Pneumatic cylinders have advantages of light weight, low heat generation, and low cost, making them potentially suit- able for coarse motion stages in large positioning systems. However, the high-precision and high-speed positioning with the pneumatic driving system has many challenges. One challenge is the dead zone, which is one of the nonlinear characteristics. The conventional dead zone compensation method using the inverse model of the valve cannot cope with the dead zone variation caused by temperature and pressure fluctuation. Furthermore, the effect of nonlinearity is strong at small flow rates near the dead zone, making flow control difficult. To solve these problems, we proposed a twin-drive system using two valves, which can control the sum and difference of mass flow rates (total flow rate and leakage). By setting the leakage of the mass flow rate, the system can be driven at an operating point with high linearity, which enables precise flow control. The interference between the two valves was decoupled by the Hadamard matrix. The experimental results show that the mass flow rate difference follows the reference value without being affected by the dead zone compared to the conventional method.

A linear motion ball guide (LMBG) has infinitesimal attitude change generated by rolling element circulation, called "waving." The waving is one of the technical issues in applying LMBG system for the ultra-precision field. Especially on the ultra-precision machine tool, the waving causes a stripe-shaped cyclic processing error on the processed surface, and this error degrades the surface quality of the workpiece. Several studies have been conducted to solve the waving problem. The first report has clarified the waving generation mechanism and the waving minimize method. The second report has clarified the influence of the rigidness of the table plate on the waving. This report has also shown the design guideline of the table plate to achieve the desired magnitude of waving. The third report has analyzed the influence of misalignments due to the machining accuracy of each part to the waving. From the analyses, although horizontal alignment influences the magnitude of waving, misalignments other four directions hardly influence the waving. This paper reported experimental results to verify these analyses. As a result, experimental results as analyses were obtained; only horizontal misalignment significantly affected waving. The theory proposed in the third report has been therefore verified.

This paper discusses the influence of Na₂SO₄-electrolytic oxidizing water (hereinafter it is referred as EO water) on the polished surface of oxygen free copper. Firstly, the Impact elucidation experiment against the polished surface of oxygen free copper, using Na₂SO₄ EO water and H₂SO₄ solution, and with or without ultrasonic, was carried out. The results showed the etching marks when immersed in Na₂SO₄ EO water are remarkable, compared to the H₂SO₄ solution, and there was almost no difference with or without the ultrasound. Next, the Impact elucidation experiment against the polished surface of oxygen free copper was also conducted after the heat treatment, was carried out. The results showed on the surface of the test piece after the immersion treatment, protrusions are generated when immersed into H₂SO₄ solution, but almost no protrusions are generated when immersed into the N₂SO₄ EO water. Lastly, the cause of protrusions was clarified by the verification experiments. By this study, we received the suggestion that a surface of oxygen free copper with higher accuracy can be obtained.