diff --git a/gazebo_grasp_plugin/include/gazebo_grasp_plugin/GazeboGraspFix.h b/gazebo_grasp_plugin/include/gazebo_grasp_plugin/GazeboGraspFix.h
index 57cf932f5aa3cafaf633d2ecca09420905ea6fba..f792ebc52ba7f4d56e9cc938ed4514de3f692857 100644
--- a/gazebo_grasp_plugin/include/gazebo_grasp_plugin/GazeboGraspFix.h
+++ b/gazebo_grasp_plugin/include/gazebo_grasp_plugin/GazeboGraspFix.h
@@ -17,14 +17,62 @@ namespace gazebo {
* ```xml
* <gazebo>
* <plugin name="gazebo_grasp_fix" filename="libgazebo_grasp_fix.so">
+ * <!-- Palm link: The link to which the object is attached -->
* <palm_link> hand_link_name </palm_link>
+ *
+ * <!-- All gripper links which collide with the object to *actively* grasp it -->
* <gripper_link> finger_index_link_1 </gripper_link>
* <gripper_link> finger_index_link_2 </gripper_link>
* <gripper_link> ... </gripper_link>
+ * <!-- tolerance angle (in degrees) between two force vectors to be considered
+ * "opposing forces". If the angle is smaller than this, they are not opposing.
+ * -->
+ * <forces_angle_tolerance>120</forces_angle_tolerance>
+ *
+ * <!-- the rate at which all collision points are checked against the "gripping criterion".
+ * Note that in-between such updates, existing collisions may be collected at
+ * a higher rate (the Gazebo world update rate). This rate is only the rate at
+ * which they are processed, which takes a bit of computation time, and therefore
+ * should be lower than the gazebo world update rate. -->
+ * <update_rate>5</update_rate>
+ *
+ * <!-- Number of times an object has to be detected as "gripped" in order to
+ * attach the object. Adjust this with the update rate. -->
+ * <grip_count_threshold>5</grip_count_threshold>
+ *
+ * <!-- Maximum number of times that a "grasped" condition counted for an
+ * object. Should be at least double of grip_count_threshold. If the object
+ * has been counted this amount of times in subsequent update iterations as
+ * "grasped", the number will not increase any further. As soon as the grasp
+ * criterion does not hold any more, the number will start to decrease by one time
+ * each time the object is detected as "not grasped" in an update iteration. This is
+ * like a "buffer" which, when it is full, maintains the state, and when it is empty again,
+ * the object is released -->
+ * <max_grip_count>10</max_grip_count>
+ *
+ * <!-- The distance which the gripper links are allowed to move away from the object
+ * *during* a grasp without the object being detached, even if there are currently no
+ * contacts. This can happen if the fingers "wobble" or move ever so slightly, and therefore
+ * the grasp is not detected as active any more. Setting this number too high will also lead
+ * to the object not being detached even if the grippers have opened up to release it. -->
+ * <release_tolerance>0.005</release_tolerance>
+ *
+ * <!-- when an object is attached, collisions with it may be disabled, in case the
+ * robot still keeps wobbling. -->
+ * <disable_collisions_on_attach>false</disable_collisions_on_attach>
+ *
+ * <!-- The gazebo topic of contacts. Should normally be left at __default_topic__ -->
+ * <contact_topic>__default_topic__</contact_topic>
* </plugin>
* </gazebo>
* ```
*
+ * Methods OnUpdate() and OnContact() contain detailed documentation on how the plugin works.
+ * Summarizing it:
+ * XXX TODO
+ *
+ * Current limitation:
+ * - Only one object can be attached per gripper.
* \author Jennifer Buehler
*/
class GazeboGraspFix : public ModelPlugin {
@@ -34,18 +82,55 @@ public:
virtual ~GazeboGraspFix();
virtual void Init();
virtual void Load(physics::ModelPtr _parent, sdf::ElementPtr _sdf);
- void OnUpdate();
private:
+ /**
+ * Collects for each object all forces which are currently applied on it.
+ * Then, for each object, checks whether of all the forces applied,
+ * there are opposing forces. This is done by calling checkGrip() with the
+ * list of all forces applied.
+ * If checkGrip() returns true, the number of "grip counts" (field \e gripCounts)
+ * is increased (but grip counts will never exceed \e max_grip_count).
+ * If the number of grip counts for this object exceeds \e grip_count_threshold,
+ * the object is attached by calling HandleAttach(object-name),
+ * setting \e attached and \e attachedObjName, and \e attachGripContacts is updated with the
+ * contact points currently existing for this object (current entry in \e contacts).
+ *
+ * Then, goes through all entries in \e gripCount, and unless it's an object
+ * we just detected as "gripped", the counter is decreased.
+ * If the counter is is smaller than \e grip_count_threshold, the object should
+ * potentially be released, but this criterion happens too easily
+ * (the fingers in gazebo may have started wobbling as the arm moves around, and although they are still
+ * close to the object, the grip is not detected any more).
+ * So to be sure, and additional criterion has to be satisfied before the object is released:
+ * check that the collision point (the place on the link where the contact originally
+ * was detected) has not moved too far from where it originally was, relative to the object.
+ */
+ void OnUpdate();
void InitValues();
+
+
+ /**
+ * Gets called upon detection of contacts.
+ * A list of contacts is passed in \_msg. One contact has two bodies, and only
+ * the ones where one of the bodies is a gripper link are considered.
+ * Each contact consists of a *list* of forces with their own origin/position each
+ * (e.g. when the object and gripper are colliding at several places).
+ * The averages of each contact's force vectors along with their origins is computed.
+ * This "average contact force/origin" for each contact is then added to the \e this->contacts map.
+ * If an entry for this object/link pair already exists, the average force (and its origin)
+ * is *added* to the existing force/origin, and the average count is increased. This is to get
+ * the average force application over time between link and object.
