Tank bot
Bulslayer85
Posts: 34
Current project is designed to put me and the robot outdoors, for that i decided to take the tank approach. Easy way was to get the tank track upgrade for the boe bot's chasis, The tracks work ok for the most part but i noticed they don't like carpet very well ( i checked all track links for snags like it said to). I had to use the extra cog wheel to keep it from slipping a track on turns. Few things i need to point out to Parallax though:
1) usually the drive cog on a rubber based tread works best at either the front or the back, where it is now on boe bot causes major slipping when the track meets any major resistance to turning. If it was a plastic tread like what Vex did then the drive cog would be fine where it is. (plastic doesn't flex and give like rubber does).
2) The extra cog wheel is needed to make the track tense enough not to slip, I have seen pictures of other people having to do the same thing i did to get it to work right.
3) Parallax might want to consider a special chasis for tank tread bots, reason being is the boe bot chasis makes it very top heavy and can cause issues if the bot tries to climb fairly steep objects like a shoe or something, mine climbed my brothers shoe last night and came down with a hard "thud" on the other side which made me flinch a bit because of the vibration being transmitted to board so easily. (most tanks have some sort of suspension system to absorb that shock.
I don't mean to sound like a dooshbag complaining, i'm just pointing out some observations i have made. I plan to build a new chasis for the robot, one with a lower center of gravity and placement of the servo motors so the drive cogs get full connection with the tread. I might even get a second tread kit and two more full rotation servos so i can do a longer tread and have both front and rear drive cogs for max drive power to tread. I do like the soft rubber effect of the tread as it is much easier on flooring than vex's plastic that can tend to scratch wooden surfaces.
1) usually the drive cog on a rubber based tread works best at either the front or the back, where it is now on boe bot causes major slipping when the track meets any major resistance to turning. If it was a plastic tread like what Vex did then the drive cog would be fine where it is. (plastic doesn't flex and give like rubber does).
2) The extra cog wheel is needed to make the track tense enough not to slip, I have seen pictures of other people having to do the same thing i did to get it to work right.
3) Parallax might want to consider a special chasis for tank tread bots, reason being is the boe bot chasis makes it very top heavy and can cause issues if the bot tries to climb fairly steep objects like a shoe or something, mine climbed my brothers shoe last night and came down with a hard "thud" on the other side which made me flinch a bit because of the vibration being transmitted to board so easily. (most tanks have some sort of suspension system to absorb that shock.
I don't mean to sound like a dooshbag complaining, i'm just pointing out some observations i have made. I plan to build a new chasis for the robot, one with a lower center of gravity and placement of the servo motors so the drive cogs get full connection with the tread. I might even get a second tread kit and two more full rotation servos so i can do a longer tread and have both front and rear drive cogs for max drive power to tread. I do like the soft rubber effect of the tread as it is much easier on flooring than vex's plastic that can tend to scratch wooden surfaces.
Comments
It uses the Tamiya track set which is similar to the BOE Bot add on, but it is a little lower to the ground. It was designed by the forum's own Gordon McComb (although I didn't know it when I bought it). It uses servos and is a cinch to control via a Basic Stamp or Propeller Chip. Note that the kit doesn't include the tilt/pan and IR eye which I built and were the whole point of this project.
Amanda is another forum member who built two tank bots so you might be able to find her threads over in the robotics sub-forum.
I've built 3 tracked vehicles... and started tinkering with a fourth.
The first and smallest, Ted 1, was built using a lot of parts from Tamiya tracked vehicle kits. In this picture, Ted is set up with IR navigation and a 2.4 GHz wireless camera. Like this, I could drive the little 'bot around the apartment using the video feed connected to a small teevee on my desk.
Ted 2 was just an expansion of the original idea with a bigger deck for more toys. Using a BS HomeWork board and powered by a 9.6 volt NiMH battery pack. I've added the mast for IR navigation and an XBee module for experimentation.
Since bigger must be better, I started on Ted 3. This Ted uses a 2 inch Lynxmotion track and sprocket set. The logic board is the, now defunct, MSR1 Prop Robot Control Board. Power comes from a 7.2 volt NiMH battery pack. This track has excellent traction and the design has way too much ground contact. Turning is a difficult chore. I'm working on a set of road wheels to get a bit of the rubber off the road!
The last chassis, Ted 1.5, uses Tamiya parts for the mechanicals... A universal plate, track and wheel kit and a twin motor gear box. Logic will come from an Arduino Uno board with a Sparkfun motor control shield.
The local 'bot Family... :-)
Of course, that would be =their= Earth, not mine! ;-)
I do hope to be there... a matter of finances right now.
Yeah i wish i had enough money to buy a kit but sadly i dont, so i'm going to do it the hard way and build with what i have lol. Point is i don't get why Parallax would have the drive cog set so high where it has so little connection with the track. First robotics set i ever got was the Mindstorms Set from Lego so i do have previous exp building tracked robots, i learned to always put Drive Cog either forward or in back corner of track for max connection.
I track I, instead of having outer side of track exposed ?
I had to remove one of the small segments of track though but this seems to work fine, amazing what happens when the drive cog is in a corner where it has full grip on track......
In a real tank the engine is usually in the back, you set the drive cog in the rear so its directly driven off the engine threw a drive assembly of course but point is you get more direct power plus the cog is in a position of max grip with tread to prevent it from slipping..
Parallax's design more closely resembles the old WW I Iron clad tanks like this one.
which would work fine if they could find a way to remount the servos so drive cog was in rear or front, this design is actually pretty cool to use if you want to design a robot that could still drive if it flipped over.
Here's a platform made from an old RC toy, made by Heng-long, They retail for about $80, but can be found for less. Very robust tank design, would work well indoors or out. It's also bit enough to hold all you electronic goodies !!