Motors

All about things that revolve

Motors are how we transmit programmed instructions into robot movements. There are a variety of types of motors that are legal and used in FRC, and many are listed in List of Electrical Components. For the most part the only motors discussed here are ones we use on our robot.

All motors we use, and the vast majority of those used in FRC, are brushless.

How motors are controlled:

This starts to connect to the programming aspects of things, which uses commands to provide voltage, or desired speed, to the motors. (Speed is not a function of power, of course, since power provides acceleration, and not a consistent acceleration either. Thus PID (link) is used to approach a speed) (position is not handled by the library, and pid for position must be done in code. thats a programming issue though) These commands are transmitted via CAN from the Rio, along with stats about the state of the motor from the motor controller. The motor controller controls the power running to the motor based on the commands it receives.

All of the motors we use have the motor controller built in, but not all motors have this luxury: and learning about how those motors work is very important for jobs such as Service Angels (link) and Pit Scout (link). Info on how these motors work is here.

Kraken Motors

For our robot we use the Kraken X60 (below) and the Kraken X44 (like below, but smaller).

For more specific information, look here: https://docs.wcproducts.com/kraken-x60

Status lights

The green lines on the back of the motor are status lights, and they are a quick reference for the status of the motor. These are used in pit checks and troubleshooting. Visit Status Lights for list of colors and what they mean.

Motor hats

Below them is where the wires are attached- and there are a few different ways this is done. The motors come with regular motor "hats" which are screwed on to fix wires to the terminals, and for the most part these are the hats we use. However there are also versions with Andersons (link) and Molexes (link) built in, and wires can be connected without disassembling the hat. However they are much more prone to failure, especially as the molex connections like to snap off.

We have historically only used the Anderson hats for one part of the robot: the swerves. This is because they allow for much easier swapping of motors. However it is unlikely we will continue to use them due to their failure points.

Things to consider when using Krakens:

  • Plan ahead so that the Kraken is oriented such that the wires are coming out in the direction you want to run them

  • They have hard stops for the screws on the front

  • The wires are interchangeable. This allows for single run wires that connect straight from motor to PDH, which can lower probability of fault. This only works for short runs such as Swerve motors. It also, unlike Falcons, justifies cutting short runs so that there is not an excess of wire.

Falcon Motors

Falcon motors are the previous generation of brushless motors, and have been replaced with the Kraken series.

Up until the 2025 we have used majority Falcons (Specifically, the Falcon 500) (well, I guess I should say 2024 season second robot), and this changed when through the course of two competitions about everything that could break on one of those motors did.

We probably swapped a motor every other match, and I think the experience was summed up with perhaps the most absurd failure I have seen throughout my time on the team: the motor shaft, which was a steel spline shaft welded into a round steel base which was then screwed to the motor (inside the housing), sheared. Specifically, the welded connection sheared. That was a tough one to diagnose.

We will not be using Falcons on any of our robots in the future, but they are still good motors. Out Falcons were old and had experienced a lifetime of strain, and this certainly played a role in their spectacular failure. Many other teams still use them, and we still have a few.

A lot of what is scattered around the pit and loft is built for Falcons, though, and its important to recognize the small differences, most importantly the shaft: just to cause endless annoyance, the Kraken spline (Spline XS) has ONE more ridge than the Falcon spline. Thus the Falcon input couplers for gearboxes will not work on Krakens and nor will belt sprockets.

A few drawbacks to consider when using Falcons, or addressing other team's issues relating to Falcons:

  • The attachment holes on the front do not have a hard stop. This means that if screws are slightly to long (still very short) they will screw into the bell of the motor and wreck the motor

  • The wires are fixed in the motor and are not interchangeable. So if Falcon wires are cut, they cannot be lengthened again. This leads to, over a while, stubby little wires and thus require connections right at the motor. For this reason, it is best practice not to cut the wires shorter, or only just a bit. This is not the case with Krakens.

Since Falcons also use TalonFX motor controllers, the status lights are the same as those on Krakens.

Last updated

Was this helpful?