2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2020
One of the key advantages of robots is the high speeds at which they can operate. In industrial s... more One of the key advantages of robots is the high speeds at which they can operate. In industrial settings, increased velocities can lead to higher throughputs and improved efficiency. Some manipulation tasks might require the robot to perform highly dynamic operations such as shaking, or swinging while grasping an object. These fast movements may produce high accelerations and thus give rise to inertial forces that can cause a grasped object to slip. In this paper a method is proposed to determine the inertial forces that arise on a grasped object during a trajectory, find the instances at which the object might slip, and avoid these slippages by changing the trajectory, namely the orientation of the object. To exemplify the usage of this approach, two grasping tasks are realised: a prehensile and a non-prehensile grasp, and strategies to successfully perform these tasks without changing the overall duration of the trajectory are defined and evaluated.
Centre for Robotics Research Department of Informatics Doctor of Philosophy Touch Based Object Po... more Centre for Robotics Research Department of Informatics Doctor of Philosophy Touch Based Object Pose Estimation For Robotic Grasping by João Bimbo Robot grasping and manipulation require very accurate and timely knowledge of the manipulated object’s shape and pose to succesfully perform a desired task. One of the main reasons current systems fail to carry out complex tasks in a real, unstructured environment is their inability to accurately determine where in the object the fingers are touching. Most systems use vision to detect the pose of an object, but the performance of this sensing modality deteriorates as soon as the robot grasps the object. When the robot hand contacts an object, it partially occludes it, which makes it difficult for vision systems to track the object’s location. This thesis presents algorithms to use the robot’s available tactile sensing to correct the visually determined pose of a grasped object. This method is extended to globally estimate the pose of the o...
We present a novel method for controlling a myoelectric prosthetic wrist. Five multiple degree-of... more We present a novel method for controlling a myoelectric prosthetic wrist. Five multiple degree-of-freedom (DOF) wrist trajectories are obtained from healthy participants that performed tasks that span the range of Activities of Daily Living (ADL) using dimensionality reduction and unsupervised machine learning techniques. The efficacy of these motions is tested as part of a pilot study where a participant used a simulated wrist device controlled using two-site surface electromyography (sEMG); two trajectories were tested in an immersive virtual reality. Novel wrist control has been demonstrated to be more intuitive to use and appears more natural while limiting the amount of body compensation.
Recent results in the field of soft manipulation showed that the direct physical interaction betw... more Recent results in the field of soft manipulation showed that the direct physical interaction between a robotic hand and the environment can be exploited to robustly grasp objects. This is possible when the hand-environment interface is compliant. This abstract presents two complementary approaches to environmental constraints exploitation. The first uses a soft robotic hand interacting with a rigid environment, the second considers a rigid gripper grasping objects over a soft environment.
One of the main goals of haptic systems is to convey realistic forces (transparency) to the user.... more One of the main goals of haptic systems is to convey realistic forces (transparency) to the user. In bilateral telemanipulation control, factors such relaxed grasp of the user, time delays and stiff environments may compromise the stability of the system. Ensuring passivity in the system, i.e. does not generate energy by itself, can prevent unstable behaviour. To preserve passivity, a 3DoF two-layer approach based on energy tanks is implemented; the energy provided to the slave side is limited by the energy obtained from the user at the master side. This energy is generated by a damping-like element that is activated when destabilizing factors occur. This work presents a strategy to prioritize damping coefficients to achieve higher transparency along a number of desired directions. The method consists of solving a quadratic optimization problem that minimizes the projection of the damping force on different directions while maintaining passivity.
