TechTalks from event: Technical session talks from ICRA 2012

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Teleoperation

  • Bilateral Teleoperation of Cooperative Manipulators Authors: Aldana, Carlos Iván; Nuno, Emmanuel; Basanez, Luis
    This paper presents an adaptive controller for the bilateral teleoperation of a system composed by a single local manipulator and multiple cooperative remote manipulators handling a common object. First, the nonlinear operational space dynamical behavior, of the complete teleoperation system, is derived and then, under the assumptions that the remote manipulators are rigidly grasping a non-deformable object and that the communications may induce constant time-delays, it is proved that velocities and position-orientation error between the local manipulator end-effector and the object asymptotically converge to zero. Simulations results are included to show the effectiveness of the proposed scheme.
  • Direct Force Reflecting Teleoperation with a Flexible Joint Robot Authors: Tobergte, Andreas; Albu-Schäffer, Alin
    This paper presents a high fidelity force feedback teleoperation control for surgical applications. Advanced control methods, such as flexible joint tracking control and passivity observation, are introduced in the direct force reflecting control architecture. A full state feedback controller of the flexible joint slave robot controls the motor position, velocity, the joint torque, and the torque derivative. The pose of the haptic device and the first three derivatives are observed to generate reference states for the robot control using the robot's inverse dynamics model. Interaction forces of the slave and the environment are measured with a force/torque sensor and directly sent back to the master device. Stability is guaranteed with a passivity observer that monitors the energy in the teleoperation system online and disconnects master and slave if the system operates beyond its stable region. The proposed control architecture is implemented with the sigma.7 haptic device and the MIRO robot. It is experimentally shown, that appropriately considering elasticities with full state reference and control of the slave, increases the dynamic range of the system enabling transparent and stable interaction with hard and soft environments.
  • Dynamic Scaling Interface for Assisted Teleoperation Authors: Munoz, Luis Miguel; Casals, Alicia
    Teleoperation, by adequately adapting computer interfaces, can benefit from the knowledge on human factors and psychomotor models in order to improve the effectiveness and efficiency in the execution of a task. While scaling is one of the performances frequently used in teleoperation tasks that require high precision, such as surgery, this article presents a scaling method that considers the system dynamics as well. The proposed dynamic scaling factor depends on the apparent position and velocity of the robot and targets. Such scaling improves the performance of teleoperation interfaces, thereby reducing user’s workload.
  • A Proportional Plus Damping Injection Controller for Teleoperators with Joint Flexibility and Time-Delays Authors: Nuno, Emmanuel; Sarras, Ioannis; Basanez, Luis; Kinnaert, Michel
    The problem of controlling a rigid bilateral teleoperator with time-delays has been effectively addressed since the late 80's. However, the control of flexible joint manipulators in a bilateral teleoperation scenario is still an open problem. In the present paper we report two versions of a proportional plus damping injection controller that are capable of globally stabilizing a nonlinear bilateral teleoperator with joint flexibility and variable time-delays. The first version controls a teleoperator composed by a rigid local manipulator and a flexible joint remote manipulator and the second version deals with local and remote manipulators with joint flexibility. For both schemes, it is proved that the joint and motor velocities and the local and remote position error are bounded. Moreover, if the human operator and remote environment forces are zero then velocities asymptotically converge to zero and position tracking is established. Simulations are presented to show the performance of the proposed controllers.
  • Stability of Position-Based Bilateral Telemanipulation Systems by Damping Injection Authors: Franken, Michel; Misra, Sarthak; Stramigioli, Stefano
    In this paper two different approaches to guaran- tee stability of bilateral telemanipulation systems are discussed. Both approaches inject damping into the system to guarantee passivity of the interaction with the device in the presence of time delays in the communication channel. The first approach derives tuning rules for a fixed viscous damper, whereas the second approach employs modulated dampers based upon the measured energy exchange with the device and enforces passivity in the time domain. Furthermore, a theoretical min- imum damping injection scheme is sketched that shows that the fixed damping approach is inherently conservative with respect to guaranteeing stability. Experimental results show that both the theoretical minimum damping scheme and a time domain passivity algorithm are successful in stabilizing the telemanipulation system for large time delays with lower gains of the damping elements than derived by the fixed damping injection approach. However, as damping is inherently present in the system, the tuning rules derived from the fixed damping injection approach can be used to identify if a time domain passivity algorithm is needed given boundary conditions on the actual time delays.
  • Bilateral Teleoperation of a Group of UAVs with Communication Delays and Switching Topology Authors: Secchi, Cristian; Franchi, Antonio; Buelthoff, Heinrich H.; Robuffo Giordano, Paolo
    In this paper, we present a passivity-based decentralized approach for bilaterally teleoperating a group of UAVs composing the slave side of the teleoperation system. In particular, we explicitly consider the presence of time delays, both among the master and slave, and within UAVs composing the group. Our focus is on analyzing suitable (passive) strategies that allow a stable teloperation of the group despite presence of delays, while still ensuring high flexibility to the group topology (e.g., possibility to autonomously split or join during the motion). The performance and soundness of the approach is validated by means of human/hardware-in-the-loop simulations (HHIL).