bullet3/examples/MultiBody/InvertedPendulumPDControl.cpp

#include "InvertedPendulumPDControl.h"

#include "BulletDynamics/Featherstone/btMultiBodyLinkCollider.h"
#include "BulletDynamics/Featherstone/btMultiBodyJointFeedback.h"

#include "../CommonInterfaces/CommonMultiBodyBase.h"
#include "../Utils/b3ResourcePath.h"
#include "../CommonInterfaces/CommonParameterInterface.h"
static btScalar radius(0.2);
static btScalar kp = 100;
static btScalar kd = 20;
static btScalar maxForce = 100;

struct InvertedPendulumPDControl : public CommonMultiBodyBase
{
	btMultiBody* m_multiBody;
	btAlignedObjectArray<btMultiBodyJointFeedback*> m_jointFeedbacks;
	bool m_once;
	int m_frameCount;

public:
	InvertedPendulumPDControl(struct GUIHelperInterface* helper);
	virtual ~InvertedPendulumPDControl();

	virtual void initPhysics();

	virtual void stepSimulation(float deltaTime);

	virtual void resetCamera()
	{
		float dist = 5;
		float pitch = -21;
		float yaw = 270;
		float targetPos[3] = {-1.34, 1.4, 3.44};
		m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
	}
};

InvertedPendulumPDControl::InvertedPendulumPDControl(struct GUIHelperInterface* helper)
	: CommonMultiBodyBase(helper),
	  m_once(true),
	  m_frameCount(0)
{
}

InvertedPendulumPDControl::~InvertedPendulumPDControl()
{
}

///this is a temporary global, until we determine if we need the option or not
extern bool gJointFeedbackInWorldSpace;
extern bool gJointFeedbackInJointFrame;

btMultiBody* createInvertedPendulumMultiBody(btMultiBodyDynamicsWorld* world, GUIHelperInterface* guiHelper, const btTransform& baseWorldTrans, bool fixedBase)
{
	btVector4 colors[4] =
		{
			btVector4(1, 0, 0, 1),
			btVector4(0, 1, 0, 1),
			btVector4(0, 1, 1, 1),
			btVector4(1, 1, 0, 1),
		};
	int curColor = 0;

	bool damping = false;
	bool gyro = false;
	int numLinks = 2;
	bool spherical = false;  //set it ot false -to use 1DoF hinges instead of 3DoF sphericals
	bool canSleep = false;
	bool selfCollide = false;
	btVector3 linkHalfExtents(0.05, 0.37, 0.1);
	btVector3 baseHalfExtents(0.04, 0.35, 0.08);

	//mbC->forceMultiDof();							//if !spherical, you can comment this line to check the 1DoF algorithm
	//init the base
	btVector3 baseInertiaDiag(0.f, 0.f, 0.f);
	float baseMass = fixedBase ? 0.f : 10.f;

	if (baseMass)
	{
		//btCollisionShape *shape = new btSphereShape(baseHalfExtents[0]);// btBoxShape(btVector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2]));
		btCollisionShape* shape = new btBoxShape(btVector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2]));
		shape->calculateLocalInertia(baseMass, baseInertiaDiag);
		delete shape;
	}

	btMultiBody* pMultiBody = new btMultiBody(numLinks, 0, baseInertiaDiag, fixedBase, canSleep);

	pMultiBody->setBaseWorldTransform(baseWorldTrans);
	btVector3 vel(0, 0, 0);
	//	pMultiBody->setBaseVel(vel);

	//init the links
	btVector3 hingeJointAxis(1, 0, 0);

	//y-axis assumed up
	btVector3 parentComToCurrentCom(0, -linkHalfExtents[1] * 2.f, 0);                      //par body's COM to cur body's COM offset
	btVector3 currentPivotToCurrentCom(0, -linkHalfExtents[1], 0);                         //cur body's COM to cur body's PIV offset
	btVector3 parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom;  //par body's COM to cur body's PIV offset