Object surface properties are among the most important information for intelligent robotic graspi... more Object surface properties are among the most important information for intelligent robotic grasping and manipulation. This paper presents a new object surface classification approach based on frictional properties. The idea is to use a robotic finger to rub over an object surface with a low acceleration and identify the frictional properties using measured friction force and sliding velocity. A quasi-static LuGre model is used to characterise the relationship between friction force and sliding velocity, and the generalized Newton-Raphson method is applied to estimate unknown frictional coefficients of this model. Since the frictional coefficients of the quasi-static LuGre model are closely related to the material physical properties, object surfaces can be classified using a naïve Bayes classifier with the identified frictional coefficients. Test results show that the proposed approach can achieve a high correctness in object surface classification.
smARTLab, Department of Computer Science, University of Liverpool, Liverpool, United Kingdom, Dep... more smARTLab, Department of Computer Science, University of Liverpool, Liverpool, United Kingdom, Department of Engineering Mathematics and Bristol Robotics Laboratory, University of Bristol, Bristol, United Kingdom, inte-R-action Lab and Centre for Autonomous Robotics (CENTAUR), University of Bath, Bath, United Kingdom, Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, United States, Department of Computer Science and Technology, Tsinghua University, Beijing, China
2019 19th International Conference on Advanced Robotics (ICAR)
Intuitive interaction is the cornerstone of efficient and effective task execution in remote robo... more Intuitive interaction is the cornerstone of efficient and effective task execution in remote robotic teleoperation. It requires high-fidelity in control actions as well as perception (vision, haptic, and sensory feedback) from the remote environment. This paper presents Vicarios, a VR-based teleoperation interface with the aim of facilitating intuitive real-time remote teleoperation, while utilizing the inherent benefits of VR, including immersive visualization, freedom of viewpoint selection, and fluidity of interaction through natural action interfaces. The overall architecture of Vicarios is described, with its components and framework. A preliminary comparative user study, with a real-world tele-manipulation task, was conducted to quantify the effectiveness of Vicarios. It is shown that the VR-based interface is easy-to-use and learn, with an overall learning rate of 0.93 sec. per trial for the users. The smoothness metric shows that the users can improve on their task performance over time as well. Vicarios allows the intuitiveness and flexibility to maintain efficiency in tele-robotic tasks. It forms the basis for an immersive perception interface in remote robotic teleoperation.
2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)
Since direct manual palpation is not possible in minimally invasive surgery procedures, there is ... more Since direct manual palpation is not possible in minimally invasive surgery procedures, there is an active field of applied research which aims to retrieve the human sense of touch and feedback tissue properties through artificial tactile feedback. This paper presents an innovative stiffness sensor to be embedded at the tip of a commercial endoscopic camera. The sensor structure is based on multiple cantilever beams, which act as springs with different stiffness when indented into soft tissue. Geometric features mounted on the beams are tracked during physical contact. Movements of the cantilevers result in shape variations of the features in the camera images. The feature size is then segmented and related to the force exerted into the contact location. As beams of different elasticity are integrated, it is possible to estimate the stiffness properties of the soft tissue by employing only visual information. In this paper, Finite Element Analysis (FEA) was implemented to simulate and estimate how contact forces will affect the material and design of the prototype. A calibration device has been developed and used to validate the outcome of the FEA simulations. An experimental test showed the ability of the proposed mechanism to compute the stiffness of a soft phantom.
Automating the act of grasping is one of the most compelling challenges in robotics. In recent ti... more Automating the act of grasping is one of the most compelling challenges in robotics. In recent times, a major trend has gained the attention of the robotic grasping community: soft manipulation. Along with the design of intrinsically soft robotic hands, it is important to devise grasp planning strategies that can take into account the hand characteristics, but are general enough to be applied to different robotic systems. In this article, we investigate how to perform top grasps with soft hands according to a model-based approach, using both power and precision grasps. The so-called closure signature (CS) is used to model closure motions of soft hands by associating to them a preferred grasping direction. This direction can be aligned to a suitable direction over the object to achieve successful top grasps. The CS-alignment is here combined with a recently developed AI-driven grasp planner for rigid grippers that is adjusted and used to retrieve an estimate of the optimal grasp to b...
