Abstract: Adaptive gyroscope bias compensation allows a vehicle navigation module to estimate position and velocity reliably during temperature changes.

Abstract: Adaptive gyroscope bias compensation allows a vehicle navigation module to estimate position and velocity reliably during temperature changes.

Abstract: A navigation system and method to utilize the internal geometry of the sensor position with respect to the vehicle's rear-wheel axis for maintaining high positioning accuracy even when GPS signals are lost for a long period of time are disclosed. One aspect is to use an analytical condition derived from a vehicle's mechanical condition so-called Ackermann Steering Geometry for enhancement in navigation accuracy. The analytical condition is a relationship between the vehicle's lateral directional velocity, the distance of the sensor position with respect to the rear wheel axis, and the angular rate with respect to the vehicle's z-axis. Another aspect is to incorporate the distance of the sensor position with respect to the rear wheel axis into the INS and Kalman filter's states as an auxiliary parameter.

Abstract: A position sensing device and method are provided for executing correction processing based on a reliability and error index of each component of GPS output data to increase positioning accuracy.

Abstract: A navigation system and method to utilize the internal geometry of the sensor position with respect to the vehicle's rear-wheel axis for maintaining high positioning accuracy even when GPS signals are lost for a long period of time are disclosed. One aspect is to use an analytical condition derived from a vehicle's mechanical condition so-called Ackermann Steering Geometry for enhancement in navigation accuracy. The analytical condition is a relationship between the vehicle's lateral directional velocity, the distance of the sensor position with respect to the rear wheel axis, and the angular rate with respect to the vehicle's z-axis. Another aspect is to incorporate the distance of the sensor position with respect to the rear wheel axis into the INS and Kalman filter's states as an auxiliary parameter.

Abstract: A system with a capability of detecting the platform stationary status is disclosed. The first aspect is to measure three raw acceleration outputs from an apparatus of the three-axis accelerometer unit. The second aspect is to compute the mean of the latest said acceleration outputs obtained from the three-axis accelerometer unit. The third aspect is to subtract the said mean acceleration outputs from the said raw acceleration outputs obtained from the three axis accelerometer unit to find the differential acceleration components between raw and mean values. The fourth aspect is to compute the amplitude of the differential acceleration, i.e., squared total sum of the three differential acceleration components. The fifth aspect is to count the number of measurements in which the amplitude of the differential acceleration is below a certain threshold, e.g., 0.05 (m/s2) to detect the stationary status if the small amplitude lasts for a certain time length, e.g., 1 second.

Abstract: A computational scheme for an INS which utilizes micro-electro mechanical systems (MEMS) sensors resolves issues of unnecessarily large computational burden and numerical instability which happen in using conventional methods using high-end inertial sensors. The first aspect is to omit computing Earth radii of curvatures that were used in a high-frequency application. The second aspect is to ignore the Earth rotation and the rotation of the local tangent plane with respect to Earth which are much smaller than noise and bias in the MEMS sensor output. The last aspect is to assume that the absolute amount of the platform pitch and roll angles is less than 90 degrees. According to the aspects noted above, the computational load will be one-fourth of the conventional method without degradation of accuracy.

Abstract: A navigation system with a capability of estimating positions of the platform vehicle and recognized landmarks using satellite information and camera measurements is disclosed. One aspect is to represent a landmark by one or few representative features by executing image recognition and feature extraction to find representative features inside the recognized landmark. Another aspect is to re-identify the recognized landmarks in the landmark database correlating the landmark attributes obtained by image recognition and mathematical feature characteristics obtained by feature extraction with the corresponding data in the landmark database. A further aspect is to enhance navigation accuracy through the Kalman filter architecture with additional imagery measurements of landmarks whose positions are known or previously estimated.

Abstract: A system with a capability of detecting the platform stationary status is disclosed. The first aspect is to measure three raw acceleration outputs from an apparatus of the three-axis accelerometer unit. The second aspect is to compute the mean of the latest said acceleration outputs obtained from the three-axis accelerometer unit. The third aspect is to subtract the said mean acceleration outputs from the said raw acceleration outputs obtained from the three axis accelerometer unit to find the differential acceleration components between raw and mean values. The fourth aspect is to compute the amplitude of the differential acceleration, i.e., squared total sum of the three differential acceleration components. The fifth aspect is to count the number of measurements in which the amplitude of the differential acceleration is below a certain threshold, e.g., 0.05 (m/s2) to detect the stationary status if the small amplitude lasts for a certain time length, e.g., 1 second.

Abstract: A navigation system with a capability of estimating positions of the platform vehicle and recognized landmarks using satellite information and camera measurements is disclosed. One aspect is to represent a landmark by one or few representative features by executing image recognition and feature extraction to find representative features inside the recognized landmark. Another aspect is to re-identify the recognized landmarks in the landmark database correlating the landmark attributes obtained by image recognition and mathematical feature characteristics obtained by feature extraction with the corresponding data in the landmark database. A further aspect is to enhance navigation accuracy through the Kalman filter architecture with additional imagery measurements of landmarks whose positions are known or previously estimated.

