Class Leadline

Inheritance Relationships

Base Type

  • public IAlgorithm

Class Documentation

class mimir::algorithm::Leadline : public IAlgorithm

Leadline predicted response.

This algorithm calculates an expected depth response of the leadline based on the provided input parameters. The output is the solution to the initial value problem over a prediction horizon of prediction_horizon_sec seconds, with discretization step equal to time_step_ms milliseconds.

Let \(x(t) \in \mathbb{R}\) be the depth in meters at a given time \(t\). Let \(x_d \in \mathbb{R}\) and \(\tau \in \mathbb{R}_{>0}\) be a setpoint depth [m] and time constant [s], respectively. Suppose \(t_f>0\) is the prediction horizon and \(\delta t\) is a descretization the step size. Define the set of discretized time points as \(\mathcal{T} := \{ t : t = k\delta t\, \forall k \in \mathbb{Z}_{\geq 0}, t \in [0, t_f] \}\). The solution to the initial value problem

\begin{align} \dat x(t) &= \frac{x(t)-x_d}{\tau} \\ x(0) &= 0 \end{align}

is \(x(t)\) and the solution set \(\mathcal{X} := \{ z : z = x(t)\, \forall t \in \mathcal{T} \}\).

The algorithm solution provides \((\mathcal{T},\mathcal{X})\) given \((x_d,\tau)\).

Public Functions

explicit Leadline(const YAML::Node &config, boost::statechart::fifo_scheduler<> &scheduler, boost::statechart::fifo_scheduler<>::processor_handle machine, dds::pub::Publisher publisher, dds::sub::Subscriber subscriber)

Leadline constructor.

The constructor parses the specification from the given YAML node. It establishes data structures and sets up DDS readers and writers according to the input/output scheme of the algorithm. The following YAML code block shows the expected layout of the Leadline map of a input config file. The inputs, outputs, and initial conditions are communicated with DDS communication. Common is their DDS topic and DDS identifier. The specification is deemed self-explanatory.

time_step_ms: 200
prediction_horizon_sec: 1000
inputs:
  parameters:                   # DDS type: fkin::IdVec2d
    topic: leadline_parameters
    id: Leadline
    default: [350, 160]
outputs:                        # DDS type: fkin::BatchIdVec1d
  depth:
    topic: leadline_response
    id: Leadline

Parameters

  • config – [in] YAML configuration from input file.

  • scheduler – [in] State machine scheduler, needed to post events to state machine.

  • machine – [in] State machine processor handle, needed to post events to state machine.

  • publisher – DDS data writer to send data.

  • subscriber – DDS data reader to receive data.

virtual ~Leadline()

Destructor.

virtual void solve(const std::atomic<bool> &cancel_token)

See base class.

virtual void initialize(const std::atomic<bool> &cancel_token)

See base class.

virtual void timer(const std::atomic<bool> &cancel_token)

See base class.

inline virtual const char *name()

Name identifier of algorithm.

void event(boost::statechart::event_base *const event)

Private Functions

inline void step_time()

March simulation time one time step ahead.

Leadline() = delete

Private Members

std::unique_ptr<Impl> m_impl

Holds the implementation of the algorithm.

boost::statechart::fifo_scheduler &m_scheduler

Members for state machine.

boost::statechart::fifo_scheduler::processor_handle m_stateMachine

Member for state machine.

const std::chrono::milliseconds m_time_step

Discrete time step.

std::chrono::steady_clock::time_point m_next_step

Simulation time point.

std::chrono::system_clock::time_point m_now
const YAML::Node m_config

YAML configuration for algorithm.