Flat objects lying on a surface are hard to grasp, but could be manipulated by sliding along the ... more Flat objects lying on a surface are hard to grasp, but could be manipulated by sliding along the surface in a non-prehensile manner. This strategy is commonly employed by humans as pre-manipulation, for example to bring a cell phone to the edge of a table to pick it up. To endow robots with a similar capability, we introduce a mathematical model of planar sliding by means of a soft finger. The model reveals various aspects of interaction through frictional contacts, which can be used for planning and control. Specifically, using a quasi-static analysis we are able to derive a hybrid dynamical system to predict the motion of the object and the interaction forces. The conditions for which the object sticks to the friction patch, pivots, or completely slides against it are obtained. It is possible to find fixed points of the system and the path taken by the object to reach such configurations. Theoretical as well as comprehensive experimental results are presented.
2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Sep 1, 2017
Robotic teleoperation in cluttered environments is attracting increasing attention for its potent... more Robotic teleoperation in cluttered environments is attracting increasing attention for its potential in hazardous scenarios, disaster response, and telemaintenance. Although haptic feedback has been proven effective in such applications, commercially-available grounded haptic interfaces still show significant limitations in terms of workspace, safety, transparency, and encumbrance. For this reason, we present a novel robotic teleoperation system with wearable haptic feedback for telemanipulation in cluttered environments. The slave system is composed of a soft robotic hand attached to a 6-axis force sensor, which is fixed to a 6-degrees-of-freedom robotic arm. The master system is composed of two wearable vibrotactile armbands and a Leap Motion. The armbands are worn on the upper arm and forearm, and convey information about collisions on the robotic arm and hand, respectively. The position of the manipulator and the grasping configuration of the robotic hand are controlled by the user's hand pose as tracked by the Leap Motion. To validate our approach, we carried out a human-subject telemanipulation experiment in a cluttered scenario. Twelve participants were asked to teleoperate the robot to grasp an object hidden between debris of various shapes and stiffnesses. Haptic feedback provided by our wearable devices significantly improved the performance of the considered telemanipulation tasks. All subjects but one preferred conditions with wearable haptic feedback.
Underactuated and compliant hands, frequently referred to as soft hands, have been recently propo... more Underactuated and compliant hands, frequently referred to as soft hands, have been recently proposed to overcome common issues of multi-fingered robotic hands. Although several prototypes have been developed, there is still a lack of systematic ways to model and control these devices to get grasps exploiting their intrinsic features. Classical tools can hardly be applied when contact surfaces are deformable and hand kinematics is not uniquely defined due to underactuation. In this work, we propose a method to model underactuated compliant hands. The model captures how the hand closes analysing the motion of suitable reference points defined on the hand. In particular, we present a procedure to compute the preferred grasping direction of a given hand, namely the closure signature (CS), and then we use this information to plan power grasps. The feasibility of the proposed method has been validated by performing experiments with a soft hand fixed to a robotic arm. The use of the closure signature proved to increase the performance of the grasp planner. The proposed method can easily be extended to other underactuated compliant hands.
We present a wearable skin stretch device for the forearm. It is composed of four cylindrical end... more We present a wearable skin stretch device for the forearm. It is composed of four cylindrical end effectors, evenly distributed around the user's forearm. They can generate independent skin stretch stimuli at the palmar, dorsal, ulnar, and radial sides of the arm. When the four end effectors rotate in the same direction, the wearable device provides cutaneous stimuli about a desired pronation/supination of the forearm. On the other hand, when two opposite end effectors rotate in different directions, the cutaneous device provides cutaneous stimuli about a desired translation of the forearm. To evaluate the effectiveness of our device in providing navigation information, we carried out two experiments of haptic navigation. In the first one, subjects were asked to translate and rotate the forearm toward a target position and orientation, respectively. In the second experiment, subjects were asked to control a 6-DoF robotic manipulator to grasp and lift a target object. Haptic feedback provided by our wearable device improved the performance of both experiments with respect to providing no haptic feedback. Moreover, it showed similar performance with respect to sensory substitution via visual feedback, without overloading the visual channel.
