Helge A Wurdemann | University College London (original) (raw)

Papers by Helge A Wurdemann

10th Hamlyn Symposium on Medical Robotics 2017

This year marks the 10 th anniversary of the Hamlyn Symposium on Medical Robotics, which was held... more This year marks the 10 th anniversary of the Hamlyn Symposium on Medical Robotics, which was held at the Royal Geographical Society from 25 th to 28 th June 2017. On this special occasion, we set the theme of this year's symposium as 'The Next 10 Years: Challenges, Innovation and Diffusion of Medical Robotics.' We had the honour of an impressive line-up of leading scientists and engineers in medical robotics, covering intra-operative imaging and sensing, smart surgical instruments, soft and continuum robotics, micro-nano robots, surgical workflow analysis, surgical vision, clinical highlights and first-inhuman studies. This year's Storz-Hopkins lecture was delivered by Professor Joseph Sung,

2021 IEEE International Conference on Robotics and Automation (ICRA)

Soft robotic manipulators have been created and investigated for a number of applications due to ... more Soft robotic manipulators have been created and investigated for a number of applications due to their advantages over rigid robots. In minimally invasive surgery, for instance, soft robots have successfully demonstrated a number of benefits due to the compliant and flexible nature of the material they are made of. However, these type of robots struggle with performing tasks that require on-demand stiffness i.e. exerting higher forces to the surrounding environment. A number of semi-active and active mechanisms have been investigated to change and control the stiffness of soft robotic manipulators. Embedding these mechanisms in soft manipulators for spacerestricted applications can be challenging though. To better understand the inherent passive stiffness properties of soft manipulators, we propose a screw theory-based stiffness analysis for fluidic-driven continuum soft robotic manipulators. First, we derive the forward kinematics based on a parameterbased piece-wise constant curvature model. It is worth noting, our stiffness analysis can be conducted based on any freespace forward kinematic model. Then our stiffness analysis and mapping methodology is conducted based on screw theory. Initial results of our approach demonstrate the feasibility comparing computational and experimental data.

Wind turbine manufacturing requires the assembly of large mechanical components, which is crucial... more Wind turbine manufacturing requires the assembly of large mechanical components, which is crucial to inspect along the production line in order to prevent high reparation costs afterwards. A critical component in this process is the turbine hub, which supports the wind blades and ball bearings allowing the pitch motion. At present, hub inspection is a manual task, which requires expert operators and long execution time. This paper proposes a novel methodology for the selfadaptive inspection of wind turbine hubs via industrial robots: a set of Critical-To-Quality parameters (CTQs), are inferred from the CAD drawing of wind turbine hub; registration between robot and hub is performed; finally a CAD2robot trajectories planning is accomplished. Methodology is implemented through a Matlab and Simulink Programming Language and combined with an Industrial PC-based control technology Beckhoff TwinCAT 3. Tests with an Fanuc Industrial M-6iB robot arm and R-30iA controller have been successfu...

This workshop aims to bring together medical experts active in the field of minimally invasive su... more This workshop aims to bring together medical experts active in the field of minimally invasive surgery and roboticists creating and studying soft and stiffness controllable robot devices. We will explore the synergies that will arise from robotic surgeons cooperating with such modern robots to conduct advanced surgical interventions previously not possible. This ICRA 2014 workshop will provide a review of current technology used in robot-assisted minimally invasive surgery and explore the current paradigm shift from traditionally rigid surgical tools to robotic systems that are highly redundant, soft and possibly capable of changing their structural stiffness to adapt to surgical needs. The workshop will explore the advantages of these new robotic concepts and the challenges that lie ahead to create functional robot systems that can be employed in the operating theatre of the future. Round table discussions will focus on obstacles and challenges and the future direction of robotic surgery. The workshop will also act as a platform for wider discussions and encourage multidisciplinary collaboration between engineers and surgeons. Welcome to Hong Kong and I hope you enjoy the workshop.

This paper presents a semantic approach to support multimodal interactions between humans and ind... more This paper presents a semantic approach to support multimodal interactions between humans and industrial robots in real industrial scenarios. This is a generic approach and it can be applied in different industrial scenarios. We explain in detail how to apply it in a specific example scenario and how the semantic technologies help not only with accurate natural request interpretation but also their benefits in terms of system maintenance and scalability.

