Question: How do I find inverse kinematics of cable-driven robot arm?

Hi, I have a cable driven robot arm consist of three joint and four links driven by cables from three pulleys. Each joint conneted to each pulley by cables independently. When I use inverse kinematic steps in maple I get these messages :

MB := zModel:-GetMultibody('simplify' = true):
                     "Analyzing system..."

              "Performing constraint analysis..."

"The system has 6 degree(s) of freedom.  It is modeled using 6 

   generalized coordinate(s) coupled by 0 algebraic constraint(s\

  )."

the problem is that I have six Generalized coordinates (3 joints + 3 pulleys) , I can find the inverse kinamatic of joint angles according to end effector position , the question is:
how can I apply it to pulley's angle?