Plucking Point Research Articles

Development and field evaluation of a robotic harvesting system for plucking high-quality tea

The critical issue of the robotic harvesting high-quality tea is to realize tea shoot detection, plucking point localization, and motion planning. In addition, the accuracy and efficiency of the robotic plucking of high-quality tea in the field are essential. Therefore, a robotic harvesting system is proposed in this paper by combining deep learning, point cloud processing, and spatial path planning. First, the deep learning method and the compressed YOLOv3 network are used to quickly and accurately identify tea shoots. Second, an efficient point cloud processing-based 3D localization algorithm for high-quality tea plucking points was proposed. The genetic algorithm is then used to shorten the end-effector's motion path by optimizing the plucking sequences. Eventually, a harvester robot with a parallel manipulator was developed to conduct field plucking experiments and evaluate the effectiveness of the proposed harvesting system. All experimental results demonstrate that the success rates of detection, localization, and motion plucking are 85.16 %, 78.90 %, and 80.23 %, respectively. Furthermore, the overall process harvesting success rate is 53.91 %, and the average plucking time for a single shoot is 2.233 s. Therefore, the proposed harvesting approach can provide technical support for the precise and rapid harvesting of high-quality tea.

Assessing the Impact of Gas Flaring on Tea Plants in the South of Kothaloni OCS in the District of Dibrugarh, Assam, India

Effect of gas flaring on physiology and growth of tea plants was done by using Randomized Complete Block Design (RCBD) and analysis was done accommodating two seasons and five levels of distances during September 2019-March 2020. Plant samples were collected from (40-50) metres, (50-60) metres, (60-70) metres, (70-80) metres and control site (150-160) metres away from the tea garden situated south of kothaloni OCS in rainy and autumn seasons. The experimental plot was laid out at a distance of 40 metres away from the flare pit. The mean value of plant parameters namely relative turgidity, tea leaf area ,specific leaf weight, stomatal count, caffeine content, chlorophyll content, polyphenol content and plucking point density were decreased near the gas flaring while mean value of water saturation deficit of tea leaves recorded highest at distances closest to the flaring site.

Impact of Oil Field Effluent on Some Physico-Chemical Properties of Soil, Quality and Growth of Tea in the Plantation of Small Growers of Dibrugarh, Assam

Aims: To study the impact of the oil field effluents discharged to the plantation on soil physicochemical, quality and growth of the tea crop.
 Study Design: The experimental design was 4x2 Factorial Randomized Block Design with 3 replications.
 Place and Duration of Study: It was conducted in Department of Tea Husbandry & Technology, Assam Agricultural University, Jorhat during September, 2019 and November, 2019.
 Methodology: The total number of bushes per treatment are 35 each of +12 years age. The soil and plant samples were collected from four different levels of distance are D1: 0-21m; D2: 21-42m; D3: 42-63m and DC: beyond 63m (Control).
 Results: The results showed that, disregarding the Flushing season the tea grown in the vicinity of the oil pit recorded the lowest value of caffeine content (1.58%), total chlorophyll (1.54 mg g-1) total polyphenol content (21.47%) which was significantly lower than the tea grown away from the oil pit. The plucking point density and number of primaries per plant recorded the lowest value in the vicinity of the effluent pit. In case of soil physical parameters, both porosity and hydraulic conductivity recorded lowest value of 45.64% and 0.25 cm min-1, respectively. The bulk density of soil near the oil effluent pit recorded the highest value (1.31 Mg m-3) and gradually decreases. Soil pH, organic carbon content and electrical conductivity recorded highest value in the vicinity of the effluent pit. Regardless of the flushing season the available nitrogen and potassium recorded the highest. Available phosphorous of the soil adjacent to the effluent pit recorded the lowest value. Both quality and growth parameters had significantly higher value in the rain flush than the autumn flush. The soil parameters did not record any significant variation among the seasons.
 Conclusion: The vicinity area of the effluent pit found to be the most vulnerable.

