A method for passivity analysis of multilateral haptic systems (original) (raw)
Related papers
A passivity criterion for N-port multilateral haptic systems
49th IEEE Conference on Decision and Control (CDC), 2010
1 . This paper presents a criterion for passivity of nport networks, which can be used to model multilateral systems involving haptic information sharing between a number of users. Such systems have recently found interesting applications in both cooperative haptic teleoperation and haptics-assisted training. The criterion presented in Theorem 1, which is necessary and sufficient for passivity of the n-port network, imposes 2n conditions on the immitance parameters of the network and on the residues of the immitance parameters at their imaginary-axis poles. It is shown that when n = 2, the proposed conditions reduce to the well-known Raisbeck's passivity criterion for two-port networks. Another special case for which the proposed criterion has been simplified corresponds to three-port networks. Finally, the passivity of a dual-user haptic system for control of a single teleoperated robot is investigated.
Conservatism of passivity criteria for stability analysis of trilateral haptic systems
Trilateral haptic systems can be modeled as three-port networks. Analysis of coupled stability of a three-port network can be accomplished in either the passivity or the absolute stability frameworks assuming all three ports are connected to passive but otherwise unknown terminations. This paper first reviews our recent results in terms of passivity and absolute stability criteria for general threeport networks -both criteria are founded on the properties of a positive-real Hermitian matrix. Next, we show that the absolute stability criterion is less conservative than the passivity criterion and that the two criteria become the same when the trilateral system is represented by a reciprocal immitance matrix. Then, to show how the two criteria may be utilized at the system design stage, we apply them to the problem of designing controllers for a dual-user haptic teleoperation system. Using the two criteria, controllers are then designed and compared in terms of conservatism and performance in simulations.
Passivity and Absolute Stability Analysesof Trilateral Haptic Collaborative Systems
Trilateral haptic systems can be modeled as threeport networks. Analysis of coupled stability of a three-port network can be accomplished in either the passivity or the absolute stability frameworks assuming all three ports are connected to passive but otherwise unknown terminations. This paper first introduces our recent results in terms of extending Raisbecks passivity criterion and Llewellyns absolute stability criterion to general three-port networks -both criteria are founded on the properties of a positive-real Hermitian matrix. Next, we show that the absolute stability criterion is less conservative than the passivity criterion. Then, to show how the two criteria may be utilized at the system design stage, we apply them to the problem of designing controllers for a dual-user haptic teleoperation system and a triple-user collaborative haptic virtual environment. Using the two criteria, controllers are then designed and compared in terms of conservatism in simulations and experiments.
University of Alberta Stability of Multilateral Haptic Teleoperation Systems
2013
Multilateral systems involving haptic information s haring between several users have recently found interesting applications in coo perative haptic teleoperation and haptic-assisted training. It is intuitively und erstood that some tasks are performed more effectively with two hands or throug h collaboration than one hand or individual operation. By using multiple use r interfaces (“masters”) and one remote robot (“slave”) or more, multilateral te le-cooperation systems enable haptic information sharing and collaboration in per forming a task in a remote environment between multiple users . Despite the aforementioned benefits, research in this area is still in its initial stage . In fact, the only multilateral system that has been thoroughly investigated is the most b asic one: the bilateral teleoperation system involving teleoperation betwee n one master and one slave. As with any other robotic system, stability of mult ilateral haptic teleoperation systems is of paramount importa...
IEEE International Conference on Intelligent Robots and Systems, 2012
Stability of a haptic teleoperation system is influenced by the typically uncertain, time-varying and/or unknown dynamics of the operator and the environment. For a stability analysis that is independent of the operator and the environment dynamics, Llewellyn's absolute stability criterion proposes certain conditions on the two-port network representing the teleoperator (comprising the master, the controller and communication channel, and the slave) assuming that the terminations (i.e., the operator and the environment) are passive. These are less-than-accurate assumptions. It is desirable to extend Llewellyn's result to the cases where the operator or the environment is non-passive. This paper revisits Llewellyn's criterion and relaxes the assumption of passivity for one of the terminations. The possibly non-passive termination is realistically assumed to have a complex impedance with an upper or lower bound on its amplitude or real part, respectively. Although the proposed stability criteria are useful for any application of two-port network systems, we specifically apply them on bilateral teleoperation systems and find the stability conditions when the operator or the environment is not passive; this is a result that Llewellyn's absolute stability criterion cannot afford.
