1626 results about "Gravitational acceleration" patented technology

The invention discloses a machine vision and inertial navigation fusion-based mobile robot motion attitude estimation method which comprises the following steps of: synchronously acquiring a mobile robot binocular camera image and triaxial inertial navigation data; distilling front / back frame image characteristics and matching estimation motion attitude; computing a pitch angle and a roll angle by inertial navigation; building a kalman filter model to estimate to fuse vision and inertial navigation attitude; adaptively adjusting a filter parameter according to estimation variance; and carrying out accumulated dead reckoning of attitude correction. According to the method, a real-time expanding kalman filter attitude estimation model is provided, the combination of inertial navigation and gravity acceleration direction is taken as supplement, three-direction attitude estimation of a visual speedometer is decoupled, and the accumulated error of the attitude estimation is corrected; and the filter parameter is adjusted by fuzzy logic according to motion state, the self-adaptive filtering estimation is realized, the influence of acceleration noise is reduced, and the positioning precision and robustness of the visual speedometer is effectively improved.

A compact navigation system for a rover is provided. The navigation system includes a housing configured to be transported by the rover; a gimbal system having two or more gimbals that includes at least an outer gimbal connected to the housing and an inner gimbal nested in and connected to the outer gimbal; a solid state three-axis gyro assembly mounted on the inner gimbal; a solid state three-axis accelerometer assembly mounted on the inner gimbal; a gyro logic circuit responsive to the three-axis gyro assembly for producing an inertial angular rate about each gyro input axis; an accelerometer logic circuit responsive to the three-axis accelerometer assembly for producing a non-gravitational acceleration along each accelerometer input axis; and a processor responsive to the gyro logic circuits and the accelerometer logic circuits for determining the attitude and the position of the housing to provide for long term accuracy of the attitude and the position for navigation of the rover.

A method of and system for detecting absolute acceleration along various axes relative to a desired movement vector while moving relative to a gravity source includes steps of determining a vertical acceleration, perpendicular to the desired movement vector and substantially anti-parallel to a gravitational acceleration due to the gravity source; determining a longitudinal acceleration, parallel to the desired movement vector and to output at vertical acceleration signal and a longitudinal acceleration signal; determining an inclination of the desired movement vector relative to the gravitational acceleration; and processing the vertical acceleration signal, the longitudinal acceleration signal, and the inclination signal to produce an absolute vertical acceleration signal and an absolute longitudinal acceleration signal.

The invention provides an unscented Kalman filter-based method for tracking an inertial pose according to acceleration compensation, which is used for an inertial measurement unit integrating a three-axis micro-gyroscope, a three-axis micro-accelerometer and a three-axis magnetoresistive sensor, and realizes pose tracking estimation on a device carrier by using rotary angular velocity vectors, acceleration vectors and magnetic field sensor vectors which are detected by the device by means of filter technology. The method comprises the following steps: 1) treating the acceleration vectors as combination of the acceleration vectors and gravity acceleration vectors of the device carrier self, and constructing observation equations respectively for amplitude and normalized direction vectors of the acceleration vectors and the gravity acceleration vectors; 2) describing quaternion, accumulated error vectors of the gyroscope and the acceleration vectors of the device carrier self by using the pose to construct a system state vector; and 3) realizing a filter estimating process of the system by using the unscented Kalman filter technology because of nonlinearity of the observation equations. Compared with the conventional method ignoring the acceleration of the carrier self, the method not only can provide a more accurate estimation result, but also widens the application range of the system.

A method for determining a position change of a handheld tool in space includes: alignment of an initial tool position with a reference position to determine at least a first position vector of the tool, at least one component of the first position vector being determined by measurement of a component of the gravitational acceleration in the direction of a predetermined axis of the tool;establishing a modification of the tool position during an actual position change by determining at least one angular discrepancy of a second position vector of at least one temporally preceding position vector, at least one component of the second position vector being determined after the position change by measuring the component of the gravitational acceleration in the direction of the predetermined axis of the tool; and providing information relating to the orientation of the tool established from the at least one angular discrepancy.

The invention relates to a human sleep monitoring method and system. The method and system synthesizes motion, heart rate and body temperature signals. The system comprises a core processor, a reflective type photoelectric pulse sensor, a temperature sensor, a three-axis gravity acceleration sensor and a capacitive skin contact sensor which are respectively used for measuring heart rate in real time, measuring body surface temperature in real time, detecting motion state in real time, and performing wearing identification. The human sleep monitoring system has the advantages that by synthesizing human body sign information and motion states, the system can automatically monitor the sleep state and the waking state of a user and can identify different sleep stages including shallow sleep, deep sleep and rapid-eye-movement sleep; the system further comprises a display module and a miniature motor vibrating module which are used for displaying specific sleep information and awakening the user on the basis of sleep quality; the problems that an existing sleep monitoring device cannot naturally awaken the user at an appropriate time, physical and mental health of the user is affected, and the existing sleep monitoring device is inconvenient to use are solved.

