In recent years, due to the increasing rate of elderly people in Japan, the needs to detect adults' diseases at the early stage becomes a high priority. In particular, an increased interest in detecting heart and cerebrovascular diseases at an early stage may allow clinicians to begin treatment sooner (when more treatment options are available), when interventions are generally more effective and less expensive. For this purpose, the introduction of robotic-assisted technology has advantages in terms of repetitiveness and accuracy of the measurement procedure. Therefore, at Waseda University, we have proposed the development of a carotid blood flow measurement system to support doctors while using ultrasound diagnostic equipments to detect arteriosclerosis and myocardial ischemia by measuring wave intensity. In this paper, the Waseda-Tokyo Women's Medical-Aloka Blood Flow Measurement System No. 1 Refined II (WTA-1RII) is detailed. The WTA-1RII is composed by an ultrasound diagnostic system and a probe-supporting robotic device. The robotic device is composed by a parallel link manipulator (for fine adjustment) and a passive arm (for rough positioning). The WTA-1RII has improved the design of the gravity compensation mechanism (composed by a constant force spring attached to a slide guide). In addition, a genetic algorithm has been implemented to determine the optimal link's position of the 6-DOF parallel manipulator to increase the workspace. Finally, a set of experiments were carried out to determine the usability of the proposed system.