navXPerformanceTuningOp.java

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package com.qualcomm.ftcrobotcontroller.opmodes;

import android.os.SystemClock;

import com.kauailabs.navx.ftc.AHRS;
import com.kauailabs.navx.ftc.navXPerformanceMonitor;
import com.qualcomm.robotcore.eventloop.opmode.OpMode;
import com.qualcomm.robotcore.util.ElapsedTime;

import java.text.DecimalFormat;

/**
 * navX-Micro Performance Tuning Op
 *
 * This opmode provides insight into the peformance of the communication
 * with the navX-Model sensor over the I2C bus via the Core Device Interface
 * Module.  Since the Android operating system is not a real-time
 * operating system, and since communication w/the navX-Model sensor is
 * occurring over a wifi-direct network which can be prone to interference,
 * the actual performance (update rate) achieved may be less than
 * one might expect.
 *
 * Since the navX-Model devices integrate sensor data onboard, to achieve
 * the best performance for device control methods like a PID controller
 * that work best with constant-time updates, the strategy is to:
 *
 * 1) Configure the navX-Model device to a high update rate (e.g., 50Hz)
 * 2) Using this performance-tuning Op-Mode (with all other
 * sensors connected, just as your robot will be configured for normal
 * use) observe the "effective" update rate, and the number of missed
 * samples over the last minute.
 * 3) Lower the navX-Model device update rate until the number of missed
 * samples over the last minute reaches zero.
 */
public class navXPerformanceTuningOp extends OpMode {

  /* This is the port on the Core Device Interface Module */
  /* in which the navX-Micro is connected.  Modify this  */
  /* depending upon which I2C port you are using.        */
  private final int NAVX_DIM_I2C_PORT = 0;

  private AHRS navx_device;
  private navXPerformanceMonitor navx_perfmon;
  private byte sensor_update_rate_hz = 40;
  private ElapsedTime runtime = new ElapsedTime();

  @Override
  public void init() {
    AHRS.setLogging(true);
    navx_device = AHRS.getInstance(hardwareMap.deviceInterfaceModule.get("dim"),
            NAVX_DIM_I2C_PORT,
            AHRS.DeviceDataType.kProcessedData,
            sensor_update_rate_hz);
    navx_perfmon = new navXPerformanceMonitor(navx_device);
  }

@Override
  public void start() {
    navx_device.registerCallback(navx_perfmon);
}

  @Override
  public void stop() {
    navx_device.close();
  }
  /*
     * Code to run when the op mode is first enabled goes here
     * @see com.qualcomm.robotcore.eventloop.opmode.OpMode#start()
     */
  @Override
  public void init_loop() {
    telemetry.addData("navX Op Init Loop", runtime.toString());
  }

  /*
   * This method will be called repeatedly in a loop
   * @see com.qualcomm.robotcore.eventloop.opmode.OpMode#loop()
   */
  @Override
  public void loop() {

      boolean connected = navx_device.isConnected();
      telemetry.addData("1 navX-Device...............:", connected ?
              "Connected" : "Disconnected" );
      String gyrocal, motion;
      DecimalFormat df = new DecimalFormat("#.##");

      telemetry.addData("2 Sensor Rate (Hz)...", Byte.toString(navx_device.getActualUpdateRate()));
      telemetry.addData("3 Transfer Rate (Hz).", Integer.toString(navx_device.getCurrentTransferRate()));
      telemetry.addData("4 Delivvered Rate (Hz)", Integer.toString(navx_perfmon.getDeliveredRateHz()));
      telemetry.addData("5 Missed Samples.....", Integer.toString(navx_perfmon.getNumMissedSensorTimestampedSamples()));
      telemetry.addData("6 Duplicate Samples..", Integer.toString(navx_device.getDuplicateDataCount()));
      telemetry.addData("7 Sensor deltaT (ms).", Long.toString(navx_perfmon.getLastSensorTimestampDeltaMS()));
      telemetry.addData("8 System deltaT (ms).", Long.toString(navx_perfmon.getLastSystemTimestampDeltaMS()));
  }
}