5 research outputs found
Multi-DoF Time Domain Passivity Approach Based Drift Compensation for Telemanipulation
When, in addition to stability, position synchronization is also desired in
bilateral teleoperation, Time Domain Passivity Approach (TDPA) alone might not
be able to fulfill the desired objective. This is due to an undesired effect
caused by admittance type passivity controllers, namely position drift.
Previous works focused on developing TDPA-based drift compensation methods to
solve this issue. It was shown that, in addition to reducing drift, one of the
proposed methods was able to keep the force signals within their normal range,
guaranteeing the safety of the task. However, no multi-DoF treatment of those
approaches has been addressed. In that scope, this paper focuses on providing
an extension of previous TDPA-based approaches to multi-DoF Cartesian-space
teleoperation. An analysis of the convergence properties of the presented
method is also provided. In addition, its applicability to multi-DoF devices is
shown through hardware experiments and numerical simulation with round-trip
time delays up to 700 ms.Comment: 2019 19th International Conference on Advanced Robotics (ICAR
Whole-Body Bilateral Teleoperation of a Redundant Aerial Manipulator
Attaching a robotic manipulator to a flying base allows for significant
improvements in the reachability and versatility of manipulation tasks. In
order to explore such systems while taking advantage of human capabilities in
terms of perception and cognition, bilateral teleoperation arises as a
reasonable solution. However, since most telemanipulation tasks require visual
feedback in addition to the haptic one, real-time (task-dependent) positioning
of a video camera, which is usually attached to the flying base, becomes an
additional objective to be fulfilled. Since the flying base is part of the
kinematic structure of the robot, if proper care is not taken, moving the video
camera could undesirably disturb the end-effector motion. For that reason, the
necessity of controlling the base position in the null space of the
manipulation task arises. In order to provide the operator with meaningful
information about the limits of the allowed motions in the null space, this
paper presents a novel haptic concept called Null-Space Wall. In addition, a
framework to allow stable bilateral teleoperation of both tasks is presented.
Numerical simulation data confirm that the proposed framework is able to keep
the system passive while allowing the operator to perform time-delayed
telemanipulation and command the base to a task-dependent optimal pose.Comment: to be published in 2020 IEEE International Conference on Robotics and
Automation (ICRA
Smoother Position-Drift Compensation for Time Domain Passivity Approach Based Teleoperation
Despite being one of the most robust methods in bilateral teleoperation, Time Domain Passivity Approach (TDPA) presents the drawback of accumulating position drift between master and slave devices. The lack of position synchronization poses an obstacle to the performance of teleoperation and may prevent the successful accomplishment of such tasks. Several techniques have been developed in order to solve the position-drift problem in TDPA-based teleoperation. However, they either present poor transparency by over-conservatively constraining force feedback or add high impulse-like force signals that can be harmful to the hardware and to the human operator. We propose a new approach to compensate position drift in TDPA-based teleoperation in a smoother way, which keeps the forces within the normal range of the teleoperation task while preserving the level of transparency and the robust stability of energy-based TDPA. We also add a way of tuning the compensator to behave in accordance with the task being performed, whether it requires faster or smoother compensation. The feasibility and performance of the method were experimentally validated. Good position tracking and regular-amplitude forces are demonstrated with up to 500 ms round-trip constant and variable delays for hard-wall contacts
Model-Augmented Haptic Telemanipulation: Concept, Retrospective Overview, and Current Use Cases
Certain telerobotic applications, including telerobotics in space, pose particularly demanding challenges to both technology and humans. Traditional bilateral telemanipulation approaches often cannot be used in such applications due to technical and physical limitations such as long and varying delays, packet loss, and limited bandwidth, as well as high reliability, precision, and task duration requirements. In order to close this gap, we research model-augmented haptic telemanipulation (MATM) that uses two kinds of models: a remote model that enables shared autonomous functionality of the teleoperated robot, and a local model that aims to generate assistive augmented haptic feedback for the human operator. Several technological methods that form the backbone of the MATM approach have already been successfully demonstrated in accomplished telerobotic space missions. On this basis, we have applied our approach in more recent research to applications in the fields of orbital robotics, telesurgery, caregiving, and telenavigation. In the course of this work, we have advanced specific aspects of the approach that were of particular importance for each respective application, especially shared autonomy, and haptic augmentation. This overview paper discusses the MATM approach in detail, presents the latest research results of the various technologies encompassed within this approach, provides a retrospective of DLR's telerobotic space missions, demonstrates the broad application potential of MATM based on the aforementioned use cases, and outlines lessons learned and open challenges