Qingyuan Zhu

Three-Dimensional Indoor Mobile Mapping With Fusion of Two-Dimensional Laser Scanner and RGB-D Camera Data

Three-dimensional mobile mapping in indoor environment, mostly global navigation satellite system-denied space, is to consecutively align the frames to build a global 3-D map of an indoor environment. One of the major difficulties of the current solutions is the failure at the insufficient overlapping between the frames, which is the reality of a lack of correspondences between the frames. To overcome this problem, a 3-D indoor mobile mapping system that integrates a 2-D laser scanner, and an RGB-Depth camera is presented in this letter. In this system, a fusion-iterative closest point (ICP) method, which combines the 2-D mobile platform pose from a Rao-Blackwellized particle filter estimation, an ICP, and a generalized-ICP method, is proposed for the consecutive frame alignment. Fusion-ICP achieves effective frame alignment, particularly in solving the insufficient overlapping frame alignment problem. Comparative experiments were conducted to evaluate the mapping system. The experimental results demonstrate the effectiveness and efficiency of our system for 3-D indoor mobile mapping.

A Computer-Aided Modeling and Measurement System for Environmental Thermal Comfort Sensing

Predicted mean vote (PMV) is a well-known thermal comfort index with four environmental variables (air temperature, relative humidity, air velocity, and average radiation temperature) and two human factors (metabolic rate and clothing thermal resistance). This paper presents a novel computer-aided thermal comfort measurement system with PMV, which combined the advanced sensors with the virtual instrument technology. The system software is developed using the LabVIEW platform. The measured data can be transmitted to the server-computer in a data center and displayed on a web page through the Internet. The impact of the measurement error of each environmental variable on PMV is analyzed via MATLAB. The system tests were conducted under the certain environmental conditions and Monte Carlo method is deployed to analyze the PMV measurement uncertainty. The experimental results show the feasibility and effectiveness of the proposed system, and confirm that the measurement uncertainty of PMV is not a constant, and varies with the environment changes.

Dimension reduction analysis in image-based species classification

Automated insect species identification and classification is of great demand in agriculture, environment and entomology areas these days. In the paper, an image-based species classification method is proposed, which includes a snake-based segmentation method and global feature extraction. For global feature data, three dimension reduction analysis methods are proposed to get more effective classification feature data, which are regression and correlation analysis, principal component analysis and multivariate analysis of variance. Species samples are selected from nine different species, which are the most harmful insect species in the agriculture orchard. Five classifiers, minimum least square linear classifier, normal density based linear classifier, K nearest neighbor classifier, Parzen density based classifier and nearest mean classifier are compared for feature data from different dimension reduction analysis methods, and the best performance is given by normal density based linear classifier. The results show that different dimension reduction methods give different classification performance according to different classifiers. Compared to the classification results before and after taking dimension reduction analysis, suitable dimension reduction method can be used to keep both efficiency and effect of classification.

Lateral stability simulation and analysis for wheel loaders based on the steady-state margin angle

Wheel loaders are prone to lateral tilting accidents due to their complex working environment, variable structure frame and the large offset of the centroid position. The accidents may seriously threaten the driver’s safety. This paper proposes a steady-state margin (SSM) angle as a new instability threat indicator to analyse lateral stability of wheel loaders. Firstly, the structural characteristics and the rollover process of a wheel loader are presented, and the SSM angle is defined. Secondly, on the assumption that the tyres are rigid, the calculation process of the SSM angle is described in detail, then the SSM angle of the XG953 wheel loader is computed. A virtual prototyping simulation was performed under the environment of ADAMS. The maximum relative error between the theoretical calculation and simulated result was 4.55%, within the permissible speed range. When changing the tyre parameters to normal tyre parameters, the relative error became larger. Finally, an indirect method is proposed to deal with the influence of tyres on the SSM angle and reduce the relative error.

Piezoelectric energy harvesting in automobiles

Powering the distributed or embedded wireless sensors from ambient vibration energy has attracted many attentions. It will reduce the installment trouble and maintenance costs. This work reports on vibration levels detected in automobiles during road test as a potential energy source for automobile sensors. A piezoelectric vibration harvester was designed and equipped with a simple harvesting circuit. The measurement results showed that the vibrations in the automobiles are large enough to possibly supply a wireless sensor.