2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2018
This paper presents a novel optimization-based passivity control algorithm for haptic-enabled bil... more This paper presents a novel optimization-based passivity control algorithm for haptic-enabled bilateral teleoperation systems involving multiple degrees of freedom. In particular, in the context of energy-bounding control, the contribution focuses on the implementation of a passivity layer for an existing time-domain scheme, ensuring optimal transparency of the interaction along subsets of the environment space which are preponderant for the given task, while preserving the energy bounds required for passivity. The involved optimization problem is convex and amenable to real-time implementation. The effectiveness of the proposed design is validated via an experiment performed on a virtual teleoperated environment.
2018 IEEE Conference on Decision and Control (CDC), 2018
This paper presents a novel control algorithm for haptic-enabled bilateral teleoperation systems ... more This paper presents a novel control algorithm for haptic-enabled bilateral teleoperation systems involving several degrees of freedom. In particular, the contribution focuses on the implementation of a passivity layer for an established time domain scheme. The proposed approach aims at preserving transparency of interaction along subsets of the environment space which are preponderant for the given task, while guaranteeing the energy bounds required for passivity. The effectiveness of the proposed design is validated via an experiment performed on a virtual teleoperated environment.
If citing, it is advised that you check and use the publisher's definitive version for pagination... more If citing, it is advised that you check and use the publisher's definitive version for pagination, volume/issue, and date of publication details. And where the final published version is provided on the Research Portal, if citing you are again advised to check the publisher's website for any subsequent corrections.
2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2016
This paper presents a methodology for the development of a multi-axis force/torque sensor based o... more This paper presents a methodology for the development of a multi-axis force/torque sensor based on optoelectronic technology. The advantages of using this sensing principle are the low manufacturing costs, the simple fabrication, and the immunity to electrical noise. The force/ torque sensor makes use of six optical sensors: each sensor measures the displacement of a reflective surface that moves integrally with a simply-supported beam. The proposed mechanical structure allows for a variety of shapes on the mechanical structure to be easily adaptable to many robot applications. In this paper, we present a five-axis force/torque sensor based on this optoelectronic principle. To measure force/torque components, two identical three-DoF force/torque sensor structures (comprised of three beams) are mounted on top of each other. Photo sensors and mirrors are fixed inside the structure to measure the six beam deflections. In this paper, we describe the sensor structure, design, fabrication, calibration, and verify our sensor development methodology.
Citing this paper Please note that where the full-text provided on King's Research Portal is ... more Citing this paper Please note that where the full-text provided on King's Research Portal is the Author Accepted Manuscript or Post-Print version this may differ from the final Published version. If citing, it is advised that you check and use the publisher's definitive version for pagination, volume/issue, and date of publication details. And where the final published version is provided on the Research Portal, if citing you are again advised to check the publisher's website for any subsequent corrections.
As robotic systems become more flexible and intelligent , they must be able to move into environm... more As robotic systems become more flexible and intelligent , they must be able to move into environments with a high degree of uncertainty or clutter, such as our homes, workplaces, and the outdoors. In these unstructured scenarios, it is possible that the body of the robot collides with its surroundings. As such, it would be desirable to characterise these contacts in terms of their location and interaction forces. This paper addresses the problem of detecting and isolating collisions between a robotic manipulator and its environment, using only on-board joint torque and position sensing. The algorithm is based on a particle filter and, under some assumptions, is able to identify the contact location anywhere on the robot body. It requires the robot to perform small exploratory movements , progressively integrating the new sensing information through a Bayesian framework. The approach was tested and benchmarked in simulation, with respect to its accuracy and robustness. Validation using a robot with joint torque sensing in a real environment demonstrated the applicability of the method to real-world scenarios.