This paper proposes the design of a robotic gripper motivated by the bin-picking problem, where a... more This paper proposes the design of a robotic gripper motivated by the bin-picking problem, where a variety of objects need to be picked from cluttered bins. The presented gripper design focuses on an enveloping cage-like approach, which surrounds the object with three hooked fingers, and then presses into the object with a movable palm. The fingers are flexible and imbue grasps with some elasticity, helping to conform to objects and, crucially, adding friction to cases where an object cannot be caged. This approach proved effective on a set of basic shapes, such as cuboids and cylinders, in which every object could be grasped. In particular, flat bottom parts could be grasped in a very stable manner, as demonstrated by testing grasps with multiple 5N and 10N disturbances. A set of supermarket items were also tested, highlighting promising features such as effective grasping of fruits and vegetables, as well as some limitations in the current embodiment, which is not always able to sl...

Frontiers in Robotics and AI

Active enrollment in rehabilitation training yields better treatment outcomes. This paper introdu... more Active enrollment in rehabilitation training yields better treatment outcomes. This paper introduces an exoskeleton-assisted hand rehabilitation system. It is the first attempt to combine fingertip cutaneous haptic stimulation with exoskeleton-assisted hand rehabilitation for training participation enhancement. For the first time, soft material 3D printing techniques are adopted to make soft pneumatic fingertip haptic feedback actuators to achieve cheaper and faster iterations of prototype designs with consistent quality. The fingertip haptic stimulation is synchronized with the motion of our hand exoskeleton. The contact force of the fingertips resulted from a virtual interaction with a glass of water was based on data collected from normal hand motions to grasp a glass of water. System characterization experiments were conducted and exoskeleton-assisted hand motion with and without the fingertip cutaneous haptic stimulation were compared in an experiment involving healthy human su...

2018 IEEE International Conference on Robotics and Automation (ICRA)

Many modern roboticists take inspiration from biology to create novel robotic structures, includi... more Many modern roboticists take inspiration from biology to create novel robotic structures, including those that are modeled after the octopus. This paper advances this trend by creating soft robots modeling the complex motion patterns of octopus tentacles employing a bio-mimetic approach. The proposed octopus robot is entirely made from soft material and uses a novel fluidic actuation mechanism that allows the robot to advance forward, change directions and rotate around its primary axis. The paper presents the robot's design and fabrication process. An experimental study is conducted showing the feasibility of the proposed robot and actuation mechanism.

IEEE Robotics and Automation Letters

This letter presents the design, prototype and kinematic model of a new adaptive underactuated fi... more This letter presents the design, prototype and kinematic model of a new adaptive underactuated finger with an articulated skin/surface that is able to bend and, at the same time, provides active rolling motion along its central axis while keeping the finger configuration (see Fig. 1). The design is based on a planar chain of overlapping spherical phalanxes that are tendon-driven. The finger has an articulated surface made of an external chain of hollow universal joints that can rotate via its central axis on the surface of the internal structure. The outer surface provides a second active Degree of Freedom (DoF). The two actuators, driving the bending and/or rolling motion, can be used independently. A set of experiments have been included to validate and measure the performance of the prototype for the grasping and rolling actions. The proposed finger can be built with a different number of phalanxes and sizes. A number of these fingers can be arranged along a palm structure resulting in a multi-finger robotic grasper for applications that require adaptation and in-hand manipulation capabilities such as pHRI.

2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

The constantly increasing amount of machines operating in the vicinity of humans makes it necessa... more The constantly increasing amount of machines operating in the vicinity of humans makes it necessary to rethink the design approach for such machines to ensure that they are safe when interacting with humans. Traditional mechanisms are rigid and heavy and as such considered unsuitable, even dangerous when a controlled physical contact with humans is desired. A huge improvement in terms of safe human-robot interaction has been achieved by a radically new approach to robotics-soft material robotics. These new robots are made of compliant materials that render them safe when compared to the conventional rigid-link robots. This undeniable advantage of compliance and softness is paired with a number of drawbacks. One of them is that a complex and sophisticated controller is required to move a soft robot into the desired positions or along a desired trajectory, especially with external forces being present. In this paper we propose an improved soft fluidic rotary actuator composed of silicone rubber and fiber-based reinforcement. The actuator is cheap and easily manufactured providing near linear actuation properties when compared to pneumatic actuators presented elsewhere. The paper presents the actuator design, manufacturing process and a mathematical model of the actuator behavior as well as an experimental validation of the model. Four different actuator types are compared including a square-shaped and three differently reinforced cylindrical actuators.

