An integrated approach to the concurrent design of arm structure and control is presented. To achieve high-speed positioning, a technique is developed in which comprehensive design parameters describing arm link geometry, actuator locations, and feedback gains are optimized with respect to the settling time of the system. First, a two-link, nonrigid arm is analyzed, and a simple dynamic model representing rapid positioning processes is obtained. A PD (proportional plus derivative) control system is designed for the dynamic model. Optimal feedback gains minimizing the settling time are obtained as functions of structural parameters involved in the dynamic model. The structural parameters are then optimized by using an optimization technique in order to obtain an overall optimal performance. The resultant arm design shows an outstanding performance, which is otherwise unattainable if one designs the structure and control separately.