The invention discloses an autocollimation method of a carrier aircraft rotating type strapdown inertial navigation system under a shaking base, and belongs to the field of navigation. The autocollimation method comprises the following steps of: firstly obtaining the longitude and latitude of the position of a carrier, secondly collecting output signals of a fiber-optic gyro and a quartz flexible accelerometer in an inertia measurement unit, and then carrying out automatic compensation on a constant error of an inertia device by adopting a double-shaft rotating table rotatory IMU (inertial measurement unit) to form a rotating type strapdown inertial navigation system; and then calculating a rough initial posture array by utilizing gravity acceleration in an inertial coordinate system as a reference vector, establishing a state equation and a measuring equation again of the system, designing a vanishing adaptation Kalman filter to accurately estimate a misalignment angle of the carrier, and correcting a strapdown posture matrix by utilizing the misalignment angle to finish initial alignment and enter a navigation state. The method isolates the influence of shake of a vessel to initial alignment of a carrier aircraft, and dynamic random disturbance in measured noise is restrained through estimating the initial posture array of the system via the vanishing adaptation Kalman filter method, so that rapid autocollimation of the carrier aircraft rotating type strapdown inertial navigation system is realized.

An omnidirectional borehole navigation system comprising a housing for traversing a borehole; an outer gimbal connected to said housing and at least two or more stacked inner gimbals that are nested in and connected to said outer gimbal, said inner gimbals each having an axis parallel to one another and perpendicular to the outer gimbal; at least one inertial sensor located on each inner gimbal, the at least one inertial sensor including at least one gyro or accelerometer, the gyros having input axes that span three dimensional space and the accelerometers having input axes that span three dimensional space; one or more gyro circuits within the housing and responsive to the at least one gyro to produce the inertial angular rate about each gyro input axis; one or more accelerometer circuits within the housing and responsive to the at least one accelerometer to produce the non-gravitational acceleration along each accelerometer input axis; a processor responsive to said gyro circuits and said accelerometer circuits for determining the attitude and the position of said housing in the borehole; an outer gimbal drive system with complete rotary freedom; and an inner gimbal drive system for controlling the orientation of each of the inner gimbals. The drive system that controls the stacked inner gimbals may be a rack and pinion gear, or a gear train such as a bicycle chain gear rotating the inner gimbals in parallel between stops while maintaining the input axis orthogonality of gyro triads and the input axis orthogonality of accelerometer triads. The inner gimbal stops may be elastic to allow for small misalignments in the inner gimbal drive system.

An anti-shake apparatus for image stabilization of a photographing apparatus comprises an imaging sensor, an acceleration sensor, and an inclination degree output unit. The imaging sensor has an imaging surface on which an optical image through a photographing optical system of the photographing apparatus is captured. The acceleration sensor detects a first gravitational acceleration component in a direction of a first detection axis and a second gravitational acceleration component in a direction of a second detection axis. The first detection axis and the second detection axis are perpendicular to an optical axis of the photographing optical system. The inclination degree output unit outputs information regarding an inclination angle caused by a roll of the photographing apparatus about the optical axis, based on the first gravitational acceleration component and the second gravitational acceleration component.

A seeding apparatus comprising: (a) seed distribution metering means including a rotating drum (1) with apertures on its periphery and a vacuum generator for generating a suction pressure inside the drum (1) so that seeds are attracted to the apertures; (b) feeding system including a hopper (31), gravitational acceleration chamber (47), velocity controlling elements such as a flap (38) and continuous belts (41) for feeding seeds at a required amount and speed to the drum (1); (c) release mechanisms including an airjet (19) for releasing metered seeds from the drum (1) along a selected trajectory (15) while unselected seeds follow another trajectory (16). (d) delivery means including an adjustable flow venturi (62) and electronic sensor (66) for controlling delivery of metered seeds.

