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A while ago I was intrigued by the soda can retrieval challenge. Particularly because at that time I had built two different designs of grip-and-lift claws: The first is based on the bar-code truck claw. It uses the flex system and lifts things (...) (25 years ago, 23-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) I'm glad to hear that I'm not the only person who's still trying to solve Joel's challenge. It sounds like you've made some great progress! (...) Congratulations! Another Lego Fan is born! (...) Same here! <snip!> (...) I had considered (...) (25 years ago, 23-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) So far I have been using the tachometers mainly to find the mid-point of the signal band, so they don't have to be too accurate. The need of accuracy will arise when I use them for soda can detection. Let's see. I have posted my current design (...) (25 years ago, 24-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) I am using the small "balloon tires" that are marked "43.2 x 28 S", and which, I believe are the ones used in all of the Mars Rover designs. These tires have nice, rounded edges that seem to make them slide sideways a bit easier than the (...) (25 years ago, 25-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) All you need is to put a differential between the wheels. If those wheels need to have traction, all you have to do is to apply the force to the differential itself and the differential will distribute the traction for the two wheels like a (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) Maybe I did not phrase my problem clearly. It's better described in Jon Shemitz's recent post (URL). In my experience, wheels are more efficient than treads. Under the same load, my wheel-based design outrun my tread-based design. However, (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) Have you seen the mars rover turn? If you have the parts for it, you could add a steering mechanism in the front wheels and another for the wheels in the back. Humm... that should make an interesting mechanical project :-) Laurentino Martins [ (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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| | RE: Homing with the IR Tower
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(...) The little lift truck in the 8062 Universal set has the same steering mechanism. Just use a standard steeing rack with the steering knuckles on opposite sides of the wheel. Sorry for the inept description, my lids are calling for dinner time.. (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) I'm intrigued too by Joel's challenge. This was the reason for I started my experiments with odometry months ago. The problem is always the same: much more projects in mind than time to carry them out :-) <snip!> (...) motors, (...) are (...) (...) (25 years ago, 27-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) I've built a PC program for the CyberMaster that pools the integrated tachometers continuously and shows the trajectory of the bot in the PC screen. It uses _tracks_, and I've found out that besides one of the tracks runs a bit better than the (...) (25 years ago, 27-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) My first thought: If you don't connect the tachometers directly to the tracks, but to the separate, unpowered wheels, you don't have to care if the tracks slip or not. My second thought: When the robot turns, there is exactly one "fixed point" (...) (25 years ago, 27-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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Mario, i am still intrigued by your creative response to posts. Good luck. & may the force be w/u. Michael Aaron (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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| | Re: odometry (was Re: Homing with the IR Tower)
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(...) Yes, 95 ticks are always 95 ticks, but the point is if your robot really *is* in the position where it's expected to be on the floor. The main problem with odometry, as you know well, is that errors accumulate very fast. The unavoidable (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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| | Re: Homing with the IR Tower
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(...) You can add more free wheels to make it very stable. (...) When I approached the Joel's challenge I was worried also about the time to collect the cans. My idea was to develop a reliable navigation system to minimize the time to find the cans. (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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| | Re: odometry (was Re: Homing with the IR Tower)
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At 09:20 28-07-1999 Wednesday , Mario Ferrari wrote: [snip] (...) I've downloaded, printed and read it all some time ago :-) (...) I've used 2 wheels instead of tracks once, and the results where terrible compared with tracks. The problem was that (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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| | Re: odometry (was Re: Homing with the IR Tower)
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(...) I see your point. Yes, F1 kind wheels are far from ideal to avoid slippage and get accurate results. The larger but thinner spoked wheels that come with the Minstorm RIS are quite better. The free wheel(s) also must be light and thin and (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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| | Re: odometry (was Re: Homing with the IR Tower)
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(...) Great source. Just found a source where Johann Borenstein discusses the original 1966 paper and gives links for the full electronic version or a CDROM or a book version. Here is the source: (URL) for the pointer! Ralph M. Deal deal@kzoo.edu -- (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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| | Re: odometry (was Re: Homing with the IR Tower)
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I haven't done any 'bot yet but I have been thinking about this problem. and here's the result: it looks like the good free wheel should do its 'wheeling' equally well in each direction. therefore it should be a ball. the design should look like (...) (25 years ago, 31-Jul-99, to lugnet.robotics)
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| | Re: Non-pivoting free wheels (was Re: odometry (was Re: Homing with the IR Tower)
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(...) <snip> Whoa! =:-o That's what a call a DESIGN! I'm almost burning a fuse trying to image one of those running, err... turning... whatever it does! OK, what are good sources of baloon tires? (sets) :-) Laurentino Martins [ (...) (25 years ago, 3-Aug-99, to lugnet.robotics)
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| | Non-pivoting free wheels (was Re: odometry (was Re: Homing with the IR Tower)
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You'll have a very hard time making a ball-and-socket design bear a load and turn without lots of friction. Putting wheels between the ball and the socket just brings us back to the problem that we were trying to avoid by not having wheels. A much (...) (25 years ago, 3-Aug-99, to lugnet.robotics)
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| | RE: Non-pivoting free wheels (was Re: odometry (was Re: Homing with the IR Tower)
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Good balloon tires are available in two service packs: Service pack 5283 (43.2 mm diameter) Service pack 5282 (68.8 mm diameter) - these suckers are huge, but have just the right shape. Tilman (...) -- Did you check the web site first?: (URL) (25 years ago, 3-Aug-99, to lugnet.robotics)
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| | Re: Non-pivoting free wheels (was Re: odometry (was Re: Homing with the IR Tower)
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Here's a couple of short motion clips of the killough platform in motion. (about 1.4 MB each in mpg format) I had been waiting to get a few really nice movies of this but a relative of mine dropped by last weekend and shot these to show a friend of (...) (25 years ago, 4-Aug-99, to lugnet.robotics)
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| | Re: Non-pivoting free wheels (was Re: odometry (was Re: Homing with the IR Tower)
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I was asked via E-mail where to get the balloon tyres. They are listed in the Shop-at-Home catalog as item 5282: (URL) just ordered some from here in the United States and they were $6.00 per package. Each package includes two tyres and two wheels (...) (25 years ago, 4-Aug-99, to lugnet.robotics)
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