This paper investigates the performance of impedance control utilizing an inner loop PI torque controller. Stiffness and damping shaping vary within a specified range of values. The impedance control problem is formulated taking into account a specified range of stiffness and damping parameters. The analysis and design is carried out in discrete time. Stability, passivity, impedance emulation as well as disturbance (friction/torque ripple) attenuation properties are discussed. The controller is evaluated on a series elastic actuator and some experimental results are presented.