Intelligent car is a high-order intelligent product integrating intelligent integrated control, visual terminal, automatic control output and cognitive computing.This paper introduces an innovative intelligent tracking car based on STM32 embedded chip.The vehicle adopts fuzzy PID algorithm to control the vehicle operation, and adopts the innovative grayscale card designed by the team hardware designer.This car fully caters to the global environmental protection trend, the new concept of green development.On the premise of low cost and low power consumption, it also ensures the smooth, smooth and high precision operation of the vehicle.
The working environment in coal mines is complex and constantly changing. Harsh conditions, such as narrow passageways, irregular road shapes, and unpredictable obstacles, pose significant challenges for the precise perception of unmanned mining vehicles. To address these issues, this paper proposes a positioning method that tightly couples an Inertial Measurement Unit (IMU) with LiDAR to overcome the challenge of precise positioning in degraded underground spaces where a single LiDAR alone cannot achieve accurate localization.First, the LiDAR point cloud is segmented, and IMU pre-integrated poses are used to eliminate nonlinear motion distortions. Line and surface features are extracted from the obtained point cloud. Next, the line and surface features of adjacent frames are matched, and in the layered pose estimation process, IMU pre-integrated pose initial values are fused to reduce the number of computational iterations, improve feature point matching accuracy, and compute the current frame's pose. Finally, local map factors, IMU factors, and keyframe factors are inserted into the factor graph to optimize the pose. Keyframes are matched with local maps, and map construction is achieved through an octree structure.Considering the specific limitations of coal mining operations in the real environment, which are characterized by high experimental difficulty, cost, limited and hard-to-obtain data, this paper combines the ACP method to simulate various coal mine tunnel scenarios within an artificial system. It includes features such as uneven ground, curves, slopes, and other complex parameters to experimentally validate the proposed method. This approach not only reduces experimental risk and costs but also significantly enriches the experimental data.The experimental results demonstrate that the method presented in this paper exhibits strong robustness and accuracy in various scenarios. The positioning accuracy of unmanned mining vehicles in actual scenarios is improved by 74% to 91% compared to traditional methods.
Abstract A symmetrical 3-PRR flexible motion platform kinematic dynamic model is built. The natural frequency analysis of the platform is studied in this paper. Firstly, a flexible lever displacement two-stage amplification mechanism is proposed. A pseudo-rigid body model is established. A kinematics model is established by using the vector closed-loop method. The relationship between the input and output of the flexible lever displacement two-stage amplification mechanism is obtained. Secondly, based on the two-stage amplification mechanism of flexible lever displacement, a 3-PRR flexible motion platform is designed. The Jacobian matrix of input displacement of piezoelectric ceramics and output displacement of flexible motion platform is obtained by using the coordinate transformation method and vector equation closed-loop method. Considering the elastic potential energy of the flexible hinge and biaxial hinge, the Lagrange equation is established, and the expression of the natural frequency of the 3-PRR flexible motion platform is obtained. Finally, the correctness of the theoretical dynamic model is verified by theoretical calculation and finite element software simulation.
Abstract This study performs an investigation of the effects of the subgrid-scale (SGS) and droplet injection models in the large eddy simulation (LES) of turbulent two-phase spray flows. Three LES SGS models (Smagorinsky, wall-adapting local eddy viscosity (WALE), and dynamic Smagorinsky) and two droplet injection models (cone nozzle injection and conditional droplet injection) are validated to the experimental measurements. For both gaseous and liquid phases, all SGS models provide comparable results, indicating that the current two-phase flow field does not exhibit a pronounced sensitivity to the LES SGS model. As for different droplet injection models and spray dispersion angles, minimal differences are observed in the prediction of the gaseous mean and root-mean-square (RMS) velocity profiles. However, for the result of liquid phase, CDIM (conditional droplet injection model) predictions of the droplet mean diameter and velocity are in better agreement with experiments, and less sensitive to spray dispersion angle settings. While the CNIM (cone nozzle injection model) prediction of droplet diameter is less accurate when increasing the dispersion angle. The study suggests that turbulent two-phase spray flows are more influenced by the spray boundary conditions rather than the LES SGS models.
