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在数控原木形状识别系统中，利用八点检测四点组合回归的方法采集到原木的三维几何数据，根据计算机图形学原理对原木上的采样点进行一系列坐标变换，模拟出原木的采样截面，按照径向排序法动态地对整根原木的外形进行三维仿真，为原木的下一步加工处理提供几何特征方面的依据。 相似文献
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介绍了一种应用激光检测技术将原木截面形状再现并计算出原木截面面积的新方法,即应用基于包络理论的原理建立测量系统模型,应用无线数据采集系统采集检测到的数据,然后利用采集到的数据在计算机中进行原木形状的再现,并进行包络线上点坐标的确定以及包络面积的计算,最后对可能出现的结果进行了分析。 相似文献
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原木8点检测4点组合回归形状描述方法的研究 总被引：2，自引：0，他引：2
介绍了利用8个检测点对圆木进行检测，取其中任意4个点进行组合，从而建立关于原木截面形状的二次仿真数学模型。依据这个原木数学模型，利用试验所得的参数，构建原木外形包络面数学模型，并进一步建立计算机描述系统，实现原木形状计算机仿真和检测自动化。 相似文献
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原木扫描技术主要用于精确识别原木外廓形状、尺寸和各种缺陷，为原木管理、优化加工提供原始信息资料。该项技术在木材加工领域应用广泛，是未来国内外木材加工研究的一个重要方向。 木材的最初加工都是从原木开始的，因此，认识原木的外廓形状，包括尖削度、弯曲度、开裂、节子、腐朽等缺陷，以及如何根据加工的需要对这些缺陷进行有效的处理和分选、分等，是木材加工中具有普遍意义的问题，也是提高木材加工利用率的一个关键问题。据有关资料报道，对原木外形扫描识别由计算机控制分选、分等来确定下锯方案，可使原木出材率提高５％以上… 相似文献
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【英《联帮林业评论》1980年第4期报道】采用激光选择最佳锯路和校准毛方,锯切形状不规则的原木,可提高出材率8—10％。该系统是利用激光扫描装置准确地测量通过主锯的每根原木尺寸和形状,并将信息 相似文献
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为满足制材厂成品(如家具部件)规格的需要,且从每根原木获得最大出材率,在原木进带锯前.须精确测量原木尺寸,检测原木质量,模拟原木形状.可是,这样做也未必就能获得满意的结果.假设原木为圆锥体,将原木按每种锯材产品规格的特定要求进行预先分类,且挑选原木特性;应用线性规划方法来逐步优化原木的出材率.我们认为:这样做既可满足一定规格板材(多为家具部件)的需要.又可获得最大的原木出材率. 相似文献
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缅甸:缅甸自然资源和环境保护部林业司负责人吴丁吞(U Tin Tun)向《缅甸时报》透露,该司正在准备允许出口从私有人工用材林采伐的原木。为了保护环境和防止毁林,缅甸从2014年4月开始禁止出口整根原木和锯材,但此项措施使近年来的出口收益明显减少。2018年7月,缅甸政府提出允许出口从私人投资林地采伐的原木,其目的是吸引对私有人工用材林的投资。 相似文献
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本文采用柱坐标,以椭圆—阿基米德螺线包络组成解析曲线椭圆柱体的弯曲原木的数学模型。定义它为C型弯曲。并以材长和弯曲弓背长度定义,提出了一个实测参数的弯曲原木材积计算公式。定量地解决了弯曲造成原木材积统计时的损失。这种方法和理论,可以解决弯曲原木最佳出材率和弯曲原条最佳截断问题。为制材的数控软件编制提供了理论基础。 相似文献
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Magnus Fredriksson Olof Broman Fredrik Persson Ann Axelsson Pedro Ah Shenga 《Wood material science & engineering》2014,9(1):31-39
With the development of scanning technology in sawmills, it is possible to optimise log rotational position when sawing. However, choosing a different rotational position than horns down might be detrimental for the board shape after drying, especially for curved logs. Thus, there is a need to investigate at what level of log curve it is possible to freely rotate logs without causing board warp. This study was carried out through a test sawing that was conducted at a sawmill situated in the middle of Sweden. The tests were made on 177 Norway spruce logs, with varying amount of curve. Half of the logs were sawn in the horns-down position, half were sawn rotated perpendicular to horns down. Log shape and warp of the dried boards were measured. The results indicated a relationship between board spring, log curve and choice of rotational position. Furthermore, board bow was related to log curve but not rotational position. It can be concluded that for straight logs, with a bow height of less than 15 mm, an unconventional rotational position does not cause excess spring in the boards. Bow and twist are not affected by the rotational position at all. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):89-95
As sawmills become increasingly efficient, the importance of focusing on value recovery becomes obvious. To maximize value recovery, sawmills require the ability to sort logs according to quality. This study compares four different combinations of three-dimensional (3D) and X-ray scanning that can be used to grade logs automatically. The study was based on 135 Scots pine (Pinus sylvestris L.) logs that had been scanned with both a 3D scanner and an X-ray scanner with two X-ray sources. The percentage of boards with correct grade sawn from automatically graded logs varied from 57% when using only 3D scanning to 66% when using a combination of 3D scanning and X-ray scanning in two directions. The highest possible result, with ideal log grading, was 81%. The result also shows that the combination of a 3D scanner and one X-ray direction results in higher accuracy than a scanner based on two X-ray directions. 相似文献
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Magnus Fredriksson 《Wood material science & engineering》2014,9(2):110-119
