Interactive human motion control using a closed-form of direct and inverse dynamics

We propose the use of inverse dynamics in a closed form with direct dynamics for interactive motion control of a human skeleton. An efficient recursive algorithm based on Newton-Euler formulae is used to calculate the force and torque produced by a joint actuator in order to fulfill a desired motion. The resulting force and torque are then used in direct dynamics to make the final motion with external force and torque. The Armstrong-Green algorithm is used for direct dynamic simulation. To decrease the errors in numerical integration, we use the fourth order Runge-Kutta method instead of the Euler method. Inverse dynamic functions calculate the required force and torque at every small time interval in the process of direct dynamic simulation. In this way, it will correct errors at each time interval. The direct and inverse dynamic functions are integrated in the software, TRACK, with direct and inverse kinematics functions that provide a more powerful method for human animation