Reviews on Various Inertial Measurement Unit (IMU) Sensor Applications Norhafizan Ahmad, Raja Ariffin Raja Ghazilla, and Nazirah M. Khairi Center of Product Design and Manufacturing, Dept. Of Mech. Eng., University of Malaya, Kuala Lumpur, Malaysia Email: {norhafizan, r_ariffin}@um.edu.my, nazirahmkhairi@gmail.com Vijayabaskar Kasi Dept. Of Electrical Engineering, University of Malaya, Kuala Lumpur, Malaysia Email: sebpeterkasi@gmail.com Abstract— Inertial Measurement Unit (IMU) sensors are used widely in many different movable applications. Across many years, the improvements and applications of IMU have increased through various areas such as manufacturing, navigation, and robotics. This paper presents a literature review of several current IMU categories and applications. A few considerations on choosing an IMU for different applications are summarized and current methods being used to improve the accuracy of the output from IMU are also presented to avoid the errors that latest IMU is facing. Improvement methods include the control algorithms and type of filters for the sensor. Pros and cons of the types and algorithms used are also discussed in relation to different applications. Index Terms— gyroscope, magnetometer, accelerometer, IMU I. INTRODUCTION History of IMU began in 1930s where it was used in aircraft navigation [1] and large devices. Because of its constraints mainly in size, cost, and power consumption, IMU usage at that time is restricted to bulk application and thus, unpopular to smaller size devices and consumer applications. Until recently, micro-electromechanical system (MEMS) IMU is introduced with a very attractive feature of low cost, compact, and low processing power [2]. The demand increases then exponentially to wider area of usage. Currently, a lot of manufacturers are competing on the best IMU designs such as Invensense, Honeywell, STMicroelectronics, Microstrain, and X-Sens. The current environment requires us to be more and more advanced in sensory system apart from the human natural sensors. Many people demand to know more information on their current position and movements to work better and more efficient. Recent trends of people bringing their own small electronic devices such as smart phones, GPS devices, and portable radios also have increased the demand of position sensors to determine their position live and update to the third party at the same time. The usage of IMU has been applied widely to determine their movements in terms of acceleration, angular velocity, and rotation [3]. Manuscript received August 18, 2013; revised November 18, 2013. This paper introduces briefly about the current technology of IMU sensors, explains the considerations for choosing an appropriate IMU, review several IMU applications in various areas, and finally discuss the major reasons for choosing proper IMU types. II. IMU TECHNOLOGIES IMU is mainly used in devices to measure velocity, orientation, and gravitational force. It can be divided into two; the earlier technology consists of two types of sensors accelerometers and gyroscopes. The accelerometer is used to measure the inertial acceleration. While gyroscope on the other hand, measures angular rotation. Both sensors typically have three degree of freedom to measure from three axes. Later, IMU technology has advanced with another sensor type – magnetometer. Magnetometer measures the bearing magnetic direction, thus it can improve the reading of gyroscope. The benefit of magnetometer will be described in this section later. A. IMU with Two Sensor Types This type of IMU consists of accelerometer and gyroscope. Typically each sensor has between two to three degrees of freedom defined for x, y, and z-axis, which combining both sensors will total up four to six DOF. Acceleration values obtained from accelerometer and angular velocity from gyros are kept separately. Angles can be measured from both sensors, thus both data can be calibrated as shown in Fig. 1 to get more accurate output data. Figure 1. IMU based on two types of sensors The advantage of using this type of IMU is that it will not be interfered by external magnetic field around the International Journal of Signal Processing Systems Vol. 1, No. 2 December 2013 256 ©2013 Engineering and Technology Publishing doi: 10.12720/ijsps.1.2.256-262