Port-Based Modeling and Optimal Control for a new Very Versatile Energy Efficient Actuator

Gerelli, Oscar; Carloni, Raffaella

doi:10.3182/20090909-4-jp-2010.00084

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…In [16,17,18], the necessary conditions which follow from Pontryagin's Maximum Principle are used to derive an explicit expression for the optimal feedback controller, provided the Hamiltonian of the system is quadratic. The authors in [19] provide full-and reduced-order LQR controllers for linear ISO-PHSs.…”

Section: Related Workmentioning

confidence: 99%

Optimal Control of Port-Hamiltonian Systems: A Time-Continuous Learning Approach

Kölsch¹,

Soneira²,

Strehle³

et al. 2020

Preprint

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Feedback controllers for port-Hamiltonian systems reveal an intrinsic inverse optimality property since each passivating state feedback controller is optimal with respect to some specific performance index. Due to the nonlinear port-Hamiltonian system structure, however, explicit (forward) methods for optimal control of port-Hamiltonian systems require the generally intractable analytical solution of the Hamilton-Jacobi-Bellman equation. Adaptive dynamic programming methods provide a means to circumvent this issue. However, the few existing approaches for port-Hamiltonian systems hinge on very specific sub-classes of either performance indices or system dynamics or require the intransparent guessing of stabilizing initial weights. In this paper, we contribute towards closing this largely unexplored research area by proposing a time-continuous adaptive feedback controller for the optimal control of general time-continuous input-state-output port-Hamiltonian systems with respect to general Lagrangian performance indices. Its control law implements an online learning procedure which uses the Hamiltonian of the system as an initial value function candidate. The time-continuous learning of the value function is achieved by means of a certain Lagrange multiplier that allows to evaluate the optimality of the current solution. In particular, constructive conditions for stabilizing initial weights are stated and asymptotic stability of the closed-loop equilibrium is proven. Our work is concluded by simulations for exemplary linear and nonlinear optimization problems which demonstrate asymptotic convergence of the controllers resulting from the proposed online adaptation procedure.

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Section: Related Workmentioning

confidence: 99%

Optimal Control of Port-Hamiltonian Systems: A Time-Continuous Learning Approach

Kölsch¹,

Soneira²,

Strehle³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…In order to solve this, two solutions have been proposed to control the energy release of springs. The first solution is to use a continuously variable transmission (CVT) to adjust the position-torque relation of the spring [11]. However, those CVTs are still not developed well enough to be widely applied in robots.…”

Section: Introductionmentioning

confidence: 99%

Lock Your Robot: A Review of Locking Devices in Robotics

Plooij

Mathijssen

Cherelle

et al. 2015

IEEE Robot. Automat. Mag.

141

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Locking devices are widely used in robotics, for instance to lock springs, joints or to reconfigure robots. This review paper classifies the locking devices currently described in literature and preforms a comparative study. Designers can, as such, better determine which locking device best matches the needs of their application. The locking devices are divided into three main categories based on different locking principles: mechanical locking, friction-based locking and singularity locking. Different lockers in each category can be passive lockers or active lockers. Based on an elaborate literature study, the paper summarizes the findings by comparing different locking devices, based on a set of properties of a theoretical ideal locking device.

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“…A solution based on an infinite variable transmission to dynamically change the output torque, and thus the apparent stiffness, without using any energy, has been proposed in [4]. Although in theory this actuator is highly energy efficient when optimal control techniques are applied [11], currently existing infinite variable transmissions rely on friction to operate and, therefore, they inherently energy inefficient. This In this work we present a port-based mathematical model for variable stiffness actuators.…”

Section: Introductionmentioning

confidence: 99%

Modeling and design of energy efficient variable stiffness actuators

Visser

Carloni

Ünal

et al. 2010

2010 IEEE International Conference on Robotics and Automation

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In this paper, we provide a port-based mathematical framework for analyzing and modeling variable stiffness actuators. The framework provides important insights in the energy requirements and, therefore, it is an important tool for the design of energy efficient variable stiffness actuators. Based on new insights gained from this approach, a novel conceptual actuator is presented. Simulations show that the apparent output stiffness of this actuator can be dynamically changed in an energy efficient way.

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Port-Based Modeling and Optimal Control for a new Very Versatile Energy Efficient Actuator

Cited by 5 publications

References 13 publications

Optimal Control of Port-Hamiltonian Systems: A Time-Continuous Learning Approach

Optimal Control of Port-Hamiltonian Systems: A Time-Continuous Learning Approach

Lock Your Robot: A Review of Locking Devices in Robotics

Modeling and design of energy efficient variable stiffness actuators

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