Bullet Collision Detection & Physics Library: btMultiBodyLink.h Source File

Bullet Collision Detection & Physics Library

btMultiBodyLink.h
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1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2013 Erwin Coumans http://bulletphysics.org
4
5 This software is provided 'as-is', without any express or implied warranty.
6 In no event will the authors be held liable for any damages arising from the use of this software.
7 Permission is granted to anyone to use this software for any purpose,
8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
10
11 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
13 3. This notice may not be removed or altered from any source distribution.
14 */
15
16 #ifndef BT_MULTIBODY_LINK_H
17 #define BT_MULTIBODY_LINK_H
18
19 #include "LinearMath/btQuaternion.h"
20 #include "LinearMath/btVector3.h"
21 #include "BulletCollision/CollisionDispatch/btCollisionObject.h"
22
23 enum btMultiBodyLinkFlags
24 {
25 BT_MULTIBODYLINKFLAGS_DISABLE_PARENT_COLLISION = 1,
26 BT_MULTIBODYLINKFLAGS_DISABLE_ALL_PARENT_COLLISION = 2,
27 };
28
29 //both defines are now permanently enabled
30 #define BT_MULTIBODYLINK_INCLUDE_PLANAR_JOINTS
31 #define TEST_SPATIAL_ALGEBRA_LAYER
32
33 //
34 // Various spatial helper functions
35 //
36
37 //namespace {
38
39
40 #include "LinearMath/btSpatialAlgebra.h"
41
42 //}
43
44 //
45 // Link struct
46 //
47
48 struct btMultibodyLink
49 {
50
51 BT_DECLARE_ALIGNED_ALLOCATOR();
52
53 btScalar m_mass; // mass of link
54 btVector3 m_inertiaLocal; // inertia of link (local frame; diagonal)
55
56 int m_parent; // index of the parent link (assumed to be < index of this link), or -1 if parent is the base link.
57
58 btQuaternion m_zeroRotParentToThis; // rotates vectors in parent-frame to vectors in local-frame (when q=0). constant.
59
60 btVector3 m_dVector; // vector from the inboard joint pos to this link's COM. (local frame.) constant.
61 //this is set to zero for planar joint (see also m_eVector comment)
62
63 // m_eVector is constant, but depends on the joint type:
64 // revolute, fixed, prismatic, spherical: vector from parent's COM to the pivot point, in PARENT's frame.
65 // planar: vector from COM of parent to COM of this link, WHEN Q = 0. (local frame.)
66 // todo: fix the planar so it is consistent with the other joints
67
68 btVector3 m_eVector;
69
70 btSpatialMotionVector m_absFrameTotVelocity, m_absFrameLocVelocity;
71
72 enum eFeatherstoneJointType
73 {
74 eRevolute = 0,
75 ePrismatic = 1,
76 eSpherical = 2,
77 ePlanar = 3,
78 eFixed = 4,
79 eInvalid
80 };
81
82
83
84 // "axis" = spatial joint axis (Mirtich Defn 9 p104). (expressed in local frame.) constant.
85 // for prismatic: m_axesTop[0] = zero;
86 // m_axesBottom[0] = unit vector along the joint axis.
87 // for revolute: m_axesTop[0] = unit vector along the rotation axis (u);
88 // m_axesBottom[0] = u cross m_dVector (i.e. COM linear motion due to the rotation at the joint)
89 //
90 // for spherical: m_axesTop[0][1][2] (u1,u2,u3) form a 3x3 identity matrix (3 rotation axes)
91 // m_axesBottom[0][1][2] cross u1,u2,u3 (i.e. COM linear motion due to the rotation at the joint)
92 //
93 // for planar: m_axesTop[0] = unit vector along the rotation axis (u); defines the plane of motion
94 // m_axesTop[1][2] = zero
95 // m_axesBottom[0] = zero
96 // m_axesBottom[1][2] = unit vectors along the translational axes on that plane
97 btSpatialMotionVector m_axes[6];
98 void setAxisTop(int dof, const btVector3 &axis) { m_axes[dof].m_topVec = axis; }
99 void setAxisBottom(int dof, const btVector3 &axis)
100 {
101 m_axes[dof].m_bottomVec = axis;
102 }
103 void setAxisTop(int dof, const btScalar &x, const btScalar &y, const btScalar &z)
104 {
105 m_axes[dof].m_topVec.setValue(x, y, z);
106 }
107 void setAxisBottom(int dof, const btScalar &x, const btScalar &y, const btScalar &z)
108 {
109 m_axes[dof].m_bottomVec.setValue(x, y, z);
110 }
111 const btVector3 & getAxisTop(int dof) const { return m_axes[dof].m_topVec; }
112 const btVector3 & getAxisBottom(int dof) const { return m_axes[dof].m_bottomVec; }
113
114 int m_dofOffset, m_cfgOffset;
115
116 btQuaternion m_cachedRotParentToThis; // rotates vectors in parent frame to vectors in local frame
117 btVector3 m_cachedRVector; // vector from COM of parent to COM of this link, in local frame.
