T6Model.cpp

/*
 * Copyright © 2012, United States Government, as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All rights reserved.
 * 
 * The NASA Tensegrity Robotics Toolkit (NTRT) v1 platform is licensed
 * under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0.
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
*/

// This module
#include "T6Model.h"
// This library
#include "core/tgBasicActuator.h"
#include "core/tgRod.h"
#include "tgcreator/tgBuildSpec.h"
#include "tgcreator/tgBasicActuatorInfo.h"
#include "tgcreator/tgRodInfo.h"
#include "tgcreator/tgStructure.h"
#include "tgcreator/tgStructureInfo.h"
// The Bullet Physics library
#include "LinearMath/btVector3.h"
// The C++ Standard Library
#include <stdexcept>

namespace
{
    // Note: This current model of the SUPERball rod is 1.5m long by 4.5cm (0.045m) radius,
    // which is 1.684m*pi*(0.040m)^2 = 0.008545132m^3.
    // For SUPERball v1.5, mass = 3.5kg per strut, which density [kg/m^3] comes out to:
    // density = 3.45kg/0.008545132m^3 = 403.738642402kg/m^3 = 0.403738642402 kg/dm^3

    // see tgBaseString.h for a descripton of some of these rod parameters
    // (specifically, those related to the motor moving the strings.)
    // NOTE that any parameter that depends on units of length will scale
    // with the current gravity scaling. E.g., with gravity as 98.1
    // Thus,
    // Rod Length = 17.00
    // Rod Radius = 0.40
    // density = 0.40374 (length is cubed, so decimal moves 3 places)

    // similarly, frictional parameters are for the tgRod objects.
    const struct Config
    {
        double density;
        double radius;
        double stiffness_passive;
        double stiffness_active;
        double damping;
        double rod_length;
        double rod_space;    
        double friction;
        double rollFriction;
        double restitution;
        double pretension;
        bool   hist;
        double maxTens;
        double targetVelocity;
    } c =
   {
                 0.40374,   // density (kg / length^3)
     0.40,      // radius (length)
     998.25,    // stiffness_passive (kg / sec^2)
     3152.36,   // stiffness_active (kg / sec^2)
     50.0,      // damping (kg / sec)
     17.00,     // rod_length (length)
     17.00/4,   // rod_space (length)
     0.99,      // friction (unitless)
     0.01,     // rollFriction (unitless)
     0.0,      // restitution (?)
     399,        // pretension
     true,                                      // History logging (boolean)
     100000,   // maxTens
     10000,    // targetVelocity
#if (0) // Removed 12/10/14
     20000     // maxAcc
#endif
     // Use the below values for earlier versions of simulation.
     // 1.152,    // density (kg / length^3)
     //         0.45,     // radius (length)
     //         613.0,    // stiffness_passive (kg / sec^2)
     //         2854.5,   // stiffness_active (kg / sec^2)
  };
} // namespace

T6Model::T6Model() : tgModel() 
{
}

T6Model::~T6Model()
{
}

void T6Model::addNodes(tgStructure& s)
{
    const double half_length = c.rod_length / 2;

    s.addNode(-c.rod_space,  -half_length, 0);            // 0
    s.addNode(-c.rod_space,   half_length, 0);            // 1
    s.addNode( c.rod_space,  -half_length, 0);            // 2
    s.addNode( c.rod_space,   half_length, 0);            // 3
    s.addNode(0,           -c.rod_space,   -half_length); // 4
    s.addNode(0,           -c.rod_space,    half_length); // 5
    s.addNode(0,            c.rod_space,   -half_length); // 6
    s.addNode(0,            c.rod_space,    half_length); // 7
    s.addNode(-half_length, 0,            c.rod_space);   // 8
    s.addNode( half_length, 0,            c.rod_space);   // 9
    s.addNode(-half_length, 0,           -c.rod_space);   // 10
    s.addNode( half_length, 0,           -c.rod_space);   // 11
}

void T6Model::addRods(tgStructure& s)
{
    s.addPair( 0,  1, "rod");
    s.addPair( 2,  3, "rod");
    s.addPair( 4,  5, "rod");
    s.addPair( 6,  7, "rod");
    s.addPair( 8,  9, "rod");
    s.addPair(10, 11, "rod");
}

void T6Model::addMuscles(tgStructure& s)
{
                // Added ability to have two muscles in a structure.
                // Configuration currently is random, at the moment [27 June 2014]
    s.addPair(0, 4,  "muscle_active");
    s.addPair(0, 5,  "muscle_passive");
    s.addPair(0, 8,  "muscle_active");
    s.addPair(0, 10, "muscle_passive");