When disjoining a log, several factors affect the value of the sawn timber. There are log features, such as outer shape, knots, rot, and so on. There are also sawing parameters, such as sawing pattern, log position, and so on. If full information about log features is available, sawing parameters can be adapted in order to maximize product value in sawmills. This is soon possible, since computed tomography (CT) scanners for the sawmill industry are being realized. This study aimed at investigating how CT data can be used to choose rotational position, parallel displacement, and skew of sawlogs, to maximize the value of the sawn products. The study was made by sawing simulation of 269 CT scanned logs of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] H. Karst.). The results showed that value recovery could be improved by 13% in average, compared to a sawing position based on log outer shape, and 21% compared to sawing logs centered and horns down. It can be concluded that a CT scanner, used in a sawline to optimize sawing parameters, has a large potential for increasing value recovery and thus profit. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):473-480
As the sawmill industry strives towards customer orientation, the need for sorting of logs according to quality has been recognized, and automatic sorting based on measurements by three-dimensional (3D) optical log scanners has been implemented at sawmills. There is even a small number of sawmills using the X-ray log scanner for automatic log-sorting. At the log-sorting stage, the potential of the raw material to fulfil the needs has already been reduced by the decisions taken when the trees were bucked (cross-cut) into logs. Thus, the application of predictions of the boards’ properties at the bucking stage is desirable. This study investigates the possibility of predicting board values from logs based on 3D scanning alone and 3D scanning in combination with X-ray scanning of stems. This study is based on 628 logs scanned by computed tomography that make up the Swedish Pine Stem Bank. Simulated sawing of the logs gave product values for each log. Prediction models on product value were adapted using partial least squares regression and x-variables derived from the properties of the logs and their original stems, measurable with a 3D log scanner and the X-ray LogScanner. The results were promising. Using a 3D scanner alone, R 2 was 0.68, and using a 3D scanner in combination with an X-ray LogScanner, R 2 was 0.72. 相似文献
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Reconstruction of Pinus Sylvestris knots using measurable log features in the Swedish Pine Stem Bank
《Scandinavian Journal of Forest Research》2012,27(5):481-491
Abstract The objective of this study was to develop a method for reconstruction of parametrically described whorls and knots from data possible to extract from industrial scanning of logs, using X-ray scanners. The method was conceived using the logs in the Swedish Pine Stem Bank as a foundation, and was based on a few predictor features extracted from these logs; namely whorl volume, distance between whorls and distance between pith and surface. These features were not measured in images but calculated from existing parameterised knots. Simulated test sawing shows that the reconstruction method results in a representative model of the knot structure in the log, when considering the grade distribution of the sawn timber produced by the simulation program. The results of this study could, for instance, be used for improved online quality predictions at sawmills. One step in this direction is to use industrial X-ray data to enlarge the amount of log data available for sawing simulation research. Future work can, therefore, focus on developing a practical application of the results presented here. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(4):374-383
