LinearSystem.h

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/**********************************************************************************************************************
This file is part of the Control Toolbox (https://github.com/ethz-adrl/control-toolbox), copyright by ETH Zurich.
Licensed under the BSD-2 license (see LICENSE file in main directory)
**********************************************************************************************************************/

#pragma once

#include <ct/core/types/StateVector.h>
#include <ct/core/types/ControlVector.h>


namespace ct {
namespace core {


template <size_t STATE_DIM, size_t CONTROL_DIM, typename SCALAR = double>
class LinearSystem : public ControlledSystem<STATE_DIM, CONTROL_DIM, SCALAR>
{
public:
    EIGEN_MAKE_ALIGNED_OPERATOR_NEW

    typedef ControlledSystem<STATE_DIM, CONTROL_DIM, SCALAR> Base;
    typedef typename Base::time_t time_t;

    typedef StateVector<STATE_DIM, SCALAR> state_vector_t;        
    typedef ControlVector<CONTROL_DIM, SCALAR> control_vector_t;  

    typedef StateMatrix<STATE_DIM, SCALAR> state_matrix_t;                              
    typedef StateControlMatrix<STATE_DIM, CONTROL_DIM, SCALAR> state_control_matrix_t;  


    LinearSystem(const ct::core::SYSTEM_TYPE& type = ct::core::SYSTEM_TYPE::GENERAL)
        : ControlledSystem<STATE_DIM, CONTROL_DIM, SCALAR>(type)
    {
    }

    virtual ~LinearSystem(){};

    virtual LinearSystem<STATE_DIM, CONTROL_DIM, SCALAR>* clone() const override = 0;


    virtual void computeControlledDynamics(const state_vector_t& state,
        const time_t& t,
        const control_vector_t& control,
        state_vector_t& derivative) override
    {
        // x_dot(t) = A(x,u,t) * x(t) + B(x,u,t) * u(t)

        derivative = getDerivativeState(state, control, t) * state + getDerivativeControl(state, control, t) * control;
    }


    virtual const state_matrix_t& getDerivativeState(const state_vector_t& x,
        const control_vector_t& u,
        const time_t t = time_t(0.0)) = 0;


    virtual const state_control_matrix_t& getDerivativeControl(const state_vector_t& x,
        const control_vector_t& u,
        const time_t t = time_t(0.0)) = 0;


    virtual void getDerivatives(state_matrix_t& A,
        state_control_matrix_t& B,
        const state_vector_t& x,
        const control_vector_t& u,
        const time_t t = time_t(0.0))
    {
        A = getDerivativeState(x, u, t);
        B = getDerivativeControl(x, u, t);
    }
};

}  // namespace core
}  // namespace ct