2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2020
One of the key advantages of robots is the high speeds at which they can operate. In industrial s... more One of the key advantages of robots is the high speeds at which they can operate. In industrial settings, increased velocities can lead to higher throughputs and improved efficiency. Some manipulation tasks might require the robot to perform highly dynamic operations such as shaking, or swinging while grasping an object. These fast movements may produce high accelerations and thus give rise to inertial forces that can cause a grasped object to slip. In this paper a method is proposed to determine the inertial forces that arise on a grasped object during a trajectory, find the instances at which the object might slip, and avoid these slippages by changing the trajectory, namely the orientation of the object. To exemplify the usage of this approach, two grasping tasks are realised: a prehensile and a non-prehensile grasp, and strategies to successfully perform these tasks without changing the overall duration of the trajectory are defined and evaluated.
Centre for Robotics Research Department of Informatics Doctor of Philosophy Touch Based Object Po... more Centre for Robotics Research Department of Informatics Doctor of Philosophy Touch Based Object Pose Estimation For Robotic Grasping by João Bimbo Robot grasping and manipulation require very accurate and timely knowledge of the manipulated object’s shape and pose to succesfully perform a desired task. One of the main reasons current systems fail to carry out complex tasks in a real, unstructured environment is their inability to accurately determine where in the object the fingers are touching. Most systems use vision to detect the pose of an object, but the performance of this sensing modality deteriorates as soon as the robot grasps the object. When the robot hand contacts an object, it partially occludes it, which makes it difficult for vision systems to track the object’s location. This thesis presents algorithms to use the robot’s available tactile sensing to correct the visually determined pose of a grasped object. This method is extended to globally estimate the pose of the o...
We present a novel method for controlling a myoelectric prosthetic wrist. Five multiple degree-of... more We present a novel method for controlling a myoelectric prosthetic wrist. Five multiple degree-of-freedom (DOF) wrist trajectories are obtained from healthy participants that performed tasks that span the range of Activities of Daily Living (ADL) using dimensionality reduction and unsupervised machine learning techniques. The efficacy of these motions is tested as part of a pilot study where a participant used a simulated wrist device controlled using two-site surface electromyography (sEMG); two trajectories were tested in an immersive virtual reality. Novel wrist control has been demonstrated to be more intuitive to use and appears more natural while limiting the amount of body compensation.
Recent results in the field of soft manipulation showed that the direct physical interaction betw... more Recent results in the field of soft manipulation showed that the direct physical interaction between a robotic hand and the environment can be exploited to robustly grasp objects. This is possible when the hand-environment interface is compliant. This abstract presents two complementary approaches to environmental constraints exploitation. The first uses a soft robotic hand interacting with a rigid environment, the second considers a rigid gripper grasping objects over a soft environment.
One of the main goals of haptic systems is to convey realistic forces (transparency) to the user.... more One of the main goals of haptic systems is to convey realistic forces (transparency) to the user. In bilateral telemanipulation control, factors such relaxed grasp of the user, time delays and stiff environments may compromise the stability of the system. Ensuring passivity in the system, i.e. does not generate energy by itself, can prevent unstable behaviour. To preserve passivity, a 3DoF two-layer approach based on energy tanks is implemented; the energy provided to the slave side is limited by the energy obtained from the user at the master side. This energy is generated by a damping-like element that is activated when destabilizing factors occur. This work presents a strategy to prioritize damping coefficients to achieve higher transparency along a number of desired directions. The method consists of solving a quadratic optimization problem that minimizes the projection of the damping force on different directions while maintaining passivity.
