With the widespread application of legged robot in various fields, the demand for a robot with hi... more With the widespread application of legged robot in various fields, the demand for a robot with high locomotion and manipulation ability is increasing. Adding an extra arm is a useful but general method for a legged robot to obtain manipulation ability. Hence, this paper proposes a novel hexapod robot with two integrated leg—arm limbs that obtain dexterous manipulation functions besides locomotion ability without adding an extra arm. The manipulation modes can be divided into coordinated manipulation condition and single-limb manipulation condition. The former condition mainly includes fixed coordinated clamping case and fixed coordinated shearing case. For the fixed coordinated clamping case, the degrees of freedom (DOFs) analysis of equivalent parallel mechanism by using screw theory and the constraint equation of two integrated limbs are established. For the fixed coordinated shearing case, the coordinated working space is determined, and an ideal coordinated manipulation ball is ...
A mechanism which is able to fold into a bundle is of particular interest: minimal size facilitat... more A mechanism which is able to fold into a bundle is of particular interest: minimal size facilitates storage and transport. The paper presents a simple and general geometric method to design bundle-folding linkages based on one-degree-of-freedom spatial overconstrained loops. The so designed mechanism can be folded into a line bundle and deployed into a spatial shape. The geometric conditions, under which an overconstrained linkage can be folded into a bundle, are discussed. Case studies of bundle-folding designs are presented and validated using simulations.
IEEE Transactions on Neural Systems and Rehabilitation Engineering
Locomotion mode recognition has been 1 shown to substantially contribute to the precise control o... more Locomotion mode recognition has been 1 shown to substantially contribute to the precise control of 2 robotic lower-limb prostheses under different walking 3 conditions. In this study, we proposed a temporal 4 convolutional capsule network (TCCN) which integrates the 5 spatial-temporal-based, dilation-convolution-based, dyna-6 mic routing and vector-based features for recognizing 7 locomotion mode recognition with small data rather than 8 big-data-based neural networks for robotic prostheses. 9 TCCN proposed in this study has four characteristics, which 10 extracts the (1) spatial-temporal information in the data 11 and then makes (2) dilated convolution to deal with small 12 data, and uses (3) dynamic routing, which produces some 13 similarities to the human brain to process the data as a 14 (4) vector, which is different from other scalar-based net-15 works, such as convolutional neural network (CNN). By com-16 parison with a traditional machine learning, e.g., support 17 vector machine(SVM) and big-data-driven neural networks, 18 e.g., CNN, recurrent neural network(RNN), temporal convo-19 lutional network(TCN) and capsule network(CN). The accu-20 racy of TCCN is 4.1% higher than CNN under 5-fold cross-21 validation of three-locomotion-mode and 5.2% higher under 22 the 5-fold cross-validation of five-locomotion modes. The 23 main confusion we found appears in the transition state. The 24 results indicate that TCCN may handle small data balancing 25 global and local information which is closer to the way how 26 the human brain works, and the capsule layer allows for 27 better processing vector information and retains not only 28 magnitude information, but also direction information. 29 Index Terms-Locomotion mode recognition, small data, 30 robotic prosthesis. 31 I. INTRODUCTION 32 R OBOTIC prostheses could assist people with lower-limb 33 injuries in performing basic movements [1]. Human loco-34 motion mode recognition plays a key role in robotic prosthesis 35 Manuscript
Volume 5B: 40th Mechanisms and Robotics Conference
This paper provides a method for modeling the center of mass (COM) of hexapod manipulation system... more This paper provides a method for modeling the center of mass (COM) of hexapod manipulation systems, which is based on the Statically Equivalent Serial Chain (SESC) model. First, the product of exponentials (POE) formula is used to construct the SESC model for the simple tree-like chain. Then, in order to apply this method to real scenarios, the situation when the robot stands on uneven terrain is studied. In addition, the static grasp constraints for the manipulation and the Jacobian matrix for the COM of the system are analyzed. Moreover, we present a modified tumble stability margin, which considers all of the possible ways that the robot can tumble. Finally, based on these kinematic analyses, a motion control scheme for statically stable manipulation is proposed. The results are validated with simulations.
