Real-time Virtual Cables based on Kinematic Simulation

We present an algorithm for the real-time simulation of virtual cables using inverse kinematics. A cable is modeled by consecutive cylinder segments of equal size. The segments are connected by ball joints. At every joint there is a spiral spring acting against the excursion of the joint. Given a start and an end position of the cable, the algorithm calculates the shape of the cable that leads to minimal total energy. The total energy is the sum of the potential energies of the segments and the elastic energies of the springs. First, the algorithm calculates a cable with minimal total energy consisting of two segments. This is taken as a starting basis for the computation of a cable consisting of four segments. At each following step, the number of segments is doubled and a new shape of the cable is calculated based on the solution of the previous step. The great advantage of this approach is the easy accommodation of the solution exactness to the available computation time. If the user of the VR application is moving the cable, he/she gets a fast but rough feedbaIf. If he/she stops moving it, he/she gets an exact shape.