Hi, I've opened a ticket for this issue https://kforge.ros.org/gazebo/trac/ticket/24 Please feel free to update the ticket. Thanks, <https://kforge.ros.org/gazebo/trac/ticket/24>John
On Tue, Mar 29, 2011 at 7:25 AM, Peter Nordin <peter.nor...@liu.se> wrote: > Hello > > Unfortunately I do not think that I can help you, but I am having a > similar problem. > > I am have been trying to use the IMU sensor, (I have added a few missing > player interface related files), but in my case the acceleration is > allways zero. Anyway I was not able to figure out why so I made some > minor additions to the gazebo code and differentiated the linear > velocity between each timestep. This way the reported acceleration will > be the actual velocity derivative. The problem is that I wont get > g=-9.81 in my output. This is OK in my ground robot case as I usually > just remove the gravity component anyway. For flying robots I do not not > know if this is Ok. > > I tried adding an additional "artificial" gravity vector (rotated into > the curent body coordinate system) but realised that when the robot was > moving along the Z-axis (very rarely), I would get double acceleration. > -9.81 as well as the actual velocity derivative (-9.81 when free > falling). I the end I removed the artificial gravity vector, as I actual > have no real use for it. > > It is probably possible to solve this in some smart way but I have not > had time to try and figure one out. > > I am using a fairly recent Gazebo svn version and player 3.0.2 > > /Peter > > > On 03/28/2011 05:26 PM, Neostek wrote: > > Hello everyone, > > i'm using Gazebo to simulate a PD controller on a quadrotor UAV. > > The control evalueates the force and torque to apply to the quadrotor and > > then i use the methods > > dBodyAddRelForce(body_id, 0, 0, thrust) and dBodyAddRelTorque(body_id, > > roll_torque, pitch_torque, 0). > > Now i would like to get information about position, velocity and > > acceleration of the quadrotor. > > To do so, i use the methods: > > body->GetPosition() > > body->GetLinearVel() > > body->GetLinearAccel() > > and the last one appears to give practically nonsense results (gravity > > acceleration depending on the mass for instance...). > > Browsing into the code i found out that GetLinearAccel() simply does > > return this->GetForce() / this->GetMass(); > > That is " F = m*a " as it should be. > > Anyway the controller works and the quadrotor get still on the target > point, > > but the acceleration i get on the z axis is positive (e.g. = 19.6) even > > though the quadrotor is not varying its height. > > I really have no point...please help me! :) > > Thanks in advance. > > > > Marco > > > > > > For the sake of completeness i'm using the following software version: > > Gazebo - 0.9.0 > > Player - 2.1.3 > > > ------------------------------------------------------------------------------ > Enable your software for Intel(R) Active Management Technology to meet the > growing manageability and security demands of your customers. Businesses > are taking advantage of Intel(R) vPro (TM) technology - will your software > be a part of the solution? Download the Intel(R) Manageability Checker > today! http://p.sf.net/sfu/intel-dev2devmar > _______________________________________________ > Playerstage-gazebo mailing list > Playerstage-gazebo@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo > ------------------------------------------------------------------------------ Enable your software for Intel(R) Active Management Technology to meet the growing manageability and security demands of your customers. Businesses are taking advantage of Intel(R) vPro (TM) technology - will your software be a part of the solution? Download the Intel(R) Manageability Checker today! http://p.sf.net/sfu/intel-dev2devmar _______________________________________________ Playerstage-gazebo mailing list Playerstage-gazebo@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo
