An end-effector for a flexible drilling robot is designed, and a novel four-point algorithm of normal attitude regulation for this end-effector is presented. Four non-coplanar points can define a unique sphere tangent...An end-effector for a flexible drilling robot is designed, and a novel four-point algorithm of normal attitude regulation for this end-effector is presented. Four non-coplanar points can define a unique sphere tangent to them in spatial geometry, and the center point of the sphere and the radius can be calculated. The shape of a workpiece surface in the machining area is approximately regarded as such a sphere. A vector from the machining point to the center point is thus approximately regarded as a normal vector to the workpiece surface. By this principle, the algorithm first measures four coordinates on the curve in the drilling region using four sensors and calculates the normal vector at the drilling point, then calculates the error between the normal vector and the axis of the spindle. According to this error, the algorithm further figures out the angles of two revolving axes on the end- effector and the displacements of three linear axes on the robot main body, thus it implements the function of adjusting the spindle to be perpendicular to the curve at the drilling point. Simulation results of two kinds of curved surfaces show that accuracy and efficiency can be realized using the proposed algorithm.展开更多
The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit.Currently,there are few researches about the end-effector,and the existing end...The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit.Currently,there are few researches about the end-effector,and the existing end-effectors have some disadvantages,such as poor misalignment tolerance capability and complex mechanical components.According to the end positioning errors and the residual vibration characters of the large space manipulators,two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are proposed.And the end-effector should accommodate the following misalignments of the mechanical interface.The translation misalignments in axial and radial directions and the angular misalignments in roll,pitch and yaw are ±100 mm,100 mm,±10°,±15°,±15°,respectively.Seven end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed elementarily.The three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes,and they are designed in detail.The capabilities of misalignment tolerance and soft capture are validated and evaluated,through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS software.The results show that the misalignment tolerance capabilities of these two schemes could satisfy the requirement.And the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll,pitch and yaw of the steel cable-snared end-effector are 30mm,15mm,6°,3° and 3° larger than those of the three fingers-three petals end-effector,respectively.And the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals end-effector.The end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and the space docking mechanism.展开更多
The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture.According to these requirements,an end-effector prototype combining the tendon-shea...The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture.According to these requirements,an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured.An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed,and it was a guideline of the end-effector design.Furthermore,the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space.The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software.The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture.The translation misalignments in radial directions are±100 mm,and angular misalignments about pitch and yaw are±15°.展开更多
In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture t...In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.展开更多
The most widely adopted method for diagnosing respiratory infectious diseases is to conduct polymerase chain reaction(PCR)assays on patients’respiratory specimens,which are collected through either nasal or oropharyn...The most widely adopted method for diagnosing respiratory infectious diseases is to conduct polymerase chain reaction(PCR)assays on patients’respiratory specimens,which are collected through either nasal or oropharyngeal swabs.The manual swab sampling process poses a high risk to the examiner and may cause false-negative results owing to improper sampling.In this paper,we propose a pneumatically actuated soft end-effector specifically designed to achieve all of the tasks involved in swab sampling.The soft end-effector utilizes circumferential instability to ensure grasping stability,and exhibits several key properties,including high load-to-weight ratio,error tolerance,and variable swab-tip stiffness,leading to successful automatic robotic oropharyngeal swab sampling,from loosening and tightening the transport medium tube cap,holding the swab,and conducting sampling,to snapping off the swab tail and sterilizing itself.Using an industrial collaborative robotic arm,we integrated the soft end-effector,force sensor,camera,lights,and remote-control stick,and developed a robotic oropharyngeal swab sampling system.Using this swab sampling system,we conducted oropharyngeal swab-sampling tests on 20 volunteers.Our Digital PCR assay results(RNase P RNA gene absolute copy numbers for the samples)revealed that our system successfully collected sufficient numbers of cells from the pharyngeal wall for respiratory disease diagnosis.In summary,we have developed a pharyngeal swab-sampling system based on an“enveloping”soft actuator,studied the sampling process,and imple-mented whole-process robotic oropharyngeal swab-sampling.展开更多
