Indirect control of the forces of constraint in dynamic systems

In this paper two problems are investigated; how to control a dynamic system such that holonomic constraints are maintained and further the forces of constraint are a priori specified. Two cases of the latter are considered: constant forces of constraint and forces that are functions of the state. The dynamic system is linearized about an operating point and linear feedback is exploited for the solution of both problems. A methodology for computing the feedback gains is developed and applied to a nonhuman biped model that possesses ankle torques in the frontal plane. Simula-tion results are carried out for the nonlinear biped model to maintain the vertical force of constraint constant under the foot. Applications to locking of joints in natural biological systems is noted.