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Unread 27-12-2006, 22:14
Lil' Lavery Lil' Lavery is offline
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Re: pic: 2 Speed Transmission

Quote:
Originally Posted by Joel J. View Post
Acceleration is a factor, as well. I agree with Jeremiah that last year (2006) was a good year to have a "zippy" speed to fly across the field, but in 2005 (and, arguably 2004) a superfast robot could have proven to be a hinderance. In 2004/5, all the stop and go and fine adjustments left the fastest of robots not usually going above 9-10 fps, even though they were capable of more speed.
Joel raises an excellent point that I meant to mention earlier. In many games there often isn't enough open space to reach full speed for any extended period of time (even in a full open field like 2006, teams wouldn't be at full speed for more than a few seconds). Designing and anticipating such a fast speed may be wasted, as it may never be reached for a long enough to make it be worth it.
A majority of the "racing" in FIRST actually happens when a bot breaks free of a defense in one "axis" and then moves along the other to create space from the defender. For example, Team A is trying to score in goal A, which is down the length of the field. Team B is blocking them by moving back and forth along the width of the field, preventing Team A from getting by. Team A eventually slips by Team B, and moves down the length of the field towards the goals as fast as possible, as to score as many points as they can before Team B and orient themselves along the length of the field to resume defending against the Team A. In this situation, the maximum speed of the bot is only reached for a couple seconds, and the speed in which Team B can turn is usually far more important than either of the robot's top speed. Additionally, in this situation, both teams pushing power and speed come into play when Team B is blocking Team A in the beginning, as the having both pushing matches, and the speed the correct their positioning is critical. The ability to shift-on-the-fly is typically fairly helpful for both teams in this situation as well.

Quote:
Originally Posted by Greg Needel
While optimization is important in design, when it comes to your high speed of a FIRST drive train, especially with one that shifts on the fly you have no need for higher torque at your max speed. At that speed any robot running the kit bot drive and upgraded wheels will be able to push you anyway. Since you would never try and push someone at high speed and it is easy enough to change gears if it ever came up. The only purpose of high gear is to move your bot as fast as possible from one place to another, as long as you can move yourself and the game element if relevant, maximum torque at that point isn't required.
While the maximum torque typically isn't required (with the exception of a few rare case pushing matches), you do have to make sure that you can get enough torque while running your 15 fps gearbox, with inefficiencies, at 80% to move. If your just moving your 130ish (battery weight) pound robot, that should be no issue, but if there is a heavy game element (such as goal, or multiple goals) that you have to move as well, it may take near your maximum torque. Or even a worst case scenario, your robot, multiple goals (and other game objects), and other robots (see Beatty 2002, although they didn't exactly move in a conventional manner or a blistering pace).
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