This study investigates the necessity for space robots to independently exchange their end-effectors due to the contradiction that exists between the requirements of various robots in space missions and the payload ca...This study investigates the necessity for space robots to independently exchange their end-effectors due to the contradiction that exists between the requirements of various robots in space missions and the payload capacity limits of rockets. The results of this study summarize the system requirements for a new end-effector exchange mechanism, including compact size, misalignment tolerance, and regolith tolerance. This is followed by the development of a prototype model with a set of test apparatus. Then the function of the prototype is verified, the prototype is optimized, and the relation between docking force and misalignment is examined through operation tests.展开更多
The automated picking technology of tea is an important part of the development of smart agriculture, which affects the development of the tea industry to a certain extent. Tea leaf recognition and robotic tea picking...The automated picking technology of tea is an important part of the development of smart agriculture, which affects the development of the tea industry to a certain extent. Tea leaf recognition and robotic tea picking end-effector are the key technologies for automated tea picking. This paper proposes a set of algorithms for tea leaf differentiation and recognition based on the principle of colour difference. And on the basis of this algorithm, a tea picking end-effector is designed. The experiments show that the designed tea picking end-effector has good recognition ability and high tea picking speed.展开更多
A suitable picking method for the end-effector is the key to achieving low-damage picking.Due to the high moisture content of fresh safflower and its fragile filaments,achieving low-damage picking is a challenge for m...A suitable picking method for the end-effector is the key to achieving low-damage picking.Due to the high moisture content of fresh safflower and its fragile filaments,achieving low-damage picking is a challenge for most picking robots.In this paper,a clamping and root-cutting end-effector for harvesting fresh safflower is developed.It utilizes dual rollers to pre-clamp the filaments and a blade to root-cut the safflower necking to realize the safflower harvesting operation.A mechanical model of dual rollers-blade-filaments cutting was constructed to theoretically analyze the harvesting process.The key factors affecting the performance of the end-effector were identified as blade feed speed,rotation speed,and roller clearance.Using the filament removal rate and damage rate as evaluation indices,the central composite design was carried out.The mathematical model between the test factors and evaluation indices was obtained,and the regression model was optimized with multiple objectives.Finally,the optimal combination of parameters was determined to be a blade feed speed of 40 mm/s,a rotation speed of 318 r/min,and a roller clearance of 0.60 mm.The field test was conducted under the optimal parameter combination,and the filament removal rate and damage rate were 91.25%and 5.57%,respectively.The optimized results had an error of less than 5%,indicating that the designed end-effector can harvest filaments with high removal and low damage rates.This study provides a reference for the low-damage harvesting of fresh safflower.展开更多
Safflower is one of the most important oil crops worldwide.To improve the efficiency and quality of harvesting soft safflower filaments,minimize filament damage by the blade,and ensure the integrity of the filaments,a...Safflower is one of the most important oil crops worldwide.To improve the efficiency and quality of harvesting soft safflower filaments,minimize filament damage by the blade,and ensure the integrity of the filaments,an end-effector with a rotary push-cut-type negative-pressure airflow was designed.The design of the rotary blade edge curve was based on Archimedean and logarithmic spirals.The effect of the Archimedean spiral on the pushing of the scattered filaments was investigated.The rotary-cutting force and speed of the logarithmic helix on the soft filaments were analyzed.The sliding cut angle and feed speed of the blade are the key factors governing filament removal and damage.A simulation model of the cutting chamber flow field was established for the change in airflow with the position and speed rotation of the blade,allowing analysis of the parameters of the negative-pressure airflow.Single-factor and Box-Behnken tests were performed with the sliding cut angle,blade feed speed,and negative-pressure airflow speed as influencing factors and filament removal,damage,and drop rate as indices.The response surface clarified the effects of various factors on these indices.Optimal parameters were a sliding cut angle of 32.20°,a blade feeding speed of 0.031 m/s,and a negative-pressure airflow speed of 4.57 m/s.The corresponding filament removal,damage,and drop rates were 93.47%,6.94%,and 4.33%,respectively.Optimization results showed that filament removal,damage,and drop rates were 93.50%,7.02%,and 4.43%,respectively.The harvesting process met the requirements of high efficiency and low damage.展开更多
The space manipulator which has advantages of high dexterity and universality, is used to the space capturing usually. According to the different types of mechanical interfaces of targets, the on orbit capturing opera...The space manipulator which has advantages of high dexterity and universality, is used to the space capturing usually. According to the different types of mechanical interfaces of targets, the on orbit capturing operation includes capturing of cooperative target and capturing of uncooperative target. The performances of the famous large space manipulators named space shuttle remote manipulator system(SRMS), the space station remote manipulator system(SSRMS) and the Europe robotic arm(ERA) are reviewed and studied respectively. Moreover, the space manipulators being developed by China for space station is also surveyed. Based on the performance analysis of the large space manipulators and end-effectors, which are adapted to the construction and daily maintenance for the large space structure such as the space station, the basic requirements of large misalignment tolerance capability, soft capturing capability and hard docking capability for the end-effector of large space manipulator are proposed in this paper. According to these requirements, the capture mechanism and methods that can enable the end-effector to have the capability of misalignment tolerance and soft capturing are presented. The development trend and key technologies of the large space manipulators and the end-effectors are also reviewed.展开更多