2018 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2018
This paper presents a connection mechanism for operating arms to assemble antenna structure as tw... more This paper presents a connection mechanism for operating arms to assemble antenna structure as two mating parts that attached to two antenna modules respectively. The geometry of the mechanism is described and optimized to include pose error according to kinematic model of the docking process. A simple approach is proposed that enables the mechanism to be pushed together with a tiny force. And unexpected disconnection is prevented by self-locking during normal operation of the antenna. With simulation, we demonstrate the high misalignment tolerance of this mechanism and the reliability of the connection.
2018 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2018
This paper presents a novel multifunctional mechanical gripper which can rotate continuously. The... more This paper presents a novel multifunctional mechanical gripper which can rotate continuously. The mechanical design of the gripper is introduced and its operation modes are given. The gripper can screw hexagon socket head cap screws, press the button besides grip objects because of its special mechanical structure. The kinematics model of the gripper is built, process planning of screwing and grapping are provided. Screwing forces when the gripper operating different size screws are analyzed. These results will be significant for application of industrial automation assembly and field investigation.
In this paper, a multi-propeller aerial robot with a passive manipulator for aerial manipulation ... more In this paper, a multi-propeller aerial robot with a passive manipulator for aerial manipulation is presented. In order to deal with the collision, external disturbance, changing inertia, and underactuated characteristic during the aerial manipulation, an adaptive trajectory linearization control (ATLC) scheme is presented to stabilize the multi-propeller aerial robot during the whole process. The ATLC controller is developed based on trajectory linearization control (TLC) method and model reference adaptive control (MRAC) method. The stability of the proposed system is analyzed by common Lyapunov function. Numerical simulations are carried out to compare the ATLC with TLC controller facing collision, external disturbance and changing inertia during an aerial manipulation. Experimental results prove that the developed robot can achieve aerial manipulation in the outdoor environment.
2018 International Conference on Reconfigurable Mechanisms and Robots (ReMAR), 2018
This paper designs a specific planar mechanism with variable topology (MVT) for automated fiber p... more This paper designs a specific planar mechanism with variable topology (MVT) for automated fiber placement which has ability to change its topological structure for accomplishing the clamping, cutting and restarting motion. Firstly, the functional requirements and moving sequence are proposed to build the foundation of design, and a MVT is developed to fill the demand. Then, the topological structures and the mobility of this mechanism in different states are analyzed to prove that the mechanism manipulates in accordance with moving sequence through transformation. Thirdly, kinematics model is established with vector equation and the corresponding simulation is carried out. Results from simulation demonstrate that the proposed mechanism can effectively realize a stable operation.
Recently, with the rapid development of aerospace technology, an increasing number of spacecraft ... more Recently, with the rapid development of aerospace technology, an increasing number of spacecraft is being launched into space. Additionally, the demands for on-orbit servicing (OOS) missions are rapidly increasing. Space robotics is one of the most promising approaches for various OOS missions; thus, research on space robotics technologies for OOS has attracted increased attention from space agencies and universities worldwide. In this paper, we review the structures, ground verification, and on-orbit kinematics calibration technologies of space robotic systems for OOS. First, we systematically summarize the development of space robotic systems and OOS programs based on space robotics. Then, according to the structures and applications, these systems are divided into three categories: large space manipulators, humanoid space robots, and small space manipulators. According to the capture mechanisms adopted, the end-effectors are systematically analyzed. Furthermore, the ground verification facilities used to simulate a microgravity environment are summarized and compared. Additionally, the on-orbit kinematics calibration technologies are discussed and analyzed compared with the kinematics calibration technologies of industrial manipulators with regard to four aspects. Finally, the development trends of the structures, verification, and calibration technologies are discussed to extend this review work.
Normal kinematic joint can be transformed to variable kinematic joint(VKJ), which refers to a kin... more Normal kinematic joint can be transformed to variable kinematic joint(VKJ), which refers to a kinematic joint that is capable of topological variation in a mechanism, by utilizing effect of friction and self-locking. In this paper a metamorphic mechanism cell which can realize deploying, self-locking, unlocking, retracting and interlocking with other cells, is designed by incorporating VKJs. Self-locking margin is proposed to estimate the selflocking capability. The variable topology configurations of this cell are presented and the mobility of this cell is analyzed. With the new metamorphic cell, a cable-driven telescopic model with 3 tubes is built, and its motion simulations are conducted to verify the design method. The results demonstrate that the impact in transformation is mitigated and multistage orderly deployable/retractable mechanisms can be built by this method.
