ah. I see the tilter has 2 motors as well, I guess 2m drive.
We didn’t have any high strength bearing flats to make the DR4B one motor, but that is one of the changes we are making, and yes it is slightly tippy, it has never tipped throughout the season.
everything needs a 4 motor drivetrain
WHy. We had a 2 motor drivetrain and it worked perfectly. Except it’s too fast and we had to make the motor speed 25%.
But with a 2 motor drive, it will accelerate to max speed slower than a 4 motor drive. You will also be more susceptible to defense (pushing). It may have worked fo your team, but it won’t work for every team.
if you’re running a 2 motor drivetrain at 25% speed max, that means your drive is 8 times as weak as a 4 motor drive. you should never ever cap your drive motors at less than 100% speed.
your robot would probably lose in a pushing contest to a 2 motor cortex drive
How do you even do a 4 motor drive? We don’t have space for another motor in the front
well the simplest way is to have a motor attached to each wheel, but sometimes you have to use chain or gears to transfer power to the front wheels.
So technically that’s not true, your motors can operate with a 25% max speed while still maintaining a 100% torque output when necessary. The V5 PID will accomodate for situations in which more than 25% torque is needed by supplying the motors with greater current, even though the motors only run at 25% speed.
I’m assuming that the cortex drive is geared down to match the speed of the v5 drive.
Because when you reduce the speed on your motor in the code, you aren’t gaining any torque, just loosing speed. But when you gear down the motor mechanically then you loose speed but gain torque.
But you’re not losing any torque either, the motor will increase the torque output to maintain the desired speed as necessary.
Capping speed in software is a reasonable thing to do, SQL does it by default on both our robots (60% by default, and we can switch to 25% or 100% with controller buttons for precise and fast movements respectively when needed).
Well if you’re never running your motors at 100% it is better to gear them down to the max speed you want. This way you still do the maximum amount of work out of the motor.
A motor spinning at 100% speed is doing more work than that same motor spinning at 50% speed.
It’s insanely difficult. You can’t support the rollers with a bar because the cubes need to pass through.
I think @RNA was referring to a tray on a DR4B, not just DR4B arms. For this type of bot, you can attach the intakes to the tray and you don’t have to brace them. You also have more liberties in bracing the lift, since the tray moves with the lift and won’t get in the way of bracing when it raises.
The tray bot design is superior in almost every way. A sure, you lose the ability to do high tower, but you get a gain in cube stacking. We have a Traybot, while our sister team had a DR4B ERS (Extending Reverse Stacker). We were able to stack higher, and with more efficiency. Another thing I noticed about ERS bots is that their maintenance is torture. Just keeping the strings wrapped, and redoing all the spacers every two meetings just seems like too much for me.
I’m using a DR4B (very successfully, especially for a rookie team) and it doesn’t seem to be that high maintenance, except for the ocassional rubber band snapping and lift gear skipping, which are problems that traybots should face as well. If you’re redoing all the spacers you’re doing something wrong.
There are ways to eliminate this. I would be hard pressed to find a traybot that has a gear skipping issue.
Ding dong!
It’s your sister team here to tell you that you didn’t give our last robot enough attention.
Anyways, the fact is that the DR4B bots are more complicated than the complex traybot, and making the DR4B traybots competitive will take some clever engineering and careful planning and designing. Since you’re packing more into the robot, the motors are going to be working harder. All this for a few advantages than may not even be decisive in a given match. Plus, as complex traybots are becoming more and more advanced, many of these advantages are no longer exclusive to the DR4B traybot.
Wait, what do they use the string for, and why do spacers need replacing
An extending reverse stacker is a whole different story. I’ve never even seen one in competiton or online other than the cad model from 81k in the early season. The fact is, with a 1 motor dr4b and a mini tray design that doesn’t lift the entire tray, dr4b trays can be just about as competitive at stacking, plus they get the additional bonus of being able to do really good protected zone autons. They also get to utilize the middle tower, which effectively gives them an extra alliance tower as traybots can’t descore them. I have a dr4b mini tray and can make a stack of 9 and place it if you give me a straight line of cubes in under 15 seconds. We also get much more efficient tower swapping.