This work addresses the problem of real-time self-collision detection for a movable tensegrity structure. We show that it can be tackled as the collision detection between two generic cylinders moving in R3. It is a simplified version of the more general problem of dynamic collision detection between two general shaped rigid bodies in the space. Two algorithms are proposed. The first presented approach is based on the exact value of the distance between two cylinders, the second is based on a new theorem which allows to estimate the exact distance for a given maximum desired error. In some circumstances, the second approach can be preferred because faster.