Characterization of Some Perennial Pigmented Tea Accessions of Assam

Tea leaves has high antioxidant activity mainly due to presence of high amount of flavonoids and to some extent presence of pigments and has been a potential important raw material for the pharmaceutical industry. Therefore a study had been under taken to evaluate twenty (20 nos.) pigmented tea accessions exhibiting morphological variations of Experimental Garden for Plantation Crops, Assam Agricultural University, Assam to profile based on shoot growth and biochemical characters by field survey and laboratory investigation during the period 2017-18. Post hoc analysis was used to test the significance level and correlation similarity co-efficient matrix was used to analyze the genetic relationship among clones.
 The plucking point density which is an important criteria from yield point of view was found to be highest in THT 028 (0.158 g) with maximum fresh weight of young shoot for both Light Prune (LP) and Medium Skiff (MS) years whereas the maximum dry weight was found in THT 035 (0.036 g) followed by THT 028 (0.035 g) in both LP and MS years. An increasing trend of, antioxidant and total catechin content observed from rain flush to autumn flush in all the germplasms. The germplasms with purple young shoot colour THT 024, THT 032 and THT 039 had the highest anthocyanin content (39 mg/l, 43.7 mg/l and 40.56 mg/l respectively) and they can be further studied for development of specialty tea. The germplasms with higher catechin content (THT 027, THT 030 and THT 034) can be studied for development of parent material for green tea manufacturing. On hierarchical cluster analysis based on dendogram, THT 024, THT 032 and THT 039 formed discriminated clusters on the basis of shoot characters and biochemical characters which can be selected for future breeding programme.

Profiling of Few of the Tea Accessions on Physiological Growth and Stress Tolerance

Tea [Camellia sinensis(L) O Kuntz] is one of the oldest, most widely consumed and least expensive natural beverages, known to the world over for its heritage brew with various flavor and antioxidant properties. The productivity of tea in world as well as in India has been raised by developing high yielding clones and seed stocks but the genetic base of the existing diversity of the crop is rapidly narrowing down. In present scenario, apart from yield and quality, physiological parameters and abiotic stress tolerance are also raising up to be the most important environmental indicator impacting on sustainability and productivity of tea. In the published research work, an effort was made to characterize and estimate the variation of 20 tea germplasm named as THT1 to THT20, growing in the Experimental Garden for Plantation Crops, AAU, Jorhat on the basis of growth parameters and abiotic stress tolerance capability of tea.
 In the experiment all the germplasm showed highly significant difference amongst them regarding growth parameters, pigment content and on abiotic stress tolerance. THT 1, THT 10, THT 3 contained higher total chlorophyll and THT 4, THT 10, THT 20 showed high carotene content. In case of growth parameters THT 11, THT 7, THT5 showed higher plucking point density whereas THT 11, THT 17, THT 7 showed good abiotic stress tolerance with high value of proline content, relative turgidity, water saturation deficit and epicuticular wax content.
 When clustering was done based on abiotic stress tolerance, pigment and growth parameters respectively, THT11 and THT 17 are found to form a discriminated cluster in the dendogram. The parameters taken especially for abiotic stress tolerance study may be subjected to environmental factors for which more elaborated field trial may be required for these clones to assess their yield and quality parameters.

In-field tea shoot detection and 3D localization using an RGB-D camera

Tea shoot detection and localization are highly challenging tasks because of varying illumination, inevitable occlusion, tiny targets, and dense growth. To achieve the automatic plucking of tea shoots in a tea garden, a reliable algorithm based on red, green, blue-depth (RGB-D) camera images was developed to detect and locate tea shoots in fields for tea harvesting robots. In this study, labeling criteria were first established for the images collected for multiple periods and varieties in the tea garden. Then, a “you only look once” (YOLO) network was used to detect tea shoot (one bud with one leaf) regions on RGB images collected by an RGB-D camera. Additionally, the detection precision for tea shoots was 93.1% and the recall rate was 89.3%. To achieve the three-dimensional (3D) localization of the plucking position, 3D point clouds of the detected target regions were acquired by fusing the depth image and RGB image captured by an RGB-D camera. Then, noise was removed using point cloud pre-processing and the point cloud of the tea shoots was obtained using Euclidean clustering processing and a target point cloud extraction algorithm. Finally, the 3D plucking position of the tea shoots was determined by combining the tea growth characteristics, point cloud features, and sleeve plucking scheme, which solved the problem that the plucking point may be invisible in fields. To verify the effectiveness of the proposed algorithm, tea shoot localization and plucking experiments were conducted in the tea garden. The plucking success rate for tea shoots was 83.18% and the average localization time for each target was about 24 ms. All the results demonstrate that the proposed method could be used for robotic tea plucking.

