54 accepted papers
Twisted string actuators (TSAs) have emerged as promising actuators in robotics owing to their compliant, lightweight nature, and high transmission ratios. However, practical utilization of TSAs remains limited due to their restricted stroke length and intrinsically nonlinear transmission ratio (TR)
The Time Domain Passivity Approach (TDPA) was developed to guarantee passivity while avoiding conservative constant controller parametrization. For this sake, the TDPA applies adaptive damping to dissipate excessive energy resulting from communication delay in bilateral teleoperation setups. Despite
Accurate global localization remains a fundamental challenge in autonomous vehicle navigation, especially in previously unexplored areas lacking prior map information. Traditional methods typically rely on high-definition (HD) maps generated through prior traversals or utilize auxiliary sensors such…
Accurate global localization remains a fundamental challenge in autonomous vehicle navigation. Traditional methods typically rely on high-definition (HD) maps generated through prior traverses or utilize auxiliary sensors, such as a global positioning system (GPS). However, the above approaches are
Autonomous driving has rapidly advanced with diverse sensors, especially Light Detection and Ranging (LiDAR), which provides precise geometry for tasks like simultaneous localization and mapping (SLAM). Recently, the performance of LiDAR-based SLAM has improved through studies leveraging intensity a…
Soft growing robots possess unique advantages, such as the ability to navigate confined and complex environments. Although securing a stable inner channel is essential for enabling a wide range of applications, such as sensor integration, tool passage, and material transfer, the pressure required fo
Robotic dressing assistance has the potential to improve the quality of life for individuals with limited mobility. Existing solutions predominantly rely on rigid robotic manipulators, which have challenges in handling deformable garments and ensuring safe physical interaction with the human body. P…
Robotic dressing assistance has the potential to improve the quality of life for individuals with limited mobility. Existing solutions predominantly rely on rigid robotic manipulators, which have challenges in handling deformable garments and ensuring safe physical interaction with the human body. P
Immediate removal of hazardous gases is critical for ensuring safety. Traditional methods, such as portable ventilation equipment, are difficult to use when hazardous gases are released in inaccessible environments. In this paper, we propose a novel mechanism that integrates an inflatable helical st
Many individuals experience knee dysfunctions attributed to the natural aging process and degenerative conditions. To aid individuals in regaining knee functionality, supportive exoskeletons were designed to be affixed to both the shin and thigh. However, a common issue encountered in knee exoskelet…
In robotics, twisted string actuators (TSAs) have attracted considerable attention owing to their high gear ratio, flexibility, and simplicity. However, TSAs face challenges such as control issues, limited lifespan, and limited stroke. Among them, their practical use is hindered by a limited stroke
Soft growing robots are being used in various fields owing to their distinct advantages. However, their ability to manipulate tools in different applications is still challenging. In this letter, we propose an inflatable-structure-based working-channel securing mechanism for soft growing robots. The
This study explores the feasibility of using simulations as a better interface to collect human object manipulation skills for learning from demonstrations (LfD). Recently, numerous researchers have started introducing teleoperation systems to acquire human manipulation skills. However, capturing th…
A bimanual haptic display supporting the full range of human arm motion and providing a sufficient haptic feedback force/torque is essential for achieving human-like manipulation in remote or virtual environments. This letter proposes the use of redundant collaborative robot arms as a bimanual hapti
Soft growing robots have garnered significant research interest owing to their unique locomotion. However, real-world applications of these robots are limited by challenges in achieving reversible and repeatable operations, particularly when faced with buckling during retraction. Although a variety
6D object pose estimation aims to infer the relative pose between the object and the camera using a single image or multiple images. Most works have focused on predicting the object pose without associated uncertainty under occlusion and structural ambiguity (symmetricity). However, these works dema
Time-discretization introduces an explicit time dependency for control laws that were originally designed to depend exclusively on an error variable: At different times, the control actions at the same error value might differ. Integrating the control action over the error reveals that this time dep…
Over the years, soft growing robots that allow the feeding of new materials at their tips have attracted considerable attention owing to their unique locomotion characteristics. However, accessing targets over highly curved passages by steering compliant continuum bodies remains challenging. To this…
