site when I was in middle school, and now that I am in college, it is definitely time to do something about it .
I think I have decided on a quadrapod as my robot of choice. It’s either that or a biped, but I like the challenge associated with quads, plus the fact that they just look awesome. However, I need some information before I jump for it. First off, I have calculated the cost to be around $700 (2 leg pairs, chassis, SSC-32, software, and 5475 servos), but I do not know if the 5475’s are powerful enough to drive the legs. I would prefer using them, as I save $240 over the 5645’s, but if they aren’t powerful enough, it’s worth the cost. (Unfortunately, I don’t work at the hobby store anymore, so no more cheap servos ) Also, would I need to buy the screws that attach the leg pairs to the chassis, or are they included?
Also, is there any way I could get some sort of student discount? College isn’t an easy money time (as I’m sure you guys know!) and it would be great even if it’s just a little bit. I can prove that I am a student if necessary.
Thanks guys, and I hope to join this community soon!
5475’s? I’m not exactly sure but I thought I heard somewhere that analog servos are better for quadrapods/hexapods. Also, I think you should get 645’s instead of 5475’s. The 645’s are only 5 more dollars a piece and are almost twice as strong.
Hmm analog > digital…I was thinking digital for the precision, but then again, what do I know . Well that would definitely cheapen things up a bit. Can anyone confirm this?
OK so 645’s it is. And I am not sure what processor I will be using…I have a lot of experience with Basic Stamps, but I am planning on moving up from basic. I am currently in a course that uses the Arduino series of microcontrollers, and programming in C. I haven’t had much experience with it yet, but I think I might end up going down that road. Basic is just a little…um…basic for me.
The Atom Pro can be programmed in C and it fits nicely on the BB2. I’m not much of a programmer but it seems to me you can go a long way with the basic language. Have you seen Zentas i-Pod? that shows the power of the Atom!
This video is curently in the Youtube spotlight at the time of this writing:
Full range is 180°
(500 <1500> 2000) so from 1500 > 500 = (1000) & 1500 < 2500 = (1000)
so 1000+1000=2000
(180/2000=0.09)
if range is 63°
(1300 <1500> 2000) so from 1500 > 1300 = (200) & 1500 < 2000 = (500) 200+500=700
(0.09*700=63)
Each pulse equals 0.09° of movement so a pulse of 11.1111111 equals 1° of movement
To move to a range of 45° from centre (“P1500#”) there should be a Pulse of “P2000#”
To move to a range of 18° from centre (“P1500#”) there should be a Pulse of “P1300#”
i think the best way for you to start is to start off small. buy parts from the SES and start working on the structure of your quad! at this point i wouldn’t worry about servos if costing is a problem. lynxmotion.com/Category.aspx?CategoryID=73
you have already worked out a costing so your first step is done.
I think you may have fallen into the trap of thinking a servo is capable of single descrete movements for any pulse width sent to it. What the controller puts out and what a servo can accuately respond to are generally two different things. Below are some previous post on servo accuracy. Take the bamboo skewer challange to see how well the servos you have do. I recently discovered that in lynxterm the up and down arrow keys will send a 1us pulse width change on each key push. Send the servo to 1500, then use the keys to send 1us changes until you see the first movement in the skewer tip and note the pulse value. Then keep sending 1us changes until you see the skewer tip move again. Note this position. The us difference between the two movements will probably be the actual resolution capability of your servo. I once had a controller with .1us timing resolution capability, which was a waste with every day servos
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) Also, would I need to buy the screws that attach the leg pairs to the chassis, or are they included?
. Well that would definitely cheapen things up a bit. Can anyone confirm this?