118
119 btVector3 m_appliedForce; // In WORLD frame
120 btVector3 m_appliedTorque; // In WORLD frame
121
122 btVector3 m_appliedConstraintForce; // In WORLD frame
123 btVector3 m_appliedConstraintTorque; // In WORLD frame
124
125 btScalar m_jointPos[7];
126
127 //m_jointTorque is the joint torque applied by the user using 'addJointTorque'.
128 //It gets set to zero after each internal stepSimulation call
129 btScalar m_jointTorque[6];
130
131 class btMultiBodyLinkCollider* m_collider;
132 int m_flags;
133
134
135 int m_dofCount, m_posVarCount; //redundant but handy
136
137 eFeatherstoneJointType m_jointType;
138
139 struct btMultiBodyJointFeedback* m_jointFeedback;
140
141 btTransform m_cachedWorldTransform;//this cache is updated when calling btMultiBody::forwardKinematics
142
143 const char* m_linkName;//m_linkName memory needs to be managed by the developer/user!
144 const char* m_jointName;//m_jointName memory needs to be managed by the developer/user!
145 const void* m_userPtr;//m_userPtr ptr needs to be managed by the developer/user!
146
147 btScalar m_jointDamping; //todo: implement this internally. It is unused for now, it is set by a URDF loader. User can apply manual damping.
148 btScalar m_jointFriction; //todo: implement this internally. It is unused for now, it is set by a URDF loader. User can apply manual friction using a velocity motor.
149 btScalar m_jointLowerLimit; //todo: implement this internally. It is unused for now, it is set by a URDF loader.
150 btScalar m_jointUpperLimit; //todo: implement this internally. It is unused for now, it is set by a URDF loader.
151 btScalar m_jointMaxForce; //todo: implement this internally. It is unused for now, it is set by a URDF loader.
152 btScalar m_jointMaxVelocity;//todo: implement this internally. It is unused for now, it is set by a URDF loader.
153
154 // ctor: set some sensible defaults
155 btMultibodyLink()
156 : m_mass(1),
157 m_parent(-1),
158 m_zeroRotParentToThis(0, 0, 0, 1),
159 m_cachedRotParentToThis(0, 0, 0, 1),
160 m_collider(0),
161 m_flags(0),
162 m_dofCount(0),
163 m_posVarCount(0),
164 m_jointType(btMultibodyLink::eInvalid),
165 m_jointFeedback(0),
166 m_linkName(0),
167 m_jointName(0),
168 m_userPtr(0),
169 m_jointDamping(0),
170 m_jointFriction(0),
171 m_jointLowerLimit(0),
172 m_jointUpperLimit(0),
173 m_jointMaxForce(0),
174 m_jointMaxVelocity(0)
175 {
176
177 m_inertiaLocal.setValue(1, 1, 1);
178 setAxisTop(0, 0., 0., 0.);
179 setAxisBottom(0, 1., 0., 0.);
180 m_dVector.setValue(0, 0, 0);
181 m_eVector.setValue(0, 0, 0);
182 m_cachedRVector.setValue(0, 0, 0);
183 m_appliedForce.setValue( 0, 0, 0);
184 m_appliedTorque.setValue(0, 0, 0);
185 //
186 m_jointPos[0] = m_jointPos[1] = m_jointPos[2] = m_jointPos[4] = m_jointPos[5] = m_jointPos[6] = 0.f;
187 m_jointPos[3] = 1.f; //"quat.w"
188 m_jointTorque[0] = m_jointTorque[1] = m_jointTorque[2] = m_jointTorque[3] = m_jointTorque[4] = m_jointTorque[5] = 0.f;
189 m_cachedWorldTransform.setIdentity();
190 }
191
192 // routine to update m_cachedRotParentToThis and m_cachedRVector
193 void updateCacheMultiDof(btScalar *pq = 0)
194 {
195 btScalar *pJointPos = (pq ? pq : &m_jointPos[0]);
196
197 switch(m_jointType)
198 {
199 case eRevolute:
200 {
201 m_cachedRotParentToThis = btQuaternion(getAxisTop(0),-pJointPos[0]) * m_zeroRotParentToThis;
202 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector);
203
204 break;
205 }
206 case ePrismatic:
207 {
208 // m_cachedRotParentToThis never changes, so no need to update