Stability of cooperative teleoperation using haptic devices with complementary degrees of freedom
IET Control Theory & Applications, 2014
In bilateral teleoperation of a dexterous task, to take full advantage of the human's intelligence, experience, and sensory inputs, a possibility is to engage multiple human arms through multiple masters (haptic devices) in controlling a single slave robot with high degrees-of-freedom (DOF); the total DOFs of the masters will be equal to the DOFs of the slave. A multi-master/single-slave cooperative haptic teleoperation system with w DOFs can be modeled as a two-port network where each port (terminal) connects to a termination defined by w inputs and w outputs. The stability analysis of such a system is not trivial due to dynamic coupling across the different DOFs of the robots, the human operators, and the physical or virtual environments. The unknown dynamics of the users and the environments exacerbate the problem. We present a novel, straightforward and convenient frequency-domain method for stability analysis of this system. As a case study, two 1-DOF and 2-DOF master haptic devices are considered to teleoperate a 3-DOF slave robot. It is qualitatively discussed how such a trilateral haptic teleoperation system may result in better task performance by splitting the various DOFs of a dexterous task between two arms of a human or two humans. Simulation and experimental results demonstrate the validity of the stability analysis framework.
Stability analysis of trilateral haptic collaboration
This paper presents a criterion for absolute stability of a general class of three-port networks. Trilateral haptic systems, which have recently found many interesting applications, can be modeled as three-port networks. Traditionally, existing criteria (Llewellyn's criterion) have facilitated the stability analysis of bilateral haptic systems modeled as two-port networks. If the same criteria were to be used for stability analysis of a three-port network, its third port would need to be assumed known for it to reduce to a two-port network. However, this is restrictive because, according to the definition of absolute stability, all three terminations of the three-port network must be allowed to be arbitrary (while passive).
PASSIVITY ANALYSIS OF DISCRETE-TIME COUNTERPARTS OF THE BILATERAL CONTROLLED TELEOPERATION SYSTEMS
International Journal of Electrical, Electronics and Data Communication (IJEEDC), 2018
This paper presents an analysis of the passivity condition for discrete-time bilateral teleoperation systems. Considering discrete-time controllers for a master-slave teleoperation system can simplify its implementation. Varieties of control schemes have been utilized for the position error based architecture of bilateral teleoperation systems and major concerns such as passivity and transparency have been studied. This paper takes into account the passivity conditions for the discrete counterparts of P-like, PD-like, and PD-like + dissipation controllers. These conditions impose bounds on the controller gains, the damping of the master and slave robots, and the sampling time which help researchers to provide guidelines to have better transparency and passive teleoperation systems. Simulation results are performed to show the effectiveness of the proposed criteria.
Bounded Environment Passivity of the Classical Position-Force Teleoperation Controller
2009
This paper derives analytic guidelines to tune the popular Position-Force bilateral controller and improve its performance by incorporating available knowledge on the bounds of the environment impedance. The proposed guidelines can prove especially useful in the domain of telesurgery where a need exists for well-understood bilateral teleoperation controllers, that show good performance and where many tasks can be characterized by restricted and relatively easily definable impedance regions. This paper firstly analyses the two-port passivity and absolute stability properties of two alternatives of the Position-Force controller. The limitations on achievable performance when guaranteeing absolute stability with arbitrary environments are detailed. Next, a novel method, called Bounded Environment Passivity method is introduced. This method enables the design of teleoperation controllers that show passive behaviour for interactions with an environment that varies over a given range of impedances. A set of guidelines that allow a smarter trade-off between performance and stability follows. The theoretical results are verified experimentally on a 1-d.o.f. teleoperation setup.
Stable Teleoperation With Time-Domain Passivity Control
IEEE Transactions on Robotics and Automation, 2004
A new bilateral control scheme is proposed to ensure stable teleoperation under a wide variety of environments and operating speeds. System stability is analyzed in terms of the time-domain definition of passivity. A previously proposed energy-based method is extended to a 2-port network, and the issues in implementing the "passivity observer" and "passivity controller" to teleoperation systems are studied. The method is tested with our two-degrees-of-freedom master/slave teleoperation system. Stable teleoperation is achieved under conditions such as hard wall contact (stiffness 150 kN/m) and hard surface following.