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.

[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.

[colin340]

Originally Posted by AdamHeard

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.

i'd take the great weight for if just to get the Reliability of a CIM
fp's are vented, have really bad bushings, and spin at 15,000rpm it's not a good combo for what we do to them

[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.

[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.

[Brandon Holley]

Originally Posted by 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.

Did you account for the weight you are going to add to get the FP motor to an equivalent spec of a CIM motor? Unless your application requires ~15000 rpm at w/e the output torque of the FP is theres going to be some weight gain there.

Sure there will be weight for the CIM too because not too many applications are goign to use the CIM at a free speed of ~5000 rpm, but to simply get the FP to be similar in speed and torque as a CIM it will require a signifigant amt. of weight.

I agree with JVN on this one, given the choice of FP or CIM I would go CIM everytime, regardless of any kind of weight gain. The reliability factor alone is worth it.

Brando