+ */
void OnContact(const ConstContactsPtr& ptr);
bool HandleAttach(const std::string& objName);
void HandleDetach(const std::string& objName);
/**
- * Checks whether any two vectors in the set have an angle greater than minAngleDiff (in rad), and one is at least
- * lengthRatio (0..1) of the other in it's length.
+ * Checks whether any two vectors in the set have an angle greater
+ * than minAngleDiff (in rad), and one is at least
+ * lengthRatio (0..1) of the other in it's length.
*/
bool checkGrip(const std::vector<math::Vector3>& forces, float minAngleDiff, float lengthRatio);
@@ -59,7 +144,16 @@ private:
event::ConnectionPtr update_connection;
transport::NodePtr node;
transport::SubscriberPtr contactSub; //subscriber to contact updates
+
+ // tolerance (in degrees) between force vectors to
+ // beconsidered "opposing"
+ float forcesAngleTolerance;
+ // when an object is attached, collisions with it may be disabled, in case the
+ // robot still keeps wobbling.
+ bool disableCollisionsOnAttach;
+
+ // list of current collisions per gripper link
std::map<std::string, physics::CollisionPtr> collisions;
/**
@@ -68,31 +162,36 @@ private:
*/
class CollidingPoint;
- //Contact forces sorted by object name the gripper collides with, and the link colliding.
- //This is a vector summed up over time, sum count is kept in contactSumCnt.
+ // Contact forces sorted by object name the gripper collides with (first key)
+ // and the link colliding (second key).
std::map<std::string, std::map<std::string, CollidingPoint> > contacts;
boost::mutex mutexContacts; //mutex protects contacts
- //when an object was attached, it had these colliding points.
+ // when an object was first attached, it had these colliding points.
+ // Key is object name.
std::map<std::string, std::map<std::string, CollidingPoint> > attachGripContacts;
- //records how many update loops (at updateRate) the grip on that object has been recorded
- //as "holding". Every loop, if a grip is not recorded, this number decreases.
- //When it reaches grip_count_threshold, it will be attached.
- //The number won't increase above max_grip_count once it has reached that number.
+ // Records how many update loops (at updateRate) the grip on that object has been recorded
+ // as "holding". Every loop, if a grip is not recorded, this number decreases.
+ // When it reaches \e grip_count_threshold, it will be attached.
+ // The number won't increase above max_grip_count once it has reached that number.
std::map<std::string, int> gripCounts;
- //maximum record in gripCounts
- int max_grip_count;
- //number of recorded "grips" in the past (in gripCount) which, when it is exceeded, counts
- //as the object grasped, and when it is lower, as released.
- int grip_count_threshold;
- //once an object is gripped, the relative position of the collision link surface to the
- //object is remembered. As soon as this distance changes more than release_tolerance,
- //the object is released.
- float release_tolerance;
+ // *maximum* number in \e gripCounts to be recorded.
+ int maxGripCount;
+
+ // number of recorded "grips" in the past (in gripCount) which, when it is exceeded, counts
+ // as the object grasped, and when it is lower, as released.
+ int gripCountThreshold;
+
+ // once an object is gripped, the relative position of the collision link surface to the
+ // object is remembered. As soon as this distance changes more than release_tolerance,
+ // the object is released.
+ float releaseTolerance;
+ // flag holding whether an object is attached. Object name in \e attachedObjName
bool attached;
+ // name of the object currently attached.
std::string attachedObjName;
//nano seconds between two updates
diff --git a/gazebo_grasp_plugin/src/GazeboGraspFix.cpp b/gazebo_grasp_plugin/src/GazeboGraspFix.cpp
index b268cfacfcf00ef383414e1b1e6f146bf2214141..81a208937bd269d25a56bf1e0d22b7054b37f094 100644
--- a/gazebo_grasp_plugin/src/GazeboGraspFix.cpp
+++ b/gazebo_grasp_plugin/src/GazeboGraspFix.cpp
@@ -10,11 +10,28 @@
using gazebo::GazeboGraspFix;
+
+#define DEFAULT_FORCES_ANGLE_TOLERANCE 120
+#define DEFAULT_UPDATE_RATE 5
+#define DEFAULT_MAX_GRIP_COUNT 10
+#define DEFAULT_RELEASE_TOLERANCE 0.005
+#define DEFAULT_DISABLE_COLLISIONS_ON_ATTACH false
+
// Register this plugin with the simulator
GZ_REGISTER_MODEL_PLUGIN(GazeboGraspFix)
/**
- * Helper class to encapsulate a collision information
+ * Helper class to encapsulate a collision information.
+ * One contact has two bodies, and only
+ * the ones where one of the bodies is a gripper link are considered.
+ * Each contact consists of a *list* of forces with their own origin/position each
+ * (e.g. when the object and gripper are colliding at several places).
+ * The averages of each contact's force vectors along with their origins are
+ * *accumulated* in the given Vector3 \e pos and \eforce objects.
+ * The number of additions is stored in \e sum.
+ * This is to get the average force application over time between link and object.
+ *
+ * \author Jennifer Buehler
*/
class GazeboGraspFix::CollidingPoint{
public:
@@ -27,17 +44,23 @@ public:
objPos(o.objPos),
sum(o.sum){}
- //the collision
+ // the collision
physics::CollisionPtr collLink, collObj;
- //average force vector of the colliding point
+ // average force vector of the colliding point
gazebo::math::Vector3 force;
- //position (relative to reference frame of gripper collision surface) where the contact happens on collision surface
+
+ // position (relative to reference frame of gripper
+ // collision surface) where the contact happens on collision surface
gazebo::math::Vector3 pos;
- //position (relative to reference frame of gripper collision surface) where the object center is located during collision.
+
+ // position (relative to reference frame of *gripper* collision surface)
+ // where the object center is located during collision.
gazebo::math::Vector3 objPos;
- //sum of force and pose (they are actually summed up from several contact points), divide force and pose by this to obtain average
+ // sum of force and pose (they are actually summed
+ // up from several contact points).