A rotational sensor for use with an in-vehicle navigation system , a navigation system that uses the sensor, and a vehicle with the sensor installed. The rotational sensor is created by placing two gravitational accelerometers configured at 90 degrees with respect to one another and mounted at the center of a vehicle wheel. As this resulting sensor is rotated, sine and cosine signals with a quadrature relationship are generated with respect to the earth's gravity vector, from which both rotation and direction of rotation can be determined. These signals may then allow the counting of the turns of the wheel, thus estimating the distance and the rate at which the vehicle has moved. A self-contained version of this device including a transmitter can relay this information to a receiving unit located within the vehicle. When one of these devices is located on each of the steerable wheels of the vehicle, the relative heading-direction of the vehicle may also be estimated.

Disclosed is a robot positioning and map construction system based on binocular vision features and IMU information, comprising a binocular information collection, feature extraction and matching module, an improved IMU initialization and motion module, a visual SLAM algorithm initialization and tracking module, a local mapping module and a loop detection and optimization module. The binocular information collection, feature extraction and matching module comprises a binocular ORB feature extraction sub-module, a binocular feature matching sub-module and an IMU information collection sub-module. The improved IMU initialization and motion module includes an IMU angular rate deviation estimation sub-module, a gravity acceleration prediction sub-module, an IMU acceleration deviation estimation sub-module and an IMU pre-integration sub-module. The visual SLAM algorithm initialization and tracking module includes a tracking inter-frame motion sub-module and a key frame generation sub-module. The local mapping module includes a new key frame insertion sub-module, a local BA optimization sub-module and a redundant key frame elimination sub-module. The loop detection and optimization module includes a loop detection sub-module and a global optimization sub-module. The invention provides a robot positioning and map construction system based on binocular vision features and IMU information, which has good robustness, high accuracy and strong adaptability.

An omnidirectional borehole navigation system is provided which features a housing for traversing a borehole; a gimbal system including at least one outer gimbal connected to the housing and at least one inner gimbal nested in and connected to the outer gimbal; a solid state three-axis gyro assembly mounted on the inner gimbal; a solid state three-axis accelerometer assembly mounted on the inner gimbal; gyro logic circuits on the inner gimbal responsive to the three-axis gyro assembly to produce the inertial angular rate about each gyro input axis; accelerometer logic circuits on the inner gimbal to produce the non-gravitational acceleration along each accelerometer input axis; and a microprocessor responsive to the gyro logic circuits and the accelerometer logic circuits for determining the attitude and the position and velocity of the housing in its borehole.

The invention relates to a robot positioning method with fusion of visual features and IMU information. The invention puts forward a method of fusion of monocular vision with IMU. Visual front-end pose tracking is performed and the post of a robot is estimated by using feature points; an IMU deviation model, an absolute scale and a gravity acceleration direction are estimated by using pure visualinformation; IMU solution is performed to obtain high-precision pose information and thus an initial reference is provided to optimize the search process, and the initial reference, a state quantity and visual navigation information are used for participating in optimization; and a rear end employs a sliding-window-based tightly coupled nonlinear optimization method to realize pose and map optimization. And the computational complexity is fixed while the speedometer is calculated based on a sliding window method, so that the robustness of the algorithm is enhanced.

A tire inflation pressure sensing apparatus according to the present invention includes a transmitter and a receiver. The transmitter is provided on a wheel of a vehicle and includes a pressure sensor working to sense an inflation pressure of a tire on the wheel and an acceleration sensor working to generate a signal as a function of a component of gravitational acceleration in the sensing direction thereof. The transmitter is configured to determine a position thereof depending on the signal generated by the acceleration sensor and transmit the signal representative of the inflation pressure of the tire toward the receiver when a transmitting request is issued and the determined position thereof falls in a predetermined range. The receiver is provided on the body of the vehicle and is configured to receive the signal transmitted from the transmitter and determine the inflation pressure of the tire depending on the received signal.

The invention discloses a bracelet capable of collecting multi-parameter health indexes. The bracelet comprises a body and a wrist strap. The body comprises a shell body, a displaying screen, a power supply, a clock part and a main control system. The displaying screen, the power supply, the clock part and the main control system are arranged in the shell body. The main control system comprises a main printed board, a microprocessor, a storage, an analogue signal processing chip and a Bluetooth transmission device. The microprocessor, the storage, the analogue signal processing chip and the Bluetooth transmission device are arranged on the main printed board. An infrared temperature sensor, an alarming device, a gravitational acceleration sensor for step counting and a charging connector are arranged on the main printed board. A flexible connecting wire cable, a measuring printed board, a body surface temperature sensor, a photosensitive sensor and a light source are arranged on the wrist strap. The body surface temperature sensor, the photosensitive sensor and the light source are integrated on the measuring printed board. A tensioning device is arranged on the wrist strap. The bracelet is small and light, wearing and using are convenient, various health parameters can be monitored accurately, human body parameters are collected near the Neiguan point under a wrist of a palm side, the number of blood vessels under the wrist is large, pulsation is obvious, and accordingly the accuracy of data testing and obtaining through the bracelet is greatly improved.