Object surface properties are among the most important information for intelligent robotic graspi... more Object surface properties are among the most important information for intelligent robotic grasping and manipulation. This paper presents a new object surface classification approach based on frictional properties. The idea is to use a robotic finger to rub over an object surface with a low acceleration and identify the frictional properties using measured friction force and sliding velocity. A quasi-static LuGre model is used to characterise the relationship between friction force and sliding velocity, and the generalized Newton-Raphson method is applied to estimate unknown frictional coefficients of this model. Since the frictional coefficients of the quasi-static LuGre model are closely related to the material physical properties, object surfaces can be classified using a naïve Bayes classifier with the identified frictional coefficients. Test results show that the proposed approach can achieve a high correctness in object surface classification.
smARTLab, Department of Computer Science, University of Liverpool, Liverpool, United Kingdom, Dep... more smARTLab, Department of Computer Science, University of Liverpool, Liverpool, United Kingdom, Department of Engineering Mathematics and Bristol Robotics Laboratory, University of Bristol, Bristol, United Kingdom, inte-R-action Lab and Centre for Autonomous Robotics (CENTAUR), University of Bath, Bath, United Kingdom, Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, United States, Department of Computer Science and Technology, Tsinghua University, Beijing, China
2019 19th International Conference on Advanced Robotics (ICAR)
Intuitive interaction is the cornerstone of efficient and effective task execution in remote robo... more Intuitive interaction is the cornerstone of efficient and effective task execution in remote robotic teleoperation. It requires high-fidelity in control actions as well as perception (vision, haptic, and sensory feedback) from the remote environment. This paper presents Vicarios, a VR-based teleoperation interface with the aim of facilitating intuitive real-time remote teleoperation, while utilizing the inherent benefits of VR, including immersive visualization, freedom of viewpoint selection, and fluidity of interaction through natural action interfaces. The overall architecture of Vicarios is described, with its components and framework. A preliminary comparative user study, with a real-world tele-manipulation task, was conducted to quantify the effectiveness of Vicarios. It is shown that the VR-based interface is easy-to-use and learn, with an overall learning rate of 0.93 sec. per trial for the users. The smoothness metric shows that the users can improve on their task performance over time as well. Vicarios allows the intuitiveness and flexibility to maintain efficiency in tele-robotic tasks. It forms the basis for an immersive perception interface in remote robotic teleoperation.
2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)
Since direct manual palpation is not possible in minimally invasive surgery procedures, there is ... more Since direct manual palpation is not possible in minimally invasive surgery procedures, there is an active field of applied research which aims to retrieve the human sense of touch and feedback tissue properties through artificial tactile feedback. This paper presents an innovative stiffness sensor to be embedded at the tip of a commercial endoscopic camera. The sensor structure is based on multiple cantilever beams, which act as springs with different stiffness when indented into soft tissue. Geometric features mounted on the beams are tracked during physical contact. Movements of the cantilevers result in shape variations of the features in the camera images. The feature size is then segmented and related to the force exerted into the contact location. As beams of different elasticity are integrated, it is possible to estimate the stiffness properties of the soft tissue by employing only visual information. In this paper, Finite Element Analysis (FEA) was implemented to simulate and estimate how contact forces will affect the material and design of the prototype. A calibration device has been developed and used to validate the outcome of the FEA simulations. An experimental test showed the ability of the proposed mechanism to compute the stiffness of a soft phantom.
Automating the act of grasping is one of the most compelling challenges in robotics. In recent ti... more Automating the act of grasping is one of the most compelling challenges in robotics. In recent times, a major trend has gained the attention of the robotic grasping community: soft manipulation. Along with the design of intrinsically soft robotic hands, it is important to devise grasp planning strategies that can take into account the hand characteristics, but are general enough to be applied to different robotic systems. In this article, we investigate how to perform top grasps with soft hands according to a model-based approach, using both power and precision grasps. The so-called closure signature (CS) is used to model closure motions of soft hands by associating to them a preferred grasping direction. This direction can be aligned to a suitable direction over the object to achieve successful top grasps. The CS-alignment is here combined with a recently developed AI-driven grasp planner for rigid grippers that is adjusted and used to retrieve an estimate of the optimal grasp to b...
