Design of a flexible end-effector based on characteristics of tomatoes

Zhou, Kehong; Xia, Liru; Li, Jun; Qian, Mingyan; Pi, Jie

doi:10.25165/j.ijabe.20221502.6672

Cited by 8 publications

(5 citation statements)

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“…The maximum allowable harvesting force for tomato picking during the TU period is based on the experimental data obtained by scholars such as Zhou [33], which is 11.13 N. Tomatoes were subjected to compression experiments using a precision push-pull force gauge, and the results were not significantly different from 11.13 N. Therefore, when picking tomatoes, once the RedPitaya development board detects that the force on the FSR sensor reaches 11.13 N, the digital output port that powers the force analysis module and controls the inflation of the end effector on the RedPitaya will be changed to a low level, that is, the force analysis circuit will be disconnected, and the attitude of the end effector will be fixed.…”

Section: Force Compensation Analysismentioning

confidence: 99%

Design of a Tomato Sorting Device Based on the Multisine-FSR Composite Measurement

et al. 2023

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The ripeness of tomatoes is crucial to determining their shelf life and quality. Most of the current methods for picking and sorting tomatoes take a long time, so this paper aims to design a device for sorting tomatoes based on force and bioelectrical impedance measurement. A force sensor installed on each of its four fingers may be used as an impedance measurement electrode. When picking tomatoes, the electrical impedance analysis circuit is first connected for pre-grasping. By applying a certain pre-tightening force, the FSR sensor on the end effector finger can be tightly attached to the tomato and establish an electric current pathway. Then, the electrical parameters of the tomato are measured to determine its maturity, and some of the electrical parameters are used for force monitoring compensation. Then, a force analysis is conducted to consider the resistance of the FSR under current stress. According to the principle of complex impedance circuit voltage division, the voltage signal on the tomato is determined. At the same time, the specific value of the grasping force at this time is determined based on the calibration of the pre-experiment and the compensation during the detection process, achieving real-time detection of the grasping force. The bioelectricity parameters of tomatoes can not only judge the ripeness of tomatoes, but also compensate for the force measurement stage to achieve more accurate non-destructive sorting. The experimental results showed that within 0.6 s of stable grasping, this system could complete tomato ripeness detection, improve the overall tomato sorting efficiency, and achieve 95% accuracy in identifying ripeness through impedance.

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Section: Force Compensation Analysismentioning

confidence: 99%

Design of a Tomato Sorting Device Based on the Multisine-FSR Composite Measurement

et al. 2023

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“…When the tomato is grasped by flexible fingers, the pulp of the tomato is squeezed, and the middle part of the tomato is the least compressive [17]. In order to study the compressive resistance of the middle position of the tomato, the compressive mechanical properties test was carried out on the tomatoes.…”

Section: Compression Mechanical Properties Testmentioning

confidence: 99%

Research on the Bionic Flexible End-Effector Based on Tomato Harvesting

Guo

Zheng

et al. 2022

Journal of Sensors

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Aiming at the problems that tomatoes are fragile and the traditional end-effector design is not suitable for tomato picking, a combination of the bionic principle of FRE structure and finger design was proposed. Based on the physical properties of tomatoes, a flexible underactuated end-effector for tomato picking and sorting was designed. The optimal structural parameters of fingers were determined by finite element analysis, and the tomato grasping experiment was carried out. The results show that the flexible end can grasp and transport tomatoes with diameters ranging from 65 to 95 mm without damage, which can withstand 7 N tensile force, the load is more than 2 times of its own weight, the tomato coverage rate is greater than 23.6%, and the effective grab rate is 100% and has the advantages of the strong stability, universality, and protection. The research provides a novel solution for the design and application of the tomato picking and sorting robot end-effector.

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“…Set θ to 75° according to the finger arc. According to the literature ( Zhou et al, 2022 ), the static friction coefficient μ s on the silicone pad is 1.34 N/N. According to the data obtained from the above experiments, the maximum instantaneous tensile force T is about 15.29 N. Bring in the formula to obtain F N ≥ 2.65 N, 3 F N ≥ 7.95 N, indicating that the total force of the three fingers on the tomato is less than the minimum damage force of the tomato.…”

Section: Gripper Simulation Experimentsmentioning

confidence: 99%

“…It has obvious advantages when grasping soft and crisp tomato fruit. The Kehong Zhou team of Jiangsu University ( Zhou et al, 2022 ) and the Asiwan Kultongkham team of King Mongkut’s University of Technology Thonburi ( Kultongkham et al, 2021 ) designed a tomato-picking soft gripper based on fluid elastic actuation, which grasps the tomato by inflating and deflating. However, when faced with the problem of tomato stacking, due to the large size of the flexible fingers, it is not easy to penetrate into the tomato gap.…”

Section: Introductionmentioning

confidence: 99%

Design and simulation of a gripper structure of cluster tomato based on manual picking behavior

Zheng

Guo

et al. 2022

Front. Plant Sci.

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Picking robot technology plays an important role in the rapid promotion of precision agriculture. The development of a successful robot gripper is critical for the final promotion and industrialization of the tomato picking robot. This paper investigated the cluster tomato picking strategy and the gripper structure design based on this strategy to address the problem of poor adaptability of the existing gripper design in the cluster tomato picking scene. Starting from the research on the behavior of artificially picking cluster tomatoes, the grasping method, finger structure parameters and picking movement pattern of the human hand are analyzed. The evaluation criteria of the gripper are summarized, a simplified mathematical model of the gripper is established, and the picking strategy under the model of the gripper is proposed. Furthermore, according to the simplified gripper model, a rigid-flexible coupling gripper structure is designed, and the gripping simulation analysis is carried out. According to the simulation results, the gripper can smoothly grab medium and large tomatoes with diameter of 65∼95 mm. The peak force and fluctuation force of tomato with different sizes during grasping were less than the tomato’s minimum damage force. The gripper has adaptability and stability characteristics, providing technical support for gripper manufacturing and the construction of a picking system for a tomato picking robot.

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Design of a flexible end-effector based on characteristics of tomatoes

Cited by 8 publications

References 0 publications

Design of a Tomato Sorting Device Based on the Multisine-FSR Composite Measurement

Design of a Tomato Sorting Device Based on the Multisine-FSR Composite Measurement

Research on the Bionic Flexible End-Effector Based on Tomato Harvesting

Design and simulation of a gripper structure of cluster tomato based on manual picking behavior

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