Manual motion can cause unexpected motion on startup

[dmcconachie]

When manual motion starts, if the robot's current joints are beyond the soft limit set by manual_motion.py, then the first time that the target positions get updated, the robot can move very abruptly. This will only happen when something is adding extra force to the arm. So for example:

1. Robot current joints are near a joint limit
2. manual_motion.py is run, robot does not move
3. Human moves arm enough to trigger setpoint update
4. New setpoint is at soft joint limits (30 degress away from current position)
5. Robot moves abruptly in unexpected direction

[bsaund]

What behavior do you want in this situation? Brainstormingj:

1. verbal + text warning that sudden motion could occur
2. on startup, manual_motions slowly moves inside limits
3. soft limits are set on startup as extrema(hardcoded soft limits, startup position)
4. Set soft limits as in 3, but dynamically shrink as robot is pushed away from limtis

[dmcconachie]

I like option 4 among the options here. I don't see any downside to it at all.