+ // Divide both \e force and \e pos by this to obtain average
int sum;
};
@@ -75,19 +98,16 @@ void GazeboGraspFix::Init(){
void GazeboGraspFix::InitValues(){
- float timeDiff=0.25;
- this->release_tolerance=0.005;
+ // float timeDiff=0.25;
+ //this->releaseTolerance=0.005;
this->attached = false;
- this->updateRate = common::Time(0, common::Time::SecToNano(timeDiff));
+ // this->updateRate = common::Time(0, common::Time::SecToNano(timeDiff));
this->prevUpdateTime = common::Time::GetWallTime();
-
-
- float graspedSecs=2;
- this->max_grip_count=floor(graspedSecs/timeDiff);
- this->grip_count_threshold=floor(max_grip_count/2);
+ //float graspedSecs=2;
+ //this->maxGripCount=floor(graspedSecs/timeDiff);
+ //this->gripCountThreshold=floor(this->maxGripCount/2);
this->attached = false;
-
this->node = transport::NodePtr(new transport::Node());
}
@@ -108,21 +128,78 @@ void GazeboGraspFix::Load(physics::ModelPtr _parent, sdf::ElementPtr _sdf)
sdf::ElementPtr handLinkElem = _sdf->GetElement("palm_link");
sdf::ElementPtr fingerLinkElem = _sdf->GetElement("gripper_link");
-
if (!handLinkElem.get() || !fingerLinkElem.get()) {
- gzerr<<"Cannot use GazeboGraspFix model plugin because no <palm_link> and/or <gripper_link> elements specified in URDF/SDF."<<std::endl;
+ std::cerr<<"ERROR: GazeboGraspFix: Cannot use GazeboGraspFix model plugin because no <palm_link> and/or <gripper_link> elements specified in URDF/SDF."<<std::endl;
return;
}
- this->palmLink = this->model->GetLink(handLinkElem->Get<std::string>());
-
+ sdf::ElementPtr forcesAngleToleranceElem = _sdf->GetElement("forces_angle_tolerance");
+ if (!forcesAngleToleranceElem.get()){
+ std::cout<<"GazeboGraspFix: Using default tolerance of "<<DEFAULT_FORCES_ANGLE_TOLERANCE<<" because no <forces_angle_tolerance> element specified."<<std::endl;
+ this->forcesAngleTolerance = DEFAULT_FORCES_ANGLE_TOLERANCE * M_PI/180;
+ } else {
+ this->forcesAngleTolerance = forcesAngleToleranceElem->Get<float>() * M_PI/180;
+ }
+
+ sdf::ElementPtr updateRateElem = _sdf->GetElement("update_rate");
+ double _updateSecs;
+ if (!updateRateElem.get()){
+ std::cout<<"GazeboGraspFix: Using "<<DEFAULT_UPDATE_RATE<<" because no <updateRate_tag> element specified."<<std::endl;
+ _updateSecs = 1.0 / DEFAULT_UPDATE_RATE;
+ } else {
+ int _rate = updateRateElem->Get<int>();
+ double _updateRate = _rate;
+ _updateSecs = 1.0/_updateRate;
+ std::cout<<"GazeboGraspFix: Using update rate "<<_rate<<std::endl;
+ }
+ this->updateRate = common::Time(0, common::Time::SecToNano(_updateSecs));
+
+ sdf::ElementPtr maxGripCountElem = _sdf->GetElement("max_grip_count");
+ if (!maxGripCountElem.get()){
+ std::cout<<"GazeboGraspFix: Using "<<DEFAULT_MAX_GRIP_COUNT<<" because no <max_grip_count> element specified."<<std::endl;
+ this->maxGripCount = DEFAULT_MAX_GRIP_COUNT;
+ } else {
+ this->maxGripCount = maxGripCountElem->Get<int>();
+ std::cout<<"GazeboGraspFix: Using max_grip_count "<<this->maxGripCount<<std::endl;
+ }
+
+ sdf::ElementPtr gripCountThresholdElem = _sdf->GetElement("grip_count_threshold");
+ if (!gripCountThresholdElem.get()){
+ this->gripCountThreshold=floor(this->maxGripCount/2.0);
+ std::cout<<"GazeboGraspFix: Using "<<this->gripCountThreshold<<" because no <grip_count_threshold> element specified."<<std::endl;
+ } else {
+ this->gripCountThreshold = gripCountThresholdElem->Get<int>();
+ std::cout<<"GazeboGraspFix: Using grip_count_threshold "<<this->gripCountThreshold<<std::endl;
+ }
+
+ sdf::ElementPtr releaseToleranceElem = _sdf->GetElement("release_tolerance");
+ if (!releaseToleranceElem.get()){
+ std::cout<<"GazeboGraspFix: Using "<<DEFAULT_RELEASE_TOLERANCE<<" because no <release_tolerance> element specified."<<std::endl;
+ this->releaseTolerance = DEFAULT_RELEASE_TOLERANCE;
+ } else {
+ this->releaseTolerance = releaseToleranceElem->Get<float>();
+ std::cout<<"GazeboGraspFix: Using release_tolerance "<<this->releaseTolerance<<std::endl;
+ }
+
+ sdf::ElementPtr disableCollisionsOnAttachElem = _sdf->GetElement("disable_collisions_on_attach");
+ if (!disableCollisionsOnAttachElem.get()){
+ std::cout<<"GazeboGraspFix: Using "<<DEFAULT_DISABLE_COLLISIONS_ON_ATTACH<<" because no <disable_collisions_on_attach> element specified."<<std::endl;
+ this->disableCollisionsOnAttach = DEFAULT_DISABLE_COLLISIONS_ON_ATTACH;
+ } else {
+ this->disableCollisionsOnAttach = disableCollisionsOnAttachElem->Get<bool>();
+ std::cout<<"GazeboGraspFix: Using disable_collisions_on_attach "<<this->disableCollisionsOnAttach<<std::endl;
+ }
+
+
+ this->palmLink = this->model->GetLink(handLinkElem->Get<std::string>());
+
std::vector<std::string> collisionScopedNames;
while (fingerLinkElem) {
physics::LinkPtr link = this->model->GetLink(fingerLinkElem->Get<std::string>());
//std::cout<<"Got link "<<fingerLinkElem->Get<std::string>()<<std::endl;
if (!link.get()){
- gzerr<<"Link "<<fingerLinkElem->Get<std::string>()<<" specified in Model URDF can't be found in gazebo for GazeboGraspFix model plugin. Skipping."<<std::endl;
+ std::cerr<<"ERROR: Link "<<fingerLinkElem->Get<std::string>()<<" specified in Model URDF can't be found in gazebo for GazeboGraspFix model plugin. Skipping."<<std::endl;
fingerLinkElem = fingerLinkElem->GetNextElement("gripper_link");
continue;
}
@@ -156,174 +233,205 @@ void GazeboGraspFix::Load(physics::ModelPtr _parent, sdf::ElementPtr _sdf)
}
void GazeboGraspFix::OnUpdate() {
-
- //std::cout<<"UPDATE!"<<std::endl;
-
- if (common::Time::GetWallTime() - this->prevUpdateTime < this->updateRate)
+ if ((common::Time::GetWallTime() - this->prevUpdateTime) < this->updateRate)
return;
- //first, copy all contact data into local struct. Don't do the complex grip check (checkGrip)
- //within the mutex, because that slows down OnContact().