2019 International Conference on Robotics and Automation (ICRA), May 1, 2019

This paper describes a novel approach in human-robot interaction driven by ergonomics. With a cle... more This paper describes a novel approach in human-robot interaction driven by ergonomics. With a clear focus on optimising ergonomics, the approach proposed here continuously observes a human user's posture and by invoking appropriate cooperative robot movements, the user's posture is, whenever required, brought back to an ergonomic optimum. Effectively, the new protocol optimises the human-robot relative position and orientation as a function of human ergonomics. An RGB-D camera is used to calculate and monitor human joint angles in real-time and to determine the current ergonomics state. A total of 6 main causes of low ergonomic states are identified, leading to 6 universal robot responses to allow the human to return to an optimal ergonomics state. The algorithmic framework identifies these 6 causes and controls the cooperating robot to always adapt the environment (e.g. change the pose of the workpiece) in a way that is ergonomically most comfortable for the interacting user. Hence, human-robot interaction is continuously re-evaluated optimizing ergonomics states. The approach is validated through an experimental study, based on established ergonomic methods and their adaptation for real-time application. The study confirms improved ergonomics using the new approach.

2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Sep 1, 2017

The constantly increasing amount of machines operating in the vicinity of humans makes it necessa... more The constantly increasing amount of machines operating in the vicinity of humans makes it necessary to rethink the design approach for such machines to ensure that they are safe when interacting with humans. Traditional mechanisms are rigid and heavy and as such considered unsuitable, even dangerous when a controlled physical contact with humans is desired. A huge improvement in terms of safe human-robot interaction has been achieved by a radically new approach to robotics-soft material robotics. These new robots are made of compliant materials that render them safe when compared to the conventional rigid-link robots. This undeniable advantage of compliance and softness is paired with a number of drawbacks. One of them is that a complex and sophisticated controller is required to move a soft robot into the desired positions or along a desired trajectory, especially with external forces being present. In this paper we propose an improved soft fluidic rotary actuator composed of silicone rubber and fiber-based reinforcement. The actuator is cheap and easily manufactured providing near linear actuation properties when compared to pneumatic actuators presented elsewhere. The paper presents the actuator design, manufacturing process and a mathematical model of the actuator behavior as well as an experimental validation of the model. Four different actuator types are compared including a square-shaped and three differently reinforced cylindrical actuators.

2018 IEEE International Conference on Robotics and Automation (ICRA), May 1, 2018

Many modern roboticists take inspiration from biology to create novel robotic structures, includi... more Many modern roboticists take inspiration from biology to create novel robotic structures, including those that are modeled after the octopus. This paper advances this trend by creating soft robots modeling the complex motion patterns of octopus tentacles employing a bio-mimetic approach. The proposed octopus robot is entirely made from soft material and uses a novel fluidic actuation mechanism that allows the robot to advance forward, change directions and rotate around its primary axis. The paper presents the robot's design and fabrication process. An experimental study is conducted showing the feasibility of the proposed robot and actuation mechanism.

