In an embodiment, a distance measuring device comprises an absolute distance measuring module, a tracking module, a two-axis rotating mechanism and a signal controlling and processing module to track an object and measure a distance between the distance measuring device and the object. The absolute distance measuring module measures an absolute distance between the distance measuring device and the object. The absolute distance measuring module and the tracking module are combined by using a dichroic beam splitter, and then all of them are further disposed in the two-axis rotating mechanism. When the object moves, a tracking optical path changes accordingly. A quadrant photodetector of the absolute distance measuring module detects the changes to avoid the distance measuring optical path being interrupted, and generates and transmits the signal to the signal controlling and processing module for controlling the two-axis rotating mechanism to rotate, thereby tracking the object.

In an embodiment, a distance measuring device comprises an absolute distance measuring module, a tracking module, a two-axis rotating mechanism and a signal controlling and processing module to track an object and measure a distance between the distance measuring device and the object. The absolute distance measuring module measures an absolute distance between the distance measuring device and the object. The absolute distance measuring module and the tracking module are combined by using a dichroic beam splitter, and then all of them are further disposed in the two-axis rotating mechanism. When the object moves, a tracking optical path changes accordingly. A quadrant photodetector of the absolute distance measuring module detects the changes to avoid the distance measuring optical path being interrupted, and generates and transmits the signal to the signal controlling and processing module for controlling the two-axis rotating mechanism to rotate, thereby tracking the object.

A tracking device broadcasts beacon signals that are separated in time by broadcast intervals. The tracking device determines the broadcast intervals based on a behavior model. The behavior model specifies one or more conditions, such as times of day within a 24-hour day, and associates a usage probability with each condition. A higher usage probability causes the tracking device to broadcast beacon signals at shorter broadcast intervals. A mobile device in communication with the tracking device can reconfigure the behavior model, either by modifying portions of the behavior model or by replacing the behavior model with a different behavior model. This allows the behavior model to adapt to different circumstances, such as different usage patterns during weekdays, weekends, and vacations.

A tracking device broadcasts beacon signals that are separated in time by broadcast intervals. The tracking device determines the broadcast intervals based on a behavior model. The behavior model specifies one or more conditions, such as times of day within a 24-hour day, and associates a usage probability with each condition. A higher usage probability causes the tracking device to broadcast beacon signals at shorter broadcast intervals. A mobile device in communication with the tracking device can reconfigure the behavior model, either by modifying portions of the behavior model or by replacing the behavior model with a different behavior model. This allows the behavior model to adapt to different circumstances, such as different usage patterns during weekdays, weekends, and vacations.

The present invention relates to a simple and effective system and method for measuring camera based tracker system accuracy, especially for a helmet-mounted tracker system, utilizing Coordinate Measuring Machine (CMM). The method comprises the steps of; computing spatial relation between tracked object and calibration pattern using CMM; computing relation between reference camera and tracker camera; computing relation between reference camera and calibration pattern; computing ground truth relation between tracker camera and tracked object; obtaining actual tracker system results; comparing these results with the ground truth relations and finding accuracy of the tracker system; recording accuracy results; testing if the accuracy results is a new calculation required. The system comprises; a reference camera; a calibration pattern visible by reference camera; a camera spatial relation computation unit; a relative spatial relation computation unit a memory unit; a spatial relation comparison unit.

Provided is a method for controlling an ultrasonic motor to reduce noise sounding during low-speed rotation in a surveying instrument adopting the ultrasonic motor for a rotary shaft, and a surveying instrument for the same. In a method for controlling an ultrasonic motor according to an aspect of the present invention, in a low-speed rotation range of an ultrasonic motor, a ratio of an acceleration period as a time of application of the drive signal in a control cycle is controlled, and a time to start the acceleration period is randomly shifted for each control cycle. In a method for controlling an ultrasonic motor according to another aspect, a time to start the acceleration period is regularly shifted for each control cycle. In a method for controlling an ultrasonic motor according to still another aspect, second-half acceleration control and first-half acceleration control are alternately repeated.

Provided is a method for controlling an ultrasonic motor to reduce noise sounding during low-speed rotation in a surveying instrument adopting the ultrasonic motor for a rotary shaft, and a surveying instrument for the same. In a method for controlling an ultrasonic motor according to an aspect of the present invention, in a low-speed rotation range of an ultrasonic motor, a ratio of an acceleration period as a time of application of the drive signal in a control cycle is controlled, and a time to start the acceleration period is randomly shifted for each control cycle. In a method for controlling an ultrasonic motor according to another aspect, a time to start the acceleration period is regularly shifted for each control cycle. In a method for controlling an ultrasonic motor according to still another aspect, second-half acceleration control and first-half acceleration control are alternately repeated.

Embodiments of the present invention relate to the field of video monitoring and provide a method, an apparatus, and a system for acquiring a visual angle, so as to acquire an accurate visual angle value. The method for acquiring a visual angle includes: receiving, by a central processing unit CPU of a camera, angle information that is sent by an accelerometer sensor arranged on the camera; converting, by the CPU, the received angle information to a visual angle value; sending, by the CPU, the visual angle value to a server, so that a client receives the visual angle value forwarded by the server. The embodiments of the present invention are applicable to a video monitoring scenario.

Embodiments of the present invention relate to the field of video monitoring and provide a method, an apparatus, and a system for acquiring a visual angle, so as to acquire an accurate visual angle value. The method for acquiring a visual angle includes: receiving, by a central processing unit CPU of a camera, angle information that is sent by an accelerometer sensor arranged on the camera; converting, by the CPU, the received angle information to a visual angle value; sending, by the CPU, the visual angle value to a server, so that a client receives the visual angle value forwarded by the server. The embodiments of the present invention are applicable to a video monitoring scenario.

A moving-object position/attitude estimation apparatus includes: an image-capturing unit configured to acquire a captured image; a comparative image acquiring unit configured to acquire a comparative image viewed from a predetermined position at a predetermined attitude angle; a likelihood setting unit configured to compare the captured image with the comparative image and to assigns a high attitude angle likelihood to the comparative image and to assigns a high position likelihood to the comparative image; a moving-object position/attitude estimation unit configured to estimate the attitude angle of the moving object based on the attitude angle of the comparative image assigned the high attitude angle likelihood and to estimate the position of the moving object based on the position of the comparative image assigned the high position likelihood.