TetraSpineKinematic.cpp

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/*
 * 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 "TetraSpineKinematic.h"
// This library
#include "core/tgCast.h"
#include "core/tgSpringCableActuator.h"
#include "core/tgString.h"
#include "core/tgSphere.h"
#include "core/abstractMarker.h"
#include "tgcreator/tgBuildSpec.h"
#include "tgcreator/tgKinematicContactCableInfo.h"
#include "tgcreator/tgRodInfo.h"
#include "tgcreator/tgSphereInfo.h"
#include "tgcreator/tgStructure.h"
#include "tgcreator/tgStructureInfo.h"
#include "tgcreator/tgUtil.h"

// The Bullet Physics library
#include "LinearMath/btVector3.h"
// The C++ Standard Library
#include <iostream>
#include <stdexcept>

TetraSpineKinematic::TetraSpineKinematic(size_t segments) : 
    BaseSpineModelLearning(segments)
{
}

TetraSpineKinematic::~TetraSpineKinematic()
{
}
namespace
{
    void addNodes(tgStructure& tetra, double edge, double height)
    {
                                // Front segment
        // right
        tetra.addNode(-edge / 2.0, 0, 0, "base");
                                // left
                                tetra.addNode( edge / 2.0, 0, 0, "base");
        // top
                                tetra.addNode(0, height, 0, "base");
                                // front
                                tetra.addNode(0, edge / 2.0 * tan(M_PI / 6.0), 2.50 * 5.0, "tip");
                                
                                // Get the next two nodes from existing nodes:
                                tgNodes oldNodes = tetra.getNodes();
                                tgNode nn1 = (oldNodes[0] + oldNodes[2])/2.0; // 4 mid
                                nn1.addTags("PCB");
                                tetra.addNode(nn1);
                                tgNode nn2 = (oldNodes[1] + oldNodes[2])/2.0; // 5 mid
                                nn2.addTags("PCB");
                                tetra.addNode(nn2);
                                
                                std::cout << (oldNodes[3] - oldNodes[2]).length() << std::endl;
                                std::cout << (oldNodes[3] - oldNodes[1]).length() << std::endl;
                                std::cout << (oldNodes[3] - oldNodes[0]).length() << std::endl;
                                
    }

    void addPairs(tgStructure& tetra)
    {
        tetra.addPair(0, 1, "back bottom rod");
                                tetra.addPair(0, 4, "back rightBottom rod");
                                tetra.addPair(4, 2, "back rightTop rod");
                                tetra.addPair(0, 3, "front right rod");
                                tetra.addPair(1, 5, "back leftBottom rod");
                                tetra.addPair(5, 2, "back leftTop rod");
                                tetra.addPair(1, 3, "front left rod");
                                tetra.addPair(2, 3, "front top rod");
    }
                
                
    void addSegments(tgStructure& snake, const tgStructure& tetra, double edge,
             size_t segmentCount)
    {
        const btVector3 offset(0, 0, -2.30 * 5.0);
                                for (size_t i = 0; i < segmentCount; ++i)
                                {
                                  tgStructure* const t = new tgStructure(tetra);
                                  t->addTags(tgString("segment num", i )); // Use num0, num1, num2 as a tag!!
                                  
                                  t->move((i + 1) * offset);
                                  
                                  // Add a child to the snake
                                  snake.addChild(t);

                                }
    }

    // Add muscles that connect the segments
    void addMuscles(tgStructure& snake)
    {
        const std::vector<tgStructure*> children = snake.getChildren();
                                for (size_t i = 1; i < children.size(); ++i)
                                {
                                                tgNodes n0 = children[i-1]->getNodes();
                                                tgNodes n1 = children[i  ]->getNodes();

                                                snake.addPair(n0[0], n1[0], tgString("outer right muscle seg", i));
                                                snake.addPair(n0[1], n1[1], tgString("outer left muscle seg", i));
                                                snake.addPair(n0[2], n1[2], tgString("outer top muscle seg", i));

                                                snake.addPair(n0[0], n1[3], tgString("inner right muscle seg", i));
                                                snake.addPair(n0[1], n1[3], tgString("inner left muscle seg", i));
                                                snake.addPair(n0[2], n1[3], tgString("inner top muscle seg", i));
                                }
    }

    void mapMuscles(TetraSpineKinematic::MuscleMap& muscleMap,
            tgModel& model)
    {
        // Note that tags don't need to match exactly, we could create
        // supersets if we wanted to
                                muscleMap["inner left"]  = model.find<tgSpringCableActuator>("inner left muscle");
                                muscleMap["inner right"] = model.find<tgSpringCableActuator>("inner right muscle");
                                muscleMap["inner top"]   = model.find<tgSpringCableActuator>("inner top muscle");
                                muscleMap["outer left"]  = model.find<tgSpringCableActuator>("outer left muscle");
                                muscleMap["outer right"] = model.find<tgSpringCableActuator>("outer right muscle");
                                muscleMap["outer top"]   = model.find<tgSpringCableActuator>("outer top muscle");
    }
                
    void trace(const tgStructureInfo& structureInfo, tgModel& model)
    {
        std::cout << "StructureInfo:" << std::endl
          << structureInfo    << std::endl
          << "Model: "        << std::endl
          << model            << std::endl;    
        // Showing the find function
        const std::vector<tgSpringCableActuator*> outerMuscles =
            model.find<tgSpringCableActuator>("outer");
        for (size_t i = 0; i < outerMuscles.size(); ++i)
        {
            const tgSpringCableActuator* const pMuscle = outerMuscles[i];
            assert(pMuscle != NULL);
            std::cout << "Outer muscle: " << *pMuscle << std::endl;
        }
    }