209 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector) + pJointPos[0] * getAxisBottom(0);
210
211 break;
212 }
213 case eSpherical:
214 {
215 m_cachedRotParentToThis = btQuaternion(pJointPos[0], pJointPos[1], pJointPos[2], -pJointPos[3]) * m_zeroRotParentToThis;
216 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector);
217
218 break;
219 }
220 case ePlanar:
221 {
222 m_cachedRotParentToThis = btQuaternion(getAxisTop(0),-pJointPos[0]) * m_zeroRotParentToThis;
223 m_cachedRVector = quatRotate(btQuaternion(getAxisTop(0),-pJointPos[0]), pJointPos[1] * getAxisBottom(1) + pJointPos[2] * getAxisBottom(2)) + quatRotate(m_cachedRotParentToThis,m_eVector);
224
225 break;
226 }
227 case eFixed:
228 {
229 m_cachedRotParentToThis = m_zeroRotParentToThis;
230 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector);
231
232 break;
233 }
234 default:
235 {
236 //invalid type
237 btAssert(0);
238 }
239 }
240 }
241 };
242
243
244 #endif //BT_MULTIBODY_LINK_H
btMultibodyLink::m_jointLowerLimit
btScalar m_jointLowerLimit
Definition: btMultiBodyLink.h:149
btMultibodyLink::m_zeroRotParentToThis
btQuaternion m_zeroRotParentToThis
Definition: btMultiBodyLink.h:58
btMultiBodyLinkFlags
btMultiBodyLinkFlags
Definition: btMultiBodyLink.h:23
btMultibodyLink::m_appliedConstraintForce
btVector3 m_appliedConstraintForce
Definition: btMultiBodyLink.h:122
btMultibodyLink::m_jointFriction
btScalar m_jointFriction
Definition: btMultiBodyLink.h:148
btVector3::setValue
void setValue(const btScalar &_x, const btScalar &_y, const btScalar &_z)
Definition: btVector3.h:652
btMultibodyLink::getAxisTop
const btVector3 & getAxisTop(int dof) const
Definition: btMultiBodyLink.h:111
btVector3.h
BT_MULTIBODYLINKFLAGS_DISABLE_PARENT_COLLISION
Definition: btMultiBodyLink.h:25
btMultibodyLink::eRevolute
Definition: btMultiBodyLink.h:74
btMultibodyLink::m_cachedRVector
btVector3 m_cachedRVector
Definition: btMultiBodyLink.h:117
btMultibodyLink::m_jointType
eFeatherstoneJointType m_jointType
Definition: btMultiBodyLink.h:137
btMultibodyLink::m_userPtr
const void * m_userPtr
Definition: btMultiBodyLink.h:145
btMultibodyLink::m_collider
class btMultiBodyLinkCollider * m_collider
Definition: btMultiBodyLink.h:131
btMultibodyLink::updateCacheMultiDof
void updateCacheMultiDof(btScalar *pq=0)
Definition: btMultiBodyLink.h:193
BT_MULTIBODYLINKFLAGS_DISABLE_ALL_PARENT_COLLISION
Definition: btMultiBodyLink.h:26
btTransform::setIdentity
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:172
btAssert
#define btAssert(x)
Definition: btScalar.h:131
btMultibodyLink::setAxisTop
void setAxisTop(int dof, const btScalar &x, const btScalar &y, const btScalar &z)
Definition: btMultiBodyLink.h:103
btMultibodyLink::m_posVarCount
int m_posVarCount
Definition: btMultiBodyLink.h:135
btMultibodyLink::m_absFrameLocVelocity
btSpatialMotionVector m_absFrameLocVelocity
Definition: btMultiBodyLink.h:70
btMultibodyLink::m_jointName
const char * m_jointName
Definition: btMultiBodyLink.h:144
btMultibodyLink::m_cfgOffset
int m_cfgOffset
Definition: btMultiBodyLink.h:114
btMultibodyLink
Definition: btMultiBodyLink.h:48
btMultiBodyJointFeedback
Definition: btMultiBodyJointFeedback.h:22
btMultibodyLink::btMultibodyLink
btMultibodyLink()
Definition: btMultiBodyLink.h:155
btMultibodyLink::m_dVector
btVector3 m_dVector
Definition: btMultiBodyLink.h:60
btMultibodyLink::getAxisBottom
const btVector3 & getAxisBottom(int dof) const
Definition: btMultiBodyLink.h:112
quatRotate
btVector3 quatRotate(const btQuaternion &rotation, const btVector3 &v)
Definition: btQuaternion.h:917