Inflatable structures have attracted considerable research attention in many fields owing to their numerous advantages, such as being light and able to engage in interactions safely. However, in most cases, the inflatable structure can only have one stable configuration, which is undesirable for rob…
This letter presents an active-type twisted string actuator (TSA)-based continuously variable transmission (CVT). The proposed mechanism improves the advantage of the intrinsic CVT nature of TSA by compensating its nonlinear transmission ratio (TR) with the active and continuous conversion of the TR
Using publicly accessible maps, we propose a novel vehicle localization method that can be applied without using prior light detection and ranging (LiDAR) maps. Our method generates OSM descriptors by calculating the distances to buildings from a location in OpenStreetMap at a regular angle, and LiD
Adding virtual damping to dissipate energy has been a major tool for designing stable haptic interfaces in most passivity-based approaches. However, virtual damping is known to dissipate a limited amount of energy. It even generates energy during high-velocity interaction because of the digitization
Many applications require robotic end-effectors and mechanisms to move along periodic trajectories of given amplitude and frequency. If motion parameters are known in advance, it might be beneficial to design the mechanism in such a way that its natural frequency is close to that of the desired traj
Twisted string actuators (TSA) are efficient, compliant cable actuators with high power density that have found their way into many engineering and robotics applications in recent years. They are generally used in the scenarios involving comparatively slow positioning, since quick motions in TSAs of…
Soft growing robots that extend through tip eversion have attracted considerable interest owing to their unique locomotion. Although the availability of visual feedback from the tip of such robots would greatly enhance their usefulness in field explorations, given that the material at the tip contin
Virtual fixtures (VFs) improve human operator performance in teleoperation scenarios. However, the generation of VFs is challenging, especially in unstructured environments. In this work, we introduce a framework for the interactive generation of VF. The method is based on the observation that a hum…
Pneumatically operated soft growing robots that extend via tip eversion are well-suited for navigation in confined spaces. Adding the ability to interact with the environment using sensors and tools attached to the robot tip would greatly enhance the usefulness of these robots for exploration in the…
This letter presents derivation and experimental evaluation of extended dynamical model of twisted string actuator (TSA). The proposed model supports more precise estimation of required motor torque for both low-speed and high-speed (up to 2 Hz) motion by considering effects of elastic deformation o
In the present paper, we first adopt explicit force control from general robotics and embed it into teleoperation systems to enhance the transparency by reducing the effect of the perceived inertia to the human operator and simultaneously improve contact perception. To ensure stability of the propos…
This paper presents a study on a compliant cable-driven exoskeleton for hip assistance in lifting tasks that is aimed at preventing low-back pain and injuries in the vocational setting. In the proposed concept, we used twisted string actuator (TSA) to design a light-weight and powerful exoskeleton t…
We propose an online incremental learning approach through teleoperation which allows an operator to partially modify a learned model, whenever it is necessary, during task execution. Compared to conventional incremental learning approaches, the proposed approach is applicable for teleoperation-base…
For safe human-robot interaction, various type of flexible manipulators have been developed. Especially series elastic actuator (SEA) based manipulators have been getting huge attention since the elastic element of SEA prevents people from injury when undesirable collision happens. Moreover, it impr…
This paper studies an effect of vibration on twisted string actuation through conduit at high bending angles. In our previous work [1], we have demonstrated that twisted string actuators can be used to transmit power even at significant deflection angles of the conduit. However, several undesirable…
Passivity has been the most often used constraint for the stable controller design of bilateral teleoperation systems. Especially, Time Domain Passivity Approach (TDPA) has been used in many applications since it has been known as one of the least conservative passivity-based approaches. Although TD…
Twisted string actuators are an emerging type of transmission systems that may benefit various applications of robotics and mechatronics. However, control of TSAs in applications that require high bandwidth has attracted comparatively little interest from research community, mainly due to complexity…
This paper proposes a practical and less conservative passivity analysis for series elastic actuators (SEAs) by introducing load port definition and shows that the achievable stiffness by the impedance control of SEA can be set higher than the inherent stiffness of SEA depending on the condition of…
