Trajectory planning of jumping over an obstacle for one-legged jumping robot

For one-legged passive jumping robot, a trajectory planning strategy is developed to jump over an obstacle integrating three various dynamics among jumping process. Manipulability ellipsoids are effective tools to perform task space analysis and motion optimization of redundant manipulators. Jumping robot can be considered as a redundant manipulator with a load held at the end-effector. The concept of inertia matching ellipsoid and directional manipulability is extended to optimize the take-off posture of jumping robot, and the optimized results have been used to plan jumping trajectory. Aimed at the sensitivity of a trajectory to constraint conditions on point-to-point motion planning, the 6th order polynomial function is proposed to plan jumping motion having a better robustness to the parameters change of constraint conditions than traditional 5th order polynomial function. In order to lift the foot over the obstacle, correction functions are constructed under unchanged boundary constraint conditions. Furthermore, the body posture is controlled based on internal motion dynamics and steady-state consecutive jumping motion principle. A prototype model is designed, and the effectiveness of the proposed method is confirmed via simulations performed on parameters of designed prototype

Heat extraction capacity and its attenuation of deep borehole heat exchanger array

A model is proposed to analyze the heat transfer of deep borehole heat exchanger (DBHE)arrays. Based on this, a dimension reduction algorithm is proposed for the numerical simulation of heat transfer of DBHE arrays, which can improve calculation speed by several orders of magnitude compared with that by the CFD software. An index of heat extraction capacity (HECI) is adopted to evaluate the heat extraction capacity of DBHE arrays. The influence of borehole spacing, operation time, annual heating duration, terrestrial heat flow rate, borehole depth, soil thermal parameters, pipe diameter and circulating fluid flow rate on DBHE array heat extraction capacity and its attenuation are analyzed. The results show that the borehole spacing, operation time, and annual heating duration all have apparent influence on DBHE array heat extraction capacity and its attenuation rate, while the others only have apparent influence on the heat extraction capacity. According to the calculation results, when the DBHE arrays have a service lifetime of 20–50 years, the recommended borehole spacing range is 40–70 m

Design and analytical analysis of foundation pile ground heat exchanger with spiral coils

Recently, utilization of building foundation piles as the ground heat exchanger (GHE) received more and more attention since it can reduce the initial cost and land area requirement compared with the borehole GHE. This study designs a foundation pile GHE with spiral coil (FPGHE) by intertwing the circulating coil pipe tightly in spiral shape against the reinforcing steel of a pile. The distinct advantage of this proposed FPGHE is that it can offer higher heat transfer efficiency, reduce pipe connection complexity, prevent air blocking and decrease the thermal "short-circuit" between the feed and return pipes compared with other existing configurations. In order to analyze its heat transfer characteristic, analytical models are established for the proposed FPGHE. Analytical thermal analysis is carried out to simulate temperature responses of the coil pipe wall and the circulating water entering/effusing the FPGHE to the short time step heat transfer loads based on the established analytical model. Furthermore, the operation performance and heat exchange capacity of the FPGHE is investigated

Thermal analysis models of deep borehole heat exchangers

With the advantages of much less land demand and higher temperature available, the deep borehole heat exchanger (DBHE) gets down to a depth of 1000-3000 m below the ground surface, and provides a new variance of ground-coupled heat pump systems especially for applications in cold-climate regions. Coaxial tubes, instead of U-tubes, are usually used in DBHEs. Two models are presented for DBHE thermal analysis in this paper. One follows the traditional approach based on analytical solutions and the concept of the effective borehole thermal resistance for the boreholes with coaxial tubes. The other is a numerical simulation scheme based on the FDM which takes the geothermal gradient into account. The latter features much higher efficiency in computation than most commercially-available software toolkits based on FEM. The performance of DBHEs is then assessed with parameter analyses

Influence of ground heat exchanger zoning operation on the GSHP system long-term operation performance