IEEE Robotics and Automation Letters

Collaborative robots (cobots) open up new avenues in the fields of industrial robotics and physic... more Collaborative robots (cobots) open up new avenues in the fields of industrial robotics and physical Human-Robot Interaction (pHRI) as they are suitable to work in close approximation and in collaboration with humans. The integration and control of variable stiffness elements allow inherently safe interaction. Apart from notable work on Variable Stiffness Actuators, the concept of Variable-Stiffness-Link (VSL) manipulators promises safety improvements in cases of unintentional physical collisions. However, position control of these type of robotic manipulators is challenging for critical task-oriented motions (e.g., pick and place). Hence, the study of open-loop position control for VSL robots is crucial to achieve high levels of safety, accuracy and hardware cost-efficiency in pHRI applications. In this paper, we propose a hybrid, learning based kinematic modelling approach to improve the performance of traditional open-loop position controllers for a modular, collaborative VSL robot. We show that our approach improves the performance of traditional open-loop position controllers for robots with VSL and compensates for position errors, in particular, for lower stiffness values inside the links: Using our upgraded and modular robot, two experiments have been carried out to evaluate the behaviour of the robot during taskoriented motions. Results show that traditional model-based kinematics are not able to accurately control the position of the end-effector: the position error increases with higher loads and lower pressures inside the VSLs. On the other hand, we demonstrate that, using our approach, the VSL robot can outperform the position control compared to a robotic manipulator with 3D printed rigid links.

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.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

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.

This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness in... more This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness information through a visual interface. The method exploits a combination of two feedback techniques, namely visual feedback of soft surface deformation and control of the indenter avatar speed, to convey stiffness information of a simulated surface of a soft object in virtual environments. The proposed method was effective in distinguishing different sizes of virtual hard nodules integrated into the simulated soft bodies. To further improve the interactive experience, the approach was extended creating a multi-point pseudo-haptic feedback system. A comparison with regards to (a) nodule detection sensitivity and (b) elapsed time as performance indicators in hard nodule detection experiments to a tablet computer incorporating vibration feedback was conducted. The multi-point pseudo-haptic interaction is shown to be more time-efficient than the single-point pseudo-haptic interaction. It is noted that multi-point pseudo-haptic feedback performs similarly well when compared to a vibration based feedback method based on both performance measures elapsed time and nod-ule detection sensitivity. This proves that the proposed method can be used to convey detailed haptic information for virtual environmental tasks, even subtle ones, using either a computer mouse or a pressure sensitive device as an input device. This pseudo-haptic feedback method provides an opportunity for low-cost simulation of objects with soft surfaces and hard inclusions, as, for example, occurring in ever more realistic video games with increasing emphasis on interaction with the physical environment and minimally inva-sive surgery in the form of soft tissue organs with embedded cancer nodules. Hence, the method can be used in many low-budget applications where haptic sensation is required, such as surgeon training or video games, either using desktop computers or portable devices, showing reasonably high fidelity in conveying stiffness perception to the user.

This paper explores methods that make use of visual cues aimed at generating actual haptic sensat... more This paper explores methods that make use of visual cues aimed at generating actual haptic sensation to the user, namely pseudo-haptics. We propose a new pseudo-haptic feedback based method capable of conveying 3D haptic information and combining visual haptics with force feedback to enhance the user's haptic experience. We focused on an application related to tumor identification during palpation and evaluated the proposed method in an experimental study where users interacted with a haptic device and graph-ical interface while exploring a virtual model of soft tissue, which represented stiffness distribution of a silicone phantom tissue with embedded hard inclusions. The performance of hard inclusion detection using force feedback only, pseudo-haptic feedback only, and the combination of the two feedbacks were compared with the direct hand touch. The combination method and direct hand touch had no significant difference in the detection results. Compared with the force feedback alone, our method increased the sensitivity by 5%, the positive predictive value by 4%, and decreased detection time by 48.7%. The proposed methodology has great potential for robot-assisted minimally inva-sive surgery and in all applications where remote haptic feedback is needed.

INTRODUCTION The inclusion of haptic palpation in training simulators is beneficial for the acqui... more INTRODUCTION The inclusion of haptic palpation in training simulators is beneficial for the acquisition of practical experience. Pseudo-haptic feedback, which creates an illusion of force and haptic feedback using only visual information, can replace expensive haptic devices [1]. In this paper, a multi-fingered palpation simulation using pseudo-haptic feedback with three indenter avatars is introduced and evaluated to prove the hypothesis that multi-fingered palpation is more time-efficient than single-fingered palpation. Multi-fingered palpation is more common than single-fingered palpation in real practice when attempting to detect differences in stiffness in the examined tissue [2]. With multiple indenter avatars, a wider tissue area can be investigated during one indentation instead of only one spot using a single indenter avatar. Moreover, the user can conveniently compare the stiffness values at different locations by observing the differences of indentation depths of those separate indenter avatars.

