Robot to glide along turning (taught) cable - suspending a pivoting display..

[thinkpix]

We imagine a servo (low power) motor to attach to a cable (carrying 15lbs max weight).  It must glide along the wire safely suspending a display beneath.  We will train the robot to follow people walking below and change direction spinning the display for about turns and so forth.  Any ideas?  has anybody seen anything like this? ?  Specifically wondering if this is actually possible and if so - need help determining the components and identifying the issues.

Something like this but simpler

[thinkpix]

We imagine a servo (low power) motor to attach to a cable (carrying 15lbs max weight).  It must glide along the wire safely suspending a display beneath.  We will train the robot to follow people walking below and change direction spinning the display for about turns and so forth.  Any ideas?  has anybody seen anything like this?  Specifically wondering if this is actually possible and if so - need help determining the components and identifying the issues.