Kinematics

Introduction

Movement is an essential component of your FTC Robot and Pod provides a set of classes and helpers through the Kinematics package for you to streamline movement operations on your robot.

These include robot tele-operated and autonomous movement, and actuators movement, for both linear and angular actuators.

Robot Movement

For a more in depth understanding of robot kinematics, we recommend reading Game Manual 0 - Kinematics guide.

Classes:

classDiagram direction RL class DeadWheelsKinematicsParams { +double y_zero +double x_zero +double wheelPerimeter +int encoderCPR } class DeadWheelsKinematics { +update(int positionLeft, int positionRight, int positionCenter) +updateAndReset(int positionLeft, int positionRight, int positionCenter, Pose2D position) +getPositionVelocity() PoseAndVelocity } class MecanumKinematicsParams { +LinearActuatorParams driveParams +double xScaler +double yScaler +double turnRadius } class MecanumForwardKinematics { +update(int flPosition, int frPosition, int rlPosition, int rrPosition) +updateAndReset(int flPosition, int frPosition, int rlPosition, int rrPosition, Pose2D position) +getPositionVelocity() PoseAndVelocity } class MecanumWheelKinematicsData~T~ { +T frontLeft +T frontRight +T rearLeft +T rearRight } class MecanumInverseKinematics { +calculate(Pose2D direction) MecanumWheelKinematicsData~Double~ } DeadWheelsKinematics ..> DeadWheelsKinematicsParams MecanumForwardKinematics ..> MecanumKinematicsParams MecanumInverseKinematics ..> MecanumWheelKinematicsData

Field Orientation

Before anything, it is important to align on a the robot and field orientation, as the robot movement is relative to field position:

Dead Wheel Kinematics

Provides an accurate field-relative localization using three unpowered encoded wheels (dead wheels) by comparing encoder delta’s over time.

update takes the integer positions of the left, right, and center dead wheel to calculate the new robot position on the field.

updateAndReset takes the integer positions of the dead wheels as well as a pose to set the robots current position to the current one and the velocity to zero.

Mecanum Forward Kinematics

Provides field-relative localization using encoded mecanum wheels. This method is prone to slippage issues but it can be used by teams who do not posses dead-wheels on the robot.

Mecanum Inverse Kinematics

Calculates motor actuation based on intended direction of movement (from gamepad or autonomous holonomic controller).

Actuator Movement

The following classes help with actuator movement. Linear actuators cause a linear motion on the robot, given and power input. Angular actuators cause a circular motion on the robot, given a power input.

Classes:

classDiagram direction RL class LinearActuatorParams { +int pulsesPerRotation = 28 // Standard GoBilda pulses per motor rotation prior reduction. +double motorGearRatio +double actuatorDiameter } class LinearActuatorCalculator { +pulsesToDistance(int pulses) double +lengthToPulses(double distance) int } class AngularActuatorParams { +int pulsesPerRotation = 28 // Standard GoBilda pulses per motor rotation prior reduction. +double motorGearRatio +double secondaryGearRatio } class AngularActuatorCalculator { +pulsesToAngle(int pulses) double +anglesToPulses(double angle) int } LinearActuatorCalculator ..> LinearActuatorParams AngularActuatorCalculator ..> AngularActuatorParams

Linear Actuator Calculator

Convert pulses to linear distance (in in chosen units) and vice versa, given the parameters of the gear-ratio’s and wheel diameters. It can be used in Linear slides or any other type of linear motion.

Angular Actuator Calculator

Convert pulses to angular rotation (in radians) and vice versa, given the parameters of the gear-ratio’s. Deals with angular motion/rotation. This type of motion refers to rotating arms, joints, and etc.