In this letter, we proposed a variable radius pulley (VRP) to linearize input-output behavior of twisted string actuators (TSAs). With the help of a VRP, it is possible to make the inherently nonlinear transmission ratio of twisted string constant. This enables design of bidirectional transmission s
Robotic systems for object handling and manipulation are hugely important for modern engineering and industry, with their efficiency, agility and robustness often depending on gripper design and performance. In this work, we investigate a gripper design that, when driven by a twisted string actuator…
Mobility by growth is a new paradigm in robotic systems design and their applications in the real world. Soft, tip-extending, or “growing”, robots have potential applications including inspection and navigation in disaster scenarios. However, due to their growing capability, such robots create uniqu…
Enhancing transparency of a teleoperation system by increasing the command-following bandwidth has not received lots of attention so far. This is considered a challenging task since in a teleoperation system the command-following bandwidth of the slave robot motion controller cannot be increased wit…
Twisted string actuators (TSAs) are gaining popularity in modern engineering and robotic applications. However, in conventional actuators of this type, the twisted part of the string should not be in contact with any surfaces or objects because this may interfere with the propagation of twisting. Th…
Twisted string actuators are widely used in different areas of robotics, however, their lifetime remains one of the main concerns for robotics. There are no comprehensive studies that relate the lifetime of a twisted string to its material properties and operation conditions, which can be important…
This paper extends the previously proposed Explicit Force Controller based on Time Domain Passivity Approach. When using the classical passivity observer, we encounter an energy accumulation problem: if the system stays a long time in stable contact, energy is dissipated and the passivity observer b…
The twisted string actuator is an actuator that is gaining popularity in various engineering and robotics and applications. However, the fundamental limitation of actuators of this type is the uni-directional action, meaning that the actuator can contract but requires external power to return to its…
Direct force control of robots is challenging, particularly since the interaction with the environment can render the robot unstable. This paper presents the results of novel approaches for passivity-based stability for a particular direct force control method, namely explicit force control. A step-…
This paper proposes an approach to enlarge the impedance range of admittance-type haptic interfaces. Admittance-type haptic interfaces have advantages over impedance-type haptic interfaces in the interaction with high impedance virtual environments. However, the performance of admittance-type haptic…
Manipulation complexity of teleoperation increases the necessity of shared autonomy. However, designing an autonomy while keeping in mind the environmental uncertainty is challenging. This paper proposes a human interactive autonomy for a shared teleoperation. The central concept is a novel methodol…
This paper presents a new robot controller for space telerobotics missions specially designed to meet the requirements of KONTUR-2, a German & Russian telerobotics mission that addressed scientific and technological questions for future planetary explorations. In KONTUR-2, Earth and ISS have been us
This paper presents initial results of a set of experiments to compare time-delayed teleoperation performance of selected architectures based on two popular passivity based methods, namely, Wave Variables Transformation (WVT) and Time Domain Passivity Approach (TDPA). Five different architectures wi…
Dividing the control authority of the slave robot among operators, based on the available information to them and their controlling strategy, is absolutely essential for cooperative teleoperation systems. Although there have been many studies on this, most of the analysis were limited to fixed autho…
This paper proposes a method to increase the impedance range of admittance-type haptic interfaces. Admittance-type haptic interfaces are used in various applications that typically require interaction with high impedance virtual environments. However, the performance of admittance haptic interfaces…
Passivity has been a major criterion on designing a stable haptic interface due to many advantages. However, passivity has been suffering from its intrinsic conservatism since it only represents a small set of the whole stable region. Therefore, there was always limitation to increase the performanc…
Actuators with adjustable transmission ratios are required in a variety of robotics and automation applications, spanning from human assistive devices and mobile robots to general manipulators. Most existing self-adjustable actuators are bulky and mechanically complex, which often makes their implem…
Passivity has been the most often used constraint for the controller design of bilateral teleoperation systems. However passivity has been suffering from its own design conservatism since this is a sufficient condition for stability and representing only a small set of overall stability region. In o…