	//////
	btScalar q0 = 1.f * SIMD_PI / 180.f;
	btQuaternion quat0(btVector3(1, 0, 0).normalized(), q0);
	quat0.normalize();
	/////

	for (int i = 0; i < numLinks; ++i)
	{
		float linkMass = 1.f;
		//if (i==3 || i==2)
		//	linkMass= 1000;
		btVector3 linkInertiaDiag(0.f, 0.f, 0.f);

		btCollisionShape* shape = 0;
		if (i == 0)
		{
			shape = new btBoxShape(btVector3(linkHalfExtents[0], linkHalfExtents[1], linkHalfExtents[2]));  //
		}
		else
		{
			shape = new btSphereShape(radius);
		}
		shape->calculateLocalInertia(linkMass, linkInertiaDiag);
		delete shape;

		if (!spherical)
		{
			//pMultiBody->setupRevolute(i, linkMass, linkInertiaDiag, i - 1, btQuaternion(0.f, 0.f, 0.f, 1.f), hingeJointAxis, parentComToCurrentPivot, currentPivotToCurrentCom, false);

			if (i == 0)
			{
				pMultiBody->setupRevolute(i, linkMass, linkInertiaDiag, i - 1,
										  btQuaternion(0.f, 0.f, 0.f, 1.f),
										  hingeJointAxis,
										  parentComToCurrentPivot,
										  currentPivotToCurrentCom, false);
			}
			else
			{
				btVector3 parentComToCurrentCom(0, -radius * 2.f, 0);                                  //par body's COM to cur body's COM offset
				btVector3 currentPivotToCurrentCom(0, -radius, 0);                                     //cur body's COM to cur body's PIV offset
				btVector3 parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom;  //par body's COM to cur body's PIV offset

				pMultiBody->setupFixed(i, linkMass, linkInertiaDiag, i - 1,
									   btQuaternion(0.f, 0.f, 0.f, 1.f),
									   parentComToCurrentPivot,
									   currentPivotToCurrentCom);
			}

			//pMultiBody->setupFixed(i,linkMass,linkInertiaDiag,i-1,btQuaternion(0,0,0,1),parentComToCurrentPivot,currentPivotToCurrentCom,false);
		}
		else
		{
			//pMultiBody->setupPlanar(i, linkMass, linkInertiaDiag, i - 1, btQuaternion(0.f, 0.f, 0.f, 1.f)/*quat0*/, btVector3(1, 0, 0), parentComToCurrentPivot*2, false);
			pMultiBody->setupSpherical(i, linkMass, linkInertiaDiag, i - 1, btQuaternion(0.f, 0.f, 0.f, 1.f), parentComToCurrentPivot, currentPivotToCurrentCom, false);
		}
	}

	pMultiBody->finalizeMultiDof();

	///
	world->addMultiBody(pMultiBody);
	btMultiBody* mbC = pMultiBody;
	mbC->setCanSleep(canSleep);
	mbC->setHasSelfCollision(selfCollide);
	mbC->setUseGyroTerm(gyro);
	//
	if (!damping)
	{
		mbC->setLinearDamping(0.f);
		mbC->setAngularDamping(0.f);
	}
	else
	{
		mbC->setLinearDamping(0.1f);
		mbC->setAngularDamping(0.9f);
	}
	//

	//////////////////////////////////////////////
	if (numLinks > 0)
	{
		btScalar q0 = 180.f * SIMD_PI / 180.f;
		if (!spherical)
		{
			mbC->setJointPosMultiDof(0, &q0);
		}
		else
		{
			btQuaternion quat0(btVector3(1, 1, 0).normalized(), q0);
			quat0.normalize();
			mbC->setJointPosMultiDof(0, quat0);
		}
	}
	///

	btAlignedObjectArray<btQuaternion> world_to_local;
	world_to_local.resize(pMultiBody->getNumLinks() + 1);

	btAlignedObjectArray<btVector3> local_origin;
	local_origin.resize(pMultiBody->getNumLinks() + 1);
	world_to_local[0] = pMultiBody->getWorldToBaseRot();
	local_origin[0] = pMultiBody->getBasePos();
	//  double friction = 1;
	{
		//	float pos[4]={local_origin[0].x(),local_origin[0].y(),local_origin[0].z(),1};
		// float quat[4]={-world_to_local[0].x(),-world_to_local[0].y(),-world_to_local[0].z(),world_to_local[0].w()};

		if (1)
		{
			btCollisionShape* shape = new btBoxShape(btVector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2]));  //new btSphereShape(baseHalfExtents[0]);
			guiHelper->createCollisionShapeGraphicsObject(shape);

