A Water hydraulic Fluid Switching Transmission (FST) has many merits such as lower environmental load and lower energy loss. Especially, when combined with energy recovery, its energy efficiency can be improved considerably. In this research, the feasibility of a FST system was examined: in the first report, the rotational velocity control performance and kinematic energy regeneration were discussed. As a result, it was shown from experimental results that the error rate during a constant phase was within 5 percent and the recovered energy during a deceleration phase was more than 30 percent of the kinetic energy of the rotating load.
In this paper, the design simulator of the FST system was evaluated. First, a mathematical model of water hydraulic FST was derived in order to examine the rotational velocity control performance. Then the simulated system behaviors were compared with the experimental results. Since the results showed good agreement, the validity of the proposed mathematical model was confirmed. Moreover, the effects of design parameters of a FST system were also examined using the simulator.

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The purpose of this study is to evaluate tele-robotic force perception using auditory feedback, which is based on a master-slave control system for a hydraulic construction robot tele-operation. The system consists of two joysticks, which control the boom, arm, swing and grapple's movement of the construction robot. During tele-operation, operators need to feel a realistic sense of task force brought about by a feedback force from the grapple. The force is detected by using hydraulic pressure sensors, which are easily influenced by cylinders' frictions and cyclic loading effects. The effects create difficulties for the operators to detect small changes within the reaction force, which influence their performance in grasping task. To improve operators' performance, we propose a solution by compensating the insufficient master-slave force feedback information with auditory feedback. Sonification method is used for mapping force gain to sound tempo. The results are observed in the driving force, and analyzed by using gripping risk index, task completion time and subjective workload, under various cases of feedback interfaces and different types of materials. We conclude that the presence of auditory feedback has the potential to improve force perception, and thus operators' performance in construction robot teleoperation.

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This paper proposes a base parameter identification method for hydraulic arms. First, the state-space equation of hydraulic arms is converted into a linear equation with respect to base parameters which are a set of unknown parameters such as the flow coefficient, the pipeline volume and the internal leakage coefficient. Second, a new parameter identification method is proposed based on the linear equation. Finally, the validity of the proposed method is confirmed via the model validation using an actual arm. By the proposed method, not only the arm position, but also the pressures of the actual arm are close to those of the nonlinear model which is constructed from the identified parameters. Especially, a characteristic response of the actual pressures is also generated by the nonlinear model.

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