+ // first, copy all contact data into local struct. Don't do the complex grip check (checkGrip)
+ // within the mutex, because that slows down OnContact().
this->mutexContacts.lock();
- std::map<std::string, std::map<std::string, CollidingPoint> > contPoints(contacts);
- this->contacts.clear();
+ std::map<std::string, std::map<std::string, CollidingPoint> > contPoints(this->contacts);
+ this->contacts.clear(); // clear so it can be filled anew by OnContact().
this->mutexContacts.unlock();
- //Gather all summed forces for all the objects (so we have all forces on one object).
+ // contPoints now contains CollidingPoint objects for each *object* and *link*.
+
+ // Gather all summed forces for all the objects (so we have all forces on one object).
std::map<std::string, std::vector<gazebo::math::Vector3> > appliedForces; //sorted by object name, all forces effecting on the object
std::map<std::string, std::map<std::string, CollidingPoint> >::iterator objIt;
- for (objIt=contPoints.begin(); objIt!=contPoints.end(); ++objIt){
+ for (objIt=contPoints.begin(); objIt!=contPoints.end(); ++objIt)
+ {
std::string objName=objIt->first;
//std::cout<<"Examining object collisions with "<<objName<<std::endl;
std::map<std::string, CollidingPoint>::iterator lIt;
-
+
+ // for all links colliding with this object...
std::vector<gazebo::math::Vector3> forces;
for (lIt=objIt->second.begin(); lIt!=objIt->second.end(); ++lIt){
std::string linkName=lIt->first;
CollidingPoint& collP=lIt->second;
gazebo::math::Vector3 avgForce=collP.force/collP.sum;
- //std::cout<<"Found collision with "<<linkName<<": "<<avgForce.x<<", "<<avgForce.y<<", "<<avgForce.z<<" (avg over "<<collP.sum<<")"<<std::endl;
+ // std::cout << "Found collision with "<<linkName<<": "<<avgForce.x<<", "<<avgForce.y<<", "<<avgForce.z<<" (avg over "<<collP.sum<<")"<<std::endl;
forces.push_back(avgForce);
}
appliedForces[objName]=forces;
}
-
+ // XXX TODO: We actually don't currently need this, because only one object can
+ // be attached at this stage! This must be a remnant of a previous version of the plugin,
+ // unless I'm missing something here. Leaving it in for now.
std::set<std::string> grippedObjects;
std::map<std::string, std::vector<gazebo::math::Vector3> >::iterator it;
for (it=appliedForces.begin(); it!=appliedForces.end(); ++it) {
std::string objName=it->first;
- float minAngleDiff=120 * M_PI/180;
+ float minAngleDiff= this->forcesAngleTolerance; //120 * M_PI/180;
- //std::cout<<"Number applied forces on "<<objName<<": "<<it->second.size()<<std::endl;
+ // std::cout<<"Number applied forces on "<<objName<<": "<<it->second.size()<<std::endl;
- if (checkGrip(it->second,minAngleDiff,0.3)) {
- int& counts=gripCounts[objName];
+ if (checkGrip(it->second, minAngleDiff, 0.3)) {
+ int& counts = this->gripCounts[objName];
- if (counts < max_grip_count) ++counts;
+ if (counts < this->maxGripCount) ++counts;
- //std::cout<<"GRIPPING "<<objName<<", grip count "<<counts<<" (threshold "<<grip_count_threshold<<") !!!!!!! "<<std::endl;
-
+ //std::cout<<"GRIPPING "<<objName<<", grip count "<<counts<<" (threshold "<<this->gripCountThreshold<<") !!!!!!! "<<std::endl;
- if (attached && (attachedObjName != objName)) {
- //if (counts > grip_count_threshold)
+ if (this->attached && (this->attachedObjName != objName)) {
+ //if (counts > this->gripCountThreshold)
gzwarn<<"GazeboGraspFix has found that object "<<
- attachedObjName<<" is already attached, can't grasp "<<objName<<" as well !"<<std::endl;
+ this->attachedObjName<<" is already attached, can't grasp "<<objName<<" as well !"<<std::endl;
continue;
}
- if (!attached && (counts > grip_count_threshold)) {
+ if (!this->attached && (counts > this->gripCountThreshold)) {
std::cout<<"GazeboGraspFix: Attaching "<<objName<<" !!!!!!!"<<std::endl;
//for this grip, backup the array of contact poses which played part in the grip, sorted by colliding link
- attachGripContacts[objName]=contPoints[objName];
+ this->attachGripContacts[objName]=contPoints[objName];
if (this->HandleAttach(objName)){
- attached=true;
- attachedObjName=objName;
+ this->attached=true;
+ this->attachedObjName=objName;
}
}
grippedObjects.insert(objName);
}
}
-
- //now, for all objects that are not gripped, decrease grip counter, and possibly release object.