Study on combine harvester speed control based on optimum threshing power consumption model

Combine harvester have to be operated in a wide range of field condition which may induce varying feeding rate. Forward speed is a main variable to control the feeding rate of combine harvester for high efficiency. In this study a control strategy based on optimum threshing power consumption model was developed and integrated into a speed control system for combine harvester automation. A conventional self-propelled combine harvester (Xinjiang-II) was equipped with multiple sensors to collect online information, including forward speed, threshing drum torque and speed. Forward speed was then adjusted by an electric-hydraulic unit based on designed PID controller to achieve an optimum range of threshing power consumption. Field test was conducted to evaluate the performance of the controller under variable feeding rate condition. From obtained results, the controller can improve the efficiency of tested machine during field operation.

Modelling of stable angle-based instability threat indicator for articulated off-road vehicles

This paper presents the modelling and simulation of a stable angle-based instability threat indicator for articulated off-road vehicles. First, a stable angle is represented by the vertical forces of four wheels and steering angle of an off-road articulated steer vehicle. Then a vehicle prototype model is built based on a specific wheel loader type and a tyre/terrain model. Finally, the prototype model and tyre/terrain model are imported to the multi-body dynamics analysis software-ADAMS to conduct a number of simulations using the stable angle-based instability threat indicator. Simulation results indicate that a stable angle of 80.5° is the threshold angle for lateral instability, and a stable angle of 90° is the threshold angle for longitudinal instability of this model. Compared with the traditional instability indicating methods for off-road vehicles, the proposed stable angle-based method is more efficient and can deal with both lateral and longitudinal instability of an articulated vehicle effectively.

General Environment Integrated Monitoring and Data Management System Based on Virtual Instrument

For the lack of integrated and advanced monitoring method and equipment, the existing general environment evaluation methods cannot entirely collect and analyze the monitoring parameters, which objectively reflect the condition of general environment, so an integrated monitoring and data management system for general environment based on virtual instrument technology is proposed in this paper. The monitoring and data management system which adopts a NI CompactDAQ data acquisition system functioning high speed real-time collection of multi-parameters of climate (temperature, wind speed, solar radiation), air quality (formaldehyde, benzene, radon, etc) soil and water quality, etc. Employing the LabVIEW programming tool, the software system was developed with friendly graphical user interface, which can display the real-time monitoring results of the multi-parameters mentioned above. Moreover, the LabSQL kit is used to access the database to search historical records of every parameter, summarize the trend of environment change and further objectively evaluate the condition of environment. This system can be used as parameter acquisition instrument for general environment, and provides a new way for evaluation of the general environment.

The Integrated Testing System for Performance Parameters of the Hydraulic Excavator

This paper designed and developed an integrated testing system for performance parameters of the Hydraulic excavator. Combined with sensing technology, computer technology and virtual instrument technology this system can detect six key parameters of the excavator including motor speed, hydraulic system pressure, attachment action time, swing speed, walking speed, current characteristics, so as to evaluate the performance of the excavator. The testing system takes full consideration of the interaction between the tester and driver, meanwhile, can automatically detect all parameters by using the parallel test method in order to make sure the whole test completed in one hour. As the testing system is designed base on the idea of modularization, it can add new modules to meet the functional requirements alone with the development of research in the future. This testing system can not only improve the test efficiency, but also be used as analysis tools for the research and optimization of performance parameters of excavators.

An Environmental Factors-Based Automatic Control System for Folding Arm Awning

This paper developed an automatic control system for folding arm awning based on environmental factors, which can overcome the disadvantages of the traditional awning of unitary control mode and low level of intelligence. The system consists of sensor unit, controller, drive motor and transmission mechanism. The sensor unit is used for testing light intensity, wind speed and rain, then an AT89S52 SCM single-chip microcomputer which is the core of the controller is applied to receive testing signal and send instructions to AC motor to realize the extending and withdrawing state of the awning according to the corresponding control logic. Meanwhile, this system is able to switch from automatic control to manual control so as to deal with power outage and other special situation and maintain operation of awning. The results of the prototype test show that this system is running steadily and can adjust the working condition of the awning in time according to the environment change. Compared with the current electric awning, the intelligent folding arm awning controlled according to environmental factors can achieve more energy conservation and environmental protection.