From: ahoward <ah...@us...> - 2003-08-31 17:09:09
|
Hi Pranav: There are a couple of basic things I would try: - Make sure the wheel speeds are being set to non-zero values in the SetParam() call. Note that the angle rates are calculated during the ODE update step, so you will need sustained velocity values to achieve non-zero angle rates. - Check the ODE documentation on the Hinge2Joint to see if there are implied joint limits (which may prevent your joint from turning). The FMax value may also be relevant here, but I'm not sure whether or not it needs to be set every time the model is updated. If this all looks good, one trick I have used in the past is to put the robot body "on blocks". Literally: place the robot body on a box so that the wheels are free to turn, then send commands to the robot. If your tires are like the ones on the P2AT, you should see the wheels turning (on the P2AT, I added visible boxes inside the cylinders for this exact purpose). Once you get the wheels turning here, you can put the robot back on the ground and start playing with ODE friction, suspension and fudge factors to make it move in the right way. A. P.S. I have cc'ed the mailing list with this one, since it will be nice to have this stuff archived. On Sun, 31 Aug 2003, Pranav U. Srivastava wrote: > For some reason the robot doesnt want to move!. I m using Hinge2 instead > of Hinge in your Pioneer2AT model and a few changes to the mass and > height.I set the velocity using the dParamVel option ( it should > set rotational velocity of the first axis for steering ) and dParamVel2 > for rotational velocity of the wheels..). I printed out Angle rates for > both axis after setting .. they both seem to be 0. do i need to set the > dParamFMax parameter everytime i set speeds?? > > havent tried the joystick option yet. > > Thanks > p > > On Sat, 30 Aug 2003, ahoward wrote: > > > > > On Sat, 30 Aug 2003, Pranav U. Srivastava wrote: > > > > > I just wrote up out ClodBuster Model for gazebo based on ur model for the > > > Pioneer2AT. it registers with gazebo and when i run gazebo with the CB as > > > part of the world , it shows up too. > > > > Sweet! > > > > > howver, when i run player / playerv > > > and try to command the position , i get this error : > > > > > > playerv: error in dev_position.c > > > libplayerc error: got NACK from request > > > > > > Any idea what i might have over looked ? > > > > Can you give me a bit more context for the error message? I would be > > surprised if you *didnt* get this message when you start playerv (due to a > > known bug in Player's gz_position driver). You should only see it at > > start-up, however, and then everything should run ok. > > > > Hmm, I suspect that your model is actually working: try selecting the > > "position:command" menu option, then drag the red cross-hairs to make the > > robot move. You can also try the playerjoy utility to drive the robot > > around with a joystick or keyboard (much more intuitive than the playerv > > interface). > > > > A. > > > > > > > > Andrew Howard email: ah...@po... > > Department of Computer Science http: www-robotics.usc.edu/~ahoward > > University of Southern California phone: 1 (213) 740 6416 > > Los Angeles, CA, U.S.A. 90089-0781 fax: 1 (213) 821 5696 > > << Insert pithy saying here >>> > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > |----------------------------------------| > | Pranav Srivastava | > | Graduate Student,ESE, U PENN | > |----------------------------------------| > Andrew Howard email: ah...@po... Department of Computer Science http: www-robotics.usc.edu/~ahoward University of Southern California phone: 1 (213) 740 6416 Los Angeles, CA, U.S.A. 90089-0781 fax: 1 (213) 821 5696 << Insert pithy saying here >>> |
From: Pranav U. S. <pr...@se...> - 2003-09-02 20:16:03
|
Andrew, The ClodBuster model works! , had the axis of the hinge 2 joint messed up. Thanks for your help. Is it possible to CVS in the model and the other changes? planning to write up a blimp model as well, any ideas on how i could hold it up in the air with a camera onboard? Also, is it possible to just use the rendering engine and the actual dynamics provided for by the ode? i mean just use it as a 3-D sim and provide all the v,w updates ourselves? Thanks p |----------------------------------------| | Pranav Srivastava | | Graduate Student,ESE, U PENN | |----------------------------------------| On Sun, 31 Aug 2003, ahoward wrote: > > Hi Pranav: > > There are a couple of basic things I would try: > > - Make sure the wheel speeds are being set to non-zero values in the > SetParam() call. Note that the angle rates are calculated during the > ODE update step, so you will need sustained velocity values to achieve > non-zero angle rates. > > - Check the ODE documentation on the Hinge2Joint to see if there are > implied joint limits (which may prevent your joint from turning). The > FMax value may also be relevant here, but I'm not sure whether or not > it needs to be set every time the model is updated. > > If this all looks good, one trick