Three Dimensional Gait Analysis Using Wearable Acceleration and Gyro Sensors Based on Quaternion Calculations

Abstract

This paper proposes a method for three dimensional gait analysis using wearable sensors and quaternion calculations. Seven sensor units consisting of a tri-axial acceleration and gyro sensors, were fixed to the lower limbs. The acceleration and angular velocity data of each sensor unit were measured during level walking. The initial orientations of the sensor units were estimated using acceleration data during upright standing position and the angular displacements were estimated afterwards using angular velocity data during gait. Here, an algorithm based on quaternion calculation was implemented for orientation estimation of the sensor units. The orientations of the sensor units were converted to the orientations of the body segments by a rotation matrix obtained from a calibration trial. Body segment orientations were then used for constructing a three dimensional wire frame animation of the volunteers during the gait. Gait analysis was conducted on five volunteers, and results were compared with those from a camera-based motion analysis system. Comparisons were made for the joint trajectory in the horizontal and sagittal plane. The average RMSE and correlation coefficient (CC) were 10.14 deg and 0.98, 7.88 deg and 0.97, 9.75 deg and 0.78 for the hip, knee and ankle flexion angles, respectively.

An IMU-to-Body Alignment Method Applied to Human Gait Analysis

“…However, those approaches suffer from some limitations. One main problem with algorithms based only on data from accelerometers and gyroscopes [11,13,23,24] is the difficulty to define a common reference frame and, consequently, measure 3D angles. To accurately measure 3D angles, a second global reference axis is necessary along with the gravity vector.…”

“…This second reference axis is commonly the magnetic field vector, measured by sensor units that include magnetometers. Since heading drift remains a problem within systems that involve only accelerometers and gyroscopes, the anatomical calibration techniques that use such systems rely on predefined user movements to define the axis of joint motion [11], or use supplementary devices such as cameras [24], anatomical landmark pointers [12] or exoskeleton harnesses [13]. The need for these additional tools also increases the experiment duration and requires experienced personnel, which may be impractical in daily clinical routine.…”

Design of a Wireless Sensor Module for Monitoring Conductor Galloping of Transmission Lines

“…Conductor galloping involving various voltage levels of transmission lines occurs frequently around the world [1,2,3,4]. It is considered as a self-excited vibration of low frequency and large amplitude caused by non-uniform icing and strong winds.…”

“…It is considered as a self-excited vibration of low frequency and large amplitude caused by non-uniform icing and strong winds. The damages produced by conductor galloping may manifest in many ways, e.g., deformation of tower cross-arms, flashovers between conductors, and even tower collapse [4,5,6,7], as shown in Figure 1.…”

“…In the past decades, with continuous improvement of theoretical galloping models, sensor technology and communication technology, the monitoring technology of conductor galloping is developing rapidly, e.g., image/video surveillance [4,5,6,7,11], and acceleration sensor monitoring methods [7,11,12]. Although the image/video surveillance method is more intuitive, the conductors are often too long to be observed using video or image, especially since the device may swing when conductors vibrate sharply.…”