The recent explosion of interest in physical system simulation may soon lead to realistic animation of passive objects, such as sliding blocks or bouncing balls. However, complex active objects (like human figures and insects) need control mechanism to direct their movements. We present a paradigm that combines the advantages of physical simulation and algorithmic specification of movement. The animator writes an algorithm to control the object and run this algorithm on physical simulator to produce the animation. Algorithms can be reused or combined to produce complex sequences of movement , eliminating the need for tedious keyframing. We have applied this paradigm to control a walking biped. The walking algorithm is presented along with the results from testing with Newton simulation system.