Title: Smart MEMS Sensors for Robot Applications
Abstract: A lot of sensors are used in robots for smart factory automation, self-supported life of elderly people, automatic driving etc. Sensors, especially multi-axis sensors, often need a lot of wires as well as additional readout, data processing and control ICs, which makes the installation of the sensors difficult in a limited inner space of robots. Our sensor platform LSI provides a solution to this problem. The LSI has functions of capacitive and resistive sensor readout, data processing, digital bus communication, configuration etc., and thus a lot of (e.g. a hundred of) different sensors can be connected to the same bus line. In addition, the LSI works in an event driven manner, and thus the first response of the sensors is fast regardless of the number of the sensors connected, which is useful for tactile sensing application, for example. To achieve a smaller form factor and better performance, we have also developed 3-axis tactile sensors directly integrated with the sensor platform LSI at wafer level. Novel via technology has enabled surface-mountable chip-scale packaging. The second topic is a high-performance MEMS gyroscope, which is necessary for the dead reckoning of robots and automated cars. For example, SLAM (simultaneous localization and mapping) is possible using a LIDAR (light detection and ranging) and an IMU (inertial measurement unit), but the existing IMU for this use is too expensive for many applications. We have developed a new controller for whole angle and frequency modulation (FM) modes of gyroscopes, and combined it with a mode-matched MEMS ring resonator. The MEMS gyroscope showed very high accuracy of angle (e.g. two order of magnitude smaller error of angle) and excellent stability of scale factor (+/-26 ppm uncertainty over 50 K temperature change without any compensation).