Sorry you are right!!
I have done that, the problem is that the detection is not quite robust. I am adding the code that I am using, just for u to have an idea.
I am doing all this when I receive a msgs of laser data from gazebo, this is a callback, is it too much code for a callback??
In the function safety_manager->is_state_safe I am just calculating the distance between the new robot s state given by a runge kutta integrator and each of the point of the laser, previously transformed to the global frame ("/map"). Has someone done this in a more efficient way??
Thanks !!!
Nicolas
void Kernel::Callback(const sensor_msgs::LaserScan::ConstPtr& cloudlaser){
try{
tlistener.waitForTransform("/map", cloudlaser->header.frame_id,
cloudlaser->header.stamp, ros::Duration(1.0));
tlistener.lookupTransform("/map", cloudlaser->header.frame_id,
cloudlaser->header.stamp, lasertransform);
pcl::transformAsMatrix(lasertransform, mat);
}
catch (tf::TransformException ex){
ROS_ERROR("%s",ex.what());
}
projector_.transformLaserScanToPointCloud(cloudlaser->header.frame_id,*cloudlaser, cloud,tlistener);
sensor_msgs::convertPointCloudToPointCloud2(cloud, cloud2);
pcl::transformPointCloud(mat, cloud2, pc_toPcl);
pcl::fromROSMsg(pc_toPcl, laser_fchecker);
double dist_states=0,best_avg=0;
if (start_callback) {
pose2d_t robot_pose = ros_link->get_robot_pose();
start_state.pose = robot_pose;
start_state.vel.front = start_state.vel.ang = 0.0;
actual_state=start_state;
current_act.acc.front = 0;
current_act.acc.ang = 0;
start_callback=false;
}
if ((current_act.acc.front==0) && ( current_act.acc.ang==0)){
pose2d_t robot_pose = ros_link->get_robot_pose();
start_state.pose = robot_pose;
start_state.vel.front = start_state.vel.ang = 0.0;
actual_state=start_state;
current_act.acc.front = 0;
current_act.acc.ang = 0;
}
Action control, best_control;
bool aux=false;
metric_t best_result = 0;
for(double fv = -0.8; fv <= 0.8; fv += 0.2){
for(double av =-0.75; av <= 0.75; av += 0.25){
control.acc.front = fv;
control.acc.ang = av;
if ((control.acc.front == current_act.acc.front) && (control.acc.ang == current_act.acc.ang))
continue;
new_state = integrator->integrate(actual_state, control);
if (!safety_manager->is_state_safe(actual_state, new_state, &laser_fchecker)){ // PICS checker and Mapcheker
ROS_INFO("State_No_Safe:\n");
aux=false;
continue;
}
else
aux=true;
best_state = new_state;
best_control.acc.front =control.acc.front ;
best_control.acc.ang=control.acc.ang;
best_control.end_pose=new_state.pose;
}
}
if (!aux){
best_control.acc.front= best_control.acc.ang=0;
best_control.end_pose=actual_state.pose;
best_state=actual_state;
}
vel2d_t cmd_vel;
pose2d_t robot_pose;
ros::Rate loop_rate(250);
current_act= best_control;
robot_pose = ros_link->get_robot_pose();
cmd_vel = calculate_control(current_act, robot_pose);
ros_link->send_cmd_vel(cmd_vel);
actual_state=best_state;
}
where :
bool Safety_Manager::is_state_safe (Phase_State state1, Phase_State state2, pcl::PointCloud<pcl::PointXYZ>* pts_laser){
robot_r = 1;
double dist_obstacles, dist_states,dist_obstacles1;
dist_states = dist2d(state1.pose, state2.pose);
int size_cloud=pts_laser->points.size();
for(int it=0; it<size_cloud; it++){
dist_obstacles=sqrt(pow(pts_laser->points[it].x-state2.pose.x,2)+pow(pts_laser->points[it].y-state2.pose.y,2)); //distancia entre 2 muestras consecutivas
if(dist_obstacles <= 1) {// quiero decir si el centro de mi robot esta a mas de la distancia del r significa q esta en un estado a seguro!!! y 4 metros es el mx alcance de mi laser
return false;
}
}
return true;
}
Date: Tue, 18 Jan 2011 09:33:13 -0800
From:
bhaskara@willowgarage.com
To:
ros-users@code.ros.org
Subject: Re: [ros-users] Obstacles Detection with laser data
Hi Nicolas, it's hard to diagnose this without more surrounding context and an explanation of what exactly 'not working well' means. But one possibility might be that pts_laser and state2.pose are not in the same coordinate frame. Have you used tf to transform the point cloud into the global frame?
- Bhaskara
2011/1/18 Nicolás Alvarez Picco <
nicolasapicco@hotmail.com>
Hi Everybody!!
I want to detect objects, but just their position to avoid them with the laser data. So I am using these lines:
for(int it=0; it<size_cloud; it++){
dist_obstacles=sqrt(pow(pts_laser->points[it].x-state2.pose.x,2)+pow(pts_laser->points[it].y-state2.pose.y,2)); //distancia entre 2 muestras consecutivas
if(dist_obstacles <= robot_r) {// quiero decir si el centro de mi robot esta a mas de la distancia del r significa q esta en un estado a seguro!!! y 4 metros es el mx alcance de mi laser
return false;
}
}
where pts_laser is a pcl_pointcloud and the state2 give me the future position of the robot.
So it is a checker, if there is a point which is closer to the robot than the radius of the robot, so that state is unsafe.
This thing is not working well. So do you have a better solution or an idea??
Thanks
Nicolas
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--
Bhaskara Marthi
Research Scientist
Willow Garage Inc.
650-475-2856
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