One of my personal quotes to my teams, that I have to chant every year:
"[Remember that] Gravity Is Your FRIEND!" (or on occasion: "Make Gravity Your Friend!")
First time added phrase for just the gravity quote:
"That downward force is always present for FREE to everyone, everywhere on the field, and adds no device weight to your robot."
It's companion:
"If Gravity fails you, next look to see if you can use a SPRING, before resorting to Cylinders or Motors..."
Once the spring quote is introduced, I often change the chant to:
"Remember: Gravity and Springs are your Friends!"
IOW, whenever possible, try to let gravity (or springs) do a
lot of your work for you, instead of immediately jumping to the big active devices.
It still amazes me every year just how many robots show up with motors and cylinders, and consume lots of their limited (precious) pneumatic air and battery power JUST to drive devices and game objects
toward the FLOOR. IMO, it is always better to only drive things
upward, and whenever possible let springs, bungee cords, surgical tubing and gravity do as much of your downward work for you. It saves energy, and device weight on the robot.
(Of course, if your robot spends a lot of its time tipped or flipped over so that Gravity is pointing the wrong way, that's a whole 'nuther problem...
)
BTW... The same thing applies to one-shot release widgets (like an end-of-round deployment device). Instead of using a honking motor, that work can often be done with a spring and simple catch, and an itty bitty cylinder, servo, or now even a solenoid as a release device.
There's more savings: Those "little force" widgets can often be driven from the already present cRio bricks (the solenoid driver for a valve or solenoid, or a pwm output for a servo), instead of requiring additional space and weight allowance for another Spike, Victor, or Jaguar, and its associated wiring and breaker.
Even if you have no other pneumatics, one tiny release catch cylinder can easily be driven with stored air, and no compressor is required on the robot. (The "infrastructure overhead" isn't as bad as many fear - a spike by the power distribution panel to operate the off board compressor with a connector, a valve, and one manifold with everything else stuck on it stuffed in some corner of the bot.)
HOWEVER, now that solenoids are allowed, IMO that's even easier than one lone cylinder, as many can be driven from the cRio with no overhead. (Hooray! It's about time solenoids entered the contest!
)
And lastly:
"When designing, it is always best to save the biggest power motors for the drivetrain, or your highest energy need payload link(s)."
Slowly accumulating energy winding up a spring with a
small motor for an
occasional big force release often saves you lots of space and weight over its big brothers and their huge, heavy gearboxes. It is also a lot easier on your battery than trying to pulse a bigger load, ...and... it saves the big guns for other uses.
Of them all, I think the first one ("Remember: Gravity is your Friend!") is heard chanted by me
several times every build season.
- Keith