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Commit ce7a57d9 authored by Derek Wu's avatar Derek Wu Committed by Android (Google) Code Review
Browse files

Merge "Add smoothing to jerk calculations and updated jerk thresholds." into main

parents cdb473cc 5e0e7cf9

data/etc/input/motion_predictor_config.xml

+5 −2
Original line number Diff line number Diff line
@@ -35,7 +35,10 @@ 


    The jerk thresholds are based on normalized dt = 1 calculations.

  -->

  <low-jerk>1.0</low-jerk>

  <high-jerk>1.1</high-jerk>

  <low-jerk>1.5</low-jerk>

  <high-jerk>2.0</high-jerk>



  <!-- The forget factor in the first-order IIR filter for jerk smoothing -->

  <jerk-forget-factor>0.25</jerk-forget-factor>

</motion-predictor>

include/input/MotionPredictor.h

+13 −0
Original line number Diff line number Diff line
@@ -56,12 +56,20 @@ public: 
    // acceleration) and has the units of d^3p/dt^3.

    std::optional<float> jerkMagnitude() const;



    // forgetFactor is the coefficient of the first-order IIR filter for jerk. A factor of 1 results

    // in no smoothing.

    void setForgetFactor(float forgetFactor);

    float getForgetFactor() const;



private:

    const bool mNormalizedDt;

    // Coefficient of first-order IIR filter to smooth jerk calculation.

    float mForgetFactor = 1;



    RingBuffer<int64_t> mTimestamps{4};

    std::array<float, 4> mXDerivatives{}; // [x, x', x'', x''']

    std::array<float, 4> mYDerivatives{}; // [y, y', y'', y''']

    float mJerkMagnitude;

};



/**
@@ -116,6 +124,11 @@ public: 


    bool isPredictionAvailable(int32_t deviceId, int32_t source);



    /**

     * Currently used to expose config constants in testing.

     */

    const TfLiteMotionPredictorModel::Config& getModelConfig();



private:

    const nsecs_t mPredictionTimestampOffsetNanos;

    const std::function<bool()> mCheckMotionPredictionEnabled;

include/input/TfLiteMotionPredictor.h

+3 −0
Original line number Diff line number Diff line
@@ -110,6 +110,9 @@ public: 
        // High jerk means more predictions will be pruned, vice versa for low.

        float lowJerk = 0;

        float highJerk = 0;



        // Coefficient for the first-order IIR filter for jerk calculation.

        float jerkForgetFactor = 1;

    };



    // Creates a model from an encoded Flatbuffer model.

libs/input/MotionPredictor.cpp

+31 −1
Original line number Diff line number Diff line
@@ -75,6 +75,9 @@ float normalizeRange(float x, float min, float max) { 
JerkTracker::JerkTracker(bool normalizedDt) : mNormalizedDt(normalizedDt) {}



void JerkTracker::pushSample(int64_t timestamp, float xPos, float yPos) {

    // If we previously had full samples, we have a previous jerk calculation

    // to do weighted smoothing.

    const bool applySmoothing = mTimestamps.size() == mTimestamps.capacity();

    mTimestamps.pushBack(timestamp);

    const int numSamples = mTimestamps.size();
@@ -115,6 +118,16 @@ void JerkTracker::pushSample(int64_t timestamp, float xPos, float yPos) { 
        }

    }



    if (numSamples == static_cast<int>(mTimestamps.capacity())) {

        float newJerkMagnitude = std::hypot(newXDerivatives[3], newYDerivatives[3]);

        ALOGD_IF(isDebug(), "raw jerk: %f", newJerkMagnitude);

        if (applySmoothing) {

            mJerkMagnitude = mJerkMagnitude + (mForgetFactor * (newJerkMagnitude - mJerkMagnitude));

        } else {

            mJerkMagnitude = newJerkMagnitude;

        }

    }



    std::swap(newXDerivatives, mXDerivatives);

    std::swap(newYDerivatives, mYDerivatives);

}
@@ -125,11 +138,19 @@ void JerkTracker::reset() { 


std::optional<float> JerkTracker::jerkMagnitude() const {

    if (mTimestamps.size() == mTimestamps.capacity()) {

        return std::hypot(mXDerivatives[3], mYDerivatives[3]);

        return mJerkMagnitude;

    }

    return std::nullopt;

}



void JerkTracker::setForgetFactor(float forgetFactor) {

    mForgetFactor = forgetFactor;

}



float JerkTracker::getForgetFactor() const {

    return mForgetFactor;

}



// --- MotionPredictor ---



MotionPredictor::MotionPredictor(nsecs_t predictionTimestampOffsetNanos,
@@ -159,6 +180,7 @@ android::base::Result<void> MotionPredictor::record(const MotionEvent& event) { 
    if (!mModel) {

        mModel = TfLiteMotionPredictorModel::create();

        LOG_ALWAYS_FATAL_IF(!mModel);

        mJerkTracker.setForgetFactor(mModel->config().jerkForgetFactor);

    }



    if (!mBuffers) {
@@ -357,4 +379,12 @@ bool MotionPredictor::isPredictionAvailable(int32_t /*deviceId*/, int32_t source 
    return true;

}



const TfLiteMotionPredictorModel::Config& MotionPredictor::getModelConfig() {

    if (!mModel) {

        mModel = TfLiteMotionPredictorModel::create();

        LOG_ALWAYS_FATAL_IF(!mModel);

    }

    return mModel->config();

}



} // namespace android

libs/input/TfLiteMotionPredictor.cpp

+1 −0
Original line number Diff line number Diff line
@@ -283,6 +283,7 @@ std::unique_ptr<TfLiteMotionPredictorModel> TfLiteMotionPredictorModel::create() 
            .distanceNoiseFloor = parseXMLFloat(*configRoot, "distance-noise-floor"),

            .lowJerk = parseXMLFloat(*configRoot, "low-jerk"),

            .highJerk = parseXMLFloat(*configRoot, "high-jerk"),

            .jerkForgetFactor = parseXMLFloat(*configRoot, "jerk-forget-factor"),

    };



    return std::unique_ptr<TfLiteMotionPredictorModel>(