Upgrades!
Last updated
Last updated
There are many ways to split robot control across two gamepads. We recommend testing different combinations with your team to decide what feels the most comfortable to you!
This version of the program is intended to be just one example for using two gamepads. Arm and wrist control has been moved to a second gamepad while the main gamepad handles driving and the servos on the intake and claw.
The associated gamepad for a button input can be changed at any time by clicking on the block's dropdown:
In this example code, we changed our drive function to only be on the left stick!
You can learn about arcade style of driving in Hello Robot!
When changing a function name this will automatically change throughout the entire code to reflect the new name.
Upgrading to a Mecanum Drivetrain (REV-45-2470) allows for new kinds of movement giving the robot the ability to strafe side-to-side across the field.
For Mecanum Drive each wheel has an individual motor!
The FTC Starter Kit V3.1 can be upgraded to the Mecanum Drivetrain V1 following this guide.
The following additional parts are needed:
Ultra 90 Degree Gearbox - QTY 4
75mm Mecanum Wheel Set - QTY 1 (set of 4)
M3 x 6mm HexCap Screws 50 Pack - QTY 1
Expansion Hub (QTY 1) OR SPARKmini Motor Controller (QTY 2)
Full build instructions can be found here!
How a Mecanum Drivetrain is programmed largely depends on the driver's preference for how the controller is configured.
In our provided example, the left joystick controls forward/back and strafe then the right joystick controls turning. This code is based on the sample provided by FIRST in Blocks (BasicOmniOpMode).
Motor
Control Hub
0
REV Robotics Ultraplanetary HD Hex Motor
frontLeft
Motor
Control Hub
1
REV Robotics Ultraplanetary HD Hex Motor
backLeft
Motor
Control Hub
2
REV Robotics Ultraplanetary HD Hex Motor
frontRight
Motor
Control Hub
3
REV Robotics Ultraplanetary HD Hex Motor
backRight
Servo
Control Hub
4
Servo
claw
Servo
Control Hub
5
Continuous Servo
intake
Motor
Expansion Hub
0
REV Robotics Core Hex Motor
wrist
Motor
Expansion Hub
1
REV Robotics Ultraplanetary HD Hex Motor
arm
Before diving into mecanum, double check the direction your motors and wheels are turning. They may need to be reversed if you're experiencing jittering or inverted controls!
At the very beginning of our program the drivetrain motors are set to RUN_WITHOUT_ENCODER.
We need to create some new variables in order to use mecanum. Let's break those down first:
FB
Moving forward and backwards
Strafe
Strafing side to side
Turn
Turning left and right
leftFrontPower
Sets the front left motor power
rightFrontPower
Sets the front right motor power
leftBackPower
Sets the back left motor power
rightBackPower
Sets the back right motor power
max
This is used to check that our values do not exceed the expected range - similar to the "clip" block
At the beginning of the MECANUM_DRIVE function, our variables for each movement direction are being set to the value generated by the movement of the matching joystick axis.
Since we now have four motors in play, our equation for setting the appropriate power to each motor gets a little more complicated.
Our robot first needs to determine the combined movement of the left stick then calculate with the right stick's value. This allows for movement when the left joystick is at an angle, such as strafing along a diagonal!
Next, similar to our original drivetrain code, there's a chance a value may fall outside the range of the motor's power (-1 to 1). Therefore, we want our robot to check and bring those values back into range so we don't miss any inputs.
For our last step, our robot sets the power of each pair of motors based on all our calculations!
Add a block to change the set direction during initialization.