Flat objects lying on a surface are hard to grasp, but could be manipulated by sliding along the ... more Flat objects lying on a surface are hard to grasp, but could be manipulated by sliding along the surface in a non-prehensile manner. This strategy is commonly employed by humans as pre-manipulation, for example to bring a cell phone to the edge of a table to pick it up. To endow robots with a similar capability, we introduce a mathematical model of planar sliding by means of a soft finger. The model reveals various aspects of interaction through frictional contacts, which can be used for planning and control. Specifically, using a quasi-static analysis we are able to derive a hybrid dynamical system to predict the motion of the object and the interaction forces. The conditions for which the object sticks to the friction patch, pivots, or completely slides against it are obtained. It is possible to find fixed points of the system and the path taken by the object to reach such configurations. Theoretical as well as comprehensive experimental results are presented.
2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Sep 1, 2017
Robotic teleoperation in cluttered environments is attracting increasing attention for its potent... more Robotic teleoperation in cluttered environments is attracting increasing attention for its potential in hazardous scenarios, disaster response, and telemaintenance. Although haptic feedback has been proven effective in such applications, commercially-available grounded haptic interfaces still show significant limitations in terms of workspace, safety, transparency, and encumbrance. For this reason, we present a novel robotic teleoperation system with wearable haptic feedback for telemanipulation in cluttered environments. The slave system is composed of a soft robotic hand attached to a 6-axis force sensor, which is fixed to a 6-degrees-of-freedom robotic arm. The master system is composed of two wearable vibrotactile armbands and a Leap Motion. The armbands are worn on the upper arm and forearm, and convey information about collisions on the robotic arm and hand, respectively. The position of the manipulator and the grasping configuration of the robotic hand are controlled by the user's hand pose as tracked by the Leap Motion. To validate our approach, we carried out a human-subject telemanipulation experiment in a cluttered scenario. Twelve participants were asked to teleoperate the robot to grasp an object hidden between debris of various shapes and stiffnesses. Haptic feedback provided by our wearable devices significantly improved the performance of the considered telemanipulation tasks. All subjects but one preferred conditions with wearable haptic feedback.
Underactuated and compliant hands, frequently referred to as soft hands, have been recently propo... more Underactuated and compliant hands, frequently referred to as soft hands, have been recently proposed to overcome common issues of multi-fingered robotic hands. Although several prototypes have been developed, there is still a lack of systematic ways to model and control these devices to get grasps exploiting their intrinsic features. Classical tools can hardly be applied when contact surfaces are deformable and hand kinematics is not uniquely defined due to underactuation. In this work, we propose a method to model underactuated compliant hands. The model captures how the hand closes analysing the motion of suitable reference points defined on the hand. In particular, we present a procedure to compute the preferred grasping direction of a given hand, namely the closure signature (CS), and then we use this information to plan power grasps. The feasibility of the proposed method has been validated by performing experiments with a soft hand fixed to a robotic arm. The use of the closure signature proved to increase the performance of the grasp planner. The proposed method can easily be extended to other underactuated compliant hands.
We present a wearable skin stretch device for the forearm. It is composed of four cylindrical end... more We present a wearable skin stretch device for the forearm. It is composed of four cylindrical end effectors, evenly distributed around the user's forearm. They can generate independent skin stretch stimuli at the palmar, dorsal, ulnar, and radial sides of the arm. When the four end effectors rotate in the same direction, the wearable device provides cutaneous stimuli about a desired pronation/supination of the forearm. On the other hand, when two opposite end effectors rotate in different directions, the cutaneous device provides cutaneous stimuli about a desired translation of the forearm. To evaluate the effectiveness of our device in providing navigation information, we carried out two experiments of haptic navigation. In the first one, subjects were asked to translate and rotate the forearm toward a target position and orientation, respectively. In the second experiment, subjects were asked to control a 6-DoF robotic manipulator to grasp and lift a target object. Haptic feedback provided by our wearable device improved the performance of both experiments with respect to providing no haptic feedback. Moreover, it showed similar performance with respect to sensory substitution via visual feedback, without overloading the visual channel.