This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna p... more This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints (FSRJs) with small clearance in the framework of the special Euclidian group SE(3). The formulation leads to an inertial frame-invariant, a compact and unified description for rigid bodies and spatial revolute joints (SRJs). The geometric constraint of the bearing is covered by four open semi-cylinders, which can be treated as bilateral constraints assuming that the impact effects are negligible. The frictional contact problem is formulated as a horizontal linear complementary problem (HLCP), which is embedded in the Lie-group integration scheme. Error of the antenna pointing mechanism is modeled by means of the adjoint transformation and POE-based formula. The evolution of errors is obtained through the solution of non-smooth dynamics. The obtained numerical results illustrate the influences of FSRJs in dynamics modeling and error analysis of the antenna pointing mechanism.
The embedment, wound by foaming resin, is an important component widely utilized in the honeycomb... more The embedment, wound by foaming resin, is an important component widely utilized in the honeycomb sandwich structure to connect with equipment. However, the wound embedment is still manufactured manually nowadays and the productivity is low. In this paper, an automatic winding mechanism is developed, which consists of foaming resin feeding, transmitting, cutting mechanism, and embedment positing and driving mechanism. Especially, embedment positing and driving mechanism which is the key part of the whole mechanism is designed and analyzed. Different experiments are provided to demonstrate the validation of the mechanism.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
IEEE Transactions on Aerospace and Electronic Systems, 2021
For multiple unmanned aerial vehicles (UAVs) performing aerial search-attack tasks, there is a tr... more For multiple unmanned aerial vehicles (UAVs) performing aerial search-attack tasks, there is a tradeoff between maximizing total benefit and minimizing consumption under the validity of constraints. This article proposes a dynamic discrete pigeon-inspired optimization algorithm to handle cooperative search-attack mission planning for UAVs, which integrates the centralized task assignment and distributed path generation aspects of the problem. Besides, a solution acceptance strategy is proposed to avoid frequent task switching. To Manuscript
Abstract To overcome the limitations of linear series elastic actuators (SEAs) with constant stif... more Abstract To overcome the limitations of linear series elastic actuators (SEAs) with constant stiffness, a novel load-adaptive actuator with variable stiffness is proposed for actuating ankle exoskeletons through an inverted slider-crank mechanism. Using the proposed actuator, the stiffness of the exoskeleton can be adjusted passively based on the external load and joint angle. To achieve compactness, a novel nonlinear spring mechanism with user-defined load–deflection behaviour is designed by combining a cam mechanism with parabolic beams; this proposed mechanism is used as the series elastic element of the proposed actuator. Dimensional optimisation of the ankle exoskeleton, including the actuator, is subsequently performed for maximising the energy efficiency based on gait biomechanics and considering the constraints of the inverted slider-crank mechanism, electric motor, and the nonlinear spring mechanism. Simulation and experimental results show that the energy efficiency is improved by using the proposed load-adaptive actuator-powered ankle exoskeleton compared with using an exoskeleton driven by linear SEAs.
Chinese Chang'e lunar exploration project aims to collect and return subsurface lunar soil sample... more Chinese Chang'e lunar exploration project aims to collect and return subsurface lunar soil samples at a minimum penetration depth of 2 m in 2017. However, in contrast to those on the Earth, automated drilling and sampling missions on the Moon raise the risk of burning bits. Test-beds are required for testing the thermal properties of drill tools in a lunar environment. In this paper, a novel temperature measuring method based on thermocouples and a slip ring was proposed. Furthermore, a data acquisition system for a drilling process was designed. A vacuous, cryogenic, and anhydrous soil environment simulating the lunar surface was established. A drilling test-bed that can reach a depth of 2.2 m was developed. A control strategy based on online monitoring signals was proposed to improve the drilling performance. Vacuum and non-vacuum experiments were performed to test the temperature rising effect on drill tools. When compared with the non-vacuum experiment, the vacuum temperature rise resulted in a 12°C increase. These experimental results provide significant support for Chinese lunar exploration missions.