To accurately predict the matching relationships between the various components and the engine performance in the whole aero-engine environment, this study introduces a two-dimensional throughflow simulation method for the whole aero-engine. This method is based on individual throughflow solvers for the turbo-machinery and the combustor. It establishes a throughflow simulation model for the whole engine by integrating with the compressor-turbine co-operating equations and boundary conditions. The turbo-machinery throughflow solver employs a circumferentially averaged form of the time-dependent Navier–Stokes equations (N-S) as the governing equation. The combustor solver uses the Reynolds Average Navier–Stokes (RANS) method to solve flow and chemical reaction processes by constructing turbulence, combustion, and radiation models. The accuracy of the component solver is validated using Pratt and Whitney’s three-stage axial compressor (P&W3S1) and General Electric’s high-pressure turbine (GE-EEE HPT), and the predicted results are consistent with the experimental data. Finally, the developed throughflow method is applied to simulate the throttling characteristics of the WZ-X turboshaft engine. The results predicted by the throughflow program are consistent with the GasTurb calculations, including the trends of shaft power delivered, specific fuel consumption (SFC), inlet airflow, and total pressure ratio of the compressor. The developed method to perform throughflow simulation of the whole aero-engine eliminates the dependence on a general component map. It can quickly obtain the meridian flow field parameters and overall engine characteristics, which is expected to guide the design and modification of the engine in the future.
How to generate the precise broad group cross section is important for the fast reactor design. In this study, a fast reactor multi-group cross-section generation code MGGC2.0 are developed in-house for processing ultrafine group MATXS format library. Validation and verification are performed for MGGC2.0 code by applying the benchmarks of ICSBEP handbook, and the results of MGGC2.0 agree well with that of MCNP. The consistent PN method with critical buckling search is in good agreement that condensed with TWODANT flux and flux moment for the inner core and outer core region. For the radial blanket and reflector, two region approximation method has been applied in MGGC2.0 by using collision Probability Method neutron flux solver. The RBEC-M benchmark was used to verify the power distribution calculation, and the relative error of power distribution comparison with the reference are less than 0.8% in the fuel region and the maximum relative error is 5.58% in the reflector region. Therefore, the precise broad cross section can be generated by MGGC2.0 for fast reactor.
With the development of modern small satellite technology, short development cycles, low cost, and high reliability have become trends in the era of New Space. To achieve the above goals, an integrated centralized architecture of onboard avionics for an internet of things CubeSat was proposed, and CAN, I2C, and 1-wire buses were employed for telemetry collection and command sending. The implementation of onboard computers (OBCs) and the power conditioning and distribution unit (PCDU) was introduced based on the PC104 industrial standards. An arbitration switching strategy between the primary and backup OBCs was proposed so that the primary OBC had priority to be on duty. Over 98% of commercial off-the-shelf (COTS) parts were used to decrease costs, so a procedure for COTS part selection and a qualified method were presented for reliable application. The onboard avionics, including OBC and PCDU, were developed in six months, and the satellite has been in orbit for more than three years and still works well. The reliability of the onboard avionics developed using the philosophy of New Space is demonstrated by the three-year flight in orbit.
To accurately predict the matching relationships between the various components and the engine performance in the whole aero-engine environment, this study introduces a two-dimensional throughflow simulation method for the whole aero-engine. This method is based on individual throughflow solvers for the turbo-machinery and the combustor. It establishes a throughflow simulation model for the whole engine by integrating with the compressor-turbine co-operating equations and boundary conditions. The turbo-machinery throughflow solver employs a circumferentially averaged form of the time-dependent Navier-Stokes equations (N-S) as the governing equation. The combustor solver uses the Reynolds Average Navier-Stokes (RANS) method to solve flow and chemical reaction processes by constructing turbulence, combustion, and radiation models. The accuracy of the component solver is validated using Pratt & Whitney’s three-stage axial compressor (P&W3S1) and General Electric’s high-pressure turbine (GE-EEE HPT), and the predicted results are consistent with the experimental data. Finally, the developed throughflow method is applied to simulate the throttling characteristics of the WZ-X turboshaft engine. The results predicted by the throughflow program are consistent with the GasTurb calculations, including the trends of shaft power delivered, specific fuel consumption (SFC), inlet airflow, and total pressure ratio of the compressor. The developed method to perform throughflow simulation of the whole aero-engine eliminates the dependence on a general component map. It can quickly obtain the meridian flow field parameters and overall engine characteristics, which is expected to guide the design and modification of the engine in the future.
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