This paper studies the problem of interaction control based on force and velocity measurements. Without restricting ourselves to fixed control structures such as admittance or impedance control, we consider the general topology of the problem. Adopting the idea of Youla-based 2DOF control, we reveal a generic control architecture that splits the problem into two independent parts: nominal admittance shaping and disturbance rejection. This pinpoints conceptual flaws in classical interaction control architectures and suggests a way to circumvent them. As a by-product, a complete and compact parameterization of all achievable admittances is derived. The potential of the proposed architecture for analysis and controller design is demonstrated and validated experimentally.

This paper describes development of a controllerfor bilateral robotic system for tele-echography with delayed communications. The system comprises two identical 6DOF robotic devices based on Stewart-Gough mechanisms, which were developed especially for the sake of the considered application. Controller design is facilitated by a symmetry of the teleoperation setup, in which the master and slave devices have identical geometry, actuation and measurement arrays. To further simplify the analysis, we treat coupling between degrees of freedom as exogenous disturbances and this allows us to split the control problem into six independent IDOF settings. The IDOF problems are addressed then using a novel approach to bilateral teleoperation control, based on a complete parameterization of feasible teleoperators. It allows to intuitively shape teleoperator performance while guaranteeing passivity and thus coupled stability of the system. The potential of the proposed control method is demonstrated with experimental results.

We present a compact and lightweight two Degrees of Freedom (DOF) needle driver to be applied to a teleoperated needle insertion-type interventional robotic system. The interventional slave manipulator is located beside the patient bed inside a CT scanner room. Physicians manipulate a master device, separately located in the control room, in order to control needle placement. The needle driver provides one translational motion and one rotational motion to a biopsy needle, and the needle is easily detachable from the needle driver. We performed several experiments to measure the repeatability and the insertion force of the needle to evaluate the basic performance of the proposed needle driver. The maximum error of the repeatability was 0.16 mm and the standard deviation was 0.0058 mm. The maximum insertion force of the needle was about 2.2 kgf, which meets the minimum insertion force of the needle for needle insertion-type interventions. Therefore, we expect the suggested needle driver is suitable to the clinical environment for CT-guided needle insertion-type interventions.

In this paper we consider a problem of delayed bilateral teleoperation control. We exploit a recent parameterization of all feasible teleoperator admittance matrices to propose a control synthesis procedure based on admittance shaping. This leads to an intuitive performance-oriented controller design that reveals important trade-offs inherent to bilateral teleoperaton. In particular, this allows a trade-off between performance and passivity, that is not accessible while using classical passivity-based methods. The proposed controller design is illustrated with simulations and a simple 1 DOF experimental case study.

In this paper we study performance achievable in delayed bilateral teleoperation control. Our goal is to characterize all teleoperation system behaviors that can be achieved with delayed communication but without any restrictive assumptions on the control law, such as passivity. To this end, a recent non-restrictive stabilizing control architecture for bilateral teleoperation is exploited. The main properties of this architecture are discussed and used to obtain parameterization of all the admittance matrices feasible under the nominal stability constraint. The use of this parameterization for shaping system behavior is demonstrated and the results are compared with those obtained using the classical passivity-based control schemes.

Stabilization of delayed bilateral teleoperation systems with two master devices is considered. It is shown that allowing communication between the master devices may greatly facilitate the solution rendering the problem quadratically invariant. A convenient structure possessed by stabilizing controllers is revealed, which can be considered as an alternative to passivity-based structures. It is shown that any stabilizing controller can be implemented to comply with this structure, which, in turn, guarantees delay-independent stability of the overall system. The behavior of stabilizing controllers having the proposed structure is illustrated by simulations.

This paper presents a novel control architecture for enhanced operator awareness and improved safety in telesurgical systems. We introduce an intermediate layer between the master and slave sides which allows us to modify the slave motion for safety and the force feedback for operator awareness. The intermediate layer is then designed with a performance objective for the specific task at hand. The control scheme is validated via experiments using a suture and an industrial manipulator. More specifically we show that operator awareness should be implemented as an integrated part of the safety level to maintain safety during surgery.

This paper presents a control design framework for robust teleoperation. The teleoperation system with uncertainties is modeled as a linear parameter varying plant to employ the gain-scheduling control framework. The time-varying transmission delay, disturbances, and uncertainty of the environment are considered in the design of the control. The usual assumption that the human operator and the environment are passive is not made in this method. The control scheme employs an online estimation of the environment including disturbance and transmission time delay between master and slave. Simulation results show that position and force tracking errors are small, and the system shows stable behavior in spite of the uncertainties. A transparency analysis in the frequency domain shows that the developed control scheme guarantees perfect transparency in the low frequencies.