NOROS robotic system is on development between Politecnico of Milan and Beijing University of Aer... more NOROS robotic system is on development between Politecnico of Milan and Beijing University of Aeronautics and Astronautics. Begun in 2004, it previews the planning and the construction of a prototype of a family of robots for the exploration and the exploitation of the lunar ground.
Volume 5B: 40th Mechanisms and Robotics Conference, 2016
This paper presents a one-degree-of-freedom network of Bennett linkages which can be deployed to ... more This paper presents a one-degree-of-freedom network of Bennett linkages which can be deployed to approximate a cylindrical surface. The geometry of the unit mechanism is parameterized and its position kinematics is solved. The influence of the geometric parameters on the deployed shape is examined. Further kinematic analysis isolates those Bennett geometries for which a cylindrical network can be constructed. The procedure for connecting the unit mechanisms in a deployable cylinder is described in detail and used to gain insight into, and formulate some general guidelines for, the design of linkage networks which unfold as curved surfaces. Case studies of deployable structures in the shape of circular and elliptical cylinders are presented. Modeling and simulation validate the proposed approach.
The paper describes an innovative fixture created within the AUTORECON project of the European Co... more The paper describes an innovative fixture created within the AUTORECON project of the European Commission's 7th Framework Program. The fixture is designed to respond to the automotive industry's needs of high modularity and full flexibility, by allowing the secure multishape grasping of a very wide range of (often large and heavy) metal workpieces typical for car-assembly operations. The fixture is used as an end-effector of an industrial robot, which in turn acts in cooperation with other machines, such as other robots performing machining or other processes on the part. The fixturing device is both a highly reconfigurable structure and a robotic mechanism: moving as a programmable robot to reconfigure and acting as a supporting structure once a hold on the part has been established. This dual functioning has been made possible by the development of a key component, a stepless lockable revolute joint, described herein. In order to get a readily modifiable system, all parts ...
With the widespread application of legged robot in various fields, the demand for a robot with hi... more With the widespread application of legged robot in various fields, the demand for a robot with high locomotion and manipulation ability is increasing. Adding an extra arm is a useful but general method for a legged robot to obtain manipulation ability. Hence, this paper proposes a novel hexapod robot with two integrated leg—arm limbs that obtain dexterous manipulation functions besides locomotion ability without adding an extra arm. The manipulation modes can be divided into coordinated manipulation condition and single-limb manipulation condition. The former condition mainly includes fixed coordinated clamping case and fixed coordinated shearing case. For the fixed coordinated clamping case, the degrees of freedom (DOFs) analysis of equivalent parallel mechanism by using screw theory and the constraint equation of two integrated limbs are established. For the fixed coordinated shearing case, the coordinated working space is determined, and an ideal coordinated manipulation ball is ...
A mechanism which is able to fold into a bundle is of particular interest: minimal size facilitat... more A mechanism which is able to fold into a bundle is of particular interest: minimal size facilitates storage and transport. The paper presents a simple and general geometric method to design bundle-folding linkages based on one-degree-of-freedom spatial overconstrained loops. The so designed mechanism can be folded into a line bundle and deployed into a spatial shape. The geometric conditions, under which an overconstrained linkage can be folded into a bundle, are discussed. Case studies of bundle-folding designs are presented and validated using simulations.
