Motors - another concept for FRC

[Bharat Nain]

When a mentor (Shaun) on my team mentioned an idea some time ago, I just could not get it out of my head. It was radical and interesting but do-able so I thought I'd post it here for your opinion.

We are given a set of roughly 10 motors every year that are legal to use. According to the rules, for most motors, we can only use what is given to us in the kit and in the same quantity that they are given. What if the rules were written as such: We are given the names of 7 (arbitrary number) motors legal for an FRC competition. We are allowed to use as many of each type of motor as long as the total number of motors is less than 10 (again, arbitrary number). There are pros and cons to this concept for the robot design and inspection. I'll let you point them out.

It's just a concept.. I am not advocating anything..

[JVN]

Battery, Maximum Weight, Maximum Size... no other restrictions.

-John

[MrForbes]

Maximum power, safety.

(I got that idea from another competition we've participated in)

[Akash Rastogi]

Its a fun idea, but not really practical in a design challenge.

+.02

[AdamHeard]

Originally Posted by Akash Rastogi

Its a fun idea, but not really practical in a design challenge.

+.02

it's practical.

[gburlison]

I predict a large demand for CIM motors, as they seem to be the most popular.

[Andrew Schreiber]

Originally Posted by JVN

Battery, Maximum Weight, Maximum Size... no other restrictions.

-John

Originally Posted by Akash Rastogi

Its a fun idea, but not really practical in a design challenge.

+.02

I gotta agree with John here. You would think that removing constraints makes things easier but it doesn't. In fact it would open up entirely new decisions to make thus further complicating the design. I would add another restriction, maximum cost. (And I assume safety is factored in too)

Akash, the reason this isn't practical is because we simply don't have the TIME to research the optimum component for each aspect of the game. By constraining us to 10 motors the GDC is restricting our decision to help us, instead of choosing from hundreds of motors we can only choose from 10. And frankly many of them only make sense in certain situations which further simplifies the decision.

A lot of times people complain about wanting a more powerful motor, I for one am actually quite happy about the motors we have. It would be interesting to open up the motor selection a little more, add some choices that make motors exclusive, ie you can have X CIMs or Y of a motor with slightly different characteristics (lower torque, less current draw etc) Perhaps add in an off the shelf linear actuator. Perhaps allow extra weight for certain drive systems, if you build a walker (a much more mechanically complex system) you get an extra X pounds and may use Y more motors of varying type. Decisions like this might encourage teams to think outside the box. While the 6wd is a nice drive system should we encourage people to keep doing what they have always done because they are comfortable or should we encourage them to try new things?

Just my $.02

[JVN]

Originally Posted by Andrew Schreiber

ie you can have X CIMs or Y of a motor with slightly different characteristics

If the manual said "You may use nothing but CIM motors and Globe motors" I'd send the GDC members each a cookie. I'd send Kate Pilotte two.

[AdamHeard]

Originally Posted by JVN

If the manual said "You may use nothing but CIM motors and Globe motors" I'd send the GDC members each a cookie. I'd send Kate Pilotte two.

No FP's? I'd like CIM, FP and Globe.

[Francis-134]

I wouldn't be totally opposed to opening up motor selection if it included some restrictions: specifically a limit to the retail cost of a motor (preferably around $30, a little more than a CIM). I would hate to see teams with fewer resources outclassed because a team could buy a $200 motor.

That being said, I really enjoy allocating motors every year. I find its a great challenge for both myself and my students. I suppose this part of the challenge is rather unique, and in turn makes FIRST a more unique experience.

[JVN]

Originally Posted by AdamHeard

No FP's? I'd like CIM, FP and Globe.

If you could have a CIM instead would you really use a FP?
To me that is a NO brainer.

[AdamHeard]

Originally Posted by JVN

If you could have a CIM instead would you really use a FP?
To me that is a NO brainer.

I would be a little hesitant about it, but I can imagine using multiple FPs instead of a CIM for higher up manipulators that still need some power. A better application is probably for multiple smaller manipulators, where the weight of CIMs would be killer.

[EricH]

John: The CIM weighs a lot more. That might be enough to put an FP in where a CIM could go. Just one of those accursed design tradeoffs that come with any design problem. And yes, I might use an FP instead of a CIM even if I could use a CIM. It depends on the application.

Back to what I was originally going to say...

I compete in the SAE Aero Design competition. There are three classes of planes, each with different power restrictions. Regular says "Thou SHALT use engine X with muffler Y, unmodified." Advanced says simply, "Your total stamped engine displacement must be less than or equal to Z cubic inches. Reciprocating engines only, please."

But the most interesting is the Micro class. There are no engine restrictions, other than that it has to be internal combustion (reciprocating) or electric. This opens up a wide variety; and my team has done both. Gas was our choice the first year, because we knew what we were doing. The next year, we chose a pair of electric motors instead. Different planes, same goal, different power, different results.

The plethora of options is one thing; it can make decisions harder. On the other hand, having few/no options makes them easier, but not necessarily. FIRST has struck a balance: You can use this number/type of motor, here are the motors.

[Fe_Will]

Originally Posted by JVN

If the manual said "You may use nothing but CIM motors and Globe motors" I'd send the GDC members each a cookie. I'd send Kate Pilotte two.

And bring back the ol' van door motor from '04 era... that thing was a beast!

[artdutra04]

I really like the idea of say, any combination of CIM, FP, Globe, and Van Door motors (or any other 12V VDC motor that costs less than say, $30 or $50), as long as the total is less than 10 motors. The only other restriction I'd maybe put is a maximum total Wattage of motors used to power the drive train. Some teams would forget or ignore whether their drive trains were torque or traction limited, and would assume that more motors is always more traction, and you'd see 10-CIM drive trains (like how we saw 4-CIM drive trains this year). This would be fine on a concrete floor, but on carpet the amount of available power there would destroy the carpet in a pushing match in seconds. (Although this scenario could be covered under a "Don't Damage the Field" rule, as if a team had a 10-CIM drive train but also had traction-control code to prevent the drivetrain wheels from slipping and thus potentially damaging the floor, they wouldn't ever actually damage the floor).

It's kind of like the idea that weight limits are unnecessary for Vex robots. If you want to build a 50-pound Vex robot, you'll pay for it in speed and battery life. You want to build an eight degree of freedom arm all powered by CIM motors? Enjoy your thirty second battery life.

As we finally saw this past season, FIRST decided to treat teams to a little more responsibility by eliminating the "No Tape Rule". Now, we could finally use duct tape if we wanted to. And you know what? The quality of the robots ended up just fine, and having the ability to use duct tape for emergency repairs was a great asset this year for many teams.

But at the same time, we still need some rules and restrictions. If we eliminated all restrictions and basically said "use up to $3000 to build anything you want to play this game", we'd end up with a lot of teams getting the Deer-in-headlights syndrome, staring at a blank sheet of paper with no idea on where to begin. Restrictions, just like engineering task specifications in the real world, help narrow down the problem effectively enough to make it easier to solve.