    s.addPair(1, 6,  "muscle_active");
    s.addPair(1, 7,  "muscle_passive");
    s.addPair(1, 8,  "muscle_passive");
    s.addPair(1, 10, "muscle_active");

    s.addPair(2, 4,  "muscle_passive");
    s.addPair(2, 5,  "muscle_active");
    s.addPair(2, 9,  "muscle_active");
    s.addPair(2, 11, "muscle_passive");

    s.addPair(3, 7,  "muscle_active");
    s.addPair(3, 6,  "muscle_passive");
    s.addPair(3, 9,  "muscle_passive");
    s.addPair(3, 11, "muscle_active");

    s.addPair(4, 10, "muscle_active");
    s.addPair(4, 11, "muscle_passive");

    s.addPair(5, 8,  "muscle_active");
    s.addPair(5, 9,  "muscle_passive");

    s.addPair(6, 10, "muscle_passive");
    s.addPair(6, 11, "muscle_active");

    s.addPair(7, 8,  "muscle_passive");
    s.addPair(7, 9,  "muscle_active");

}

void T6Model::setup(tgWorld& world)
{

    const tgRod::Config rodConfig(c.radius, c.density, c.friction, 
                                                                c.rollFriction, c.restitution);
    
    tgBasicActuator::Config muscleConfig_passive(c.stiffness_passive, c.damping, c.pretension, c.hist, 
                                                                                    c.maxTens, c.targetVelocity);

    tgBasicActuator::Config muscleConfig_active(c.stiffness_active, c.damping, c.pretension, c.hist, 
                                                                                    c.maxTens, c.targetVelocity);
            
    // Start creating the structure
    tgStructure s;
    addNodes(s);
    addRods(s);
    addMuscles(s);
    s.move(btVector3(0, 10, 0));

    // Add a rotation. This is needed if the ground slopes too much,
    // otherwise  glitches put a rod below the ground.
    btVector3 rotationPoint = btVector3(0, 0, 0); // origin
    btVector3 rotationAxis = btVector3(0, 1, 0);  // y-axis
    double rotationAngle = M_PI/2;
    s.addRotation(rotationPoint, rotationAxis, rotationAngle);

    // Create the build spec that uses tags to turn the structure into a real model
    tgBuildSpec spec;
    spec.addBuilder("rod", new tgRodInfo(rodConfig));
    spec.addBuilder("muscle_passive", new tgBasicActuatorInfo(muscleConfig_passive));
    spec.addBuilder("muscle_active", new tgBasicActuatorInfo(muscleConfig_active));
    
    // Create your structureInfo
    tgStructureInfo structureInfo(s, spec);

    // Use the structureInfo to build ourselves
    structureInfo.buildInto(*this, world);

    // We could now use tgCast::filter or similar to pull out the
    // models (e.g. muscles) that we want to control. 
    allMuscles = tgCast::filter<tgModel, tgBasicActuator> (getDescendants());
    // Not really sure how to use the find() function in tgModel.h
    passiveMuscles = tgCast::find<tgModel, tgBasicActuator>(tgTagSearch("muscle_passive"), getDescendants());
    activeMuscles = tgCast::find<tgModel, tgBasicActuator>(tgTagSearch("muscle_active"), getDescendants());

    // call the onSetup methods of all observed things e.g. controllers
    notifySetup();

    // Actually setup the children
    tgModel::setup(world);
}

void T6Model::step(double dt)
{
    // Precondition
    if (dt <= 0.0)
    {
        throw std::invalid_argument("dt is not positive");
    }
    else
    {
        // Notify observers (controllers) of the step so that they can take action
        notifyStep(dt);
        tgModel::step(dt);  // Step any children
    }
}

void T6Model::onVisit(tgModelVisitor& r)
{
    tgModel::onVisit(r);
}

const std::vector<tgBasicActuator*>& T6Model::getAllMuscles() const
{
    return allMuscles;
}

const std::vector<tgBasicActuator*>& T6Model::getPassiveMuscles() const
{
    return passiveMuscles;
}

const std::vector<tgBasicActuator*>& T6Model::getActiveMuscles() const
{
    return activeMuscles;
}

const double T6Model::muscleRatio()
{
                return (c.stiffness_passive/c.stiffness_active);
                //return 2.5;
}
    
void T6Model::teardown()
{
    tgModel::teardown();
}