IEEE Transactions on Neural Systems and Rehabilitation Engineering
Locomotion mode recognition has been 1 shown to substantially contribute to the precise control o... more Locomotion mode recognition has been 1 shown to substantially contribute to the precise control of 2 robotic lower-limb prostheses under different walking 3 conditions. In this study, we proposed a temporal 4 convolutional capsule network (TCCN) which integrates the 5 spatial-temporal-based, dilation-convolution-based, dyna-6 mic routing and vector-based features for recognizing 7 locomotion mode recognition with small data rather than 8 big-data-based neural networks for robotic prostheses. 9 TCCN proposed in this study has four characteristics, which 10 extracts the (1) spatial-temporal information in the data 11 and then makes (2) dilated convolution to deal with small 12 data, and uses (3) dynamic routing, which produces some 13 similarities to the human brain to process the data as a 14 (4) vector, which is different from other scalar-based net-15 works, such as convolutional neural network (CNN). By com-16 parison with a traditional machine learning, e.g., support 17 vector machine(SVM) and big-data-driven neural networks, 18 e.g., CNN, recurrent neural network(RNN), temporal convo-19 lutional network(TCN) and capsule network(CN). The accu-20 racy of TCCN is 4.1% higher than CNN under 5-fold cross-21 validation of three-locomotion-mode and 5.2% higher under 22 the 5-fold cross-validation of five-locomotion modes. The 23 main confusion we found appears in the transition state. The 24 results indicate that TCCN may handle small data balancing 25 global and local information which is closer to the way how 26 the human brain works, and the capsule layer allows for 27 better processing vector information and retains not only 28 magnitude information, but also direction information. 29 Index Terms-Locomotion mode recognition, small data, 30 robotic prosthesis. 31 I. INTRODUCTION 32 R OBOTIC prostheses could assist people with lower-limb 33 injuries in performing basic movements [1]. Human loco-34 motion mode recognition plays a key role in robotic prosthesis 35 Manuscript
Volume 5B: 40th Mechanisms and Robotics Conference
This paper provides a method for modeling the center of mass (COM) of hexapod manipulation system... more This paper provides a method for modeling the center of mass (COM) of hexapod manipulation systems, which is based on the Statically Equivalent Serial Chain (SESC) model. First, the product of exponentials (POE) formula is used to construct the SESC model for the simple tree-like chain. Then, in order to apply this method to real scenarios, the situation when the robot stands on uneven terrain is studied. In addition, the static grasp constraints for the manipulation and the Jacobian matrix for the COM of the system are analyzed. Moreover, we present a modified tumble stability margin, which considers all of the possible ways that the robot can tumble. Finally, based on these kinematic analyses, a motion control scheme for statically stable manipulation is proposed. The results are validated with simulations.
2018 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2018
This paper presents a connection mechanism for operating arms to assemble antenna structure as tw... more This paper presents a connection mechanism for operating arms to assemble antenna structure as two mating parts that attached to two antenna modules respectively. The geometry of the mechanism is described and optimized to include pose error according to kinematic model of the docking process. A simple approach is proposed that enables the mechanism to be pushed together with a tiny force. And unexpected disconnection is prevented by self-locking during normal operation of the antenna. With simulation, we demonstrate the high misalignment tolerance of this mechanism and the reliability of the connection.
2018 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2018
This paper presents a novel multifunctional mechanical gripper which can rotate continuously. The... more This paper presents a novel multifunctional mechanical gripper which can rotate continuously. The mechanical design of the gripper is introduced and its operation modes are given. The gripper can screw hexagon socket head cap screws, press the button besides grip objects because of its special mechanical structure. The kinematics model of the gripper is built, process planning of screwing and grapping are provided. Screwing forces when the gripper operating different size screws are analyzed. These results will be significant for application of industrial automation assembly and field investigation.
In this paper, a multi-propeller aerial robot with a passive manipulator for aerial manipulation ... more In this paper, a multi-propeller aerial robot with a passive manipulator for aerial manipulation is presented. In order to deal with the collision, external disturbance, changing inertia, and underactuated characteristic during the aerial manipulation, an adaptive trajectory linearization control (ATLC) scheme is presented to stabilize the multi-propeller aerial robot during the whole process. The ATLC controller is developed based on trajectory linearization control (TLC) method and model reference adaptive control (MRAC) method. The stability of the proposed system is analyzed by common Lyapunov function. Numerical simulations are carried out to compare the ATLC with TLC controller facing collision, external disturbance and changing inertia during an aerial manipulation. Experimental results prove that the developed robot can achieve aerial manipulation in the outdoor environment.
