Improved numeric robustness of angular distance calculation

As angular distance is composed of many floating point additions, it is changed in a increment counter followed by a multiplication to reduce floating point errors from escalating.

Author: JaapvanEkris

app/engine/Flywheel.js

@@ -61,8 +61,11 @@ export function createFlywheel (rowerSettings) {
   const cyclicErrorFilter = createCyclicErrorFilter(rowerSettings, minimumDragFactorSamples, recoveryDeltaTime)
   const strokedetectionMinimalGoodnessOfFit = rowerSettings.minimumStrokeQuality
   const minimumRecoverySlope = createWeighedSeries(rowerSettings.dragFactorSmoothing, rowerSettings.minimumRecoverySlope)
-  let totalTime
-  let currentAngularDistance
+  let rawTime = 0
+  let rawNumberOfImpulses = 0
+  let totalTimeSpinning = 0
+  let totalNumberOfImpulses = 0
+  let _totalWork = 0
   let _deltaTimeBeforeFlank = {}
   let _angularVelocityAtBeginFlank
   let _angularVelocityBeforeFlank
@@ -72,9 +75,6 @@ export function createFlywheel (rowerSettings) {
   let _torqueBeforeFlank
   let inRecoveryPhase
   let maintainMetrics
-  let totalNumberOfImpulses
-  let totalTimeSpinning
-  let _totalWork
   reset()
 
   /**
@@ -138,14 +138,15 @@ export function createFlywheel (rowerSettings) {
     }
 
     const cleanCurrentDt = cyclicErrorFilter.applyFilter(dataPoint, totalNumberOfImpulses + flankLength)
-    totalTime += cleanCurrentDt.value
-    currentAngularDistance += angularDisplacementPerImpulse
+    rawTime += cleanCurrentDt.value
+    rawNumberOfImpulses++
+    const currentAngularDistance = rawNumberOfImpulses * angularDisplacementPerImpulse
 
     // Let's feed the stroke detection algorithm
-    _deltaTime.push(totalTime, cleanCurrentDt.value)
+    _deltaTime.push(rawTime, cleanCurrentDt.value, cleanCurrentDt.goodnessOfFit)
 
     // Calculate the metrics that are needed for more advanced metrics, like the foce curve
-    _angularDistance.push(totalTime, currentAngularDistance)
+    _angularDistance.push(rawTime, currentAngularDistance, cleanCurrentDt.goodnessOfFit)
     _angularVelocityAtBeginFlank = _angularDistance.firstDerivative(0)
     _angularAccelerationAtBeginFlank = _angularDistance.secondDerivative(0)
     _torqueAtBeginFlank = (rowerSettings.flywheelInertia * _angularAccelerationAtBeginFlank + drag.weighedAverage() * Math.pow(_angularVelocityAtBeginFlank, 2))
@@ -190,10 +191,10 @@ export function createFlywheel (rowerSettings) {
       if (rowerSettings.autoAdjustRecoverySlope) {
         // We are allowed to autoadjust stroke detection slope as well, so let's do that
         minimumRecoverySlope.push((1 - rowerSettings.autoAdjustRecoverySlopeMargin) * recoveryDeltaTime.slope(), recoveryDeltaTime.goodnessOfFit())
-        log.debug(`*** Calculated recovery slope: ${recoveryDeltaTime.slope().toFixed(6)}, Goodness of Fit: ${recoveryDeltaTime.goodnessOfFit().toFixed(4)}`)
+        log.trace(`*** Calculated recovery slope: ${recoveryDeltaTime.slope().toFixed(6)}, Goodness of Fit: ${recoveryDeltaTime.goodnessOfFit().toFixed(4)}`)
       } else {
         // We aren't allowed to adjust the slope, let's report the slope to help help the user configure it
-        log.debug(`*** Calculated recovery slope: ${recoveryDeltaTime.slope().toFixed(6)}, Goodness of Fit: ${recoveryDeltaTime.goodnessOfFit().toFixed(4)}, not used as autoAdjustRecoverySlope isn't set to true`)
+        log.trace(`*** Calculated recovery slope: ${recoveryDeltaTime.slope().toFixed(6)}, Goodness of Fit: ${recoveryDeltaTime.goodnessOfFit().toFixed(4)}, not used as autoAdjustRecoverySlope isn't set to true`)
       }
     } else {
       // As the drag calculation is considered unreliable, we must skip updating the systematic error filter that depends on it
@@ -397,24 +398,32 @@ export function createFlywheel (rowerSettings) {
     }
   }
 
+  /**
+   * @param {float} slope - Recovery slope to be converted
+   * @returns {float} Dragfactor to be used in all calculations
+   * @description Helper function to convert a recovery slope into a dragfactor
+   */
   function slopeToDrag (slope) {
     return ((slope * rowerSettings.flywheelInertia) / angularDisplacementPerImpulse)
   }
 
+  /**
+   * @description This function is used for clearing all data, returning the flywheel.js to its initial state
+   */
   function reset () {
     maintainMetrics = false
     inRecoveryPhase = false
+    rawTime = 0
+    rawNumberOfImpulses = 0
+    totalTimeSpinning = 0
+    totalNumberOfImpulses = -1
+    _totalWork = 0
     drag.reset()
     cyclicErrorFilter.reset()
     cyclicErrorFilter.applyFilter(0, flankLength - 1)
     recoveryDeltaTime.reset()
     _deltaTime.reset()
     _angularDistance.reset()
-    totalTime = 0
-    currentAngularDistance = 0
-    totalNumberOfImpulses = -1
-    totalTimeSpinning = 0
-    _totalWork = 0
     _deltaTime.push(0, 0)
     _angularDistance.push(0, 0)
     _deltaTimeBeforeFlank.clean = 0