gtsam/gtsam_unstable/dynamics/DynamicsPriors.h

/**
 * @file DynamicsPriors.h
 *
 * @brief Priors to be used with dynamic systems (Specifically PoseRTV)
 *
 * @date Nov 22, 2011
 * @author Alex Cunningham
 */

#pragma once

#include <gtsam_unstable/slam/PartialPriorFactor.h>

#include <gtsam_unstable/dynamics/PoseRTV.h>

namespace gtsam {

/**
 * Forces the value of the height in a PoseRTV to a specific value
 * Dim: 1
 */
struct DHeightPrior : public gtsam::PartialPriorFactor<PoseRTV> {
  typedef gtsam::PartialPriorFactor<PoseRTV> Base;
  DHeightPrior(Key key, double height, const gtsam::SharedNoiseModel& model)
  : Base(key, 5, height, model)  {  }
};

/**
 * Forces the roll to a particular value - useful for flying robots
 * Implied value is zero
 * Dim: 1
 */
struct DRollPrior : public gtsam::PartialPriorFactor<PoseRTV> {
  typedef gtsam::PartialPriorFactor<PoseRTV> Base;

  /** allows for explicit roll parameterization - uses canonical coordinate */
  DRollPrior(Key key, double wx, const gtsam::SharedNoiseModel& model)
  : Base(key, 0, wx, model)  {  }

  /** Forces roll to zero */
  DRollPrior(Key key, const gtsam::SharedNoiseModel& model)
  : Base(key, 0, 0.0, model)  {  }
};

/**
 * Constrains the full velocity of a state to a particular value
 * Useful for enforcing a stationary state
 * Dim: 3
 */
struct VelocityPrior : public gtsam::PartialPriorFactor<PoseRTV> {
  typedef gtsam::PartialPriorFactor<PoseRTV> Base;
  VelocityPrior(Key key, const gtsam::Vector& vel, const gtsam::SharedNoiseModel& model)
  : Base(key, model) {
    this->prior_ = vel;
    assert(vel.size() == 3);
    this->mask_.resize(3);
    this->mask_[0] = 6;
    this->mask_[1] = 7;
    this->mask_[2] = 8;
    this->H_ = Matrix::Zero(3, 9);
    this->fillH();
  }
};

/**
 * Ground constraint: forces the robot to be upright (no roll, pitch), a fixed height, and no
 * velocity in z direction
 * Dim: 4
 */
struct DGroundConstraint : public gtsam::PartialPriorFactor<PoseRTV> {
  typedef gtsam::PartialPriorFactor<PoseRTV> Base;

  /**
   * Primary constructor allows for variable height of the "floor"
   */
  DGroundConstraint(Key key, double height, const gtsam::SharedNoiseModel& model)
  : Base(key, model) {
    this->prior_ = Vector::Unit(4,0)*height; // [z, vz, roll, pitch]
    this->mask_.resize(4);
    this->mask_[0] = 5; // z = height
    this->mask_[1] = 8; // vz
    this->mask_[2] = 0; // roll
    this->mask_[3] = 1; // pitch
    this->H_ = Matrix::Zero(3, 9);
    this->fillH();
  }

  /**
   * Fully specify vector - use only for debugging
   */
  DGroundConstraint(Key key, const Vector& constraint, const gtsam::SharedNoiseModel& model)
  : Base(key, model) {
    assert(constraint.size() == 4);
    this->prior_ = constraint; // [z, vz, roll, pitch]
    this->mask_.resize(4);
    this->mask_[0] = 5; // z = height
    this->mask_[1] = 8; // vz
    this->mask_[2] = 0; // roll
    this->mask_[3] = 1; // pitch
    this->H_ = Matrix::Zero(3, 9);
    this->fillH();
  }
};

} // \namespace gtsam