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include/odometry/odom_differential.h

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+#pragma once
+
+#include <cstdint>
+#include <math.h>
+#include <boost/accumulators/accumulators.hpp>
+#include <boost/accumulators/statistics/stats.hpp>
+#include <boost/accumulators/statistics/rolling_mean.hpp>
+#include <boost/function.hpp>
+
+namespace differential
+{
+  namespace bacc = boost::accumulators;
+
+  /**
+   * \brief The Odometry class handles odometry readings
+   * (2D pose and velocity with related timestamp)
+   */
+  class Odometry
+  {
+  public:
+
+    /// Integration function, used to integrate the odometry:
+    typedef boost::function<void(double, double)> IntegrationFunction;
+
+    /**
+     * \brief Constructor
+     * Timestamp will get the current time value
+     * Value will be set to zero
+     * \param velocity_rolling_window_size Rolling window size used to compute the velocity mean
+     */
+    Odometry(size_t velocity_rolling_window_size = 10);
+
+    /**
+     * \brief Initialize the odometry
+     * \param time Current time
+     */
+    void init(const double &time);
+
+    /**
+     * \brief Updates the odometry class with latest wheel angular velocities
+     * \param left_vel  Left  wheel angular velocity [rad/s]
+     * \param right_vel Right wheel angular velocity [rad/s]
+     * \param time      Current time
+     * \return true if the odometry is actually updated
+     */
+    bool updateWheel(double left_vel, double right_vel, const double &time);
+
+    /**
+     * \brief Updates odometry from cumulative encoder tick counts
+     *
+     * Converts tick deltas to wheel arc lengths, then integrates pose with the
+     * same exact/RK2 path as updateWheel. The first call after init() only
+     * seeds the previous tick counts and returns false.
+     *
+     * Caller should unwrap hardware counter overflow into a monotonic int64
+     * cumulative count before calling.
+     *
+     * \param left_ticks  Cumulative left  wheel ticks (after gearbox, wheel side)
+     * \param right_ticks Cumulative right wheel ticks (after gearbox, wheel side)
+     * \param time        Current time [s]
+     * \return true if the odometry is actually updated
+     */
+    bool updateTicks(std::int64_t left_ticks, std::int64_t right_ticks, const double &time);
+
+    /**
+     * \brief Updates the odometry class with latest velocity command
+     * \param linear  Linear velocity [m/s]
+     * \param angular Angular velocity [rad/s]
+     * \param time    Current time
+     */
+    void updateOdom(double linear, double angular, const double &time);
+
+    /**
+     * \brief heading getter
+     * \return heading [rad]
+     */
+    double getHeading() const
+    {
+      return heading_;
+    }
+
+    /**
+     * \brief x position getter
+     * \return x position [m]
+     */
+    double getX() const
+    {
+      return x_;
+    }
+
+    /**
+     * \brief y position getter
+     * \return y position [m]
+     */
+    double getY() const
+    {
+      return y_;
+    }
+
+    /**
+     * \brief linear velocity getter
+     * \return linear velocity [m/s]
+     */
+    double getLinear() const
+    {
+      return linear_;
+    }
+
+    /**
+     * \brief angular velocity getter
+     * \return angular velocity [rad/s]
+     */
+    double getAngular() const
+    {
+      return angular_;
+    }
+
+    /**
+     * \brief Sets the wheel parameters: radius and separation
+     * \param wheel_separation   Separation between left and right wheels [m]
+     * \param left_wheel_radius  Left wheel radius [m]
+     * \param right_wheel_radius Right wheel radius [m]
+     */
+    void setWheelParams(double wheel_separation, double left_wheel_radius, double right_wheel_radius);
+
+    /**
+     * \brief Sets encoder resolution for both wheels (same CPR)
+     * \param ticks_per_revolution Ticks per wheel revolution (wheel side)
+     */
+    void setEncoderParams(double ticks_per_revolution);
+
+    /**
+     * \brief Sets encoder resolution per wheel
+     * \param left_ticks_per_revolution  Left  wheel ticks per revolution
+     * \param right_ticks_per_revolution Right wheel ticks per revolution
+     */
+    void setEncoderParams(double left_ticks_per_revolution, double right_ticks_per_revolution);
+
+    /**
+     * \brief Velocity rolling window size setter
+     * \param velocity_rolling_window_size Velocity rolling window size
+     */
+    void setVelocityRollingWindowSize(size_t velocity_rolling_window_size);
+
+  private:
+
+    /// Rolling mean accumulator and window:
+    typedef bacc::accumulator_set<double, bacc::stats<bacc::tag::rolling_mean> > RollingMeanAcc;
+    typedef bacc::tag::rolling_window RollingWindow;
+
+    /**
+     * \brief Integrates the velocities (linear and angular) using 2nd order Runge-Kutta
+     * \param linear  Linear  displacement [m]
+     * \param angular Angular displacement [rad]
+     */
+    void integrateRungeKutta2(double linear, double angular);
+
+    /**
+     * \brief Integrates the velocities (linear and angular) using exact method
+     * \param linear  Linear  displacement [m]
+     * \param angular Angular displacement [rad]
+     */
+    void integrateExact(double linear, double angular);
+
+    /**
+     *  \brief Reset linear and angular accumulators
+     */
+    void resetAccumulators();
+
+    /// Current timestamp:
+    double timestamp_;
+
+    /// Current pose:
+    double x_;        //   [m]
+    double y_;        //   [m]
+    double heading_;  // [rad]
+
+    /// Current velocity:
+    double linear_;  //   [m/s]
+    double angular_; // [rad/s]
+
+    /// Wheel kinematic parameters [m]:
+    double wheel_separation_;
+    double left_wheel_radius_;
+    double right_wheel_radius_;
+
+    /// Encoder resolution [ticks / wheel revolution]:
+    double left_ticks_per_revolution_;
+    double right_ticks_per_revolution_;
+
+    /// Previous cumulative tick counts for delta computation:
+    bool ticks_initialized_;
+    std::int64_t left_ticks_prev_;
+    std::int64_t right_ticks_prev_;
+
+    /// Rolling mean accumulators for the linear and angular velocities:
+    size_t velocity_rolling_window_size_;
+    RollingMeanAcc linear_acc_;
+    RollingMeanAcc angular_acc_;
+
+    /// Integration function, used to integrate the odometry:
+    IntegrationFunction integrate_fun_;
+  };
+}