Description

By Following the tutorial of jog_arm with current moveit master branch (ad88e18) and then publishing twists with 1 and -1 in y axis, the robot gets high angular twists as well.
Depending on the chosen robot (ur like in tutorial or prbt) there are different rotations in size and magnitude.

for example, achieved with jogging only linear y axis!

Your environment

• ROS Distro: Melodic
• OS Version: Ubuntu 18.04
• Source build
• ad88e18

Steps to reproduce

1. Run the steps of the ReadMe
2. Move to a position that is not near a singularity.
3. Send delta_jogs for a linear axis for example by using a script like the following:

    delta_jog_cmds_publisher = rospy.Publisher("jog_server/delta_jog_cmds", TwistStamped, queue_size=10)
    rospy.sleep(1)
    for i in range(10):
        for p in range(100):
            delta_jog_cmds_publisher.publish(TwistStamped(header=Header(stamp=rospy.Time.now()),
                                                          twist=Twist(linear=Vector3(y=1))))
            rospy.sleep(.01)
        for m in range(100):
            delta_jog_cmds_publisher.publish(TwistStamped(header=Header(stamp=rospy.Time.now()),
                                                          twist=Twist(linear=Vector3(y=-1))))
            rospy.sleep(.01)

Expected behaviour

robot moves on y axis and ends somewhere near the starting position, without rotating the tcp

Actual behaviour

unexpected rotations and movements increasing over the time

Comment

Its hard to believe, a bug like this has gone unnoticed, so if you can not reproduce this, please tell me. I tested it on a second PC with newly setup environment, still maybe there is something that i missed here.