virtualx-engine/thirdparty/bullet/BulletInverseDynamics/details/MultiBodyTreeImpl.hpp

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// The structs and classes defined here provide a basic inverse fynamics implementation used
// by MultiBodyTree
// User interaction should be through MultiBodyTree
#ifndef MULTI_BODY_REFERENCE_IMPL_HPP_
#define MULTI_BODY_REFERENCE_IMPL_HPP_
#include "../IDConfig.hpp"
#include "../MultiBodyTree.hpp"
namespace btInverseDynamics
{
/// Structure for for rigid body mass properties, connectivity and kinematic state
/// all vectors and matrices are in body-fixed frame, if not indicated otherwise.
/// The body-fixed frame is located in the joint connecting the body to its parent.
struct RigidBody
{
ID_DECLARE_ALIGNED_ALLOCATOR();
// 1 Inertial properties
/// Mass
idScalar m_mass;
/// Mass times center of gravity in body-fixed frame
vec3 m_body_mass_com;
/// Moment of inertia w.r.t. body-fixed frame
mat33 m_body_I_body;
// 2 dynamic properties
/// Left-hand side of the body equation of motion, translational part
vec3 m_eom_lhs_translational;
/// Left-hand side of the body equation of motion, rotational part
vec3 m_eom_lhs_rotational;
/// Force acting at the joint when the body is cut from its parent;
/// includes impressed joint force in J_JT direction,
/// as well as constraint force,
/// in body-fixed frame
vec3 m_force_at_joint;
/// Moment acting at the joint when the body is cut from its parent;
/// includes impressed joint moment in J_JR direction, and constraint moment
/// in body-fixed frame
vec3 m_moment_at_joint;
/// external (user provided) force acting at the body-fixed frame's origin, written in that
/// frame
vec3 m_body_force_user;
/// external (user provided) moment acting at the body-fixed frame's origin, written in that
/// frame
vec3 m_body_moment_user;
// 3 absolute kinematic properties
/// Position of body-fixed frame relative to world frame
/// this is currently only for debugging purposes
vec3 m_body_pos;
/// Absolute velocity of body-fixed frame
vec3 m_body_vel;
/// Absolute acceleration of body-fixed frame
/// NOTE: if gravitational acceleration is not zero, this is the accelation PLUS gravitational
/// acceleration!
vec3 m_body_acc;
/// Absolute angular velocity
vec3 m_body_ang_vel;
/// Absolute angular acceleration
/// NOTE: if gravitational acceleration is not zero, this is the accelation PLUS gravitational
/// acceleration!
vec3 m_body_ang_acc;
// 4 relative kinematic properties.
// these are in the parent body frame
/// Transform from world to body-fixed frame;
/// this is currently only for debugging purposes
mat33 m_body_T_world;
/// Transform from parent to body-fixed frame
mat33 m_body_T_parent;
/// Vector from parent to child frame in parent frame
vec3 m_parent_pos_parent_body;
/// Relative angular velocity
vec3 m_body_ang_vel_rel;
/// Relative linear velocity
vec3 m_parent_vel_rel;
/// Relative angular acceleration
vec3 m_body_ang_acc_rel;
/// Relative linear acceleration
vec3 m_parent_acc_rel;
// 5 Data describing the joint type and geometry
/// Type of joint
JointType m_joint_type;
/// Position of joint frame (body-fixed frame at q=0) relative to the parent frame
/// Components are in body-fixed frame of the parent
vec3 m_parent_pos_parent_body_ref;
/// Orientation of joint frame (body-fixed frame at q=0) relative to the parent frame
mat33 m_body_T_parent_ref;
/// Joint rotational Jacobian, ie, the partial derivative of the body-fixed frames absolute
/// angular velocity w.r.t. the generalized velocity of this body's relative degree of freedom.
/// For revolute joints this is the joint axis, for prismatic joints it is a null matrix.
/// (NOTE: dimensions will have to be dynamic for additional joint types!)
vec3 m_Jac_JR;
/// Joint translational Jacobian, ie, the partial derivative of the body-fixed frames absolute
/// linear velocity w.r.t. the generalized velocity of this body's relative degree of freedom.
/// For prismatic joints this is the joint axis, for revolute joints it is a null matrix.
