continuous_system_interface.h

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#pragma once

#include <string>

#include "drake/systems/framework/context.h"
#include "drake/systems/framework/state_vector.h"
#include "drake/systems/framework/system_output.h"
#include "drake/systems/framework/system_interface.h"

namespace drake {
namespace systems {

template <typename T>
class ContinuousSystemInterface : public SystemInterface<T> {
 public:
  virtual std::unique_ptr<ContinuousState<T>> AllocateTimeDerivatives()
      const = 0;

  virtual void EvalTimeDerivatives(const Context<T>& context,
                                   ContinuousState<T>* derivatives) const = 0;

  virtual void MapVelocityToConfigurationDerivatives(
      const Context<T>& context, const StateVector<T>& generalized_velocity,
      StateVector<T>* configuration_derivatives) const = 0;

  // TODO(david-german-tri): Add MapConfigurationDerivativesToVelocity.

  // TODO(sherm): these two power methods should be present only for continuous
  // systems that represent some kind of physical system that can inject or
  // dissipate energy into the simulation. Consider whether to introduce
  // a class like PhysicalSystemInterface that could add these methods only
  // when appropriate; that is awkward to mix with ContinuousSystemInterface
  // so for now I'm breaking the no-code-in-interface rule to provide
  // zero defaults so that these don't have to be implemented in non-physical
  // systems.

  virtual T EvalConservativePower(const Context<T>& context) const {
    return T(0);
  }

  virtual T EvalNonConservativePower(const Context<T>& context) const {
    return T(0);
  }

 protected:
  ContinuousSystemInterface() {}

 private:
  // ContinuousSystemInterface objects are neither copyable nor moveable.
  ContinuousSystemInterface(const ContinuousSystemInterface<T>& other) = delete;
  ContinuousSystemInterface& operator=(
      const ContinuousSystemInterface<T>& other) = delete;
  ContinuousSystemInterface(ContinuousSystemInterface<T>&& other) = delete;
  ContinuousSystemInterface& operator=(ContinuousSystemInterface<T>&& other) =
      delete;
};

}  // namespace systems
}  // namespace drake