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View Full Version : Questions about Tri-Track Chassis and included gear,



nagmier
04-15-2009, 06:35 AM
I am starting a project here in the next couple of weeks once my tax return finally arrives (ok ok, I didn't file until this week :P)

I intend to use the "Lynxmotion Tri-Track Chassis Kit" as a base for a Rover w/a robotic arm

The nuts and bolts are 99% Lynxmotion, SES Brackets, rotation base gripper etc.

and a customized "ala sans plastic housing" Logitech Orbit USB Web cam.

The "Brains" Are where it gets tricky, I'll be controlling the arm servos, cam, and motor controller (phidgets adv servo, and lv or hv phidgets controller) with a netbook I have an acer aspire one that will be running those chores with a wifi rdp session for control initially. Eventually autonomy will be worked on eventually.

Batteries: the 2x12v 2300mha Batteries (1 for each motor)
and a 3rd to power my servo controller. I am unsure at this time actually if I can go with another of the above and be ok as the servo controller states is accepts a 12v power supply however I am still unclear if this will burn up my servos, I'll be running a hybrid of several brands (Due to inclusion in parts kits).

Servos:
HS-422 servo Base Rotate
HS-475H Wrist
2 HS-645MG on the bottom
4 HS322 to fill out the rest

My question is.... I'm looking at weight as one of my primary concerns here with the netbook do you think that is too much weight for the chassis? I plan on extending the deck forward and also creating a raised deck that is slightly off axis to the rear to help balance it out.


Again my primary concerns are the 3rd battery pack, would this be too heavy?

I don't know how the rules are about linking to external photos but here they are

Basically this http://www.lynxmotion.com/images/jpg/ttrk02.jpg
(image from: lynxmotion.com)
with one of these on the back http://1.bp.blogspot.com/_qEHkR13hRsU/STPnK81g8EI/AAAAAAAAAkg/PwKYtmPmMSM/s320/100_1812.JPG
http://2.bp.blogspot.com/_qEHkR13hRsU/STPnJ4EldJI/AAAAAAAAAkY/NhMzuju9744/s320/100_1810.JPG
(images from: http://translate.google.com/translate?u=http://toolex.blogspot.com/2008/12/acer-aspire-one-arduino-rover-aa1.html&hl=en&ie=UTF-8&sl=es&tl=en )

The Netbook weighs less than 2.5lbs

After re-reading I noted various different weight amalgamations and I'm happy with those estimates I am still going to stick with the same basic Idea only I'll modify the chassis basically remove the current setup and raise the deck basically making the top deck line the bottom of the chassis. replacing the motors will also be replaced eventually but those that come with the tracks will suffice for phase 1 I think

Adrenalynn
04-15-2009, 02:01 PM
Just a note: It's unlikely the 322 will actually lift anything. It might be able to lift itself if you keep the arm REALLY short. But if you're wanting to pick up more than a pencil or piece of paper - that's the wrong servo to be using. There is absolutely no way you're going to be using 322's in the elbow with an elbow longer than an inch or two and still lift the mini gripper and wrist servos.

What motor controller are you planning on going with?

nagmier
04-15-2009, 02:21 PM
For the motor controller I would like to use the Phidgets LV or HV Motor controller which ever would be better for the motors of course I'm thinking the HV is the better option as it will open up options for me. as for the 322s they are part of the planning phase they will not be permanent. I recieved them as part of the Phig adv servo kit and will be replaced with 645s when able I get 3-4 for the price, of course I'm thinking I may forgoe that and pick up a couple of extra 645s
oh and I was contemplating using one of the 645s and a 322 on the base and a 645 in the elbow temporarily I'll only be using 2 322s for example:

HS-422 servo Base Rotate
HS-475H Wrist
1 HS-645MG on the bottom
1 HS-322 on the bottom
1 HS-645MG elbow
1 HS-322 to Wrist Pivot (not rotate)

If you still don't think that would be sufficient I'm happier to hear about it now that after I spend the $$$ you know so please do rip it apart, I'm not placing my order for a couple of weeks while I await uncle sam's check and I flesh out the idea.

Tymtravler
05-28-2009, 12:45 PM
Hi
Before you start trying to reinvent the wheel, I would recommend that you take a look at the Crustcrawler smart arm. Programming is great and it can lift a 12oz beer. It a little costly, but it will do what you want and works great.
http://www.crustcrawler.com/products/smartarm/index.php?prod=12

As for your question on the track system from Lynmotion, I am in the process of making a longer and taller track system using Lynx's 3" tracks. I called tech support at Lynx, because my concern was also how much weight can it handle (sprockets, treads) and I was told that my 65lb robot would be no problem. Lynx makes a great product and so far thing look great.

Regards
Tymtravler

darkback2
05-28-2009, 02:18 PM
Ok...

Last year I built and mounted a Lynxmotion arm on Vivian for artbots last year, and while I'm not sure you need to just "go with the crust crawler smart arm", I think you do need to lay this robot out a little better, and possibly think of it as two seperate projects.

First the base. I'm not sure the tritrack system is strong enough to carry the laptop you have. While it may "only" weigh 2.5 pounds, the tritrack system does seam to be pretty small...Tybes had a hard time cramming a pico ITX into his...You may end up upgrading it to the point that it would be better to just start with something custom...or a different system alltogether. Are you going with tracks for a reason? because if not there are a greater number of wheel/motor combinations that may work much better.

As for the arm, you have to factor the weight of each segment of the arm into your choice of servo. In my experience I was using 2 hs 433s as the base lift servos and one hs 422 at each other joint at first, and ended up upgrading to hs 645s for everything. The 433s were simply not strong enough, even at higher voltages.

Ok...I know...my two cents...probably not worth the paper they are not written on.

:)

DB

nagmier
05-28-2009, 05:03 PM
Thanks DB I pretty much scrapped this idea, check out what I went with here:

http://forums.trossenrobotics.com/showthread.php?t=3210

I plan on using your micro rocket idea on the rotate kit eventually for now I'm happy with the design I just want to get the chassis built with some precision my cutting skills are junk I'm better with a tape measure than a power tool.

and everyones 2 cent here is worthwhile otherwise I wouldn't be posting here ;)