Optical Speed Sensor Research Articles

Speed Sensor-Aided Navigation Filter for Robust Localization in GNSS-Denied Mining Environments

<h3>Abstract</h3> The automation of mining haulage vehicles has great potential in terms of safety and economy. The performance of autonomous vehicles depends largely on highly accurate vehicle state information. Deep mines are especially challenging, as satellite-based localization methods are reaching their limits. Therefore, we introduce a new navigation filter concept for the precise and robust localization of the haulage fleet that can handle temporary GNSS interruptions in deep open-pit mines. The multi-sensor navigation filter utilizes an inertial measurement unit and is aided by GNSS. We introduce a new optical speed sensor update within the tightly coupled unscented Kalman filter. The speed sensor measures the slip-free two-dimensional speed above ground. The filter was validated with an articulated dumper in a gravel pit. The new filter achieved a mean position error of 0.24 m during a test drive of 190 s with a simulated GNSS outage of 90 s.

A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor.

Traffic speed meters are important legal measuring instruments specially used for traffic speed enforcement and must be tested and verified in the field every year using a vehicular mobile standard speed-measuring instrument to ensure speed-measuring performances. The non-contact optical speed sensor and the GPS speed sensor are the two most common types of standard speed-measuring instruments. The non-contact optical speed sensor requires extremely high installation accuracy, and its speed-measuring error is nonlinear and uncorrectable. The speed-measuring accuracy of the GPS speed sensor is rapidly reduced if the amount of received satellites is insufficient enough, which often occurs in urban high-rise regions, tunnels, and mountainous regions. In this paper, a new standard speed-measuring instrument using a dual-antenna Doppler radar sensor is proposed based on a tradeoff between the installation accuracy requirement and the usage region limitation, which has no specified requirements for its mounting distance and no limitation on usage regions and can automatically compensate for the effect of an inclined installation angle on its speed-measuring accuracy. Theoretical model analysis, simulated speed measurement results, and field experimental results compared with a GPS speed sensor with high accuracy showed that the dual-antenna Doppler radar sensor is effective and reliable as a new standard speed-measuring instrument.

POSITIONING BASED ON INTEGRATION OF MUTI-SENSOR SYSTEMS USING KALMAN FILTER AND LEAST SQUARE ADJUSTMENT

Abstract. Sensor fusion is to combine different sensor data from different sources in order to make a more accurate model. In this research, different sensors (Optical Speed Sensor, Bosch Sensor, Odometer, XSENS, Silicon and GPS receiver) have been utilized to obtain different kinds of datasets to implement the multi-sensor system and comparing the accuracy of the each sensor with other sensors. The scope of this research is to estimate the current position and orientation of the Van. The Van's position can also be estimated by integrating its velocity and direction over time. To make these components work, it needs an interface that can bridge each other in a data acquisition module. The interface of this research has been developed based on using Labview software environment. Data have been transferred to PC via A/D convertor (LabJack) and make a connection to PC. In order to synchronize all the sensors, calibration parameters of each sensor is determined in preparatory step. Each sensor delivers result in a sensor specific coordinate system that contains different location on the object, different definition of coordinate axes and different dimensions and units. Different test scenarios (Straight line approach and Circle approach) with different algorithms (Kalman Filter, Least square Adjustment) have been examined and the results of the different approaches are compared together.

EVALUATION OF SLIDING MODE OBSERVER FOR VEHICLE SIDESLIP ANGLE

Vehicle sideslip angle is the principal variable used in computing the transversal forces governing tire/road contact. It is the most important variable determining a vehicle's lateral stability. This paper presents a sliding mode observer of vehicle sideslip angle. A model is developed and then simplified. The observer was tested on a validated simulator and on experimental data acquired using a real vehicle. A “Correvit” optical speed sensor was used to measure the sideslip angle. We discuss the limitations of using a nonlinear vehicle model with linear transversal forces. This paper also presents the relation between nonlinear observability and certain vehicle parameters.

Experimental evaluation of vehicle sideslip angle observers

The lateral behavior of a vehicle is defined by the transversal forces between theroad and the wheels. The sideslip angle is the principal variable for the transversal forces. This paper compares four observers of vehicle sideslip angle. Modeling, model simplification are performed. This study validates observers on experimental data acquired by the Heudiasyc laboratory car. An optical speed sensor “Correvit” is used to acquire the sideslip angle. This paper shows that observers can give good results in spite of constraining assumptions.

Rotating Brush Seal

This article has no abstract.

Speed photodetectors based on amorphous and microcrystalline silicon p–i–n devices

A sensitive optical speed sensor has been developed utilizing the transient lateral photoeffect induced in a Si thin-film p–i–n photodetector by a moving light spot. The local time dependent illumination changes the lateral photocurrent and modulates the potential barrier across the junction allowing the sensing of the light spot velocity. The performances of an amorphous (a-Si:H) and a microcrystalline (μc-Si:H) silicon-based sensor will be compared and discussed taking into account the differences in material properties and device geometry. The μc-p–i–n structure has the advantage of faster response, high current capability, and excellent stability under illumination when compared with the amorphous counterpart.