I have used in the past is to put the > robot body "on blocks". Literally: place the robot body on a box so that > the wheels are free to turn, then send commands to the robot. If your > tires are like the ones on the P2AT, you should see the wheels turning (on > the P2AT, I added visible boxes inside the cylinders for this exact > purpose). Once you get the wheels turning here, you can put the robot > back on the ground and start playing with ODE friction, suspension and > fudge factors to make it move in the right way. > > A. > > P.S. I have cc'ed the mailing list with this one, since it will be nice to > have this stuff archived. > > > > On Sun, 31 Aug 2003, Pranav U. Srivastava wrote: > > > For some reason the robot doesnt want to move!. I m using Hinge2 instead > > of Hinge in your Pioneer2AT model and a few changes to the mass and > > height.I set the velocity using the dParamVel option ( it should > > set rotational velocity of the first axis for steering ) and dParamVel2 > > for rotational velocity of the wheels..). I printed out Angle rates for > > both axis after setting .. they both seem to be 0. do i need to set the > > dParamFMax parameter everytime i set speeds?? > > > > havent tried the joystick option yet. > > > > Thanks > > p > > > > On Sat, 30 Aug 2003, ahoward wrote: > > > > > > > > On Sat, 30 Aug 2003, Pranav U. Srivastava wrote: > > > > > > > I just wrote up out ClodBuster Model for gazebo based on ur model for the > > > > Pioneer2AT. it registers with gazebo and when i run gazebo with the CB as > > > > part of the world , it shows up too. > > > > > > Sweet! > > > > > > > howver, when i run player / playerv > > > > and try to command the position , i get this error : > > > > > > > > playerv: error in dev_position.c > > > > libplayerc error: got NACK from request > > > > > > > > Any idea what i might have over looked ? > > > > > > Can you give me a bit more context for the error message? I would be > > > surprised if you *didnt* get this message when you start playerv (due to a > > > known bug in Player's gz_position driver). You should only see it at > > > start-up, however, and then everything should run ok. > > > > > > Hmm, I suspect that your model is actually working: try selecting the > > > "position:command" menu option, then drag the red cross-hairs to make the > > > robot move. You can also try the playerjoy utility to drive the robot > > > around with a joystick or keyboard (much more intuitive than the playerv > > > interface). > > > > > > A. > > > > > > > > > > > > Andrew Howard email: ah...@po... > > > Department of Computer Science http: www-robotics.usc.edu/~ahoward > > > University of Southern California phone: 1 (213) 740 6416 > > > Los Angeles, CA, U.S.A. 90089-0781 fax: 1 (213) 821 5696 > > > << Insert pithy saying here >>> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > |----------------------------------------| > > | Pranav Srivastava | > > | Graduate Student,ESE, U PENN | > > |----------------------------------------| > > > > Andrew Howard email: ah...@po... > Department of Computer Science http: www-robotics.usc.edu/~ahoward > University of Southern California phone: 1 (213) 740 6416 > Los Angeles, CA, U.S.A. 90089-0781 fax: 1 (213) 821 5696 > << Insert pithy saying here >>> > > > > > > > > > > > > > |
From: ahoward <ah...@us...> - 2003-09-02 23:08:56
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On Tue, 2 Sep 2003, Pranav U. Srivastava wrote: > The ClodBuster model works! , had the axis of the hinge 2 joint messed up. > Thanks for your help. Is it possible to CVS in the model and the other > changes? That's fantastic. Yes, please send me the files so I can patch them into the main CVS tree. If you have a SourceForge login, I can also add you to the developer list so that you have full CVS access in future. > planning to write up a blimp model as well, any ideas on how i could hold > it up in the air with a camera onboard? While I havent tried it yet, I've been toying with the idea of making some flying models using ODE's dBodyAddForce*() family of functions. For your blimp, you can add a basic bouyancy force for the lifting envelope, and then additional forces for each of the propellors. I *think* it should be possible to do a reasonably good job simulating still-air conditions. Like I said, however, I havent tried this yet... > Also, is it possible to just use the rendering engine and the actual > dynamics provided for by the ode? i mean just use it as a 3-D sim and > provide all the v,w updates ourselves? Not sure exactly what you mean by this. Do you not want to use the Player interface, or do you not want to use the ODE dynamics? Both are possible: the former by using the libgazebo interface (documented in the manual), the latter by overwriting ODE's pose updates (somewhat hacky). A. Andrew Howard email: ah...@po... Department of Computer Science http: www-robotics.usc.edu/~ahoward University of Southern California phone: 1 (213) 740 6416 Los Angeles, CA, U.S.A. 90089-0781 fax: 1 (213) 821 5696 << Insert pithy saying here >>> |