vpAdaptiveGain.h

/****************************************************************************
 *
 * This file is part of the ViSP software.
 * Copyright (C) 2005 - 2017 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See http://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Adaptive gain.
 *
 * Authors:
 * Nicolas Mansard
 *
 *****************************************************************************/
#ifndef __VP_ADAPTIVE_GAIN_H
#define __VP_ADAPTIVE_GAIN_H

#include <iostream>
#include <visp3/core/vpConfig.h>

class vpColVector;
class VISP_EXPORT vpAdaptiveGain
{
public:
  static const double DEFAULT_LAMBDA_ZERO;
  static const double DEFAULT_LAMBDA_INFINITY;
  static const double DEFAULT_LAMBDA_SLOPE;

private:
  // Coefficient such as lambda (x) = a * exp (-b*x) + c
  double coeff_a; // \f$ a = \lambda(0) - \lambda(\infty) \f$
  double coeff_b; // \f$ b = {\dot \lambda}(0) / a \f$
  double coeff_c; // \f$ c = \lambda(\infty) \f$

  // Last computed value
  mutable double lambda;

public:
  /* --- CONSTRUCTOR --------------------------------------------------------
   */

  vpAdaptiveGain();
  explicit vpAdaptiveGain(double c);
  vpAdaptiveGain(double gain_at_zero, double gain_at_infinity, double slope_at_zero);

  /* --- INIT ---------------------------------------------------------------
   */
  void initFromConstant(double c);
  void initFromVoid(void);
  void initStandard(double gain_at_zero, double gain_at_infinity, double slope_at_zero);

  /* --- MODIFIORS ----------------------------------------------------------
   */
  double setConstant(void);

  /* --- COMPUTE ------------------------------------------------------------
   */
  /* \brief Calcule la valeur de lambda au point courrant.
   *
   * Determine la valeur du lambda adaptatif en fonction de la valeur
   * de la norme de la fonction de tache e par extrapolation exponentielle.
   * La fonction est : (en_infini - en_zero) * exp (-pente * ||e|| ) +
   * en_infini. On a bien :
   *    - lambda(10^5) = en_infini ;
   *    - lambda(0) = en_zero ;
   *    - lambda(x ~ 0) ~ - pente * x + en_zero.
   * \param val_e: valeur de la norme de l'erreur.
   * \return: valeur de gain au point courrant.
   */
  double value_const(double x) const;

  /* \brief Calcule la valeur de lambda au point courrant et stockage du
   * resultat.
   *
   * La fonction calcule la valeur de lambda d'apres la valeur de la norme
   * de l'erreur, comme le fait la fonction valeur_const.
   * La fonction non constante stocke de plus le resultat dans this ->lambda.
   * \param val_e: valeur de la norme de l'erreur.
   * \return: valeur de gain au point courrant.
   */
  double value(double x) const;

  double limitValue_const(void) const;

  double limitValue(void) const;

  /* --- ACCESSORS ----------------------------------------------------------
   */

  inline double getLastValue(void) const { return this->lambda; }

  double operator()(double x) const;

  /* \brief Lance la fonction valeur avec la norme INFINIE du vecteur. */
  double operator()(const vpColVector &x) const;

  /* \brief Idem function limitValue. */
  double operator()(void) const;

  /* --- IOSTREAM -----------------------------------------------------------
   */
  friend VISP_EXPORT std::ostream &operator<<(std::ostream &os, const vpAdaptiveGain &lambda);
};

#endif