concatenated_dynamical_system.h

/*
 * Copyright (c) 2019, The Regents of the University of California (Regents).
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
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 *    1. Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *    2. Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *
 *    3. Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Please contact the author(s) of this library if you have any questions.
 * Authors: David Fridovich-Keil   ( dfk@eecs.berkeley.edu )
 */

///////////////////////////////////////////////////////////////////////////////
//
// Multi-player dynamical system comprised of several single player subsystems.
//
///////////////////////////////////////////////////////////////////////////////

#ifndef ILQGAMES_DYNAMICS_CONCATENATED_DYNAMICAL_SYSTEM_H
#define ILQGAMES_DYNAMICS_CONCATENATED_DYNAMICAL_SYSTEM_H

#include <ilqgames/dynamics/multi_player_dynamical_system.h>
#include <ilqgames/dynamics/single_player_dynamical_system.h>
#include <ilqgames/utils/linear_dynamics_approximation.h>
#include <ilqgames/utils/types.h>

#include <algorithm>

namespace ilqgames {

using SubsystemList = std::vector<std::shared_ptr<SinglePlayerDynamicalSystem>>;

class ConcatenatedDynamicalSystem : public MultiPlayerDynamicalSystem {
 public:
  ~ConcatenatedDynamicalSystem() {}
  ConcatenatedDynamicalSystem(const SubsystemList& subsystems);

  // Compute time derivative of state.
  VectorXf Evaluate(Time t, const VectorXf& x,
                    const std::vector<VectorXf>& us) const;

  // Compute a discrete-time Jacobian linearization.
  LinearDynamicsApproximation Linearize(Time t, const VectorXf& x,
                                        const std::vector<VectorXf>& us) const;

  // Distance metric between two states.
  float DistanceBetween(const VectorXf& x0, const VectorXf& x1) const;

  // Stitch between two states of the system. Interprets the first one as best
  // for ego and the second as best for other players.
  VectorXf Stitch(const VectorXf& x_ego, const VectorXf& x_others) const {
    VectorXf x(x_ego.size());

    const Dimension ego_state_dim = subsystems_[0]->XDim();
    x.head(ego_state_dim) = x_ego.head(ego_state_dim);
    x.tail(x_others.size() - ego_state_dim) =
        x_others.tail(x_others.size() - ego_state_dim);

    return x;
  }

  // Getters.
  const SubsystemList& Subsystems() const { return subsystems_; }
  PlayerIndex NumPlayers() const { return subsystems_.size(); }
  Dimension SubsystemStartDim(PlayerIndex player_idx) const {
    return subsystem_start_dims_[player_idx];
  }
  Dimension SubsystemXDim(PlayerIndex player_idx) const {
    return subsystems_[player_idx]->XDim();
  }
  Dimension UDim(PlayerIndex player_idx) const {
    return subsystems_[player_idx]->UDim();
  }
  std::vector<Dimension> PositionDimensions() const;

 private:
  // List of subsystems, each of which controls the affects of a single player.
  const SubsystemList subsystems_;

  // Cumulative sum of dimensions of each subsystem.
  std::vector<Dimension> subsystem_start_dims_;
};  // namespace ilqgames

}  // namespace ilqgames

#endif