pid.hpp

// MIT License
//
// Copyright (c) 2023 Benjamin von Snarski
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#pragma once

namespace pid
{
  template<typename T> class Base
  {
    public:
      T dt;

      virtual T operator()(const T error) = 0;

    protected:
      using ValueType = T;
  };

  template<typename T> class P : virtual public Base<T>
  {
    public:
      T Kp;

      T operator()(const T error) override
      {
        return Kp * error;
      }
  };

  template<typename T> class I : virtual public Base<T>
  {
    public:
      T Ki;

      T operator()(const T error) override
      {
        M_sum += error * this->dt;
        return Ki * M_sum;
      }

      virtual T total_error() const final
      {
        return M_sum;
      }

    private:
      T M_sum;
  };

  template<typename T> class D : virtual public Base<T>
  {
    public:
      T Kd;

      T operator()(const T error) override
      {
        T out = (error - M_prev) / this->dt;
        M_prev = error;
        return Kd * out;
      }

      virtual T prev_error() const final
      {
        return M_prev;
      }

    private:
      T M_prev;
  };

  template<class... C> class Controller : public C...
  {
    using T = typename Controller::ValueType;

    public:
      T operator()(const T err) override
      {
        return (C::operator()(err) + ...);
      }
  };

  template<typename T = double> using PI = Controller<P<T>, I<T>>;
  template<typename T = double> using PD = Controller<P<T>, D<T>>;
  template<typename T = double> using PID = Controller<P<T>, I<T>, D<T>>;
}