10th Hamlyn Symposium on Medical Robotics 2017

This year marks the 10 th anniversary of the Hamlyn Symposium on Medical Robotics, which was held... more This year marks the 10 th anniversary of the Hamlyn Symposium on Medical Robotics, which was held at the Royal Geographical Society from 25 th to 28 th June 2017. On this special occasion, we set the theme of this year's symposium as 'The Next 10 Years: Challenges, Innovation and Diffusion of Medical Robotics.' We had the honour of an impressive line-up of leading scientists and engineers in medical robotics, covering intra-operative imaging and sensing, smart surgical instruments, soft and continuum robotics, micro-nano robots, surgical workflow analysis, surgical vision, clinical highlights and first-inhuman studies. This year's Storz-Hopkins lecture was delivered by Professor Joseph Sung,

2021 IEEE International Conference on Robotics and Automation (ICRA)

Soft robotic manipulators have been created and investigated for a number of applications due to ... more Soft robotic manipulators have been created and investigated for a number of applications due to their advantages over rigid robots. In minimally invasive surgery, for instance, soft robots have successfully demonstrated a number of benefits due to the compliant and flexible nature of the material they are made of. However, these type of robots struggle with performing tasks that require on-demand stiffness i.e. exerting higher forces to the surrounding environment. A number of semi-active and active mechanisms have been investigated to change and control the stiffness of soft robotic manipulators. Embedding these mechanisms in soft manipulators for spacerestricted applications can be challenging though. To better understand the inherent passive stiffness properties of soft manipulators, we propose a screw theory-based stiffness analysis for fluidic-driven continuum soft robotic manipulators. First, we derive the forward kinematics based on a parameterbased piece-wise constant curvature model. It is worth noting, our stiffness analysis can be conducted based on any freespace forward kinematic model. Then our stiffness analysis and mapping methodology is conducted based on screw theory. Initial results of our approach demonstrate the feasibility comparing computational and experimental data.

Wind turbine manufacturing requires the assembly of large mechanical components, which is crucial... more Wind turbine manufacturing requires the assembly of large mechanical components, which is crucial to inspect along the production line in order to prevent high reparation costs afterwards. A critical component in this process is the turbine hub, which supports the wind blades and ball bearings allowing the pitch motion. At present, hub inspection is a manual task, which requires expert operators and long execution time. This paper proposes a novel methodology for the selfadaptive inspection of wind turbine hubs via industrial robots: a set of Critical-To-Quality parameters (CTQs), are inferred from the CAD drawing of wind turbine hub; registration between robot and hub is performed; finally a CAD2robot trajectories planning is accomplished. Methodology is implemented through a Matlab and Simulink Programming Language and combined with an Industrial PC-based control technology Beckhoff TwinCAT 3. Tests with an Fanuc Industrial M-6iB robot arm and R-30iA controller have been successfu...

This workshop aims to bring together medical experts active in the field of minimally invasive su... more This workshop aims to bring together medical experts active in the field of minimally invasive surgery and roboticists creating and studying soft and stiffness controllable robot devices. We will explore the synergies that will arise from robotic surgeons cooperating with such modern robots to conduct advanced surgical interventions previously not possible. This ICRA 2014 workshop will provide a review of current technology used in robot-assisted minimally invasive surgery and explore the current paradigm shift from traditionally rigid surgical tools to robotic systems that are highly redundant, soft and possibly capable of changing their structural stiffness to adapt to surgical needs. The workshop will explore the advantages of these new robotic concepts and the challenges that lie ahead to create functional robot systems that can be employed in the operating theatre of the future. Round table discussions will focus on obstacles and challenges and the future direction of robotic surgery. The workshop will also act as a platform for wider discussions and encourage multidisciplinary collaboration between engineers and surgeons. Welcome to Hong Kong and I hope you enjoy the workshop.

This paper presents a semantic approach to support multimodal interactions between humans and ind... more This paper presents a semantic approach to support multimodal interactions between humans and industrial robots in real industrial scenarios. This is a generic approach and it can be applied in different industrial scenarios. We explain in detail how to apply it in a specific example scenario and how the semantic technologies help not only with accurate natural request interpretation but also their benefits in terms of system maintenance and scalability.