To alleviate the ground heat accumulation after long term running of ground source heat pumps (GSHP), ground heat exchanger (GHE) zoning operation can be adopted. Two GHE operation modes - zoning operation and full running - are compared in a case where heat release to the ground in summer is larger than the heat extraction from the ground in winter. In this study the soil thermal conductivity, volumetric specific heat capacity, borehole depth and spacing are 2.0 W(mK)-1, 5.0x106 J(m3K)-1, 100m and 5m respectively with the boreholes arranged in a square 20x20 array. Under the given conditions the simulation results show that GHE zoning operation depresses the increase in amplitude of GHE outlet water temperature and so that the GSHP systems operate normally throughout the whole service life. By adopting GHE zoning operation, the energy consumption of the GSHP system is found to be reduced compared with that of a GHE operated without zoning. Operation without zoning shows that the GHE summer outlet water temperature increases faster than that with zoning operation and power demands are increased for the given GSHP load. Furthermore, in this case, the GSHP would not be able to run normally in the last several years due to the condensing temperature exceeding its upper limit

A novel model for photovoltaic array performance prediction

Based on the I-V curves of a photovoltaic (PV) module, a novel and simple model is proposed in this paper to predict the PV module performance for engineering applications. Five parameters are introduced in this model to account for the complex dependence of the PV module performance upon solar-irradiance intensity and PV module temperature. Accordingly, the most important parameters, i.e. the short-circuit current, open-circuit voltage, fill factor and maximum power-output of the PV module, may be determined under different solar irradiance intensities and module temperatures. To validate the developed model, field measured data from one existing building-integrated photovoltaic system (BIPV) in Hong Kong was studied, and good agreements between the simulated results and the field data are found. This model is simple and especially useful for engineers to calculate the actual performances of the PV modules under operating conditions, with limited data provided by the PV module manufacturers needed.PV module I-V curve Short-circuit current Open-circuit voltage Fill factor Maximum power output

Spectral and Image Integrated Analysis of Hyperspectral Data for Waxy Corn Seed Variety Classification

The purity of waxy corn seed is a very important index of seed quality. A novel procedure for the classification of corn seed varieties was developed based on the combined spectral, morphological, and texture features extracted from visible and near-infrared (VIS/NIR) hyperspectral images. For the purpose of exploration and comparison, images of both sides of corn kernels (150 kernels of each variety) were captured and analyzed. The raw spectra were preprocessed with Savitzky-Golay (SG) smoothing and derivation. To reduce the dimension of spectral data, the spectral feature vectors were constructed using the successive projections algorithm (SPA). Five morphological features (area, circularity, aspect ratio, roundness, and solidity) and eight texture features (energy, contrast, correlation, entropy, and their standard deviations) were extracted as appearance character from every corn kernel. Support vector machines (SVM) and a partial least squares–discriminant analysis (PLS-DA) model were employed to build the classification models for seed varieties classification based on different groups of features. The results demonstrate that combining spectral and appearance characteristic could obtain better classification results. The recognition accuracy achieved in the SVM model (98.2% and 96.3% for germ side and endosperm side, respectively) was more satisfactory than in the PLS-DA model. This procedure has the potential for use as a new method for seed purity testing

Feasibility Investigation of the Low Energy Consumption Cooling Mode with Ground Heat Exchanger and Terminal Radiator

AbstractDue to its huge heat capacity, ground can provide heat source in winter and heat sink in summer as the so called shallow geothermal energy, which is mainly utilized by the ground coupled heat pump system. In fact, free cooling can be provided by circulating water between the ground heat exchanger (GHE) and the indoor terminal directly. Recently, radiator for cooling developed rapidly due to it possesses high energy efficiency and comfortable level, however, condensation arises if entering water temperature is lower than dew point of the ambient air. Therefore, this study proposes a low energy consumption cooling mode by combining the GHE and the terminal radiator to utilize the ground cooling directly and to prevent the condensation problem of terminal radiator. The simulation model of this novel mode is established, and the feasibility of this low energy consumption cooling mode is analyzed based on simulation results