+ // now, for all objects that are not currently gripped,
+ // decrease grip counter, and possibly release object.
std::map<std::string, int>::iterator gripCntIt;
- for (gripCntIt=gripCounts.begin(); gripCntIt!=gripCounts.end(); ++gripCntIt){
+ for (gripCntIt = this->gripCounts.begin(); gripCntIt != this->gripCounts.end(); ++gripCntIt){
std::string objName=gripCntIt->first;
- if (grippedObjects.find(objName)!=grippedObjects.end()) continue;
+ if (grippedObjects.find(objName) != grippedObjects.end())
+ { // this object is one we just detected as "gripped", so no need to check for releasing it...
+ // std::cout<<"NOT considering "<<objName<<" for detachment."<<std::endl;
+ continue;
+ }
- //std::cout<<"NOT-GRIPPING "<<objName<<", grip count "<<gripCntIt->second<<" (threshold "<<grip_count_threshold<<") !!!!!!! "<<std::endl;
+ // the object does not satisfy "gripped" criteria, so potentially has to be released.
- if (gripCntIt->second > 0) --(gripCntIt->second);
-
- if (!attached || (gripCntIt->second > grip_count_threshold)) continue;
+ //std::cout<<"NOT-GRIPPING "<<objName<<", grip count "<<gripCntIt->second<<" (threshold "<<this->gripCountThreshold<<") !!!!!!! "<<std::endl;
- //object should potentially be detached now. However, this happens too easily when just considering the count, as the fingers
- //in gazebo start wobbling as the arm moves around, and albeit they are still close to the object, the grip is not
- //detected any more. So to be sure, we will check that the collision point has not moved too far from where it originally was.
+ if (gripCntIt->second > 0) --(gripCntIt->second);
- std::map<std::string, std::map<std::string, CollidingPoint> >::iterator collIt=attachGripContacts.find(objName);
- if (collIt==attachGripContacts.end()) {
- gzerr<<"Consistency: Could not find attachGripContacts for "<<objName<<std::endl;
+ if (!this->attached || (gripCntIt->second > this->gripCountThreshold)) continue;
+
+ // std::cout<<"Considering "<<objName<<" for detachment."<<std::endl;
+
+ // Object should potentially be detached now.
+ // However, this happens too easily when just considering the count, as the fingers
+ // in gazebo start wobbling as the arm moves around, and although they are still
+ // close to the object, the grip is not detected any more. So to be sure, we will
+ // check that the collision point (the place on the link where the contact originally
+ // was detected) has not moved too far from where it originally was, relative to the object.
+
+ // get the initial set of CollidingPoints for this object
+ // note that it is enough to use the initial contact points, because the object won't
+ // have "slipped" after being attached, and the location of the original contact point
+ // on the link itself is considered as a fixed point on the link, regardless whether this
+ // point is currently still colliding with the object or not. We only want to know whether
+ // this fixed point on the link has increased in distance from the corresponding fixed
+ // point (where the contact originally happened) on the object.
+ std::map<std::string, std::map<std::string, CollidingPoint> >::iterator initCollIt=this->attachGripContacts.find(objName);
+ if (initCollIt == this->attachGripContacts.end()) {
+ std::cerr<<"ERROR: Consistency: Could not find attachGripContacts for "<<objName<<std::endl;
continue;
}
- std::map<std::string, CollidingPoint>& colls=collIt->second;
+ std::map<std::string, CollidingPoint>& initColls=initCollIt->second;
int cntRelease=0;
-
+
+ // for all links which have initially been detected to collide:
std::map<std::string, CollidingPoint>::iterator pointIt;
- for (pointIt=colls.begin(); pointIt!=colls.end(); ++pointIt) {
-
+ for (pointIt=initColls.begin(); pointIt!=initColls.end(); ++pointIt)
+ {
CollidingPoint& cpInfo=pointIt->second;
+ // initial distance from link to contact point (relative to link)
gazebo::math::Vector3 relContactPos=cpInfo.pos/cpInfo.sum;
+ // initial distance from link to object (relative to link)
gazebo::math::Vector3 relObjPos=cpInfo.objPos/cpInfo.sum;
-
+
+ // get current world pose of object
gazebo::math::Pose currObjWorldPose=cpInfo.collObj->GetLink()->GetWorldPose();
- //now, get the contact location on the collision surface in world coordinates now.
- gazebo::math::Pose currCollWorldPose=cpInfo.collLink->GetLink()->GetWorldPose();
- gazebo::math::Matrix4 worldToCollision=currCollWorldPose.rot.GetAsMatrix4();
- worldToCollision.SetTranslate(currCollWorldPose.pos);
+ // get world pose of link
+ gazebo::math::Pose currLinkWorldPose=cpInfo.collLink->GetLink()->GetWorldPose();
+
+ // Get transform for currLinkWorldPose as matrix
+ gazebo::math::Matrix4 worldToLink=currLinkWorldPose.rot.GetAsMatrix4();
+ worldToLink.SetTranslate(currLinkWorldPose.pos);
- //transform from collision link to contact point
- gazebo::math::Matrix4 collToContact=gazebo::math::Matrix4::IDENTITY;
- collToContact.SetTranslate(relContactPos);
+ // Get the transform from collision link to contact point
+ gazebo::math::Matrix4 linkToContact=gazebo::math::Matrix4::IDENTITY;
+ linkToContact.SetTranslate(relContactPos);
- //now, current world position of the contact point is:
- gazebo::math::Matrix4 _currContactWorldPose=worldToCollision*collToContact;
+ // the current world position of the contact point right now is:
+ gazebo::math::Matrix4 _currContactWorldPose=worldToLink*linkToContact;
gazebo::math::Vector3 currContactWorldPose=_currContactWorldPose.GetTranslation();
- gazebo::math::Vector3 oldObjDist=relContactPos-relObjPos;
- gazebo::math::Vector3 newObjDist=currContactWorldPose-currObjWorldPose.pos;
+ // the initial contact point location on the link should still correspond
+ // to the initial contact point location on the object.
