Controlled passive walking is an approach that extends the passive walking by adapting the compliance of the joints. Natural motions can be chosen in order to obtain a controllable and energy-efficient walking motion. In this paper, actuators with online adaptable compliance are used based on the concept of controlled passive walking, to obtain adjustable step length and velocity during dynamic bipedal walking. We designed and constructed a bipedal walking robot Veronica which is actuated by the MACCEPA actuators, in which the compliance and equilibrium position can be controlled independently. In addition, a 2-D seven-link bipedal model for simulated walking of Veronica is built to analyze the relation between joint compliance and walking characteristics. Experimental results show that effective walking transitions between different walking speeds and step lengths are realized in both simulations and physical robot experiments.