The harvesting of fresh kiwifruit is a labor-intensive operation that accounts for more than 25%of annual production costs.Mechanized harvesting technologies are thus being developed to reduce labor requirements for h...The harvesting of fresh kiwifruit is a labor-intensive operation that accounts for more than 25%of annual production costs.Mechanized harvesting technologies are thus being developed to reduce labor requirements for harvesting kiwifruit.To improve the efficiency of a harvesting robot for picking kiwifruit,we designed an end-effector,which we report herein along with the results of tests to verify its operation.By using the established method of automated picking discussed in the literature and which is based on the characteristics of kiwifruit,we propose an automated method to pick kiwifruit that consists of separating the fruit from its stem on the tree.This method is experimentally verified by using it to pick clustered kiwifruit in a scaffolding canopy cultivation.In the experiment,the end-effector approaches a fruit from below and then envelops and grabs it with two bionic fingers.The fingers are then bent to separate the fruit from its stem.The grabbing,picking,and unloading processes are integrated,with automated picking and unloading performed using a connecting rod linkage following a trajectory model.The trajectory was analyzed and validated by using a simulation implemented in the software Automatic Dynamic Analysis of Mechanical Systems(ADAMS).In addition,a prototype of an end-effector was constructed,and its bionic fingers were equipped with fiber sensors to detect the best position for grabbing the kiwifruit and pressure sensors to ensure that the damage threshold was respected while picking.Tolerances for size and shape were incorporated by following a trajectory groove from grabbing and picking to unloading.The end-effector separates clustered kiwifruit and automatically grabs individual fruits.It takes on average 4–5 s to pick a single fruit,with a successful picking rate of 94.2%in an orchard test featuring 240 samples.This study shows the grabbing–picking–unloading robotic end-effector has significant potential to facilitate the harvesting of kiwifruit.展开更多
The end-effector is the last executing part of the interaction between robots and fruits.In this study,the physical characteristics of tomatoes and the tomato end-effector of the fluidic elastomer actuator type were s...The end-effector is the last executing part of the interaction between robots and fruits.In this study,the physical characteristics of tomatoes and the tomato end-effector of the fluidic elastomer actuator type were studied.There was no correlation between the test point,the mass,the size and the rupture force of tomatoes.The non-destructive clamping force of tomatoes was 11.13 N.There were statistically significant correlations between the number of finger chambers,the transverse diameter of tomatoes,the inflation pressure and the clamping force.The inflation pressure and the size of tomatoes were directly proportional to the clamping force.Since fingers with more chambers had higher flexibility,the number of chambers was inversely proportional to the slope of the horizontal force-pressure curve,and the number of chambers was directly proportional to the angle between the total clamping force and the horizontal direction.A flexible end-effector was designed by genetic algorithm according to the physical characteristics of tomatoes and the simulation results of the finger of the end-effector.The test results of the end-effector showed that the tomatoes would be successfully clamped by the end-effector composed of three four-chamber fingers in a static situation with the inflation pressure less than the optimized inflation pressure(28.293 kPa).When in a dynamic situation,the success rate of tomatoes being clamped by the end-effector with an inflation pressure of 29 kPa was 97%.The tomatoes in the static clamping test and the dynamic clamping test were not damaged.展开更多
基金National Science and Technology Major Project(No.2009ZX04014-023)
文摘An end-effector for a flexible drilling robot is designed, and a novel four-point algorithm of normal attitude regulation for this end-effector is presented. Four non-coplanar points can define a unique sphere tangent to them in spatial geometry, and the center point of the sphere and the radius can be calculated. The shape of a workpiece surface in the machining area is approximately regarded as such a sphere. A vector from the machining point to the center point is thus approximately regarded as a normal vector to the workpiece surface. By this principle, the algorithm first measures four coordinates on the curve in the drilling region using four sensors and calculates the normal vector at the drilling point, then calculates the error between the normal vector and the axis of the spindle. According to this error, the algorithm further figures out the angles of two revolving axes on the end- effector and the displacements of three linear axes on the robot main body, thus it implements the function of adjusting the spindle to be perpendicular to the curve at the drilling point. Simulation results of two kinds of curved surfaces show that accuracy and efficiency can be realized using the proposed algorithm.