/// (NOTE: dimensions might have to be dynamic for additional joint types!)
vec3 m_Jac_JT;
/// m_Jac_JT in the parent frame, it, m_body_T_parent_ref.transpose()*m_Jac_JT
vec3 m_parent_Jac_JT;
/// Start of index range for the position degree(s) of freedom describing this body's motion
/// relative to
/// its parent. The indices are wrt the multibody system's q-vector of generalized coordinates.
int m_q_index;
// 6 Scratch data for mass matrix computation using "composite rigid body algorithm"
/// mass of the subtree rooted in this body
idScalar m_subtree_mass;
/// center of mass * mass for subtree rooted in this body, in body-fixed frame
vec3 m_body_subtree_mass_com;
/// moment of inertia of subtree rooted in this body, w.r.t. body origin, in body-fixed frame
mat33 m_body_subtree_I_body;
#if (defined BT_ID_HAVE_MAT3X) && (defined BT_ID_WITH_JACOBIANS)
/// translational jacobian in body-fixed frame d(m_body_vel)/du
mat3x m_body_Jac_T;
/// rotationsl jacobian in body-fixed frame d(m_body_ang_vel)/du
mat3x m_body_Jac_R;
/// components of linear acceleration depending on u
/// (same as is d(m_Jac_T)/dt*u)
vec3 m_body_dot_Jac_T_u;
/// components of angular acceleration depending on u
/// (same as is d(m_Jac_T)/dt*u)
vec3 m_body_dot_Jac_R_u;
#endif
};
/// The MBS implements a tree structured multibody system
class MultiBodyTree::MultiBodyImpl
{
friend class MultiBodyTree;
public:
ID_DECLARE_ALIGNED_ALLOCATOR();
enum KinUpdateType
{
POSITION_ONLY,
POSITION_VELOCITY,
POSITION_VELOCITY_ACCELERATION
};
/// constructor
/// @param num_bodies the number of bodies in the system
/// @param num_dofs number of degrees of freedom in the system
MultiBodyImpl(int num_bodies_, int num_dofs_);
/// \copydoc MultiBodyTree::calculateInverseDynamics
int calculateInverseDynamics(const vecx& q, const vecx& u, const vecx& dot_u,
vecx* joint_forces);
///\copydoc MultiBodyTree::calculateMassMatrix
int calculateMassMatrix(const vecx& q, const bool update_kinematics,
const bool initialize_matrix, const bool set_lower_triangular_matrix,
matxx* mass_matrix);
/// calculate kinematics (vector quantities)
/// Depending on type, update positions only, positions & velocities, or positions, velocities
/// and accelerations.
int calculateKinematics(const vecx& q, const vecx& u, const vecx& dot_u, const KinUpdateType type);
#if (defined BT_ID_HAVE_MAT3X) && (defined BT_ID_WITH_JACOBIANS)
/// calculate jacobians and (if type == POSITION_VELOCITY), also velocity-dependent accelration terms.
int calculateJacobians(const vecx& q, const vecx& u, const KinUpdateType type);
/// \copydoc MultiBodyTree::getBodyDotJacobianTransU
int getBodyDotJacobianTransU(const int body_index, vec3* world_dot_jac_trans_u) const;
/// \copydoc MultiBodyTree::getBodyDotJacobianRotU
int getBodyDotJacobianRotU(const int body_index, vec3* world_dot_jac_rot_u) const;
/// \copydoc MultiBodyTree::getBodyJacobianTrans
int getBodyJacobianTrans(const int body_index, mat3x* world_jac_trans) const;
/// \copydoc MultiBodyTree::getBodyJacobianRot
int getBodyJacobianRot(const int body_index, mat3x* world_jac_rot) const;
/// Add relative Jacobian component from motion relative to parent body
/// @param body the body to add the Jacobian component for
void addRelativeJacobianComponent(RigidBody& body);
#endif
/// generate additional index sets from the parent_index array
/// @return -1 on error, 0 on success
int generateIndexSets();
/// set gravity acceleration in world frame
/// @param gravity gravity vector in the world frame
/// @return 0 on success, -1 on error
int setGravityInWorldFrame(const vec3& gravity);
/// pretty print tree
void printTree();
/// print tree data
void printTreeData();
/// initialize fixed data
void calculateStaticData();
/// \copydoc MultiBodyTree::getBodyFrame
int getBodyFrame(const int index, vec3* world_origin, mat33* body_T_world) const;
/// \copydoc MultiBodyTree::getParentIndex
int getParentIndex(const int body_index, int* m_parent_index);
/// \copydoc MultiBodyTree::getJointType
int getJointType(const int body_index, JointType* joint_type) const;
/// \copydoc MultiBodyTree::getJointTypeStr
int getJointTypeStr(const int body_index, const char** joint_type) const;
/// \copydoc MultiBodyTree::getParentRParentBodyRef
int getParentRParentBodyRef(const int body_index, vec3* r) const;