+
+ // initial vector from object center to contact point (relative to link,
+ // because relObjPos and relContactPos are from center of link)
+ gazebo::math::Vector3 oldObjDist= relContactPos - relObjPos;
+ // the same vector as \e oldObjDist, but calculated by the current world pose
+ // of object and the current location of the initial contact location on the link.
+ gazebo::math::Vector3 newObjDist= currContactWorldPose - currObjWorldPose.pos; // new distance from contact to object
//std::cout<<"Obj Trans "<<cpInfo.collLink->GetName()<<": "<<relObjPos.x<<", "<<relObjPos.y<<", "<<relObjPos.z<<std::endl;
//std::cout<<"Cont Trans "<<cpInfo.collLink->GetName()<<": "<<relContactPos.x<<", "<<relContactPos.y<<", "<<relContactPos.z<<std::endl;
-
+
+ // the difference between these vectors should not be too large...
float diff=fabs(oldObjDist.GetLength() - newObjDist.GetLength());
//std::cout<<"Diff for link "<<cpInfo.collLink->GetName()<<": "<<diff<<std::endl;
- if (diff > release_tolerance) {
+ if (diff > releaseTolerance) {
++cntRelease;
}
}
- if (cntRelease > 0){ //sufficient links did not meet the criteria to be close enough to the object.
+ if (cntRelease > 0)
+ { // sufficient links did not meet the criteria to be close enough to the object.
std::cout<<"GazeboGraspFix: Detaching "<<objName<<" !!!!!!!"<<std::endl;
this->HandleDetach(objName);
- attached=false;
- attachedObjName="";
+ this->attached=false;
+ this->attachedObjName="";
gripCntIt->second=0;
- attachGripContacts.erase(collIt);
+ this->attachGripContacts.erase(initCollIt);
}
}
-
-
this->prevUpdateTime = common::Time::GetWallTime();
-
}
-
double angularDistance(const gazebo::math::Vector3& _v1, const gazebo::math::Vector3& _v2) {
gazebo::math::Vector3 v1=_v1;
gazebo::math::Vector3 v2=_v2;
v1.Normalize();
- v2.Normalize();
+ v2.Normalize();
return acos(v1.Dot(v2));
}
bool GazeboGraspFix::checkGrip(const std::vector<gazebo::math::Vector3>& forces, float minAngleDiff, float lengthRatio){
if (((lengthRatio > 1) || (lengthRatio < 0)) && (lengthRatio > 1e-04 && (fabs(lengthRatio-1) > 1e-04))) {
- gzerr<<"checkGrip: always specify a lengthRatio of [0..1]"<<std::endl;
+ std::cerr<<"ERROR: checkGrip: always specify a lengthRatio of [0..1]"<<std::endl;
return false;
}
if (minAngleDiff < M_PI_2){
- gzerr<<"checkGrip: min angle must be at least 90 degrees (PI/2)"<<std::endl;
+ std::cerr<<"ERROR: checkGrip: min angle must be at least 90 degrees (PI/2)"<<std::endl;
return false;
}
std::vector<gazebo::math::Vector3>::const_iterator it1, it2;
@@ -334,46 +442,52 @@ bool GazeboGraspFix::checkGrip(const std::vector<gazebo::math::Vector3>& forces,
float l1=v1.GetLength();
float l2=v2.GetLength();
if ((l1<1e-04) || (l2<1e-04)) continue;
- gazebo::math::Vector3 _v1=v1;
+ /*gazebo::math::Vector3 _v1=v1;
gazebo::math::Vector3 _v2=v2;
_v1/=l1;
_v2/=l2;
- float angle=acos(_v1.Dot(_v2));
+ float angle=acos(_v1.Dot(_v2));*/
+ float angle=angularDistance(v1, v2);
+ // std::cout<<"Angular distance between v1.len="<<v1.GetLength()<<" and v2.len="<<v2.GetLength()<<": "<<angle*180/M_PI<<std::endl;
if (angle > minAngleDiff) {
float ratio;
if (l1>l2) ratio=l2/l1;
else ratio=l1/l2;
- if (ratio >= lengthRatio) return true;
+ // std::cout<<"Got angle "<<angle<<", ratio "<<ratio<<std::endl;
+ if (ratio >= lengthRatio)
+ {
+ // std::cout<<"checkGrip() is true"<<std::endl;
+ return true;
+ }
}
}
}
+ return false;
}
-
-void GazeboGraspFix::OnContact(const ConstContactsPtr &_msg) {
-
-
+void GazeboGraspFix::OnContact(const ConstContactsPtr &_msg)
+{
//std::cout<<"CONTACT! "<<std::endl;//<<_contact<<std::endl;
+ // for all contacts...
for (int i = 0; i < _msg->contact_size(); ++i) {
physics::CollisionPtr collision1 = boost::dynamic_pointer_cast<physics::Collision>(
this->world->GetEntity(_msg->contact(i).collision1()));
physics::CollisionPtr collision2 = boost::dynamic_pointer_cast<physics::Collision>(
this->world->GetEntity(_msg->contact(i).collision2()));
- if ((collision1 && !collision1->IsStatic()) && (collision2 && !collision2->IsStatic())) {
-
+ if ((collision1 && !collision1->IsStatic()) && (collision2 && !collision2->IsStatic()))
+ {
std::string name1 = collision1->GetScopedName();
std::string name2 = collision2->GetScopedName();
-
//std::cout<<"OBJ CONTACT! "<<name1<<" / "<<name2<<std::endl;
-
int count = _msg->contact(i).position_size();
// Check to see if the contact arrays all have the same size.