基金supported by National Hi-tech Research and Development Program of China(863 Program,Grant No. 2006AA04Z228)
文摘The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit.Currently,there are few researches about the end-effector,and the existing end-effectors have some disadvantages,such as poor misalignment tolerance capability and complex mechanical components.According to the end positioning errors and the residual vibration characters of the large space manipulators,two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are proposed.And the end-effector should accommodate the following misalignments of the mechanical interface.The translation misalignments in axial and radial directions and the angular misalignments in roll,pitch and yaw are ±100 mm,100 mm,±10°,±15°,±15°,respectively.Seven end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed elementarily.The three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes,and they are designed in detail.The capabilities of misalignment tolerance and soft capture are validated and evaluated,through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS software.The results show that the misalignment tolerance capabilities of these two schemes could satisfy the requirement.And the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll,pitch and yaw of the steel cable-snared end-effector are 30mm,15mm,6°,3° and 3° larger than those of the three fingers-three petals end-effector,respectively.And the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals end-effector.The end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and the space docking mechanism.
基金Project(2006AA04Z228) supported by National Hi-tech Research and Development Program of China
文摘The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture.According to these requirements,an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured.An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed,and it was a guideline of the end-effector design.Furthermore,the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space.The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software.The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture.The translation misalignments in radial directions are±100 mm,and angular misalignments about pitch and yaw are±15°.
基金Project(2006AA04Z228) supported by the National High Technology Research and Development Program of China
文摘In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.
基金Supported by National Natural Science Foundation of China(Grant Nos.52222502,92048302,and 51975306)Research Project of State Key Laboratory of Mechanical System and Vibration of China(Grant No.MSV201904)Emergency Research Project for COVID-19 from Institute for Precision Medicine of Tsinghua University of China.
文摘The most widely adopted method for diagnosing respiratory infectious diseases is to conduct polymerase chain reaction(PCR)assays on patients’respiratory specimens,which are collected through either nasal or oropharyngeal swabs.The manual swab sampling process poses a high risk to the examiner and may cause false-negative results owing to improper sampling.In this paper,we propose a pneumatically actuated soft end-effector specifically designed to achieve all of the tasks involved in swab sampling.The soft end-effector utilizes circumferential instability to ensure grasping stability,and exhibits several key properties,including high load-to-weight ratio,error tolerance,and variable swab-tip stiffness,leading to successful automatic robotic oropharyngeal swab sampling,from loosening and tightening the transport medium tube cap,holding the swab,and conducting sampling,to snapping off the swab tail and sterilizing itself.Using an industrial collaborative robotic arm,we integrated the soft end-effector,force sensor,camera,lights,and remote-control stick,and developed a robotic oropharyngeal swab sampling system.Using this swab sampling system,we conducted oropharyngeal swab-sampling tests on 20 volunteers.Our Digital PCR assay results(RNase P RNA gene absolute copy numbers for the samples)revealed that our system successfully collected sufficient numbers of cells from the pharyngeal wall for respiratory disease diagnosis.In summary,we have developed a pharyngeal swab-sampling system based on an“enveloping”soft actuator,studied the sampling process,and imple-mented whole-process robotic oropharyngeal swab-sampling.
