Abstract: The principle of series elastic actuation offers considerable advantages for haptic displays compared to stiff actuators. The interaction force between motor and load is directly proportional to their relative position, which corresponds to the elongation of the elastic element. This way, the torque control task is transformed to a position control task, which comes natural to traditional DC motors. In this paper, several existing control strategies are analyzed and compared with respect to passivity concerns. Cascaded control with a fast inner velocity loop results to be the best option. Based on the analysis, boundaries for the parameters are presented, such that the force controller may contain integral action without jeopardizing passivity.

Abstract: This paper investigates vision-based robot control based on passivity for three-dimensional (3-D) target tracking. First, using standard body-attached coordinate frames (the world frame, camera frame, and object frame), we represent the relative position and orientation between a moving target and a camera as an element of SE(3). Using this representation we derive a nonlinear observer to estimate the relative rigid body motion from the measured camera data. We then establish the relationship between the estimation error in a 3-D workspace and in the image plane. We show passivity of the dynamic visual feedback system by combining the passivity of both the visual feedback system and the manipulator dynamics which allows us to prove stability in the sense of Lyapunov for the full 3-D dynamic visual feedback system. The L2 -gain performance analysis, which deals with the disturbance attenuation problem, is then considered via dissipative systems theory. Finally, experimental results are presented to verify the stability and L2-gain performance of the dynamic visual feedback system

Abstract: This paper studies the control of buck converters subjected to constant-power loads using a passivity-based technique. This technique allows for global analysis and avoids the limitations present in small-signal-based techniques. Passivity-based control in this application leads to a systematic derivation of a linear proportional-differential controller. It is also proved that the equilibrium point is only locally stable due to the infeasibility of duty ratio values larger than unity. The paper presents a method to obtain the region of attraction and shows that this region is not affected by controller gains. Experimental work is included to verify the analysis.

Abstract: The passivity condition for delayed neural networks with uncertainties is considered in this article. From simple extension of a recent work for stability analysis of the system, a new criterion for the passivity of the system is derived in terms of linear matrix inequalities (LMIs), which can be easily solved by using various convex optimization algorithms. A numerical example is given to show the usefulness of our result.

Abstract: In this paper, modified two-port time-domain passivity approach is proposed for stable bilateral control of teleoperators under time-varying communication delay. We separate input and output energy at each port of a bilateral controller, and propose a sufficient condition for satisfying the passivity of the bilateral controller including time-delay. Output energy at the master port should be less than the transmitted input energy from the slave port with time-delay, and output energy at the slave port should be less than the transmitted input energy from the master port with time-delay. For satisfying above two conditions, two passivity controllers are attached at each port of the bilateral controller. Teleoperation experiment with about 120 (msec) of time-delay each way is performed. Stable teleoperation is achieved in free motion and hard contact as well.

Abstract: This paper studies the control of DC-DC converters subjected to constant-power loads using a passivity-based technique. This technique allows for global analysis and avoids the limitations present in small-signal-based techniques. Passivity-based control in this application leads to a systematic derivation of a linear proportional-differential controller for a buck converter and a nonlinear proportional differential controller for boost and buck-boost converters. The latter are emphasized here. It is discussed how for boost and buck-boost converters an equivalent linear proportional differential controller achieves stable operation with a constant power load. It is also suggested that for all types of converters an integral control term achieves line and load regulation. Experimental work is included to verify the analysis.

Abstract: In this paper, a new fast technique of passivity enforcement of a nonpassive rational model is introduced. The technique disturbs poles of the model to restore passivity in such way that the frequency response of a device being modeled is preserved. The passivity enforcement procedure is defined as an optimization routine with the gradients of the cost function evaluated using the theory of matrix perturbation. The rational model can be based either on passive (electromagnetic simulations, measurements) or nonpassive (surrogate models) data. In the second case, the proposed technique can lead to a parameterized SPICE networks. Some advanced examples are given to show the application of proposed approach in interconnect, packaging, and signal integrity analysis

Abstract: Recent investigations have shown that with stronger periodic load perturbation power system is experiencing complex chaotic oscillations which threaten the secure and stable operation of power system, even induce the interconnected power system collapse. To control these undesirable chaotic oscillations, a passivity-based adaptive control law is presented in this paper, which transforms the power system into an equivalent passive system. It is proved that the equivalent system can be asymptotically stabilized at different equilibrium points without influence of undeterministic parameters. Simulation results show the proposed control law is very effective and robust against both the uncertainty in system parameters and external noise interference. The research of this paper may help to maintain the power system’s security operation.

Abstract: This paper deals with the characterization and enforcement of passivity for linear lumped interconnect macromodels. An adaptive accuracy-controlled frequency sampling process is employed to identify a set of frequency bands where the macromodel is locally passive. These results are employed as a preliminary step, enabling the fast computation of imaginary eigenvalues of the Hamiltonian matrix associated to the macromodel. Then, iterative perturbation is employed to remove these eigenvalues from the imaginary axis and to achieve global passivity. The resulting scheme is highly optimized for macromodels having large dynamic order and with a sparse structure. Significant speedup factors up to two orders of magnitude are achieved with respect to a standard implementation of the same passivity compensation scheme based on a full eigensolver

Abstract: This paper presents a novel approach for nonlinear model predictive control based on the concept of passivity. The proposed nonlinear model predictive control scheme is inspired by the relationship between optimal control and passivity as well as by the relationship between optimal control and model predictive control. In particular, a passivity-based state constraint is used to obtain a nonlinear model predictive control scheme with guaranteed closed loop stability. Since passivity and stability are closely related, the proposed approach can be seen as an alternative to control Lyapunov function based approaches. To demonstrate its applicability, the passivity-based nonlinear model predictive control scheme is applied to control a quadruple tank system.