Computer vision-based high-quality tea automatic plucking robot using Delta parallel manipulator

Aiming to reduce the labour cost and improve the competitiveness of the tea production, this paper presents a complete solution, including the mechanical structure, the visual recognition system (VRS) and the motion control system of the high-quality tea automatic plucking robot. The design objectives involve high reliability and stability, ease of maintenance, cost-effectiveness, accurate recognition and localization of tea shoots, and high-efficient plucking manipulation. The VRS is established using the computer vision together with corresponding machine learning algorithms, where the Particle swarm optimization-Support vector machine algorithm and the deep convolutional neural YOLOv3 model are developed to recognize the tender tea shoots and localize the plucking point, according to the images captured by the global and local cameras, respectively. The Delta parallel manipulator equipped with a shear cutter is adopted to execute the trajectory tracking and tea plucking operations. The improved ant colony algorithm is utilized for path planning and trajectory smoothing of the manipulator. Simulation and laboratory platform experiment results verify the feasibility and effectiveness of the presented solution.

Localizing plucking points of tea leaves using deep convolutional neural networks

Tea (Camellia sinensis) is one of the most commonly consumed beverages worldwide. Tea leaves are plucked by hand or using a machine. Hand plucking prevents broken leaves and ensures that only the most essentially favorable parts are plucked (e.g., one tip with two leaves [OTTL]); thus, hand-plucked tea usually has high economic value. Localizing the plucking points of tea is the first step to develop a high-quality tea-plucking machine. In this study, we proposed to identify the plucking points of tea shoots in fields using machine vision and deep learning. In the study, images of various tea bush varieties were acquired from tea gardens using digital cameras and cell phones. A faster region-based convolutional neural network (Faster R-CNN) was first trained to detect OTTL regions in the images. A fully convolutional network (FCN) was subsequently trained to identify the plucking points in the OTTL regions. The Faster R-CNN model achieved a precision of 79% and a recall of 90%. The FCN achieved a mean accuracy of 84.91% and a mean intersection-over-union of 70.72%. The experiment demonstrated that the developed algorithms can also be used on varieties other than those used to train the model.

Algorithmic derivation of CO2 assimilation based on some physiological parameters of tea bushes in North-East India

Tea, an evergreen shrub, is commercially cultivated in dense population as bushes in tea gardens. Periodical pruning of tea bushes makes tea plants distinct from other tree plants. Tea bushes have almost constant height throughout their life-time and have more compact canopy as compared to any forest trees. Hence, established methods of elucidating carbon dioxide (CO2) absorption in forest trees could not be employed for measuring CO2 assimilation in tea bushes. In this study, CO2 assimilation potentials of a high-yielding tea cultivar and a better quality producing tea cultivar had been periodically measured by closed-chamber method under field condition. Such type of experiment was not conducted before. This study revealed that tea bushes had potential to assimilate 1243.8–2526.7 kg CO2 ha−1 year−1 and the high yielding tea cultivar absorbed significantly higher amount of CO2 as compared to better quality producing tea cultivar. Several physiological parameters namely number of branches, plucking point density, leaf area and stomatal index were positively correlated to the annual CO2 assimilation by tea bushes. Higher CO2 assimilation in high yielding tea cultivars can be attributed to their larger and dense canopy structure due to more branching, higher plucking point density and higher leaf area. An algorithm has been derived for computing CO2 assimilation in tea bushes by considering the above-mentioned variable as indicators. This will enable to determine CO2 assimilation by tea plantation over a large area by measuring the physiological indicators without exercising in-situ experiments.

Evaluating the efficacy of six novel indigenous free-living soil bacteria on tea plant of North Bengal tea gardens of West Bengal India and their antagonistic effect on some tea pathogenic fungi

: Efficay of six indigenous nonsymbiotic free living soil bacteria namely DS-1-20 (Stenotrophomonas sp Accession No. KY636360), DS-2-10 (Herbaspirillum sp Accession No. KX587468), DJ-1-22 (Burkholderia sp Accession No. KY 859855), DJ-1-3 (Burkholderia sp Accession No. KY 636359 ), TS-3-15 (Stenotrophomonas sp Accession No. KY631488 ) and AS-1-4 (Stenotrophomonas sp Accession No. KY636361 ) has evaluated in tea fields of North Bengal Tea Gardens for subsequent two years . Remarkable increase in yield ( green leave production) and plucking point compare to the control is observed. Among the six strains so far tested the DS-2-10 i.e. a bacterium of the genus Herbaspirillum sp have showed maximum response compare to the other five strains in the context of green leave production(145kg in first year and 150.87kg in second year) and plucking point (88.75 in first year and 91 in second year) which are statistically significant (P

Pickup position and plucking point estimation on an electric guitar via autocorrelation.

