Hello everybody,

I want to move a link of my robot using SetPosition.

I have several joints :

• body -> left_arm (prismatic joints)
• body -> right_arm (prismatic joints)
  
• body -> bottom (fixed joints)
• bottom -> left_wheel (continuous
  joints)
• bottom -> right_wheel (continuous
  joints)

I have made some changes in the same diff drive plugin. The continuous joints with SetParam("vel",...) work fine. But when I do a SetPosition on an arm joint, the value is also sent to the wheel joints.

Is there a simple way to move a link on a prismatic joint with a model plugin ?

Update :

How I get the joints in Load function :

 joints_.resize ( 2 );
joints_[LEFT] = gazebo_ros_->getJoint ( parent, "leftJoint", "left_joint" );
joints_[RIGHT] = gazebo_ros_->getJoint ( parent, "rightJoint", "right_joint" );
joints_right_arm_ = gazebo_ros_->getJoint ( parent, "rightArmJoint", "body_right_arm_prismatic" );

with joints a vector of physics::JointPtr and jointsrightarm_ a physics::JointPtr.

How i send command :

joints_[LEFT]->SetParam("vel", 0, wheel_speed_[LEFT]/ ( wheel_diameter_ / 2.0 ));
joints_[RIGHT]->SetParam("vel", 0, wheel_speed_[RIGHT]/ ( wheel_diameter_ / 2.0 ));
joints_right_arm_->SetPosition( 0, right_arm_pos_);

Update 2:

I still have this problem. When I comment SetPosition (arm not controlled) wheels can reach a speed of 2m/s. When SetPosition is not commented, wheels only reach a position of 0.6 m/s.

I have seen on other posts that a high effort on a joint can be transmitted to another links. So I tried to play with damping params but without success.

I also tried to tune fmax param but without success. Is there other parameters that I had to set to make the wheels respect the sent velocity ?

Thanks in advance.