if ((count != _msg->contact(i).normal_size()) ||
(count != _msg->contact(i).wrench_size()) ||
- (count != _msg->contact(i).depth_size())) {
+ (count != _msg->contact(i).depth_size()))
+ {
gzerr << "GazeboGraspFix: Contact message has invalid array sizes\n";
continue;
}
@@ -381,142 +495,167 @@ void GazeboGraspFix::OnContact(const ConstContactsPtr &_msg) {
std::string collidingObjName, collidingLink;
physics::CollisionPtr linkCollision;
physics::CollisionPtr objCollision;
+
physics::Contact contact;
contact = _msg->contact(i);
- if (contact.count<1){
- gzerr<<"GazeboGraspFix: Not enough forces given for contact of ."<<name1<<" / "<<name2<<std::endl;
+ if (contact.count<1)
+ {
+ std::cerr<<"ERROR: GazeboGraspFix: Not enough forces given for contact of ."<<name1<<" / "<<name2<<std::endl;
continue;
}
+ // all force vectors which are part of this contact
std::vector<gazebo::math::Vector3> force;
- //find out which part of the colliding objects is not the gripper
- if (this->collisions.find(name1) == this->collisions.end()) {
+ // find out which part of the colliding entities is the object, *not* the gripper,
+ // and copy all the forces applied to it into the vector 'force'.
+ if (this->collisions.find(name1) == this->collisions.end())
+ { // collision 1 is the object
collidingObjName=name1;
collidingLink=name2;
linkCollision=collision2;
objCollision=collision1;
- for (int k=0; k<contact.count; ++k) force.push_back(contact.wrench[k].body1Force);
- }else if (this->collisions.find(name2) == this->collisions.end()) {
+ for (int k=0; k<contact.count; ++k)
+ force.push_back(contact.wrench[k].body1Force);
+ }
+ else if (this->collisions.find(name2) == this->collisions.end())
+ { // collision 2 is the object
collidingObjName=name2;
collidingLink=name1;
linkCollision=collision1;
objCollision=collision2;
- for (int k=0; k<contact.count; ++k) force.push_back(contact.wrench[k].body2Force);
+ for (int k=0; k<contact.count; ++k)
+ force.push_back(contact.wrench[k].body2Force);
}
- gazebo::math::Vector3 sumForce;
- //compute sum of the body wrenches
+ gazebo::math::Vector3 avgForce;
+ // compute average/sum of the forces applied on the object
for (int k=0; k<force.size(); ++k){
- sumForce+=force[k];
+ avgForce+=force[k];
}
- sumForce/=force.size();
+ avgForce/=force.size();
gazebo::math::Vector3 avgPos;
+ // compute center point (average pose) of all the origin positions of the forces appied
for (int k=0; k<contact.count; ++k) avgPos+=contact.positions[k];
avgPos/=contact.count;
- //now, get average pose relative to the colliding link
- gazebo::math::Pose collWorldPose=linkCollision->GetLink()->GetWorldPose();
+ // now, get average pose relative to the colliding link
+ gazebo::math::Pose linkWorldPose=linkCollision->GetLink()->GetWorldPose();
- //To find out the collision point relative to the Link's local coordinate system, first get the Poses as 4x4 matrices
- gazebo::math::Matrix4 worldToCollision=collWorldPose.rot.GetAsMatrix4();
- worldToCollision.SetTranslate(collWorldPose.pos);
+ // To find out the collision point relative to the Link's local coordinate system, first get the Poses as 4x4 matrices
+ gazebo::math::Matrix4 worldToLink=linkWorldPose.rot.GetAsMatrix4();
+ worldToLink.SetTranslate(linkWorldPose.pos);
gazebo::math::Matrix4 worldToContact=gazebo::math::Matrix4::IDENTITY;
//we can assume that the contact has identity rotation because we don't care about its orientation.
//We could always set another rotation here too.
worldToContact.SetTranslate(avgPos);
-
- //now, worldToCollision * contactInLocal = worldToContact
- //hence, contactInLocal = worldToCollision.Inv * worldToContact
- gazebo::math::Matrix4 worldToCollisionInv = worldToCollision.Inverse();
- gazebo::math::Matrix4 contactInLocal = worldToCollisionInv * worldToContact;
+ // now, worldToLink * contactInLocal = worldToContact
+ // hence, contactInLocal = worldToLink.Inv * worldToContact
+ gazebo::math::Matrix4 worldToLinkInv = worldToLink.Inverse();
+ gazebo::math::Matrix4 contactInLocal = worldToLinkInv * worldToContact;
gazebo::math::Vector3 contactPosInLocal = contactInLocal.GetTranslation();
//std::cout<<"---------"<<std::endl;
//std::cout<<"CNT in loc: "<<contactPosInLocal.x<<","<<contactPosInLocal.y<<","<<contactPosInLocal.z<<std::endl;
- /*gazebo::math::Vector3 sDiff=avgPos-collWorldPose.pos;
+ /*gazebo::math::Vector3 sDiff=avgPos-linkWorldPose.pos;
std::cout<<"SIMPLE trans: "<<sDiff.x<<","<<sDiff.y<<","<<sDiff.z<<std::endl;
- std::cout<<"coll world pose: "<<collWorldPose.pos.x<<", "<<collWorldPose.pos.y<<", "<<collWorldPose.pos.z<<std::endl;
+ std::cout<<"coll world pose: "<<linkWorldPose.pos.x<<", "<<linkWorldPose.pos.y<<", "<<linkWorldPose.pos.z<<std::endl;
std::cout<<"contact avg pose: "<<avgPos.x<<", "<<avgPos.y<<", "<<avgPos.z<<std::endl;
- gazebo::math::Vector3 lX=collWorldPose.rot.GetXAxis();
- gazebo::math::Vector3 lY=collWorldPose.rot.GetYAxis();
- gazebo::math::Vector3 lZ=collWorldPose.rot.GetZAxis();
+ gazebo::math::Vector3 lX=linkWorldPose.rot.GetXAxis();
+ gazebo::math::Vector3 lY=linkWorldPose.rot.GetYAxis();
+ gazebo::math::Vector3 lZ=linkWorldPose.rot.GetZAxis();
- std::cout<<"World ori: "<<collWorldPose.rot.x<<","<<collWorldPose.rot.y<<","<<collWorldPose.rot.z<<","<<collWorldPose.rot.w<<std::endl;
+ std::cout<<"World ori: "<<linkWorldPose.rot.x<<","<<linkWorldPose.rot.y<<","<<linkWorldPose.rot.z<<","<<linkWorldPose.rot.w<<std::endl;
std::cout<<"x axis: "<<lX.x<<","<<lX.y<<","<<lX.z<<std::endl;
std::cout<<"y axis: "<<lY.x<<","<<lY.y<<","<<lY.z<<std::endl;
std::cout<<"z axis: "<<lZ.x<<","<<lZ.y<<","<<lZ.z<<std::endl;*/
- //now, get the pose of the object and compute it's relative position to the collision surface.