This paper proposes a technique that estimates the locations along the string of the plucking event and the magnetic pickup of an electric guitar based on the autocorrelation of the spectral peaks. To improve accuracy, a method is introduced to flatten the spectrum before applying the autocorrelation function to the spectral peaks. The minimum mean squared error between the autocorrelation of the observed data and the electric guitar model is found in order to estimate the model parameters. The accuracy of the algorithm is tested on various plucking positions on all open strings for each pickup configuration. The accuracy of the proposed method for various plucking dynamics and fret positions is also evaluated. The method yields accurate results: the average absolute errors of the pickup position and plucking point estimates for single pickups are 3.53 and 5.11 mm, respectively, and for mixed pickups are 8.47 and 9.95 mm, respectively. The model can reliably distinguish which pickup configuration is selected using the pickup position estimates. Moreover, the method is robust to changes in plucking dynamics and fret positions.

Effect of foliar fertilizer application on yield, and yield components of tea (Camellia sinensis Var. Assamica (Mast.) Kitamura)

The experiment on the effect of foliar fertilizer (29% N, 10% P2O5, 10% K2O, 3% MgO, 5% SO3, and micro compound B, 0,0075% Cu, 0,026% Fe, 0,032% Mn and 0,023% Zn) concentration on growing tea (Camellia sinensis) and productivity was con­ducted in Research Institute for Tea and Cin­chona Experimental Plantation on the altitude of 1.350 m above sea level and Andisol type soilfrom August to November 2013 with GMB 7 clones. The experiment was arranged in a randomized block design with 3 treatments and 4 replicates. Concentration levels of fertilizer were 1) 0% as control, 2) 2%, and 3) 4%. The results showed that productivity increased significantly, control (465,25 g/10 plantation) compared with the plants were treated with 2% (564,58 g/10 plantation) and 4% (573,46 g/10 plantation) fertilizer, respectively. The increase of productivity was due to increased of plucking point, quantity and weight of pecco and length of leaves.Â

Influence of potassium solubilizing bacteria on crop productivity and quality of tea (Camellia sinensis)

A field experiment was conducted to study the efficacy of indigenous potassium solubilizing bacteria (KSB) in combination with various dosages of potash fertilizers along with recommended dose of nitrogen (N) and phosphorus (P) fertilizers in tea plants. Soil and leaf samples were drawn from the respective plots and they were subjected for the analysis of various parameters related to nutrients and quality aspects. Among various treatments, plants treated with N100 P100 K75 + KSB concentration formulation was found to be the best in terms of high chlorophyll, carotenoid, N, P and K contents in the crop shoots followed by other treatments. Significantly higher yield of the green leaf was achieved by the same treatment. K content in soil and also in crop shoots was greatly improved due to the application of KSB along with possible reduced doses of potash source. On the other hand, N100 P100 K25 + KSB formulation and untreated control plots have exhibited least green leaf yield and nutrient status of soil and crop shoots. The biochemical parameters, total polyphenols, catechins, amino acids and sugars were significantly at higher level in plants after imposing treatments in combination with KSB. Biometric parameters such as plucking surface of the tea bush canopy, plucking points per unit area, internodal length, leaf moisture and dry matter contents were analyzed and found to be high in tea plants treated with N100 P100 K75 + KSB combination. Banji content was significantly reduced invariably in all the treatments except the untreated control plots. Evaluation of KSB population in soil revealed thatwherever KSB was incorporated, there was a significant increase in population level and has coincided with dehydrogenase enzyme activity. The flush shoots of tea comprising of three leaves and a bud were subjected to manufacture black tea, and it was revealed that almost all the tea quality parameters such as theaflavin, thearubigin, highly polymerized substances, total liquor colour, caffeine, briskness, colour and flavour indexes were greatly improved in KSB treated plants, which in turn improve the quality as well. This finding confirms that the influence of indigenous potassium solubilizing bacteria upon potassium nutrient exhibited improvement in the productivity and nutrient uptake in plants and retained in soil including quality parameters in tea plantations. Key words: Tea, potassium solubilizing bacteria, biofertilizer, nutrient status, crop productivity, tea quality.

