OMCollisionCostPrediction.cpp

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#include "OMCollisionCostPrediction.h"
#include "OMCollisionCost.h"

#include <Rcs_collisionModel.h>
#include <Rcs_typedef.h>
#include <Rcs_VecNd.h>
#include <Rcs_macros.h>

#include <stdexcept>

namespace Rcs
{

OMCollisionCostPrediction::OMCollisionCostPrediction(
    RcsGraph* graph, RcsCollisionMdl* collisionMdl,
    const ActionModel* actionModel, size_t horizon,
    double maxCollCost) : realGraph(graph), horizon(horizon),
                          maxCollCost(maxCollCost)
{
    // Copy graph and action model for prediction
    predictGraph = RcsGraph_clone(graph);
    predictActionModel = actionModel->clone(predictGraph);
    
    // Copy collision model for predict graph.
    this->collisionMdl = RcsCollisionModel_clone(collisionMdl, predictGraph);
}


OMCollisionCostPrediction::~OMCollisionCostPrediction()
{
    // Destroy cloned collision model
    RcsCollisionModel_destroy(collisionMdl);
    
    delete predictActionModel;
    RcsGraph_destroy(predictGraph);
}

unsigned int OMCollisionCostPrediction::getStateDim() const
{
    return 1;
}

unsigned int OMCollisionCostPrediction::getVelocityDim() const
{
    return 0;
}

void OMCollisionCostPrediction::computeObservation(
    double* state, double* velocity, const MatNd* currentAction,
    double dt) const
{
    // NOTE: prediction doesn't update q_dot, since we don't simulate it and it's not relevant for the collision model.
    
    // Reset prediction state
    RcsGraph_setState(predictGraph, realGraph->q, realGraph->q_dot);
    predictActionModel->reset();
    
    // Compute cost for initial step
    RcsCollisionModel_compute(collisionMdl);
    double predCostSum = RcsCollisionMdl_cost(collisionMdl);
    
    // This OM can only predict the future collision costs if the current action was given
    if (currentAction != NULL) {
        // Execute prediction
        for (size_t i = 0; i <= horizon; ++i) {
            // Compute action from action model
            // Passing NULL to q_dot_des and T_des is not strictly allowed, but since we can't support them, this
            // will at least cause an error with unsupported action models.
            predictActionModel->computeCommand(predictGraph->q, predictGraph->q_dot, NULL, currentAction, dt);
            
            // Update graph using forward kinematics (no physics simulation)
            RcsGraph_setState(predictGraph, NULL, predictGraph->q_dot);
            
            // Sum up step cost
            RcsCollisionModel_compute(collisionMdl);
            predCostSum += RcsCollisionMdl_cost(collisionMdl);
        }
        // Compute average
        predCostSum /= (horizon + 1.);
    }
    // The state is the average collision cost
    state[0] = predCostSum;
}

std::vector<std::string> OMCollisionCostPrediction::getStateNames() const
{
    return {"PredCollCost_h" + std::to_string(horizon)};
}

void OMCollisionCostPrediction::getLimits(double* minState, double* maxState, double* maxVelocity) const
{
//    ObservationModel::getLimits(minState, maxState, maxVelocity);
    VecNd_setZero(minState, getStateDim()); // minimum cost is 0
    VecNd_setElementsTo(maxState, maxCollCost, getStateDim());  // maximum cost (theoretically infinite)
}
    
} /* namespace Rcs */