2018 International Conference on Reconfigurable Mechanisms and Robots (ReMAR), 2018
This paper designs a specific planar mechanism with variable topology (MVT) for automated fiber p... more This paper designs a specific planar mechanism with variable topology (MVT) for automated fiber placement which has ability to change its topological structure for accomplishing the clamping, cutting and restarting motion. Firstly, the functional requirements and moving sequence are proposed to build the foundation of design, and a MVT is developed to fill the demand. Then, the topological structures and the mobility of this mechanism in different states are analyzed to prove that the mechanism manipulates in accordance with moving sequence through transformation. Thirdly, kinematics model is established with vector equation and the corresponding simulation is carried out. Results from simulation demonstrate that the proposed mechanism can effectively realize a stable operation.
Recently, with the rapid development of aerospace technology, an increasing number of spacecraft ... more Recently, with the rapid development of aerospace technology, an increasing number of spacecraft is being launched into space. Additionally, the demands for on-orbit servicing (OOS) missions are rapidly increasing. Space robotics is one of the most promising approaches for various OOS missions; thus, research on space robotics technologies for OOS has attracted increased attention from space agencies and universities worldwide. In this paper, we review the structures, ground verification, and on-orbit kinematics calibration technologies of space robotic systems for OOS. First, we systematically summarize the development of space robotic systems and OOS programs based on space robotics. Then, according to the structures and applications, these systems are divided into three categories: large space manipulators, humanoid space robots, and small space manipulators. According to the capture mechanisms adopted, the end-effectors are systematically analyzed. Furthermore, the ground verification facilities used to simulate a microgravity environment are summarized and compared. Additionally, the on-orbit kinematics calibration technologies are discussed and analyzed compared with the kinematics calibration technologies of industrial manipulators with regard to four aspects. Finally, the development trends of the structures, verification, and calibration technologies are discussed to extend this review work.
Normal kinematic joint can be transformed to variable kinematic joint(VKJ), which refers to a kin... more Normal kinematic joint can be transformed to variable kinematic joint(VKJ), which refers to a kinematic joint that is capable of topological variation in a mechanism, by utilizing effect of friction and self-locking. In this paper a metamorphic mechanism cell which can realize deploying, self-locking, unlocking, retracting and interlocking with other cells, is designed by incorporating VKJs. Self-locking margin is proposed to estimate the selflocking capability. The variable topology configurations of this cell are presented and the mobility of this cell is analyzed. With the new metamorphic cell, a cable-driven telescopic model with 3 tubes is built, and its motion simulations are conducted to verify the design method. The results demonstrate that the impact in transformation is mitigated and multistage orderly deployable/retractable mechanisms can be built by this method.
This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna p... more This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints (FSRJs) with small clearance in the framework of the special Euclidian group SE(3). The formulation leads to an inertial frame-invariant, a compact and unified description for rigid bodies and spatial revolute joints (SRJs). The geometric constraint of the bearing is covered by four open semi-cylinders, which can be treated as bilateral constraints assuming that the impact effects are negligible. The frictional contact problem is formulated as a horizontal linear complementary problem (HLCP), which is embedded in the Lie-group integration scheme. Error of the antenna pointing mechanism is modeled by means of the adjoint transformation and POE-based formula. The evolution of errors is obtained through the solution of non-smooth dynamics. The obtained numerical results illustrate the influences of FSRJs in dynamics modeling and error analysis of the antenna pointing mechanism.