			btMultiBodyLinkCollider* col = new btMultiBodyLinkCollider(pMultiBody, -1);
			col->setCollisionShape(shape);

			btTransform tr;
			tr.setIdentity();
			//if we don't set the initial pose of the btCollisionObject, the simulator will do this
			//when syncing the btMultiBody link transforms to the btMultiBodyLinkCollider

			tr.setOrigin(local_origin[0]);
			btQuaternion orn(btVector3(0, 0, 1), 0.25 * 3.1415926538);

			tr.setRotation(orn);
			col->setWorldTransform(tr);

			bool isDynamic = (baseMass > 0 && !fixedBase);
			int collisionFilterGroup = isDynamic ? int(btBroadphaseProxy::DefaultFilter) : int(btBroadphaseProxy::StaticFilter);
			int collisionFilterMask = isDynamic ? int(btBroadphaseProxy::AllFilter) : int(btBroadphaseProxy::AllFilter ^ btBroadphaseProxy::StaticFilter);

			world->addCollisionObject(col, collisionFilterGroup, collisionFilterMask);  //, 2,1+2);

			btVector4 color(0.0, 0.0, 0.5, 1);
			guiHelper->createCollisionObjectGraphicsObject(col, color);

			//                col->setFriction(friction);
			pMultiBody->setBaseCollider(col);
		}
	}

	for (int i = 0; i < pMultiBody->getNumLinks(); ++i)
	{
		const int parent = pMultiBody->getParent(i);
		world_to_local[i + 1] = pMultiBody->getParentToLocalRot(i) * world_to_local[parent + 1];
		local_origin[i + 1] = local_origin[parent + 1] + (quatRotate(world_to_local[i + 1].inverse(), pMultiBody->getRVector(i)));
	}

	for (int i = 0; i < pMultiBody->getNumLinks(); ++i)
	{
		btVector3 posr = local_origin[i + 1];
		//	float pos[4]={posr.x(),posr.y(),posr.z(),1};

		const btScalar quat[4] = {-world_to_local[i + 1].x(), -world_to_local[i + 1].y(), -world_to_local[i + 1].z(), world_to_local[i + 1].w()};
		btCollisionShape* shape = 0;

		if (i == 0)
		{
			shape = new btBoxShape(btVector3(linkHalfExtents[0], linkHalfExtents[1], linkHalfExtents[2]));  //btSphereShape(linkHalfExtents[0]);
		}
		else
		{
			shape = new btSphereShape(radius);
		}

		guiHelper->createCollisionShapeGraphicsObject(shape);
		btMultiBodyLinkCollider* col = new btMultiBodyLinkCollider(pMultiBody, i);

		col->setCollisionShape(shape);
		btTransform tr;
		tr.setIdentity();
		tr.setOrigin(posr);
		tr.setRotation(btQuaternion(quat[0], quat[1], quat[2], quat[3]));
		col->setWorldTransform(tr);
		//       col->setFriction(friction);
		bool isDynamic = 1;  //(linkMass > 0);
		int collisionFilterGroup = isDynamic ? int(btBroadphaseProxy::DefaultFilter) : int(btBroadphaseProxy::StaticFilter);
		int collisionFilterMask = isDynamic ? int(btBroadphaseProxy::AllFilter) : int(btBroadphaseProxy::AllFilter ^ btBroadphaseProxy::StaticFilter);

		//if (i==0||i>numLinks-2)
		{
			world->addCollisionObject(col, collisionFilterGroup, collisionFilterMask);  //,2,1+2);
			btVector4 color = colors[curColor];
			curColor++;
			curColor &= 3;
			guiHelper->createCollisionObjectGraphicsObject(col, color);

			pMultiBody->getLink(i).m_collider = col;
		}
	}

	return pMultiBody;
}

void InvertedPendulumPDControl::initPhysics()
{
	{
		SliderParams slider("Kp", &kp);
		slider.m_minVal = -200;
		slider.m_maxVal = 200;
		m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
	}
	{
		SliderParams slider("Kd", &kd);
		slider.m_minVal = -50;
		slider.m_maxVal = 50;
		m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
	}
	{
		SliderParams slider("max force", &maxForce);
		slider.m_minVal = 0;
		slider.m_maxVal = 100;
		m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
	}

	int upAxis = 1;
	gJointFeedbackInWorldSpace = true;
	gJointFeedbackInJointFrame = true;

