height_map_examples.h

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#ifndef TOWR_TOWR_ROS_INCLUDE_TOWR_ROS_HEIGHT_MAP_EXAMPLES_H_
#define TOWR_TOWR_ROS_INCLUDE_TOWR_ROS_HEIGHT_MAP_EXAMPLES_H_

#include <towr/terrain/height_map.h>

namespace towr {

class FlatGround : public HeightMap {
public:
  FlatGround(double height = 0.0);
  double GetHeight(double x, double y)  const override { return height_; };

private:
  double height_; // [m]
};

class Block : public HeightMap {
public:
  double GetHeight(double x, double y)  const override;
  double GetHeightDerivWrtX(double x, double y) const override;

private:
  double block_start = 0.7;
  double length_     = 3.5;
  double height_     = 0.5; // [m]

  double eps_ = 0.03; // approximate as slope
  const double slope_ = height_/eps_;
};

class Stairs : public HeightMap {
public:
  double GetHeight(double x, double y) const override;

private:
  double first_step_start_  = 1.0;
  double first_step_width_  = 0.4;
  double height_first_step  = 0.2;
  double height_second_step = 0.4;
  double width_top = 1.0;
};

class Gap : public HeightMap {
public:
  double GetHeight(double x, double y) const override;
  double GetHeightDerivWrtX(double x, double y) const override;
  double GetHeightDerivWrtXX(double x, double y) const override;

private:
  const double gap_start_ = 1.0;
  const double w = 0.5;
  const double h = 1.5;

  const double slope_ = h/w;
  const double dx = w/2.0;
  const double xc = gap_start_ + dx; // gap center
  const double gap_end_x = gap_start_ + w;

  // generated with matlab
  // see matlab/gap_height_map.m
  // coefficients of 2nd order polynomial
  // h = a*x^2 + b*x + c
  const double a = (4*h)/(w*w);
  const double b = -(8*h*xc)/(w*w);
  const double c = -(h*(w - 2*xc)*(w + 2*xc))/(w*w);
};

class Slope : public HeightMap {
public:
  double GetHeight(double x, double y) const override;
  double GetHeightDerivWrtX(double x, double y) const override;

private:
  const double slope_start_ = 1.0;
  const double up_length_   = 1.0;
  const double down_length_ = 1.0;
  const double height_center = 0.7;

  const double x_down_start_ = slope_start_+up_length_;
  const double x_flat_start_ = x_down_start_ + down_length_;
  const double slope_ = height_center/up_length_;
};

class Chimney : public HeightMap {
public:
  double GetHeight(double x, double y) const override;
  double GetHeightDerivWrtY(double x, double y) const override;

private:
  const double x_start_ = 1.0;
  const double length_  = 1.5;
  const double y_start_ = 0.5; // distance to start of slope from center at z=0
  const double slope_   = 3.0;

  const double x_end_ = x_start_+length_;
};

class ChimneyLR : public HeightMap {
public:
  double GetHeight(double x, double y) const override;
  double GetHeightDerivWrtY(double x, double y) const override;

private:
  const double x_start_ = 0.5;
  const double length_  = 1.0;
  const double y_start_ = 0.5; // distance to start of slope from center at z=0
  const double slope_   = 2;

  const double x_end1_ = x_start_+length_;
  const double x_end2_ = x_start_+2*length_;
};

} /* namespace towr */

#endif /* TOWR_TOWR_ROS_INCLUDE_TOWR_ROS_HEIGHT_MAP_EXAMPLES_H_ */