The embedment, wound by foaming resin, is an important component widely utilized in the honeycomb... more The embedment, wound by foaming resin, is an important component widely utilized in the honeycomb sandwich structure to connect with equipment. However, the wound embedment is still manufactured manually nowadays and the productivity is low. In this paper, an automatic winding mechanism is developed, which consists of foaming resin feeding, transmitting, cutting mechanism, and embedment positing and driving mechanism. Especially, embedment positing and driving mechanism which is the key part of the whole mechanism is designed and analyzed. Different experiments are provided to demonstrate the validation of the mechanism.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
IEEE Transactions on Aerospace and Electronic Systems, 2021
For multiple unmanned aerial vehicles (UAVs) performing aerial search-attack tasks, there is a tr... more For multiple unmanned aerial vehicles (UAVs) performing aerial search-attack tasks, there is a tradeoff between maximizing total benefit and minimizing consumption under the validity of constraints. This article proposes a dynamic discrete pigeon-inspired optimization algorithm to handle cooperative search-attack mission planning for UAVs, which integrates the centralized task assignment and distributed path generation aspects of the problem. Besides, a solution acceptance strategy is proposed to avoid frequent task switching. To Manuscript
Abstract To overcome the limitations of linear series elastic actuators (SEAs) with constant stif... more Abstract To overcome the limitations of linear series elastic actuators (SEAs) with constant stiffness, a novel load-adaptive actuator with variable stiffness is proposed for actuating ankle exoskeletons through an inverted slider-crank mechanism. Using the proposed actuator, the stiffness of the exoskeleton can be adjusted passively based on the external load and joint angle. To achieve compactness, a novel nonlinear spring mechanism with user-defined load–deflection behaviour is designed by combining a cam mechanism with parabolic beams; this proposed mechanism is used as the series elastic element of the proposed actuator. Dimensional optimisation of the ankle exoskeleton, including the actuator, is subsequently performed for maximising the energy efficiency based on gait biomechanics and considering the constraints of the inverted slider-crank mechanism, electric motor, and the nonlinear spring mechanism. Simulation and experimental results show that the energy efficiency is improved by using the proposed load-adaptive actuator-powered ankle exoskeleton compared with using an exoskeleton driven by linear SEAs.
Chinese Chang'e lunar exploration project aims to collect and return subsurface lunar soil sample... more Chinese Chang'e lunar exploration project aims to collect and return subsurface lunar soil samples at a minimum penetration depth of 2 m in 2017. However, in contrast to those on the Earth, automated drilling and sampling missions on the Moon raise the risk of burning bits. Test-beds are required for testing the thermal properties of drill tools in a lunar environment. In this paper, a novel temperature measuring method based on thermocouples and a slip ring was proposed. Furthermore, a data acquisition system for a drilling process was designed. A vacuous, cryogenic, and anhydrous soil environment simulating the lunar surface was established. A drilling test-bed that can reach a depth of 2.2 m was developed. A control strategy based on online monitoring signals was proposed to improve the drilling performance. Vacuum and non-vacuum experiments were performed to test the temperature rising effect on drill tools. When compared with the non-vacuum experiment, the vacuum temperature rise resulted in a 12°C increase. These experimental results provide significant support for Chinese lunar exploration missions.
NOROS robotic system is on development between Politecnico of Milan and Beijing University of Aer... more NOROS robotic system is on development between Politecnico of Milan and Beijing University of Aeronautics and Astronautics. Begun in 2004, it previews the planning and the construction of a prototype of a family of robots for the exploration and the exploitation of the lunar ground.
Volume 5B: 40th Mechanisms and Robotics Conference, 2016
This paper presents a one-degree-of-freedom network of Bennett linkages which can be deployed to ... more This paper presents a one-degree-of-freedom network of Bennett linkages which can be deployed to approximate a cylindrical surface. The geometry of the unit mechanism is parameterized and its position kinematics is solved. The influence of the geometric parameters on the deployed shape is examined. Further kinematic analysis isolates those Bennett geometries for which a cylindrical network can be constructed. The procedure for connecting the unit mechanisms in a deployable cylinder is described in detail and used to gain insight into, and formulate some general guidelines for, the design of linkage networks which unfold as curved surfaces. Case studies of deployable structures in the shape of circular and elliptical cylinders are presented. Modeling and simulation validate the proposed approach.
The paper describes an innovative fixture created within the AUTORECON project of the European Co... more The paper describes an innovative fixture created within the AUTORECON project of the European Commission's 7th Framework Program. The fixture is designed to respond to the automotive industry's needs of high modularity and full flexibility, by allowing the secure multishape grasping of a very wide range of (often large and heavy) metal workpieces typical for car-assembly operations. The fixture is used as an end-effector of an industrial robot, which in turn acts in cooperation with other machines, such as other robots performing machining or other processes on the part. The fixturing device is both a highly reconfigurable structure and a robotic mechanism: moving as a programmable robot to reconfigure and acting as a supporting structure once a hold on the part has been established. This dual functioning has been made possible by the development of a key component, a stepless lockable revolute joint, described herein. In order to get a readily modifiable system, all parts ...
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