摘要:
Methods and apparatus for accelerometer autocalibration in a mobile device are provided. In an example, a signal is received from the accelerometer. A substantially constant state of the signal, such as that caused by a freefall of the accelerometer, is detected. When the signal remains in the substantially constant state for at least a predetermined period of time, the signal's noise level is measured. A compensating signal based upon the measured noise level is determined and can be output to the accelerometer, thus compensating the accelerometer to mitigate the noise level. In examples, the compensating signal can be a reference voltage, a reference frequency, and/or a reference pulse train. In a further example, the compensating is performed only when the noise level of the signal is within a range for at least the predetermined period of time.
摘要:
Methods and apparatus for detecting, measuring, and/or mitigating effects of moving an inertial navigation device's cradle are provided. In an example, provided are methods and apparatus to mitigate cradle rotation-induced inertial navigation errors. In an example, a method for mitigating an inertial navigation error includes receiving inertial sensor data and processing the inertial sensor data with a first navigation algorithm having a non-holonomic constraint (NHC). A second navigation algorithm, lacking a NHC, also processes the inertial sensor data simultaneously with the first algorithm. A cradle rotation is detected by the second navigation algorithm. A first navigation algorithm result, produced from the inertial sensor data generated during the cradle rotation, is discarded. The first algorithm can be computationally realigned, based on a second navigation algorithm result produced from the inertial sensor data generated during the cradle rotation.
摘要:
An apparatus and method for efficient and concurrent sampling of a sensor signal to create multiple output signals each at different sampling rates is provided. The apparatus and method determine an aperiodic sampling rate or sampling schedule such that only samples representing samples at the different sampling rates are taken. The aperiodic samples are taken then de-interleaved to filter wanted samples for a particular application or user. As a result, the aperiodic samples is just a combination of all of the subsets to each application. Such aperiodic sampling reduces a total number of samples taken and, as a direct result, reduces the number of samples needing to be processed and stored and also reduced the power otherwise consumed to sample, process and store unused samples.
摘要:
Apparatus and methods for calibrating dynamic parameters of a vehicle navigation system are presented. One method may include determining whether reference position data of a vehicle is available, and measuring composite accelerations of the vehicle. The method may further include generating distance and turn angle data based upon a wheel speed sensors data, computing distance and turn angle errors based upon the independent position data, and associating the distance and turn angle errors with composite accelerations. A second method presented includes calibrating an inertial navigation sensor within a vehicle navigation system. The second method may include determining reference position data and Inertial Navigation System (INS) data, aligning an IMU with the vehicle, and aligning the IMU with an Earth fixed coordinate system. The second method may further include computing the vehicle alignment with respect to a horizontal plane, and determining calibration parameters for distance sensors associated with the vehicle.
摘要:
An apparatus and method for providing an improved heading estimate of a mobile device in a vehicle is presented. First, the mobile device determines if it is mounted in a cradle attached to the vehicle; if so, inertia sensor data may be valid. While in a mounted stated, the mobile device determines whether it has been rotated in the cradle; if so, inertia sensor data may no longer be reliable and a recalibration to determine a new relative orientation between the vehicle and the mobile device is needed. If the mobile device is mounted and not recently rotated, heading data from multiple sensors (e.g., GPS, gyroscope, accelerometer) may be computed and combined to form the improved heading estimate. This improved heading estimate may be used to form an improved velocity estimate. The improved heading estimate may also be used to compute a bias to correct a gyroscope.
摘要:
Provided are methods and apparatus for improving motion sensing. In an example, provided is a method of mitigating an error in a motion sensor signal in a mobile device. A user input signal, based on a user input to the mobile device, is received. The user input can be a keystroke, and the user input signal can be a signal resulting from the keystroke. The user input signal triggers performing a function on a motion sensor signal for a period of time. The motion sensor signal can be an output from an accelerometer and/or a gyroscope. The period of time can be based on the duration of the user input signal, and can be in a range between substantially 100 milliseconds to substantially 700 milliseconds.
摘要:
Provided are methods and apparatus for improving motion sensing. In an example, provided is a method of mitigating an error in a motion sensor signal in a mobile device. A user input signal, based on a user input to the mobile device, is received. The user input can be a keystroke, and the user input signal can be a signal resulting from the keystroke. The user input signal triggers performing a function on a motion sensor signal for a period of time. The motion sensor signal can be an output from an accelerometer and/or a gyroscope. The period of time can be based on the duration of the user input signal, and can be in a range between substantially 100 milliseconds to substantially 700 milliseconds.
摘要:
Systems and methods are described for measuring orientation of sensors associated with a mobile device with respect to pedestrian motion of a user of the mobile device. An example technique described herein includes obtaining acceleration information associated with the mobile device, partitioning the acceleration information according to respective detected pedestrian steps of the user, identifying a forward motion direction of the user of the mobile device based on the acceleration information and the detected pedestrian steps, and computing a misalignment angle between the forward motion direction of the user of the mobile device and an orientation of the mobile device.
摘要:
An apparatus and method for efficient and concurrent sampling of a sensor signal to create multiple output signals each at different sampling rates is provided. The apparatus and method determine an aperiodic sampling rate or sampling schedule such that only samples representing samples at the different sampling rates are taken. The aperiodic samples are taken then de-interleaved to filter wanted samples for a particular application or user. As a result, the aperiodic samples is just a combination of all of the subsets to each application. Such aperiodic sampling reduces a total number of samples taken and, as a direct result, reduces the number of samples needing to be processed and stored and also reduced the power otherwise consumed to sample, process and store unused samples.