The use of the dynamics equations of motion offers a means of constraining animated motion to physical reality.Dynamic simulation treats objects as masses acting under the influence of forces and torques. Motion is derived by solving the dynamics equations of motion, rather than being exactly specified by an animator. Though dynamic simulation can create complex motion with less user input than strictlykinematic (Position-based) methods, it is also computationally expensive and difficult to control. The equations of motion are, in themselves, not difficult to program, but adding constraints for controlled motion is complex. The control issues are now being further explored. These include: low-level control issues such as collision response, elasticity, friction, joint limits, damping, and general motion constraints; user-interface issues such as interface design, menu options, and integration into a general animation system; and high-level control issues such as the automatic generation of coordinated, goal-directed motion. This paper concentrates on the first two of these areas, and describes an animation system,Kaya, developed to explore them.