Evaluation of various fungicides and microbial based biocontrol agents against bird’s eye spot disease of tea plants

A field experiment was conducted to study the efficacy of six fungicides comprising contact, systemic and botanical fungicides and three biocontrol agents for the management of bird’s eye spot disease in tea plantations. Among 16 treatments, systemic fungicides were found to be superior to biocontrol agents in controlling the disease whereas the maximum green leaf yield was significantly increased in those applied with biocontrol agents. On the whole, Streptomyces sannanensis offered the maximum yield of 3998 kg ha −1 made tea followed by Trichoderma harzianum (3884 kg ha −1 made tea). Between the two different carrier materials evaluated for the application of biocontrol agents, vermicompost-based bioformulation showed better efficacy than talc-based formulation. Of the three (bacteria, fungi and actinomycetes) groups of biocontrol agents, S. sannanensis was better than Pseudomonas fluorescens and Trichoderma atroviride belonging to bacterial and fungal antagonists; respectively in terms of disease protection and increasing yield potential. Similarly, the biometric, physiological and biochemical parameters were also increased in plants greatly after imposing various treatments. Plucking surface of the bush, number of plucking points per unit area, internodal length, leaf moisture and dry matter contents were found higher in plots applied with biocontrol agents than those treated with fungicides. Almost all of the tea quality parameters such as total liquor colour, thearubigins, theaflavins, highly polymerized substance and caffeine were significantly improved in biocontrol treated plants. Theaflavin and thearubigin contents were increased in the range of 9.00–9.57% and 1.27–1.54% respectively in vermin based treatment. Similarly the amount of caffeine content (3.66–4.08%) and flavour index (4.18–5.31%) were considerably enhanced.

A time-domain approach to estimating the plucking point of guitar tones obtained with an under-saddle pickup

A method for estimating the plucking point of guitar tones is proposed. The algorithm is based on investigating the time lag between two consecutive pulses arriving at the bridge of the guitar. The signal is detected with an under-saddle pickup attached to the bridge. The method determines the minimum of the autocorrelation function for one period of the signal. The time lag of the minimum can be converted into the distance from the bridge where the string was plucked. The results obtained with the method are good, the error remains smaller than one centimetre, except for a few outliers. The algorithm is easy to implement and can be used to analyse playing styles. The efficiency of the method gives the potential to also use it in real-time computer music applications.

Synthesizer detecting pitch and plucking point of stringed instrument to generate tones

In an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting device utilizes a pickup (3) for picking up the acoustic vibration to convert the same into a waveform signal. Further, a first detector (13) operates according to a fast algorithm for processing the waveform signal so as to responsively produce a first output representative of the pitch of the acoustic vibration, and a second detector (12) operates in parallel to the first detector (13) for processing the same waveform signal according to a slow algorithm so as to stably produce a second output representative of the pitch of the acoustic vibration. A selector (17) selectively feeds one of the first output and the second output to the tone generator so that the first detector (13) and the second detector (12) can cooperate complementarily with each other to ensure responsive and stable detection of the pitch of the acoustic vibration. An additional detector (15) processes the waveform signal to measure a time interval between a pair of the peaks so as to detect a plucking point. A controller (21) controls the tone generator according to the detected plucking point to change the timbre of the tone generator in response to the plucking point.

Early Flemish harpsichord string scalings and their acoustical implications

Measurements of string lengths and diameters in historical harpsichords such as those made by the Ruckers family, active in Antwerp from 1579 to the 1680s, are commonly used to calculate: (1) the pitch at which they were intended to be tuned, based on the assumption that strings were stressed to the practical limits of their tensile strength; and (2) the resulting tensions. Consideration of early music theory and workshop design practices have led to the proposal of alternative assumptions that some pre-Ruckers’ makers employed shorter string lengths. With other variables remaining constant, higher calculated coefficients of inharmonicity result. The strings, however, were probably thinner, therefore resulting in inharmonicities similar to those of Ruckers’ instruments. Further, coupling with sympathetically vibrating generally undamped strings of the earliest harpsichords might have reduced the theoretically calculated inharmonicities of the upper partials of bass and tenor strings. Other aspects to consider in light of early instrument makers’ use of traditional geometrical methods of design include: (1) the Ruckers’ slight lengthening of virginal (rectangular harpsichord) E, F-sharp, and G-sharp strings intended to be tuned in meantone temperament, in which these pitches are flatter than in equal temperament; and (2) the development of reasonable plucking points.

Scaling rules for organ flue pipe ranks and for the string choirs of harpsichords

The criteria for design of an organ flue pipe rank, properly balanced and coherent in power and harmonic development, are discussed in terms of present understanding of the sound production process. A scaling with pipe diameter D proportional to ν1−x, where ν1 is pipe fundamental frequency and x = 0.83, is found to give approximately constant harmonic development across the rank but too much loudness in the bass. The traditional scaling rule with x = 0.75 nearly equalizes the loudness and increases harmonic development towards the bass of the rank. Similar criteria applied to the string choirs of harpsichords, in which decay time must be considered as well, lead to scaling rules which increase wire diameter and move the plucking point progressively towards the end of the string in the bass. The relations between the two types of scaling rule are discussed.