This paper proposes the design of a robotic gripper motivated by the bin-picking problem, where a... more This paper proposes the design of a robotic gripper motivated by the bin-picking problem, where a variety of objects need to be picked from cluttered bins. The presented gripper design focuses on an enveloping cage-like approach, which surrounds the object with three hooked fingers, and then presses into the object with a movable palm. The fingers are flexible and imbue grasps with some elasticity, helping to conform to objects and, crucially, adding friction to cases where an object cannot be caged. This approach proved effective on a set of basic shapes, such as cuboids and cylinders, in which every object could be grasped. In particular, flat bottom parts could be grasped in a very stable manner, as demonstrated by testing grasps with multiple 5N and 10N disturbances. A set of supermarket items were also tested, highlighting promising features such as effective grasping of fruits and vegetables, as well as some limitations in the current embodiment, which is not always able to sl...

Frontiers in Robotics and AI

Active enrollment in rehabilitation training yields better treatment outcomes. This paper introdu... more Active enrollment in rehabilitation training yields better treatment outcomes. This paper introduces an exoskeleton-assisted hand rehabilitation system. It is the first attempt to combine fingertip cutaneous haptic stimulation with exoskeleton-assisted hand rehabilitation for training participation enhancement. For the first time, soft material 3D printing techniques are adopted to make soft pneumatic fingertip haptic feedback actuators to achieve cheaper and faster iterations of prototype designs with consistent quality. The fingertip haptic stimulation is synchronized with the motion of our hand exoskeleton. The contact force of the fingertips resulted from a virtual interaction with a glass of water was based on data collected from normal hand motions to grasp a glass of water. System characterization experiments were conducted and exoskeleton-assisted hand motion with and without the fingertip cutaneous haptic stimulation were compared in an experiment involving healthy human su...

2018 IEEE International Conference on Robotics and Automation (ICRA)

Many modern roboticists take inspiration from biology to create novel robotic structures, includi... more Many modern roboticists take inspiration from biology to create novel robotic structures, including those that are modeled after the octopus. This paper advances this trend by creating soft robots modeling the complex motion patterns of octopus tentacles employing a bio-mimetic approach. The proposed octopus robot is entirely made from soft material and uses a novel fluidic actuation mechanism that allows the robot to advance forward, change directions and rotate around its primary axis. The paper presents the robot's design and fabrication process. An experimental study is conducted showing the feasibility of the proposed robot and actuation mechanism.

IEEE Robotics and Automation Letters

This letter presents the design, prototype and kinematic model of a new adaptive underactuated fi... more This letter presents the design, prototype and kinematic model of a new adaptive underactuated finger with an articulated skin/surface that is able to bend and, at the same time, provides active rolling motion along its central axis while keeping the finger configuration (see Fig. 1). The design is based on a planar chain of overlapping spherical phalanxes that are tendon-driven. The finger has an articulated surface made of an external chain of hollow universal joints that can rotate via its central axis on the surface of the internal structure. The outer surface provides a second active Degree of Freedom (DoF). The two actuators, driving the bending and/or rolling motion, can be used independently. A set of experiments have been included to validate and measure the performance of the prototype for the grasping and rolling actions. The proposed finger can be built with a different number of phalanxes and sizes. A number of these fingers can be arranged along a palm structure resulting in a multi-finger robotic grasper for applications that require adaptation and in-hand manipulation capabilities such as pHRI.

2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

The constantly increasing amount of machines operating in the vicinity of humans makes it necessa... more The constantly increasing amount of machines operating in the vicinity of humans makes it necessary to rethink the design approach for such machines to ensure that they are safe when interacting with humans. Traditional mechanisms are rigid and heavy and as such considered unsuitable, even dangerous when a controlled physical contact with humans is desired. A huge improvement in terms of safe human-robot interaction has been achieved by a radically new approach to robotics-soft material robotics. These new robots are made of compliant materials that render them safe when compared to the conventional rigid-link robots. This undeniable advantage of compliance and softness is paired with a number of drawbacks. One of them is that a complex and sophisticated controller is required to move a soft robot into the desired positions or along a desired trajectory, especially with external forces being present. In this paper we propose an improved soft fluidic rotary actuator composed of silicone rubber and fiber-based reinforcement. The actuator is cheap and easily manufactured providing near linear actuation properties when compared to pneumatic actuators presented elsewhere. The paper presents the actuator design, manufacturing process and a mathematical model of the actuator behavior as well as an experimental validation of the model. Four different actuator types are compared including a square-shaped and three differently reinforced cylindrical actuators.

