Chen Dianzhong, Liu Xiaowei, Zhang Haifeng, Li Hai, Weng Rui, Li Ling, Zhang Zhongzhao
MEMS Center, Harbin Institute of Technology, Harbin 150001, China.
State Key Laboratory of Urban Water Resource & Environment, Harbin Institute of Technology, Harbin 150001, China.
Micromachines (Basel). 2017 Jul 17;8(7):223. doi: 10.3390/mi8070223.
Friction between contacting surfaces of metal materials restricts the application of mechanical support in the high-precision inertial device of a rotational gyroscope. Instead, a disk- or ring-shaped rotor is electrostatically or magnetically suspended. However, stability of the rotor suspension restricts further improvement of the measurement precision. In the developed rotational gyroscope, a stable mechanical rotor supporting scheme with low friction is achieved by fabrication of a superhydrophobic surface with similar nanostructures of the lotus leaf on the carbon steel ball of the ball-disk-shaped rotor and the addition of a water film between the rotor ball and bronze hemispherical supporting bowl, which forms a water film bearing. The special design of the ball-disk-shaped rotor makes it possible for the application of a low-friction water bearing in the gyroscope, with rotor tilting motion. With a superhydrophobic surface, friction is further decreased and the rated spinning speed increases 12.4%, resulting in approximately the same proportion of increase in the scale factor. Moreover, superhydrophobic surface reduces mechanical damping torque for precessional motion to one order smaller than electrostatic feedback torque. Thus, through close-loop control, stable damping characteristics for precessional motion are obtained. The gyroscope exhibits excellent performance with the parameters of the measurement range, scale factor, nonlinearity, resolution, bias stability, and dynamic setting time tested to be -30°/s to 30°/s, -0.0985 V/(°/s), 0.43%, 0.1°/s, 0.5°/h, 0.1 s, respectively.
金属材料接触表面之间的摩擦限制了机械支撑在旋转陀螺仪高精度惯性装置中的应用。取而代之的是，盘形或环形转子通过静电或磁悬浮。然而，转子悬浮的稳定性限制了测量精度的进一步提高。在已开发的旋转陀螺仪中，通过在球盘形转子的碳钢球上制造具有类似荷叶纳米结构的超疏水表面，并在转子球和青铜半球形支撑碗之间添加水膜，形成水膜轴承，实现了一种低摩擦的稳定机械转子支撑方案。球盘形转子的特殊设计使得在陀螺仪中应用低摩擦水轴承并实现转子倾斜运动成为可能。有了超疏水表面，摩擦力进一步降低，额定旋转速度提高了12.4%，比例因子也有近似相同比例的增加。此外，超疏水表面将进动运动的机械阻尼扭矩降低到比静电反馈扭矩小一个数量级。因此，通过闭环控制，可获得进动运动的稳定阻尼特性。该陀螺仪在测量范围、比例因子、非线性、分辨率、偏置稳定性和动态设置时间等参数方面表现出色，经测试分别为-30°/s至30°/s、-0.0985 V/(°/s)、0.43%、0.1°/s、0.5°/h、0.1 s。