Abstract: Dynamic neural networks with different time-scales include the aspects of fast and slow phenomenons. Some applications require that the equilibrium points of the designed networks are stable. In this paper, the passivity-based approach is used to derive stability conditions for dynamic neural networks with different time-scales. Several stability properties, such as passivity, asymptotic stability, input-to-state stability and bounded input bounded output stability, are guaranteed in certain senses. A numerical example is also given to demonstrate the effectiveness of the theoretical results.

Abstract: This paper introduces a new error control strategy in passivity enforcement schemes for linear lumped macromodels. We consider the general class of a posteriori passivity enforcement algorithms based on Hamiltonian matrix perturbation. Standard available formulations preserve the accuracy during passivity enforcement using special matrix norms associated to the controllability Gramian of the macromodel. This procedure leads to absolute error control. On the other hand, it is well known that relative error control in the macromodel is sometimes preferable, especially for structures that are characterized by small coupling coefficients or high dynamic range in their responses. Here, we present a frequency-weighting scheme leading to the definition of a modified Gramian that, when employed during passivity enforcement, effectively leads to relative error control. Several examples illustrate the reliability of the proposed technique.

Abstract: Interconnection and damping assignment passivity-based control (IDA-PBC) is a recently developed method for nonlinear controller design. A majority of the examples of IDA-PBC found in literature are from the electro-mechanical domain. To show its applicability in other domains, in this work IDA-PBC is used to design a stabilizing controller for a process control example, the four-tank system. Both simulations and real experiments are provided for this example system.

Abstract: The passivity problem of uncertain fuzzy systems with bounded time delay is first studied. The passivity conditions, expressed in terms of linear matrix inequalities (LMIs), are delay-dependent, and may be delay-derivative-dependent when the delay is differentiable. Numerical example is given to show the correctness and effectiveness of our theoretical results.

Abstract: This paper compares three synthesis methods for controlling a three-level three-cell dc-dc converter. The main contribution of this paper is to analyse different strategies: i) The Passivity Based Control that uses the notion of average model, ii) A stabilizing method in which a unique Lyapunov function is introduced and iii) A new predictive control approach, which relies on the use of optimization procedures.

Abstract: The classic proper energy element in electric vehicle consists of batteries and fuel cell (FQ, which allow a relatively high autonomy, but they are with moderate power capability. On the other hand, the capacitors have high power capability they can only be considered for applications which require little energy. In term of specifics energy and power, supercapacitors are situated between accumulators and traditional capacitors. The hybridation of these sources with a power source as supercapacitor (SC) is proposed. A recent approach of passivity- based control (PBC) is the interconnection and damping assignment (IDA-PBC) which is a very useful technique to control systems assigning a desired port-controlled Hamiltonian (PCH) structure to the closed-loop.

Abstract: Passivity-based control (PBC) is a generic name given to a family of controller design techniques that achieves system stabilization via the route of passivation, that is, rendering the closed-loop system passive with a desired storage function (that usually qualifies as a Lyapunov function for the stability analysis.) If the passivity property turns out to be output strict, with an output signal with respect to which the system is detectable, then asymptotic stability is ensured. See the monographs [5, 12], and [6] for a recent survey.

Abstract: This paper addresses control of structural vibrations using semi-active actuators that are capable of manipulating stiffness and/or producing variable stiffness. Usually vibration suppression is achieved using damping devices rather than stiffness ones. However, stiffness devices can produce large forces and have significant advantages for shock isolation purposes. In this work we use a passivity approach to establish the requirements for the control law for a structure equipped with semi-active stiffness devices. We also solve an optimal control problem that demonstrates that our passive, resetting feedback control law approximates the optimal control. Simulation and experimental results are presented in support of the proposed approach.

Abstract: This paper proposes a passivity-based controller for a single-phase PWM current-source inverter feeding a resistive load. The controller design is based on the dynamic model of the inverter and the energy shaping plus damping injection idea of the passivity-based approach for a known resistive load case. It is shown that the unknown load resistance can be estimated by an adaptive estimation algorithm. However, since the inductance value ( L ) is directly proportional to the estimation accuracy and is inversely proportional to the dynamic response of the proposed controller, it should be chosen to make a compromise between dynamic response and correct reference estimation for the inductor current. Computer simulations and experiments are presented to show the feasibility and the performance of the proposed control strategy.

Abstract: Recently, two-port time-domain passivity approach was modified for time-varying communication delay. The newly proposed approach could achieve stable teleoperation even under the serious time-varying delay and packet loss communication condition. However, after some operation hour, the accumulated energy difference between the input energy from one port and the output energy at the other port caused unstable behavior until the passivity controller is activated. Resetting scheme is introduced for solving this problem, and stable bilateral teleoperation can be guaranteed without worrying about the accumulated energy difference.

Abstract: Magnetostrictive materials display large force and displacement in response to an applied field, as well as short response time. However, their nonlinear and hysteretic behavior has hindered their use. We prove, using the physics of the material, that these materials are passive. The corresponding energy storage function is shown to be the Helmholtz energy. This result is independent of the model used. The effect of varying load is included. Passivity is important because it can be used to obtain control systems that maintain stability despite uncertainties and disturbances. The minima of the storage function are also obtained. The storage function is written explicitly in the case of a common model for these materials, the Preisach model.

Abstract: We investigate the stabilization of closed sets for passive nonlinear systems which are contained in the zero level set of the storage function.

Abstract: Passivity is a well known phenomenon. Due to its interesting properties, it is widely used in several areas of control engineering. In general, passivity is lost under direct discretization. In this work, a new methodology which allows to preserve continuous-time passivity is revisited. This methodology is based on choosing a proper output which preserves the passivity structure, while keeping the continuous-time energy function. As this new output needs information about the system state, an state observer is added.