- gazebo::math::Pose objWorldPose=objCollision->GetLink()->GetWorldPose();
- gazebo::math::Matrix4 worldToObj=objWorldPose.rot.GetAsMatrix4();
+ // now, get the pose of the object and compute it's relative position to the collision surface.
+ gazebo::math::Pose objWorldPose = objCollision->GetLink()->GetWorldPose();
+ gazebo::math::Matrix4 worldToObj = objWorldPose.rot.GetAsMatrix4();
worldToObj.SetTranslate(objWorldPose.pos);
- gazebo::math::Matrix4 objInLocal = worldToCollisionInv * worldToObj;
+ gazebo::math::Matrix4 objInLocal = worldToLinkInv * worldToObj;
gazebo::math::Vector3 objPosInLocal = objInLocal.GetTranslation();
{
boost::mutex::scoped_lock lock(this->mutexContacts);
- CollidingPoint& p=contacts[collidingObjName][collidingLink];
+ CollidingPoint& p = this->contacts[collidingObjName][collidingLink]; // inserts new entry if doesn't exist
p.collLink=linkCollision;
p.collObj=objCollision;
- p.force+=sumForce;
+ p.force+=avgForce;
p.pos+=contactPosInLocal;
p.objPos+=objPosInLocal;
p.sum++;
}
- //std::cout<<"Average force of contact= "<<sumForce.x<<", "<<sumForce.y<<", "<<sumForce.z<<" out of "<<force.size()<<" vectors."<<std::endl;
-
+ //std::cout<<"Average force of contact= "<<avgForce.x<<", "<<avgForce.y<<", "<<avgForce.z<<" out of "<<force.size()<<" vectors."<<std::endl;
}
}
}
-bool GazeboGraspFix::HandleAttach(const std::string& objName) {
+// #define USE_MODEL_ATTACH // this only works if the object is a model in itself, which is usually not
+ // the case. Leaving this in here anyway for documentation of what has been
+ // tried, and for and later re-evaluation.
+bool GazeboGraspFix::HandleAttach(const std::string& objName)
+{
if (!this->palmLink) {
gzwarn << "palm link not found, not enforcing grasp hack!\n";
return false;
}
+#ifdef USE_MODEL_ATTACH
+ physics::ModelPtr obj = this->world->GetModel(objName);
+ if (!obj.get()){
+ std::cerr<<"ERROR: Object ModelPtr "<<objName<<" not found in world, can't attach it"<<std::endl;
+ return false;
+ }
+ gazebo::math::Pose diff = obj->GetLink()->GetWorldPose() - this->palmLink->GetWorldPose();
+ this->palmLink->AttachStaticModel(obj,diff);
+#else
physics::CollisionPtr obj = boost::dynamic_pointer_cast<physics::Collision>(this->world->GetEntity(objName));
if (!obj.get()){
- gzerr<<"Object "<<objName<<" not found in world, can't attach it"<<std::endl;
+ std::cerr<<"ERROR: Object "<<objName<<" not found in world, can't attach it"<<std::endl;
return false;
}
-
-
gazebo::math::Pose diff = obj->GetLink()->GetWorldPose() - this->palmLink->GetWorldPose();
this->fixedJoint->Load(this->palmLink,obj->GetLink(), diff);
this->fixedJoint->Init();
this->fixedJoint->SetHighStop(0, 0);
this->fixedJoint->SetLowStop(0, 0);
-
- //we should disable collisions of the grasped object, because when the fingers keep colliding with
- //it, the fingers keep wobbling, which can create difficulties when moving the arm.
- obj->GetLink()->SetCollideMode("none");
+ if (this->disableCollisionsOnAttach) {
+ // we can disable collisions of the grasped object, because when the fingers keep colliding with
+ // it, the fingers keep wobbling, which can create difficulties when moving the arm.
+ obj->GetLink()->SetCollideMode("none");
+ }
+#endif // USE_MODEL_ATTACH
return true;
}
-void GazeboGraspFix::HandleDetach(const std::string& objName){
-
+void GazeboGraspFix::HandleDetach(const std::string& objName)
+{
+#ifdef USE_MODEL_ATTACH
+ physics::ModelPtr obj = this->world->GetModel(objName);
+ if (!obj.get()){
+ std::cerr<<"ERROR: Object ModelPtr "<<objName<<" not found in world, can't detach it"<<std::endl;
+ return;
+ }
+ this->palmLink->DetachStaticModel(objName);
+#else
physics::CollisionPtr obj = boost::dynamic_pointer_cast<physics::Collision>(this->world->GetEntity(objName));
if (!obj.get()){
- gzerr<<"Object "<<objName<<" not found in world, can't attach it"<<std::endl;
+ std::cerr<<"ERROR: Object "<<objName<<" not found in world, can't attach it"<<std::endl;
return;
- }else{
+ }
+ else if (this->disableCollisionsOnAttach)
+ {
obj->GetLink()->SetCollideMode("all");
}
-
this->fixedJoint->Detach();
-
+#endif // USE_MODEL_ATTACH
}
-
-
-
-
-