文摘This study investigates the necessity for space robots to independently exchange their end-effectors due to the contradiction that exists between the requirements of various robots in space missions and the payload capacity limits of rockets. The results of this study summarize the system requirements for a new end-effector exchange mechanism, including compact size, misalignment tolerance, and regolith tolerance. This is followed by the development of a prototype model with a set of test apparatus. Then the function of the prototype is verified, the prototype is optimized, and the relation between docking force and misalignment is examined through operation tests.
文摘The automated picking technology of tea is an important part of the development of smart agriculture, which affects the development of the tea industry to a certain extent. Tea leaf recognition and robotic tea picking end-effector are the key technologies for automated tea picking. This paper proposes a set of algorithms for tea leaf differentiation and recognition based on the principle of colour difference. And on the basis of this algorithm, a tea picking end-effector is designed. The experiments show that the designed tea picking end-effector has good recognition ability and high tea picking speed.
基金supported by the National Natural Science Foundation of China(Grants No.32460449,52265041,and 31901417)The authors also acknowledge the Central Guidance for Local Science and Technology Development Funding Projects under Grant No.ZYYD2025ZY11 and Key Laboratory of Xinjiang Intelligent Agricultural Equipment,China for their assistance in conducting field experiments.
文摘A suitable picking method for the end-effector is the key to achieving low-damage picking.Due to the high moisture content of fresh safflower and its fragile filaments,achieving low-damage picking is a challenge for most picking robots.In this paper,a clamping and root-cutting end-effector for harvesting fresh safflower is developed.It utilizes dual rollers to pre-clamp the filaments and a blade to root-cut the safflower necking to realize the safflower harvesting operation.A mechanical model of dual rollers-blade-filaments cutting was constructed to theoretically analyze the harvesting process.The key factors affecting the performance of the end-effector were identified as blade feed speed,rotation speed,and roller clearance.Using the filament removal rate and damage rate as evaluation indices,the central composite design was carried out.The mathematical model between the test factors and evaluation indices was obtained,and the regression model was optimized with multiple objectives.Finally,the optimal combination of parameters was determined to be a blade feed speed of 40 mm/s,a rotation speed of 318 r/min,and a roller clearance of 0.60 mm.The field test was conducted under the optimal parameter combination,and the filament removal rate and damage rate were 91.25%and 5.57%,respectively.The optimized results had an error of less than 5%,indicating that the designed end-effector can harvest filaments with high removal and low damage rates.This study provides a reference for the low-damage harvesting of fresh safflower.
基金funded by Central Guidance for Local Science and Technology Development Funding Projects under Grant,China(Grant No.ZYYD2025ZY11)the National Natural Science Foundation of China(Grant Nos.32460449 and 52265041)+1 种基金the Key Laboratory of Modern Agricultural Equipment and Technology(Jiangsu University),Ministry of Education,China(Grant No.MAET202305)the Graduate School-level Research and Innovation Program of Xinjiang Agricultural University,China(Grant No.XJAUGRI2023021).
文摘Safflower is one of the most important oil crops worldwide.To improve the efficiency and quality of harvesting soft safflower filaments,minimize filament damage by the blade,and ensure the integrity of the filaments,an end-effector with a rotary push-cut-type negative-pressure airflow was designed.The design of the rotary blade edge curve was based on Archimedean and logarithmic spirals.The effect of the Archimedean spiral on the pushing of the scattered filaments was investigated.The rotary-cutting force and speed of the logarithmic helix on the soft filaments were analyzed.The sliding cut angle and feed speed of the blade are the key factors governing filament removal and damage.A simulation model of the cutting chamber flow field was established for the change in airflow with the position and speed rotation of the blade,allowing analysis of the parameters of the negative-pressure airflow.Single-factor and Box-Behnken tests were performed with the sliding cut angle,blade feed speed,and negative-pressure airflow speed as influencing factors and filament removal,damage,and drop rate as indices.The response surface clarified the effects of various factors on these indices.Optimal parameters were a sliding cut angle of 32.20°,a blade feeding speed of 0.031 m/s,and a negative-pressure airflow speed of 4.57 m/s.The corresponding filament removal,damage,and drop rates were 93.47%,6.94%,and 4.33%,respectively.Optimization results showed that filament removal,damage,and drop rates were 93.50%,7.02%,and 4.43%,respectively.The harvesting process met the requirements of high efficiency and low damage.