/// \copydoc MultiBodyTree::getBodyTParentRef
int getBodyTParentRef(const int body_index, mat33* T) const;
/// \copydoc MultiBodyTree::getBodyAxisOfMotion
int getBodyAxisOfMotion(const int body_index, vec3* axis) const;
/// \copydoc MultiBodyTree:getDoFOffset
int getDoFOffset(const int body_index, int* q_index) const;
/// \copydoc MultiBodyTree::getBodyOrigin
int getBodyOrigin(const int body_index, vec3* world_origin) const;
/// \copydoc MultiBodyTree::getBodyCoM
int getBodyCoM(const int body_index, vec3* world_com) const;
/// \copydoc MultiBodyTree::getBodyTransform
int getBodyTransform(const int body_index, mat33* world_T_body) const;
/// \copydoc MultiBodyTree::getBodyAngularVelocity
int getBodyAngularVelocity(const int body_index, vec3* world_omega) const;
/// \copydoc MultiBodyTree::getBodyLinearVelocity
int getBodyLinearVelocity(const int body_index, vec3* world_velocity) const;
/// \copydoc MultiBodyTree::getBodyLinearVelocityCoM
int getBodyLinearVelocityCoM(const int body_index, vec3* world_velocity) const;
/// \copydoc MultiBodyTree::getBodyAngularAcceleration
int getBodyAngularAcceleration(const int body_index, vec3* world_dot_omega) const;
/// \copydoc MultiBodyTree::getBodyLinearAcceleration
int getBodyLinearAcceleration(const int body_index, vec3* world_acceleration) const;
/// \copydoc MultiBodyTree::getUserInt
int getUserInt(const int body_index, int* user_int) const;
/// \copydoc MultiBodyTree::getUserPtr
int getUserPtr(const int body_index, void** user_ptr) const;
/// \copydoc MultiBodyTree::setUserInt
int setUserInt(const int body_index, const int user_int);
/// \copydoc MultiBodyTree::setUserPtr
int setUserPtr(const int body_index, void* const user_ptr);
///\copydoc MultiBodytTree::setBodyMass
int setBodyMass(const int body_index, const idScalar mass);
///\copydoc MultiBodytTree::setBodyFirstMassMoment
int setBodyFirstMassMoment(const int body_index, const vec3& first_mass_moment);
///\copydoc MultiBodytTree::setBodySecondMassMoment
int setBodySecondMassMoment(const int body_index, const mat33& second_mass_moment);
///\copydoc MultiBodytTree::getBodyMass
int getBodyMass(const int body_index, idScalar* mass) const;
///\copydoc MultiBodytTree::getBodyFirstMassMoment
int getBodyFirstMassMoment(const int body_index, vec3* first_mass_moment) const;
///\copydoc MultiBodytTree::getBodySecondMassMoment
int getBodySecondMassMoment(const int body_index, mat33* second_mass_moment) const;
/// \copydoc MultiBodyTree::clearAllUserForcesAndMoments
void clearAllUserForcesAndMoments();
/// \copydoc MultiBodyTree::addUserForce
int addUserForce(const int body_index, const vec3& body_force);
/// \copydoc MultiBodyTree::addUserMoment
int addUserMoment(const int body_index, const vec3& body_moment);
private:
// debug function. print tree structure to stdout
void printTree(int index, int indentation);
// get string representation of JointType (for debugging)
const char* jointTypeToString(const JointType& type) const;
// get number of degrees of freedom from joint type
int bodyNumDoFs(const JointType& type) const;
// number of bodies in the system
int m_num_bodies;
// number of degrees of freedom
int m_num_dofs;
// Gravitational acceleration (in world frame)
vec3 m_world_gravity;
// vector of bodies in the system
// body 0 is used as an environment body and is allways fixed.
// The bodies are ordered such that a parent body always has an index
// smaller than its child.
idArray<RigidBody>::type m_body_list;
// Parent_index[i] is the index for i's parent body in body_list.
// This fully describes the tree.
idArray<int>::type m_parent_index;
// child_indices[i] contains a vector of indices of
// all children of the i-th body
idArray<idArray<int>::type>::type m_child_indices;
// Indices of rotary joints
idArray<int>::type m_body_revolute_list;
// Indices of prismatic joints
idArray<int>::type m_body_prismatic_list;
// Indices of floating joints
idArray<int>::type m_body_floating_list;
// Indices of spherical joints
idArray<int>::type m_body_spherical_list;
// a user-provided integer
idArray<int>::type m_user_int;
// a user-provided pointer
idArray<void*>::type m_user_ptr;
#if (defined BT_ID_HAVE_MAT3X) && (defined BT_ID_WITH_JACOBIANS)
mat3x m_m3x;
#endif
};
} // namespace btInverseDynamics
#endif