In the forestry–wood chain the concept and the technologies of traceability are in a mature development phase. Important advances in marking and reading techniques have been made in different parts along the forestry–wood chain. For Swedish sawmills the most critical information gap is located between the log sorting station and the saw intake, where the forest log batch identity disappears and the logs are mixed according to different sorting criteria. This study utilizes radiofrequency identification tags for automatic log marking/reading to develop a traceability system for logs, which is free of marking/reading, between the log sorting station and the saw intake, i.e. the fingerprint method. The originality of the fingerprint approach rests on the hypothesis that logs are separate entities with individual features. The results show that the log parameters and the search algorithm developed, combined with the negative influence of the measurement uncertainty due to bark thickness and bark damage, made it possible to achieve an individual separation for 57% of the tested logs. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):119-126
The use of new technology such as 3D scanners for measuring log shape at sawmills is increasing. These scanners can provide a detailed model of log shape and evenness of the log mantle area. These data can be used for optimizing yield but also for predicting quality of the sawn goods. This report presents a model for quality - related log features based on data from a 3D log scanner. The model includes routines for development of variables related to four categories of log properties: surface unevenness, log taper, cross - sectional out - of - roundness and straightness. In total, 230 Scots pine (Pinus sylvestris L.) logs are used for developing and validating logistic regression models for sorting logs into classes of log type and knot size. The models are tested on validation data: 97% of the logs were sorted correctly according to log type and 79% were sorted correctly according to knot size. 相似文献
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Glen Murphy John Lyons Michael O’Shea Garret Mullooly Enda Keane Ger Devlin 《European Journal of Forest Research》2010,129(6):1057-1067
A set of tools are described for optimal allocation of wood fibre at an operational planning level. These were applied to
a case study in Ireland. Allocation was based on optimising net value recovery (delivered price minus harvesting and transportation
costs) while meeting market demands and operational constraints (mainly crew capability and productivity limits). Two new
models were developed to predict harvesting costs and transportation costs for Irish forest conditions. A new model was developed
to link Sitka spruce biomass expansion factors to optimal log-making algorithms so that log and bio-energy product yields
could be estimated for individual harvest areas. An existing operational allocation model based on a tabu search heuristic
procedure was used. The case study included 16 forest harvest areas and 12 processing plants (saw logs, pallet logs, stakes,
pulp, bio-energy slash bundles, etc.). New terrestrial lidar scanning procedures were used to obtain representative stem profiles
from over 4,000 trees for the 16 forests. We demonstrated that optimal allocation of bio-energy and log products, while complex,
can be achieved through the use of appropriate management tools. 相似文献
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A mill study of 62 trees, in which boards were reassembled into their original logs, permitted the construction of wood quality maps. In this instance stiffness profiles were obtained from butt to upper-top logs, based on machine stress grading of all boards and then averaging values from the 62 trees. Traditionally the butt log has been perceived to be the most valuable log in a tree, because it is bigger and gives a higher recovery of lumber. However, it is shown to contain a wide cone of very low stiffness wood that is confined to the first 2.4–2.7 m above ground level. Above this point stiffness gradients become cylindrical with no noticeable decrease in stiffness up the tree stem. Stiffness in all logs increased radially from pith to cambium with the greatest change being associated with the wood nearest the pith. The low stiffness at the base of the tree suggests that an alternative log bucking strategy should be considered, namely cutting a short 2.4–2.7 m butt log for plywood/LVL or for bolter sawing and only cutting standard length logs above this point.The least stiff logs (lowest 20%) yielded lumber that had an average stiffness that was over 1 GPa less than the average for the population. A case can be made for separating these logs and processing them differently. 相似文献