btMultibodyLink::eFixed
Definition: btMultiBodyLink.h:78
btSpatialAlgebra.h
btMultibodyLink::m_jointTorque
btScalar m_jointTorque[6]
Definition: btMultiBodyLink.h:129
btMultibodyLink::m_jointUpperLimit
btScalar m_jointUpperLimit
Definition: btMultiBodyLink.h:150
btQuaternion.h
btMultibodyLink::m_dofCount
int m_dofCount
Definition: btMultiBodyLink.h:135
btMultibodyLink::m_cachedRotParentToThis
btQuaternion m_cachedRotParentToThis
Definition: btMultiBodyLink.h:116
btMultibodyLink::eFeatherstoneJointType
eFeatherstoneJointType
Definition: btMultiBodyLink.h:72
btMultibodyLink::m_axes
btSpatialMotionVector m_axes[6]
Definition: btMultiBodyLink.h:97
btMultibodyLink::m_jointMaxForce
btScalar m_jointMaxForce
Definition: btMultiBodyLink.h:151
btMultibodyLink::m_linkName
const char * m_linkName
Definition: btMultiBodyLink.h:143
btMultibodyLink::m_mass
btScalar m_mass
Definition: btMultiBodyLink.h:53
btMultibodyLink::setAxisBottom
void setAxisBottom(int dof, const btVector3 &axis)
Definition: btMultiBodyLink.h:99
btSpatialMotionVector::m_bottomVec
btVector3 m_bottomVec
Definition: btSpatialAlgebra.h:70
btSpatialMotionVector
Definition: btSpatialAlgebra.h:68
btMultibodyLink::m_eVector
btVector3 m_eVector
Definition: btMultiBodyLink.h:68
btMultibodyLink::m_jointPos
btScalar m_jointPos[7]
Definition: btMultiBodyLink.h:125
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
btMultibodyLink::m_dofOffset
int m_dofOffset
Definition: btMultiBodyLink.h:114
btMultibodyLink::m_jointDamping
btScalar m_jointDamping
Definition: btMultiBodyLink.h:147
btMultibodyLink::m_appliedTorque
btVector3 m_appliedTorque
Definition: btMultiBodyLink.h:120
btMultibodyLink::eSpherical
Definition: btMultiBodyLink.h:76
btMultibodyLink::eInvalid
Definition: btMultiBodyLink.h:79
btMultibodyLink::m_flags
int m_flags
Definition: btMultiBodyLink.h:132
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
btMultibodyLink::m_absFrameTotVelocity
btSpatialMotionVector m_absFrameTotVelocity
Definition: btMultiBodyLink.h:70
btMultiBodyLinkCollider
Definition: btMultiBodyLinkCollider.h:23
btMultibodyLink::m_appliedConstraintTorque
btVector3 m_appliedConstraintTorque
Definition: btMultiBodyLink.h:123
btSpatialMotionVector::m_topVec
btVector3 m_topVec
Definition: btSpatialAlgebra.h:70
btMultibodyLink::BT_DECLARE_ALIGNED_ALLOCATOR
BT_DECLARE_ALIGNED_ALLOCATOR()
btCollisionObject.h
btMultibodyLink::m_cachedWorldTransform
btTransform m_cachedWorldTransform
Definition: btMultiBodyLink.h:141
btMultibodyLink::setAxisTop
void setAxisTop(int dof, const btVector3 &axis)
Definition: btMultiBodyLink.h:98
btQuaternion
The btQuaternion implements quaternion to perform linear algebra rotations in combination with btMatr...
Definition: btQuaternion.h:55
btMultibodyLink::m_jointFeedback
struct btMultiBodyJointFeedback * m_jointFeedback
Definition: btMultiBodyLink.h:139
btMultibodyLink::m_inertiaLocal
btVector3 m_inertiaLocal
Definition: btMultiBodyLink.h:54
btMultibodyLink::m_appliedForce
btVector3 m_appliedForce
Definition: btMultiBodyLink.h:119
btMultibodyLink::setAxisBottom
void setAxisBottom(int dof, const btScalar &x, const btScalar &y, const btScalar &z)
Definition: btMultiBodyLink.h:107
btMultibodyLink::ePlanar
Definition: btMultiBodyLink.h:77
btMultibodyLink::ePrismatic
Definition: btMultiBodyLink.h:75
btMultibodyLink::m_parent
int m_parent
Definition: btMultiBodyLink.h:56
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292
btMultibodyLink::m_jointMaxVelocity
btScalar m_jointMaxVelocity
Definition: btMultiBodyLink.h:152