A method of measuring pose of mobile robot, and method and apparatus for measuring for measuring position of mobile robot using the same are provided. The apparatus for measuring the pose of a mobile robot includes an accelerometer measuring acceleration of the mobile robot in a forward direction, a uniform-motion-determining unit determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section, and a pose-calculating unit calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity.

An integrated calibration system and process for a three-axis (X, Y, Z) accelerometer estimates Z-axis bias, Z-axis bias drift and determines X, Y, and Z-axes error sources based on measurements taken when the accelerometer is static, i.e., sensing only the earth's gravitational acceleration. Optimal on-the-fly error estimates for the three-axis accelerometer are obtained so that the measurements provided by the three-axis accelerometer remain error-free.

The invention discloses a control method and a control system for a worming torque of an electric automobile. The control method comprises the following steps: acquiring a basic part T1 of the worming torque according to a vehicle speed u look-up table; calculating a gravity acceleration component a3 of a vehicle according to a longitudinal acceleration a1 and a travel acceleration a2 of the vehicle; calculating a gradient resistance compensation part initial value T2' of the worming torque according to a complete vehicle mass m, the gravity acceleration component a3 and a tire rolling radius R; attenuating the obtained gradient resistance compensation part initial value T2' of the worming torque with increase of the vehicle speed according to a current vehicle speed u, thereby obtaining a gradient resistance compensation part T2 of the worming torque; adding the basic part T1 of the worming torque with the gradient resistance compensation part T2 of the worming torque to obtain a total worming torque T; and controlling a driving motor to output the total worming torque T to enable the vehicle to worm. The control method and the control system take a road grade into consideration to achieve compensation of gradient resistance, thereby enabling the vehicle to have same acceleration performance and good comfort no matter traveling uphill, downhill or on a level road.

The invention provides an optical fibre gyro strapdown inertial navigation system error inhibiting method based on single-shaft rotation. The initial position parameters of a carrier are confirmed; the data outputted by an optical fibre gyroscope and a quartz accelerometer are collected; the pose information of the carrier is confirmed by the relation between the output of the accelerometer and an acceleration of gravity as well as the relation between the output of the gyroscope and the earth rotation rate; and the initial aligning of the system is finished; an inertial measuring unit coordinate system rotates by 45 degrees along the front direction of the shaft oyb of a carrier coordinate system and the initial opposite position between the two coordinate systems is confirmed; IMU continuously rotates along the front direction of the orientation shaft ozb of the carrier coordinate system by an angular velocity that Omega is equal to 6 degrees / s. The data generated by the optical fibre gyroscope and the quartz accelerometer after the rotation of the IMU is converted under the carrier coordinate system to obtain the modulating form of the constant deviation of an inertial apparatus. The output vale Omega ib of the optical fibre gyroscope is used to update a strapdown matrix Tb; the speed and the position of the carrier after the IMU is rotated and modulated are calculated. The invention modulates the constant deviation of the inertial device on the directions of three shafts to improve the navigation and location precisions.

An aspect of the present invention is directed to an avalanche photodiode (APD) device for use in oil well drilling applications in harsh, down-hole environments where shock levels are near 250 gravitational acceleration (G) and / or temperatures approach or exceed 150° C. Another aspect of the present invention is directed to an APD device fabricated using SiC materials. Another aspect of the present invention is directed to an APD device fabricated using GaN materials. According to an embodiment of the present invention, an avalanche photodiode for detecting ultraviolet photons comprises a substrate having a first dopant; a first layer having the first dopant, positioned on top of the substrate; a second layer having a second dopant, positioned on top of the first layer; a third layer having a second dopant, positioned on top of the second layer; a passivation layer for providing electrical passivation on a surface of the avalanche photodiode; a phosphorous silicate glass layer for limiting mobile ion transport, positioned on top of the third layer; and a pair of metal electrodes for providing an ohmic contact wherein a first electrode is positioned below the substrate and a second electrode is positioned above the third layer; wherein the avalanche photodiode comprises a first sidewall and a second sidewall forming a sloped mesa shape; and wherein the avalanche photodiode operates in an environment comprising a temperature approximately equal to 150 degrees Celsius.