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Hex crawler — Parallax Forums

Hex crawler

bobbbobb Posts: 3
edited 2005-08-29 02:11 in Robotics
I just finished building my BOE BOT, well I shouldn't say just, but a few months ago, and I want something new, I have been looking at the HEX CRAWLER, but it's a big investment and I want to know if I should get that or the Toddler first?· I realize the difference in the two, but would building one first help make programming easier on the other?··· I hope this makes sense...blush.gif

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-07-29 22:37
    Bob,

    ·· The Hex Crawler is definately for the advanced roboticist.· You should definately be familiar with a walking robot before working with one.· But at the same time you should also be aware of the fact that there are 12 servos for 6 legs, so each leg has 2 axis of motion.· The overhead is handled by our servo controller, but I certainly wouldn't recommend it as a first robot unless you're experienced in robotics.

    ·· That said, they are certainly fun to build, program and design walking gaits for.· Not to mention all kinds of neat things that can be mounted on them, and plenty of options for sensors (Including a pan/tilt add-on) and other gizmos.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Ken GraceyKen Gracey Posts: 7,390
    edited 2005-07-29 23:12
    Bob,

    I'd like to offer an alternative viewpoint. I think you should build whichever robot you desire.

    Both of them are a challenge to program. The primary difference is that the Toddler uses a series of DATA tables to store movement patterns. The BASIC Stamp manages the servos and all of the sensors- there are no coprocessors to make the programming easy. The code examples and the Advanced Robotics with the Toddler book make this very step-wise, though. With the HexCrawler, you'll trade direct servo management with serial commands to a Parallax Servo Controller which will generate the servo pulses. In some ways this is easier because you give it a start/stop and step rate, whereas with the Toddler every pulse is generated by the BASIC Stamp. The dearth of educational material available for the Toddler does not exist with the HexCrawler.

    The HexCrawler is more capable when it comes to traversing terrain. It can handle small obstacles such as changes in carpet to tile, as well as thicker carpet. The Toddler needs a flat surface, such as a desktop or kitchen floor. I can walk on a low-pile carpet, too.

    The sensors included with the Toddler are infrared and photoresistors. There is an optional Toddler Toes kit which is quite useful, too. The HexCrawler may include infrared (these are cheap anyway) but nothing else. Both robots could be supplemented with a variety of sensors.

    The Toddler is easier to build - two hours or so. It is also easier to tune. There are only two servos to deal with, whereas the HexCrawler has 12-18. It can be very frustrating to get them all just right. The HexCrawler takes eight hours to build. And it has to be done carefully to get good results.

    The amount of customization that can be done with each robot is quite different. Toddler can be customized to a point with infrared, ultrasnic, photoresistors, bumper toes, and wireless radios. The large deck of the HexCrawler opens some opportunities for video cameras, extra batteries, tons of sensors, etc.

    Now, which one do you want? For comparison, I can tell you that neither robot is as difficult as building and flying an R/C airplane. Neither one will sustain substantial damage other than broken servo horns if "crashed". I'd compare the construction difficulty of the Toddler to about three times as tough as the Boe-Bot. The HexCrawler is about two times as difficult as the Toddler. Both have excellent assembly instructions.

    Also, do you get Servo magazine? There have been two articles (one this month) about building our HexCrawler.

    I've built both robots several times. I prefer simplicity, so I like the Toddler. The Toddler may even be a bit faster than the HexCrawler - need to try a test.

    Hope this helps.

    - Ken
  • Ken GraceyKen Gracey Posts: 7,390
    edited 2005-07-29 23:16
    Oh, a few more points about the HexCrawler. There's no limit to what you can spend on that kit. The stock kit will get you started, but you still need batteries and a charger, plus some time to build the ideal wiring harnesses. And it doesn't stop there - you can buy all metal gear / high torque servos for precision control (and slop management) and that expense can add $500 or so. This isn't necessary, but more than one customer has taken that route.

    One of the coolest robots that ever walked Parallax was a HexCrawler equipped with wireless video camera. Our staff would open doors for it as it walked through the building. Controlling it from my desk was really fun. I could walk all the way to our Shipping and Production department, then back to my office on a single charge (over an hour).

    - Ken
  • sumeetsumeet Posts: 28
    edited 2005-07-30 08:40
    """"""""·I realize the difference in the two, but would building one first help make programming easier on the other?·""""""""

    Hi bobb,

    If u hav learnt how to control the·Boe-bot and expertise in Basic stamp then u can start with either one.

    Toddler or hexcrawler - - each one·has its own functionality.

    Toddler is again a·2 servo robot with a different walking movement then hexcralwer which is 12 servo based robot with servo contoller.

    The challenge·to make these robot walk is a challenge enough to persue the concept.

    You can even upgrade the hexcrawler with tilt pans & Robotics ARM.
    How would you feel if you have a walking platform with object catcher(ARM).

    Offcource you have to make price cosideration.
    if there is no·price barrier i'll suggest u try out both, truly you will find lot of learning.



    ·
  • bobbbobb Posts: 3
    edited 2005-07-30 19:17
    Oh no, there is a price barrier, but I have been saving. Thanks, this helps alot. I definetely need a robot capable of diverse terains, since my house has carpet, wood floors, tile, etc. Not to mention I have dogs that love to bark, and circle my BOE BOT. Time really isn't an issue, and I will be taking some classes where I could definetly use it/them, since my school uses Parallax products! Thanks agian.
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-08-01 18:20
    You might want to add the 'Track' part to your BOE-BOT then. I think this is reasonable in price, and is more adaptable to terrain (carpets, etc).
  • HiTekGizmosHiTekGizmos Posts: 14
    edited 2005-08-29 02:11
    You could build your own hexapod platform pretty inexpensively... Drawings are online at HiTekGizmos.com. I used an OOPic but the BasicStamp series us quite able to handle the task too...
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