	m_guiHelper->setUpAxis(upAxis);

	this->createEmptyDynamicsWorld();
	m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
	m_dynamicsWorld->getDebugDrawer()->setDebugMode(
		//btIDebugDraw::DBG_DrawConstraints
		+btIDebugDraw::DBG_DrawWireframe + btIDebugDraw::DBG_DrawContactPoints + btIDebugDraw::DBG_DrawAabb);  //+btIDebugDraw::DBG_DrawConstraintLimits);

	m_dynamicsWorld->setGravity(btVector3(0, -10, 0));
	btTransform baseWorldTrans;
	baseWorldTrans.setIdentity();
	baseWorldTrans.setOrigin(btVector3(1, 2, 3));
	m_multiBody = createInvertedPendulumMultiBody(m_dynamicsWorld, m_guiHelper, baseWorldTrans, true);

	//for (int i=pMultiBody->getNumLinks()-1;i>=0;i--)//
	for (int i = 0; i < m_multiBody->getNumLinks(); i++)
	{
		btMultiBodyJointFeedback* fb = new btMultiBodyJointFeedback();
		m_multiBody->getLink(i).m_jointFeedback = fb;
		m_jointFeedbacks.push_back(fb);
		//break;
	}
}
char fileName[1024];

static btAlignedObjectArray<btScalar> qDesiredArray;
void InvertedPendulumPDControl::stepSimulation(float deltaTime)
{
	static btScalar offset = -0.1 * SIMD_PI;

	m_frameCount++;
	if ((m_frameCount & 0xff) == 0)
	{
		offset = -offset;
	}
	btScalar target = SIMD_PI + offset;
	qDesiredArray.resize(0);
	qDesiredArray.resize(m_multiBody->getNumLinks(), target);

	for (int joint = 0; joint < m_multiBody->getNumLinks(); joint++)
	{
		int dof1 = 0;
		btScalar qActual = m_multiBody->getJointPosMultiDof(joint)[dof1];
		btScalar qdActual = m_multiBody->getJointVelMultiDof(joint)[dof1];
		btScalar positionError = (qDesiredArray[joint] - qActual);
		double desiredVelocity = 0;
		btScalar velocityError = (desiredVelocity - qdActual);
		btScalar force = kp * positionError + kd * velocityError;
		btClamp(force, -maxForce, maxForce);
		m_multiBody->addJointTorque(joint, force);
	}

	if (m_frameCount == 100)
	{
		const char* gPngFileName = "pendulum";

		if (gPngFileName)
		{
			//printf("gPngFileName=%s\n",gPngFileName);

			sprintf(fileName, "%s%d.png", gPngFileName, m_frameCount);
			b3Printf("Made screenshot %s", fileName);
			this->m_guiHelper->getAppInterface()->dumpNextFrameToPng(fileName);
		}
	}
	m_dynamicsWorld->stepSimulation(1. / 60., 0);  //240,0);

	static int count = 0;
	if ((count & 0x0f) == 0)
	{
#if 0
	for (int i=0;i<m_jointFeedbacks.size();i++)
	{

			b3Printf("F_reaction[%i] linear:%f,%f,%f, angular:%f,%f,%f",
			i,
			m_jointFeedbacks[i]->m_reactionForces.m_topVec[0],
			m_jointFeedbacks[i]->m_reactionForces.m_topVec[1],
			m_jointFeedbacks[i]->m_reactionForces.m_topVec[2],

		m_jointFeedbacks[i]->m_reactionForces.m_bottomVec[0],
			m_jointFeedbacks[i]->m_reactionForces.m_bottomVec[1],
			m_jointFeedbacks[i]->m_reactionForces.m_bottomVec[2]

		);

	}
#endif
	}
	count++;

	/*
    b3Printf("base angvel = %f,%f,%f",m_multiBody->getBaseOmega()[0],
             m_multiBody->getBaseOmega()[1],
             m_multiBody->getBaseOmega()[2]
             );
    */
	//   btScalar jointVel =m_multiBody->getJointVel(0);

	//    b3Printf("child angvel = %f",jointVel);
}

class CommonExampleInterface* InvertedPendulumPDControlCreateFunc(struct CommonExampleOptions& options)
{
	return new InvertedPendulumPDControl(options.m_guiHelper);
}