Abstract: A method of GPS accuracy adjustment for an integrated INS/GPS navigation system which utilizes microelectro mechanical systems (MEMS) based inertial sensors to mitigate multipath problems arising when a vehicle is in an area with many high-rise buildings is disclosed. Even when GPS measurement output values are deviated from that expected, the INS/GPS navigation system uses as many measurement outliers as possible without discarding, unless they are obvious error values, thereby maintaining a practical level of accuracy. The measurement outliers typically occur when the integrated INS/GPS navigation system receives GPS signals which have transmitted through multipaths such as reflection by buildings, since the signal path lengths vary.

Abstract: A navigation system with a capability of receiving positioning aiding signals from other users is disclosed. The first aspect is to serve both roles of mobile GPS receiver and mobile GPS station by receiving signals from positioning reference sources and transmitting out the estimated position. The second aspect is to receive other users' position estimates information and to measure distances from other users in the positioning aiding purpose. According to the aspects noted above: (1) the users will have much better chances in finding positioning aiding signals than conventional differential GPS receivers; (2) the more users exist, the better positioning accuracy is obtained; (3) without building local stations, ubiquitous positioning aiding signals are available.

Abstract: A computational scheme for an INS which utilizes micro-electro mechanical systems (MEMS) sensors is disclosed resolving issues of unnecessarily large computational burden and numerical instability which happen in using conventional methods using high-end inertial sensors. The first aspect to reduce computational burden in MEMS application is to omit computing Earth radii of curvatures that were used in a high-frequency application. The second aspect is to ignore the Earth rotation and the rotation of the local tangent plane with respect to Earth in the computation which are much smaller than noise and bias in the MEMS sensor output. The last aspect is to assume that the absolute amount of the platform pitch and roll angles is less than 90 degrees. This assumption results in only four parameters required to track in the direction cosine matrix describing the transformation from the local tangent plane to the platform where all the nine elements are tacked in the conventional method.

Abstract: A method of updating the position and orientation of a vehicle at startup of a navigation system using both a GPS receiver and a dead reckoning sensor includes the acts of storing the vehicle position and orientation when the navigation system is inoperative and setting the stored vehicle position and orientation as the initial vehicle position and orientation when the navigation system is operative; estimating a vehicle position and orientation by using a signal output from the dead reckoning sensor and the initial vehicle position and orientation after the navigation system becomes operative; determining whether the reliability of a GPS orientation obtained by the GPS receiver becomes sufficiently high after the navigation system becomes operative; and updating the current vehicle position by using the GPS orientation and the estimated vehicle position when the reliability of the GPS orientation obtained by the GPS receiver becomes sufficiently high.

Abstract: A position sensing device and method are provided for executing correction processing based on a reliability and error index of each component of GPS output data to increase positioning accuracy.

Abstract: A dead reckoning unit calculates vehicle position from a pitch angle and a yaw angle of dead reckoning sensors, a sensor installation pitch angle and a sensor installation yaw angle, and a moving distance calculated by a speed sensor, and calculates vehicle speed from an acceleration signal. On a first cycle, a first correction unit calculates the vehicle speed from signals output from the speed sensor, and corrects the pitch angle, the sensor installation pitch angle, and the sensor installation yaw angle, based on the difference between the thus calculated vehicle speed and the vehicle speed calculated by the dead reckoning unit. On a second cycle, a second correction unit corrects the pitch angle, the sensor installation pitch angle, the yaw angle, and the sensor installation yaw angle, by using vehicle position and speed output from a GPS receiver and vehicle position and speed output from the dead reckoning unit.

Abstract: A method of GPS accuracy adjustment for an integrated INS/GPS navigation system which utilizes microelectro mechanical systems (MEMS) based inertial sensors to mitigate multipath problems arising when a vehicle is in an area with many high-rise buildings is disclosed. Even when GPS measurement output values are deviated from that expected, the INS/GPS navigation system uses as many measurement outliers as possible without discarding, unless they are obvious error values. The measurement outliers occur when the integrated INS/GPS navigation system receives GPS signals which have transmitted through multipaths such as reflection by buildings, since the signal path lengths vary. Even in such a condition, rather than simply discarding such measurement outliers, the method utilizes the measurement outliers while adjusting the accuracy thereof depending on the degree of deviation.

Abstract: A method of compensating performance of low-cost MEMS (microelectro mechanical systems) inertial sensors in an integrated INS/GPS navigation system for automotive application is disclosed. The proposed method includes velocity and inertial sensor output conditions featured in ground vehicle dynamics. Using the conventional Kalman filter based INS/GPS system, implementation of the prescribed conditions in the present invention additionally to the GPS measurements shows accurate motion tracking even when GPS signal dropouts last for more than 2 minutes. Another aspect of the disclosure is an integrated INS/GPS navigation system which utilizes MEMS based inertial sensors for maintaining high position tracking accuracy even when a GPS signal is lost or unavailable for a long period of time by incorporating the predefined vehicle dynamics conditions when calculating optimum estimates through the Kalman filtering process.