基金supported by the National Basic Research Program of China(Grant No.973-2013CB733103)State Key Laboratory of Robotics and System(HIT)(Grant No.SKLRS-2016-MF-05)
文摘The space manipulator which has advantages of high dexterity and universality, is used to the space capturing usually. According to the different types of mechanical interfaces of targets, the on orbit capturing operation includes capturing of cooperative target and capturing of uncooperative target. The performances of the famous large space manipulators named space shuttle remote manipulator system(SRMS), the space station remote manipulator system(SSRMS) and the Europe robotic arm(ERA) are reviewed and studied respectively. Moreover, the space manipulators being developed by China for space station is also surveyed. Based on the performance analysis of the large space manipulators and end-effectors, which are adapted to the construction and daily maintenance for the large space structure such as the space station, the basic requirements of large misalignment tolerance capability, soft capturing capability and hard docking capability for the end-effector of large space manipulator are proposed in this paper. According to these requirements, the capture mechanism and methods that can enable the end-effector to have the capability of misalignment tolerance and soft capturing are presented. The development trend and key technologies of the large space manipulators and the end-effectors are also reviewed.
基金This research was conducted in the College of Mechanical and Electronic Engineering,Northwest A&F University,and was supported by research grants from the General Program of the National Natural Science Foundation of China(61175099).
文摘The harvesting of fresh kiwifruit is a labor-intensive operation that accounts for more than 25%of annual production costs.Mechanized harvesting technologies are thus being developed to reduce labor requirements for harvesting kiwifruit.To improve the efficiency of a harvesting robot for picking kiwifruit,we designed an end-effector,which we report herein along with the results of tests to verify its operation.By using the established method of automated picking discussed in the literature and which is based on the characteristics of kiwifruit,we propose an automated method to pick kiwifruit that consists of separating the fruit from its stem on the tree.This method is experimentally verified by using it to pick clustered kiwifruit in a scaffolding canopy cultivation.In the experiment,the end-effector approaches a fruit from below and then envelops and grabs it with two bionic fingers.The fingers are then bent to separate the fruit from its stem.The grabbing,picking,and unloading processes are integrated,with automated picking and unloading performed using a connecting rod linkage following a trajectory model.The trajectory was analyzed and validated by using a simulation implemented in the software Automatic Dynamic Analysis of Mechanical Systems(ADAMS).In addition,a prototype of an end-effector was constructed,and its bionic fingers were equipped with fiber sensors to detect the best position for grabbing the kiwifruit and pressure sensors to ensure that the damage threshold was respected while picking.Tolerances for size and shape were incorporated by following a trajectory groove from grabbing and picking to unloading.The end-effector separates clustered kiwifruit and automatically grabs individual fruits.It takes on average 4–5 s to pick a single fruit,with a successful picking rate of 94.2%in an orchard test featuring 240 samples.This study shows the grabbing–picking–unloading robotic end-effector has significant potential to facilitate the harvesting of kiwifruit.
基金This work was supported by Jiangsu Agricultural Science and Technology Innovation Fund(CX(21)1007).
文摘The end-effector is the last executing part of the interaction between robots and fruits.In this study,the physical characteristics of tomatoes and the tomato end-effector of the fluidic elastomer actuator type were studied.There was no correlation between the test point,the mass,the size and the rupture force of tomatoes.The non-destructive clamping force of tomatoes was 11.13 N.There were statistically significant correlations between the number of finger chambers,the transverse diameter of tomatoes,the inflation pressure and the clamping force.The inflation pressure and the size of tomatoes were directly proportional to the clamping force.Since fingers with more chambers had higher flexibility,the number of chambers was inversely proportional to the slope of the horizontal force-pressure curve,and the number of chambers was directly proportional to the angle between the total clamping force and the horizontal direction.A flexible end-effector was designed by genetic algorithm according to the physical characteristics of tomatoes and the simulation results of the finger of the end-effector.The test results of the end-effector showed that the tomatoes would be successfully clamped by the end-effector composed of three four-chamber fingers in a static situation with the inflation pressure less than the optimized inflation pressure(28.293 kPa).When in a dynamic situation,the success rate of tomatoes being clamped by the end-effector with an inflation pressure of 29 kPa was 97%.The tomatoes in the static clamping test and the dynamic clamping test were not damaged.
