## playerstage-users

 [Playerstage-users] PatrolBot with player From: Alberto Valero - 2008-10-16 16:11:36 Attachments: robot_params.cc ```Hi all, We have generated the robot_params.cc for p2os (enclosed in this mail in case anyone wants it). We have found the following things that seem strange: -Linear speed cannot be lesser than 0.01 m/s (We can understand this) -If linear speed is 0.0 m/s it only parse rotation commands greater than 0.65 deg/sec -If linear speed is greater than 0.01 m/s it parse all rotational commands (deg/sec). So, it is not possible to set low jogs (<6.5 deg/sec) when there is no linear speed. Is this normal?? Please, some advice will help. Alberto. ```
 Re: [Playerstage-users] PatrolBot with player From: Brian Gerkey - 2008-10-16 16:34:08 ```On Oct 16, 2008, at 9:11 AM, Alberto Valero wrote: > We have generated the robot_params.cc for p2os (enclosed in this > mail in > case anyone wants it). We have found the following things that seem > strange: > > -Linear speed cannot be lesser than 0.01 m/s (We can understand this) > -If linear speed is 0.0 m/s it only parse rotation commands greater > than > 0.65 deg/sec > -If linear speed is greater than 0.01 m/s it parse all rotational > commands (deg/sec). > > So, it is not possible to set low jogs (<6.5 deg/sec) when there is no > linear speed. Is this normal?? I'm not familiar with the PatrolBot, but I would believe that when the robot is sitting still, a small desired rotational velocity produces a PWM motor command that's not sufficient to overcome the static friction of the wheels and make the robot move. This would not be a problem when the robot is already moving. brian. ```
 Re: [Playerstage-users] PatrolBot with player From: Alberto Valero - 2008-10-17 13:48:32 ```> I'm not familiar with the PatrolBot, but I would believe that when the > robot is sitting still, a small desired rotational velocity produces a > PWM motor command that's not sufficient to overcome the static > friction of the wheels and make the robot move. This would not be a > problem when the robot is already moving. > > brian. > We have used directly the ARIA libraries for commanding the PatrolBot and we have had no problem setting the jog to 1 deg/sec. There must be something related with the p2os. Do you have any idea on how to solve it, otherwise we will have to build our own servers, and that's our last choice, as all our software has been already tested and works properly with plather (and P2AT). Alberto. > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Playerstage-users mailing list > Playerstage-users@... > https://lists.sourceforge.net/lists/listinfo/playerstage-users ```
 Re: [Playerstage-users] PatrolBot with player From: Brian Gerkey - 2008-10-17 16:29:09 ```On Oct 17, 2008, at 6:48 AM, Alberto Valero wrote: > >> I'm not familiar with the PatrolBot, but I would believe that when >> the >> robot is sitting still, a small desired rotational velocity >> produces a >> PWM motor command that's not sufficient to overcome the static >> friction of the wheels and make the robot move. This would not be a >> problem when the robot is already moving. >> > We have used directly the ARIA libraries for commanding the PatrolBot > and we have had no problem setting the jog to 1 deg/sec. There must be > something related with the p2os. Something to try: add this line to the p2os block of your .cfg file: direct_wheel_vel_control 0 By default the driver converts your desired (vx,vyaw) to left and right wheel velocities, then sends the wheel velocities to the robot. Setting direct_wheel_vel_control to 0 will make the driver send (vx,vyaw) directly to the robot. The two velocity representations should be equivalent, but a different command is used to issue each one, and perhaps the robot interprets them differently. The default is to convert to wheel velocities because a pair of wheel velocities can be sent as one command, whereas (vx,vyaw) takes two commands, yielding a lower effective control rate. Other p2os parameters that you can play with are in the docs: http://playerstage.sourceforge.net/doc/Player-2.1.0/player/group__driver__p2os.html brian. ```