Small lift jumps when changing mode

[hello-binit]

When a command is sent that changes the mode the lift stepper is in, you'll occasionally see a small jump. For example, the following script can sometimes cause a jump to appear:

import stretch_body.robot
r = stretch_body.robot.Robot()
r.startup()

# This can cause the small jump
r.lift.motor.enable_safety()
r.push_command()

# This can also cause the small jump
r.lift.move_to(0.3)
r.push_command()

# So can this
r.lift.motor.enable_pos_traj_waypoint()
r.push_command()

Turn the volume up to hear the jumps in these videos:

• Video 1: Changing from MODE_SAFETY to MODE_POS_TRAJ
• Video 2: Changing from MODE_POS_TRAJ TO MODE_POS_TRAJ_WAYPOINT