inverse kinematics in ur_driver is not accurate
I am trying to use the inverse kinematics (IK) solver in ur_driver for my UR5 robot. My goal is to move the robot to a target joint position given a set of robot TCP pose/end-effector pose. However, there is always a small error (about 1mm) in each x/y/z axis after positioning. So I did this quick test for the ur_driver as follows.
1 First, position robot using movegroup.
map<string, double> jointPose;
jointPos["shoulder_pan_joint"] = -0.9217;
jointPos["shoulder_lift_joint"] = -1.5935;
jointPos["elbow_joint"] = 2.236;
jointPos["wrist_1_joint"] = -0.4291;
jointPos["wrist_2_joint"] = 0.2916;
jointPos["wrist_3_joint"] = 0.7746;
move_group.setPoseTarget(another_pose);
move_group.move();
2. Second, record robot tool0 pose as shown in RViz, result as follows.
[position(m),orientation(quaternion)] = [0.33561, -0.13135, 0.1815, 0.64684, 0.33476, 0.68078, 0.077926].
3. Third, position robot with URScript movej() command, record robot tool pose as shown on the polyscope.
[position(m),orientation(rxryrz)] = [0.33667,-0.13125,0.18217,0.7471,-1.4515,-0.1768]
As I can see, there is a slight position difference in each x/y/z direction. So my assumption is the IK solution given by ur_driver is not precise.
I have compared the DH parameters in the driver to that given by [1]. They seem to be the same.
Does anyone know how to compute the accurate IK solution for UR robot? I appreciate any help and insight that could potentially solve the problem.