} // namespace

// This is basically a manual setup of a model.
// There are things that do this for us (@todo: reference the things that do this for us)
void TetraSpineKinematic::setup(tgWorld& world)
{
    const double edge = 3.8 * 5.0;
    const double height = tgUtil::round(std::sqrt(3.0)/2 * edge);
    std::cout << "edge: " << edge << "; height: " << height << std::endl;
                
    // Create the tetrahedra
    tgStructure tetra;
    addNodes(tetra, edge, height);
    addPairs(tetra);

    // Move the first one so we can create a longer snake.
    // Or you could move the snake at the end, up to you. 
    tetra.move(btVector3(0.0, 8.0, 10.0));

    // Create our snake segments
    tgStructure snake;
    addSegments(snake, tetra, edge, m_segments);
    addMuscles(snake);

    // Create the build spec that uses tags to turn the structure into a real model
    // Note: This needs to be high enough or things fly apart...
    

    // Params for In Won
    const double radius  = 0.635 / 2.0;
    const double sphereRadius  = 0.635 / 2.0;
    const double density = .0201 / (pow(radius, 2) * M_PI * edge); // Mass divided by volume... should there be a way to set this automatically??
    const double friction = 0.5;
    const tgRod::Config rodConfig(radius, density, friction);
    tgBuildSpec spec;
    spec.addBuilder("rod", new tgRodInfo(rodConfig));
    
    // 1000 is so the units below can be in grams
    const double sphereVolume1 = 1000.0 * 4.0 / 3.0 * M_PI * pow(sphereRadius, 3);
    const double sphereVolume2 = 1000.0 * 4.0 / 3.0 * M_PI * pow(sphereRadius, 3);
    
    const double baseCornerMidD = 180.0 / sphereVolume1;
    const tgSphere::Config baseCornerMidConfig(sphereRadius, baseCornerMidD, friction);
    spec.addBuilder("base", new tgSphereInfo(baseCornerMidConfig));

    const double tipCornerMidD = 120.0 / sphereVolume1;
    const tgSphere::Config tipCornerMidConfig(sphereRadius, tipCornerMidD, friction);
    spec.addBuilder("tip", new tgSphereInfo(tipCornerMidConfig));
    
    const double PCBD = 70.0 / sphereVolume2;
    const tgSphere::Config PCB_1_Config(radius, PCBD, friction);
    spec.addBuilder("PCB", new tgSphereInfo(PCB_1_Config));
    
    
    // Two different string configs
        const double elasticity = 229.16;
    const double damping = 20;
    const double pretension = 0.0;
    const bool   history = false;
    const double maxTens = 5000.0;
    const double maxSpeed = 7.0;

    const double mRad = 1.0;
    const double motorFriction = 10.0;
    const double motorInertia = 1.0;
    const bool backDrivable = false;
    tgKinematicActuator::Config muscleConfig(elasticity * 2.0, damping, pretension,
                                            mRad, motorFriction, motorInertia, backDrivable,
                                            history, maxTens, maxSpeed);
    
    tgKinematicActuator::Config muscleConfig2(elasticity * 2.0, damping, pretension,
                                            mRad, motorFriction, motorInertia, backDrivable,
                                            history, maxTens, maxSpeed);

#if (0)
    spec.addBuilder("top muscle", new tgKinematicContactCableInfo(muscleConfig));
    spec.addBuilder("left muscle", new tgKinematicContactCableInfo(muscleConfig2));
    spec.addBuilder("right muscle", new tgKinematicContactCableInfo(muscleConfig2));
#else
    spec.addBuilder("muscle", new tgKinematicContactCableInfo(muscleConfig2));
#endif
    // Create your structureInfo
    tgStructureInfo structureInfo(snake, 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.    
    m_allMuscles = this->find<tgSpringCableActuator> ("muscle");
    m_allSegments = this->find<tgModel> ("segment");
    mapMuscles(m_muscleMap, *this);
    
    #if (0)
    trace(structureInfo, *this);
    #endif
    
    // Actually setup the children
    BaseSpineModelLearning::setup(world);
}
      
void TetraSpineKinematic::teardown()
{

    BaseSpineModelLearning::teardown();
    
} 
    
void TetraSpineKinematic::step(double dt)
{
    if (dt < 0.0)
    {
        throw std::invalid_argument("dt is not positive");
    }
    else
    {
        // Step any children, notify observers
        BaseSpineModelLearning::step(dt);
    }
}