org.usfirst.frc.team1736.lib.MotorCurrentEstimators

Class CIMCurrentEstimator

java.lang.Object

org.usfirst.frc.team1736.lib.MotorCurrentEstimators.CIMCurrentEstimator

public class CIMCurrentEstimator
extends java.lang.Object

DESCRIPTION:
Current draw estimator for full-sized (2.5") CIM motor plus nominal wiring. Tweaked around FRC1736's 2016 robot. Given a applied voltage and speed, the current draw is estimated. This is useful for determining if a driver command will draw too much current. Treats a group of motors as a single current-drawing device (useful for single side of drivetrain where all motors run the same speed). Estimation is based off of a whitepaper by FRC1736 from the 2016 competition season.

Whitepaper link: Current Estimation.

USAGE:

1. Instantiate Class with proper values
2. Call estimator function during periodic loop to estimate motor current draw

Constructor Summary

Constructors

Constructor and Description
CIMCurrentEstimator(int numMotors, double controllerVDrop_V, PowerDistributionPanel pdp) Sets up the current estimator with the system parameters.

Method Summary

Modifier and Type	Method and Description
double	getCurrentEstimate(double motorSpeed_radpersec, double motorCommand) Determines a unique file name, and opens a file in the data captures directory and writes the initial lines to it.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CIMCurrentEstimator

public CIMCurrentEstimator(int numMotors,
                           double controllerVDrop_V,
                           PowerDistributionPanel pdp)

Sets up the current estimator with the system parameters.

Parameters:

numMotors - Integer number of motors in the gearbox system. Usually 2 or 3 for a side of a drivetrain, or 1 for a single motor.

controllerVDrop_V - voltage drop induced by the motor controller, in V.

pdp - Instance of the PDP class from the top level (needed for voltage measurements)

Method Detail

getCurrentEstimate

public double getCurrentEstimate(double motorSpeed_radpersec,
                                 double motorCommand)

Determines a unique file name, and opens a file in the data captures directory and writes the initial lines to it.

Parameters:

motorSpeed_radpersec - The speed of the motor input shaft in radians per second. Measured from an encoder attached to the same mechanism as the motor(s).

motorCommand - The command sent to the motor (-1 to 1 range).

Returns:

The current (in amps) drawn from the motor under the speed/voltage conditions given at the input.