I’m sure this question has already been asked a few times but i’m kinda curious. I know that last year my team, Team #64 the Gila Monsters used the drill motors with 4x4 direct drive, and we had a heck of a time trying to drag the goals around. I know it’s because the way we had our robot geared, we had plenty of speed but no tourque.
So i know teams like #45, who’s robots i really liked by the way, and the cheesy poofs had no problem double balancing everytime. I was wondering which motors you used and how you geared them to get that kind of tourque? this question is directed at all teams by the way.
Team 535 used two drill motors (one per side) with associated transmission. We had one motor driving two wheels using a chain. On the output shaft of the drill motor we attached an 18 tooth gear and at the wheels we had a 60 tooth gear.
During testing we tried 12, 14, 16 and 18 tooth output gears and found the 18 tooth was the best for speed and torque.
We were able to pull the goals or the stretcher with absolutely no problem.
We also had the speed to auto-balance on the bridge with one or two goals securred to our robot.
Dont forget to factor in Wheel Size and Traction Level when considering just the gearing. When we increased our traction by a large amount we started breaking drivetrain components since the old system had more slip that was easier on the system
Sorry, forgot to mention the wheels we used.
We used the 8" wheelchair wheels that we grooved with a soldering iron with a “V” groove tip.
Major traction. Also if the grooves start to disappear you can go over them again with the iron. We ran a full season with just one set of tires.
Team 151 used a direct drive van door motor set up. We went for all torque and little speed. The gamble proved good at The UTC regional where we were the only team to successfully pull a fully loaded stretcher, and we seeded our way into the finals at a respectable 8 out of 51. However the gamble didn’t pay off at nationals where we couldn’t achieve high enough scores (due to no time multipliers) to run with the “big dogs” and seeded a respectable 48 out of 81 in the Acrhimedies division, and didn’t make the finals. Once again however our high torque proved very useful at BattleCry at WPI where we were able to “steal” goals from some teams due to our high power.
We have already decided that more speed is essential next year.
On the drill motor front I know some teams who used them this year did very well in the traction department, because their grabbing mechanism transferred the weight of the goal onto their drive-train thus putting more weight on their wheels giving them better traction. For example I know the killer bees (33) and Tesla (95) used this approach.
It’s been a few months since I’ve seen our robot, but from memory… We used the bosch drill motors in low gear, and then from there we had a reduction (that I forget at the moment) to the small wheelchair wheels.
We also use the drill motors for 4 wheel drive. There two main reasons we had no problems with pulling the goals or traction on the bridge.
We were able to switch gears, so once we had both goals and/or got to the bridge - we would switch to low gear.
The real key was that we used the pnematics to pick up one end of one goal - which transferred the weight to the robot and made it much easier to pull up the bridge.
The other team you mentioned, #45 the TechnoKats, had a different system. They also switch gears, but their big advantage was that they used the drill motors AND fisher price motors in tandem. Basically attaching the motors together - making the robot either faster without giving up much power, or more power without giving up much speed depending on the gear they were in. Very cool innovation on their part - which we are experimenting with ourselves over the summer.
Off the topic - do you know where the GilaMonsters are going to compete in 2002. I know you normally do 2 regionals, with LA being your home event. We might not go to LA this year, so we’re hoping you guys (64) might compete at the Silicon Valley again. Partners in the National playoffs in 99 & 2000, and regional competitors (qualifying partners) all three years at regionals - it just won’t feel right if we don’t see team 64 at a regional!!!
Sorry its off subject but the question was asked by team 254 where we (64) were going this year. We really haven’t set anything in stone but as far as we can see the LA regional thanks to team 22 will be the biggest next year so we hope to compete there again. And obviously we would like to return the virginia regiongal this year due to our success last year. Really hope to see team 254 in action before nationals. Hope everything works out with you guys this year, and know that the Gilas love the Cheesy Poofs. And I would also like to compliment you to the greatest extent for your excelent robot and driver in the 2001 season and all seasons before, and it was a shame we couldn’t have taken it all in 2000.
We have used the drill motors for drive train for several robots now. These motors have some very strict limitations and production differences (like speed variance from motor to motor and forward to reverse) but if consideration is give to correct gearing, speed and torque can be optimized very well. The same can be said for the the Fisher Price motors which we have also used this year as boost motors for four wheel drive when needed. Please note that motors should not be expected to work for heavy loads at low RPM. Extended use in this way WILL cause overheating and eventual failure.:mad: Check the data sheets, they are your friend.
Al
We here at #5 used our drill motors with the shifters they came with. At first, we grinded. Really, really bad. Than we made it go very, very slowely when it shifted, to catch the gears, and we where fine! And as for the wheels, we used tank-tracks! Just some timing belts with some “dead-wheels” under-neath, non-moving. (For all the ppl that are mad of the wording, sorry, i kan’t spel!)
I had a chance to see your robot and the shifter was a good idea. You obviously overcame the problem with shifting. What did you use to accomplish the shift?
Al
We used a seat motor to change gears with an offset cam to actuate the linkage. In addition, limit switches were used to make sure that the seatmotor didn’t walk out of gear. The grinding gears came from inadequate programming. Even though we used springs in the linkage, some programming has to be done to ensure proper gear engagement. Otherwise, the motors are too fast and never let the gears properly mesh (hence the grinding).
I’ll try to post some pictures soon (or maybe email them to #111)
Our gear shifting was simply a servo over the tranmission. We stuck screws in the white triangle thing (sorry, I don’t know what it’s called :rolleyes: ) so that when the servo turned it would move the metal thing (once again… :rolleyes: ) that shifted gears in the transmission. Then, we wrote a program to make the motors move backwards and forwards really quickly (not even long enough to move the robot) to set the gears in place. The program also does not allow shifting while the robot is moving and doesn’t allow moving while the robot is shifting (which takes about 3/4 sec). It worked really well and I don’t think we ever grinded the gears (maybe once or twice while we were fiddling around with the program).
What’s even better was it was completely designed and programmed by us (the students). The engineers were surprised one day to find that our robot could shift, which turned out was incredibly important to us (we always balanced in low gear).
