FTC:Electronics

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Electronics are what allows the robot to function properly. These different electronic parts are the main components used in the electronics of a robot in FIRST Tech Challenge.

Driver Hub and Control Hub Interaction

Hardware.png

This diagram shows the basic layout for a robot’s electronics. First, the drivers input commands into the game controllers that are programmed for specific tasks on the robot. The inputs then go to the Driver Hub. The Driver Hub then transmits commands to the Control Hub via Wifi Direct. The Control Hub in turn sends commands to the motors and sensors.  It also connects directly with the Expansion Hub via the blue transmission wire. The Expansion Hub is used to add additional motors and sensors.

REV Driver Hub

The Driver Hub is an Android device and has a touch screen and multiple ports for the game controllers.

REV Control Hub

The Control Hub is an Android device and has ports for 4 DC motors, 6 servos and 16 sensors. It is the main controller of the robot, controlling even the Expansion Hub.

REV Expansion Hub

The Expansion Hub is used if you need more than for DC motors on your robot.  It is also nice to have on your robot on the side opposite the control hub to allow for shorter wire spans for electronics connections.

DC Motors

There are many different types of motors that can be used for driving or various subsystems. Choose an appropriate motor for the task it should complete. The list below is a partial list of DC Motors that are legal to use in FTC. Evaluate these motors to determine which will be the best for your subsystem.

Common Motor Examples

Name Pros Cons Uses
NeveRest Orbital 20 Gearmotor
  • High speed
  • Reliable
  • Can’t adjust tension for a chain drive easily
  • Low torque
Good for use in high speed subsystems such as launchers
NeveRest 40
  • Decent Torque and Speed
  • Easy adjustment of chain tension
  • Uses a D pattern axle
Good for use in driving
NeveRest 60
  • Good Torque
  • Easy adjustment of chain tension
  • Uses a D pattern axle
Good for high torque subsystems
TETRIX MAX DC Motor
  • Small
  • D-pattern axle not as strong
  • Low power
  • Wire connection at the back of the motor can come off easily
This motor is outperformed by many other motors.
REV Ultra Planetary Gearmotor
  • Durable
  • Easy to change the gearbox
  • Can’t adjust tension for a chain drive easily
High speed subsystems and driving
REV HD Hex Motor 20:1 Planetary
  • High Speed
  • Can’t adjust tension for a chain drive easily
High speed subsystems and driving
REV HD Hex Motor 40:1
  • High Torque
  • Durable
  • Decent speed
Good for driving and for high torque subsystems
REV Core Hex Motor
  • Allows use of hex axle
  • Strong attachment point for those axles
  • Reliable
  • Slow
  • Not super powerful
Good for low speed subsystems
TETRIX Torquenado
  • Super high torque
  • Not super fast
Great for heavy subsystems or lifting heavy things.
goBilda 5202 Series Yellow Jacket Planetary Gear Motor
  • Many option on torque and speed
  • Uses a D axle
  • Can’t adjust tension for a chain drive easily
Good for subsystems and driving. It can be put into a goBilda U-channel.
goBilda 5203 Series Yellow Jacket Planetary Gear Motor
  • Many option on torque and speed
  • Uses a hex axle
  • Can’t adjust tension for a chain drive easily
Good for subsystems and driving. It can be put into a goBilda U-channel.

Servos

In FTC, servos are used in many different subsystems for moving or lifting smaller parts because they aren’t as strong as normal motors. They are also typically more precise than motors. However, most servos only rotate 180 degrees. Continuous servos do not have that rotation restriction. Servos go well with custom parts to perform multiple functions.  Below is a partial list of legal servos. Do some research to find the best servo for your subsystem.

Name Function
REV Smart Robot Servo The REV Smart Servo is able to be programmed to be both continuous and angular. Continuous allows for the servo to act like a motor. Angular Mode allows the servo to move to set positions.
VEX EDR 393 The VEX EDR 393, although called a motor, counts as a servo in FTC. To use it teams need to connect it to a REV Servo Power Module. The EDR has a higher stall torque than most servos, so it can be used to manipulate heavier objects.
GoBuilda 2000 Series Dual Mode Servo There are two versions of this servo, speed and torque. The speed version moves twice as fast as the torque version, while the torque version has twice the stall torque. Both types are able to be programmed to positions.
20KG Digital Servo The 20KG servo has incredibly high torque for a servo. It is an angular servo, meaning that it is able to be programmed to go to set positions.
TETRIX® MAX Standard-Scale Servo Motor The Tetrix MAX Servo is able to turn 180 degrees. It is weaker than the other servos and isn’t able to move as fast.

Sensors

There are many different sensors that an FTC team can use.

Name Function
Gyro/IMU Measures how many degrees your robot is turning, which allows for better turning in autonomous.The IMU is an internal gyro sensor built into the REV Control and Expansion Hubs.
Vision Webcams are a great way to detect many things on the field. This could be used to make the robot move to an object, aim for certain positions, and much more.
Touch A touch sensor is a button that when pressed, will tell the robot to implement a certain command.
Light Detects various amounts of light that will be present in certain areas of the field. The robot then can perform a task based on the light level.
Distance Determines how far something is from the robot so it knows not to run into it, or how close it can get to it.

Wires

Name Function
Power Provide power from the battery to the REV hubs. The REV hubs then distribute it to the other electronics

PowerWire.png

Encoder Accurately controls the motors to make the robot have better movement and turning.

EncoderWire.png

Motor/Servo Wires Provide power and control to motors and servos.

MotorWire.png

JST PH 3-pin Communication Cable Connects together REV hubs like the Control and Expansion Hub.

JSTwire.png

Additional Resources

References