2019 International Conference on Robotics and Automation (ICRA), May 1, 2019

This paper describes a novel approach in human-robot interaction driven by ergonomics. With a cle... more This paper describes a novel approach in human-robot interaction driven by ergonomics. With a clear focus on optimising ergonomics, the approach proposed here continuously observes a human user's posture and by invoking appropriate cooperative robot movements, the user's posture is, whenever required, brought back to an ergonomic optimum. Effectively, the new protocol optimises the human-robot relative position and orientation as a function of human ergonomics. An RGB-D camera is used to calculate and monitor human joint angles in real-time and to determine the current ergonomics state. A total of 6 main causes of low ergonomic states are identified, leading to 6 universal robot responses to allow the human to return to an optimal ergonomics state. The algorithmic framework identifies these 6 causes and controls the cooperating robot to always adapt the environment (e.g. change the pose of the workpiece) in a way that is ergonomically most comfortable for the interacting user. Hence, human-robot interaction is continuously re-evaluated optimizing ergonomics states. The approach is validated through an experimental study, based on established ergonomic methods and their adaptation for real-time application. The study confirms improved ergonomics using the new approach.

2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Sep 1, 2017

The constantly increasing amount of machines operating in the vicinity of humans makes it necessa... more The constantly increasing amount of machines operating in the vicinity of humans makes it necessary to rethink the design approach for such machines to ensure that they are safe when interacting with humans. Traditional mechanisms are rigid and heavy and as such considered unsuitable, even dangerous when a controlled physical contact with humans is desired. A huge improvement in terms of safe human-robot interaction has been achieved by a radically new approach to robotics-soft material robotics. These new robots are made of compliant materials that render them safe when compared to the conventional rigid-link robots. This undeniable advantage of compliance and softness is paired with a number of drawbacks. One of them is that a complex and sophisticated controller is required to move a soft robot into the desired positions or along a desired trajectory, especially with external forces being present. In this paper we propose an improved soft fluidic rotary actuator composed of silicone rubber and fiber-based reinforcement. The actuator is cheap and easily manufactured providing near linear actuation properties when compared to pneumatic actuators presented elsewhere. The paper presents the actuator design, manufacturing process and a mathematical model of the actuator behavior as well as an experimental validation of the model. Four different actuator types are compared including a square-shaped and three differently reinforced cylindrical actuators.

2018 IEEE International Conference on Robotics and Automation (ICRA), May 1, 2018

Many modern roboticists take inspiration from biology to create novel robotic structures, includi... more Many modern roboticists take inspiration from biology to create novel robotic structures, including those that are modeled after the octopus. This paper advances this trend by creating soft robots modeling the complex motion patterns of octopus tentacles employing a bio-mimetic approach. The proposed octopus robot is entirely made from soft material and uses a novel fluidic actuation mechanism that allows the robot to advance forward, change directions and rotate around its primary axis. The paper presents the robot's design and fabrication process. An experimental study is conducted showing the feasibility of the proposed robot and actuation mechanism.

