Design

Teams that consistently go to the FIRST Championships (aka Worlds), have many years of experience to influence their robot designs. Explore the links below to study the possibilities and, more importantly, understand why particular design elements were chosen. Spectrum has a very good YouTube channel that reviews other teams' design that is a very good resource (link).

Before every FRC kickoff in January, explore past designs so that you are best prepared to make design inputs.

TECH BINDERS

• • 2024 OP Robotics (Tech Binder / Drawings)

  • 2023 Buck's Wrath (Tech Binder / Website)

Design calculators simplifiy design decisions without the need to understand math calculations and physics. Calculators also reduce potential for math errors and speeds up critical decisions.

• ReCalc

• AMBCalc

• Spectrum Design Sheet

  • More than just a calculator. It records the team's design decisions for later reference by other team members

• • Gear ratios of a gearbox should be designed to produce a desired end torque or end speed

  • Consider the following factors for drivebase gear ratios to avoid overheating motors, causing brownouts or underperforming the robot:

    • Weight of robot: the heavier it is, the more torque it needs (more gear reduction ratio)

    • Power of the motor

    • Aggressiveness of PID: the more acceleration that is programmed, the more power the motor will draw to try and get to speed

    • Software current limits: Controls maximum amount of current allowed by the motors, but it allows momentary overshoot if PIDs are aggressive

  • The story of the robot Magnus of 2022's Rapid React is a lesson in improper gearbox design and programming practice

    • Magnus was plagued with motors overheating the entire season resulting in Falcon motors auto-shutting down midmatch, all season

    • At NTX/STEMGals off-season event several factors were discovered and corrected:

      • Gearbox incorrectly assembled with no spacers causing motors to rub against gearbox housing resulting in friction and higher current usage (ie. generated more heat)

      • Gearbox was geared too fast for the weight of the robot

      • Third motor added to handle the greater torque needed due to the fast gear ratio

      • Current limits were implemented to keep motor from overworking due to ffriction in gearbox and fast gear ratio

      • Leaf blowers were implemented to cool motors between matches

      • These corrections completely fixed the issue in one day and resulted in 100% mobility with no overheat issues (without the need for leaf blowers)

  • Design gear ratio to operate at motor's Peak Power curve if max power is needed for short duration

    • Use Max power if work is needed to be done within a specified amount of time

    • 2022's Rapid React climbing end game required lifting the robot, as quick as possible, across traversal rungs -- required full power for less than 30 seconds

  • Design gear ratio to operate at motor's max efficiency if there is no time element in the amount work needed to be done, preserving battery life is desired, and/or maximum controllability is needed

    • Operating a motor near it's max efficiency allows the motor to more easily handle precise control of the end effect

    • Analogy: writing on a board with a marker close by (more efficient, takes less power) is much more controllable than holding a marker at the end of a 10 foot stick (takes more power, less efficient) -- just because a motor can handle the torque, doesn't mean it can control it just as well

REV MAXPLANETARY GEARBOX

• • 1 to 125 gear reduction possible

  • 1:1 reduction require cutting shaft length to fit

  • Great for prototyping or reductions where precise positioning required due to gear backlash

  • The more cartridges used, the more gear backlash

  • Never connect gearbox as the last stage to the mechanism if precise positioning desired

    • Use chain or belt reductions as last stage of reduction to hide any gearbox backlash

  • Read Rev docs to understand limitations of the gearbox 

  • Link: MAXPlanetary System Kit - REV Robotics