2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2018
This paper presents a novel optimization-based passivity control algorithm for haptic-enabled bil... more This paper presents a novel optimization-based passivity control algorithm for haptic-enabled bilateral teleoperation systems involving multiple degrees of freedom. In particular, in the context of energy-bounding control, the contribution focuses on the implementation of a passivity layer for an existing time-domain scheme, ensuring optimal transparency of the interaction along subsets of the environment space which are preponderant for the given task, while preserving the energy bounds required for passivity. The involved optimization problem is convex and amenable to real-time implementation. The effectiveness of the proposed design is validated via an experiment performed on a virtual teleoperated environment.
2018 IEEE Conference on Decision and Control (CDC), 2018
This paper presents a novel control algorithm for haptic-enabled bilateral teleoperation systems ... more This paper presents a novel control algorithm for haptic-enabled bilateral teleoperation systems involving several degrees of freedom. In particular, the contribution focuses on the implementation of a passivity layer for an established time domain scheme. The proposed approach aims at preserving transparency of interaction along subsets of the environment space which are preponderant for the given task, while guaranteeing the energy bounds required for passivity. The effectiveness of the proposed design is validated via an experiment performed on a virtual teleoperated environment.
If citing, it is advised that you check and use the publisher's definitive version for pagination... more If citing, it is advised that you check and use the publisher's definitive version for pagination, volume/issue, and date of publication details. And where the final published version is provided on the Research Portal, if citing you are again advised to check the publisher's website for any subsequent corrections.
2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2016
This paper presents a methodology for the development of a multi-axis force/torque sensor based o... more This paper presents a methodology for the development of a multi-axis force/torque sensor based on optoelectronic technology. The advantages of using this sensing principle are the low manufacturing costs, the simple fabrication, and the immunity to electrical noise. The force/ torque sensor makes use of six optical sensors: each sensor measures the displacement of a reflective surface that moves integrally with a simply-supported beam. The proposed mechanical structure allows for a variety of shapes on the mechanical structure to be easily adaptable to many robot applications. In this paper, we present a five-axis force/torque sensor based on this optoelectronic principle. To measure force/torque components, two identical three-DoF force/torque sensor structures (comprised of three beams) are mounted on top of each other. Photo sensors and mirrors are fixed inside the structure to measure the six beam deflections. In this paper, we describe the sensor structure, design, fabrication, calibration, and verify our sensor development methodology.
Citing this paper Please note that where the full-text provided on King's Research Portal is ... more Citing this paper Please note that where the full-text provided on King's Research Portal is the Author Accepted Manuscript or Post-Print version this may differ from the final Published version. If citing, it is advised that you check and use the publisher's definitive version for pagination, volume/issue, and date of publication details. And where the final published version is provided on the Research Portal, if citing you are again advised to check the publisher's website for any subsequent corrections.
As robotic systems become more flexible and intelligent , they must be able to move into environm... more As robotic systems become more flexible and intelligent , they must be able to move into environments with a high degree of uncertainty or clutter, such as our homes, workplaces, and the outdoors. In these unstructured scenarios, it is possible that the body of the robot collides with its surroundings. As such, it would be desirable to characterise these contacts in terms of their location and interaction forces. This paper addresses the problem of detecting and isolating collisions between a robotic manipulator and its environment, using only on-board joint torque and position sensing. The algorithm is based on a particle filter and, under some assumptions, is able to identify the contact location anywhere on the robot body. It requires the robot to perform small exploratory movements , progressively integrating the new sensing information through a Bayesian framework. The approach was tested and benchmarked in simulation, with respect to its accuracy and robustness. Validation using a robot with joint torque sensing in a real environment demonstrated the applicability of the method to real-world scenarios.
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