IEEE Robotics and Automation Letters

Collaborative robots (cobots) open up new avenues in the fields of industrial robotics and physic... more Collaborative robots (cobots) open up new avenues in the fields of industrial robotics and physical Human-Robot Interaction (pHRI) as they are suitable to work in close approximation and in collaboration with humans. The integration and control of variable stiffness elements allow inherently safe interaction. Apart from notable work on Variable Stiffness Actuators, the concept of Variable-Stiffness-Link (VSL) manipulators promises safety improvements in cases of unintentional physical collisions. However, position control of these type of robotic manipulators is challenging for critical task-oriented motions (e.g., pick and place). Hence, the study of open-loop position control for VSL robots is crucial to achieve high levels of safety, accuracy and hardware cost-efficiency in pHRI applications. In this paper, we propose a hybrid, learning based kinematic modelling approach to improve the performance of traditional open-loop position controllers for a modular, collaborative VSL robot. We show that our approach improves the performance of traditional open-loop position controllers for robots with VSL and compensates for position errors, in particular, for lower stiffness values inside the links: Using our upgraded and modular robot, two experiments have been carried out to evaluate the behaviour of the robot during taskoriented motions. Results show that traditional model-based kinematics are not able to accurately control the position of the end-effector: the position error increases with higher loads and lower pressures inside the VSLs. On the other hand, we demonstrate that, using our approach, the VSL robot can outperform the position control compared to a robotic manipulator with 3D printed rigid links.

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.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

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.

This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness in... more This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness information through a visual interface. The method exploits a combination of two feedback techniques, namely visual feedback of soft surface deformation and control of the indenter avatar speed, to convey stiffness information of a simulated surface of a soft object in virtual environments. The proposed method was effective in distinguishing different sizes of virtual hard nodules integrated into the simulated soft bodies. To further improve the interactive experience, the approach was extended creating a multi-point pseudo-haptic feedback system. A comparison with regards to (a) nodule detection sensitivity and (b) elapsed time as performance indicators in hard nodule detection experiments to a tablet computer incorporating vibration feedback was conducted. The multi-point pseudo-haptic interaction is shown to be more time-efficient than the single-point pseudo-haptic interaction. It is noted that multi-point pseudo-haptic feedback performs similarly well when compared to a vibration based feedback method based on both performance measures elapsed time and nod-ule detection sensitivity. This proves that the proposed method can be used to convey detailed haptic information for virtual environmental tasks, even subtle ones, using either a computer mouse or a pressure sensitive device as an input device. This pseudo-haptic feedback method provides an opportunity for low-cost simulation of objects with soft surfaces and hard inclusions, as, for example, occurring in ever more realistic video games with increasing emphasis on interaction with the physical environment and minimally inva-sive surgery in the form of soft tissue organs with embedded cancer nodules. Hence, the method can be used in many low-budget applications where haptic sensation is required, such as surgeon training or video games, either using desktop computers or portable devices, showing reasonably high fidelity in conveying stiffness perception to the user.

This paper explores methods that make use of visual cues aimed at generating actual haptic sensat... more This paper explores methods that make use of visual cues aimed at generating actual haptic sensation to the user, namely pseudo-haptics. We propose a new pseudo-haptic feedback based method capable of conveying 3D haptic information and combining visual haptics with force feedback to enhance the user's haptic experience. We focused on an application related to tumor identification during palpation and evaluated the proposed method in an experimental study where users interacted with a haptic device and graph-ical interface while exploring a virtual model of soft tissue, which represented stiffness distribution of a silicone phantom tissue with embedded hard inclusions. The performance of hard inclusion detection using force feedback only, pseudo-haptic feedback only, and the combination of the two feedbacks were compared with the direct hand touch. The combination method and direct hand touch had no significant difference in the detection results. Compared with the force feedback alone, our method increased the sensitivity by 5%, the positive predictive value by 4%, and decreased detection time by 48.7%. The proposed methodology has great potential for robot-assisted minimally inva-sive surgery and in all applications where remote haptic feedback is needed.

INTRODUCTION The inclusion of haptic palpation in training simulators is beneficial for the acqui... more INTRODUCTION The inclusion of haptic palpation in training simulators is beneficial for the acquisition of practical experience. Pseudo-haptic feedback, which creates an illusion of force and haptic feedback using only visual information, can replace expensive haptic devices [1]. In this paper, a multi-fingered palpation simulation using pseudo-haptic feedback with three indenter avatars is introduced and evaluated to prove the hypothesis that multi-fingered palpation is more time-efficient than single-fingered palpation. Multi-fingered palpation is more common than single-fingered palpation in real practice when attempting to detect differences in stiffness in the examined tissue [2]. With multiple indenter avatars, a wider tissue area can be investigated during one indentation instead of only one spot using a single indenter avatar. Moreover, the user can conveniently compare the stiffness values at different locations by observing the differences of indentation depths of those separate indenter avatars.