Search results for "Control and Optimization"

Force/Torque-Sensorless Joint Stiffness Estimation in Articulated Soft Robots

2022

Currently, the access to the knowledge of stiffness values is typically constrained to a-priori identified models or datasheet information, which either do not usually take into ac- count the full range of possible stiffness values or need extensive experiments. This work tackles the challenge of stiffness estimation in articulated soft manipulators, and it proposes an innovative solution adding value to the previous research by removing the necessity for force/torque sensors and generalizing to multi-degree- of-freedom robots. Built upon the theory of unknown input-state observers and recursive least-square algorithms, the solution is independent of the actuator model parameters and its in…

Robust and Decoupled Position and Stiffness Control for Electrically-Driven Articulated Soft Robots

2022

The control of articulated soft robots, i.e. robots with flexible joints and rigid links, presents a challenge due to their in- trinsic elastic elements and nonlinear force-deflection dependency. This letter first proposes a discrete-time delayed unknown input- state observer based on a nominal robot model that reconstructs the total torque disturbance vector, resulting from the imperfect knowledge of the elastic torque characteristic, external torques, and other model uncertainties. Then, it introduces a robust controller, that actively compensates for the estimated uncertainty and allows bounded stability for the tracking of independent link position and joint stiffness reference signals.…

Fault Detection, Isolation, andTolerant Control of Vehicles using Soft Computing Methods

2014

Assessment of the Usability and Accuracy of Two-Diode Models for Photovoltaic Modules

2017

Many diode-based equivalent circuits for simulating the electrical behaviour of photovoltaic (PV) cells and panels are reported in the scientific literature. Two-diode equivalent circuits, which require more complex procedures to calculate the seven model parameters, are less numerous. The model parameters are generally calculated using the data extracted from the datasheets issued by the PV panel manufactures and adopting simplifying hypotheses and numerical solving techniques. A criterion for rating both the usability and accuracy of two-diode models is proposed in this paper with the aim of supporting researchers and designers, working in the area of PV systems, to select and use a model…

A Criterion for Rating the Usability and Accuracy of the One-Diode Models for Photovoltaic Modules

2016

In selecting a mathematical model for simulating physical behaviours, it is important to reach an acceptable compromise between analytical complexity and achievable precision. With the aim of helping researchers and designers working in the area of photovoltaic systems to make a choice among the numerous diode-based models, a criterion for rating both the usability and accuracy of one-diode models is proposed in this paper. A three-level rating scale, which considers the ease of finding the data used by the analytical procedure, the simplicity of the mathematical tools needed to perform calculations and the accuracy achieved in calculating the current and power, is used. The proposed criter…

Assessment of the Usability and Accuracy of the Simplified One-Diode Models for Photovoltaic Modules

2016

Models for photovoltaic (PV) cells and panels, based on the diode equivalent circuit, have been widely used because they are effective tools for system design. Many authors have presented simplified one-diode models whose three or four parameters are calculated using the data extracted from the datasheets issued by PV panel manufactures and adopting some simplifying hypotheses and numerical solving techniques. Sometimes it may be difficult to make a choice among so many models. To help researchers and designers working in the area of photovoltaic systems in selecting the model that is fit for purpose, a criterion for rating both the usability and accuracy of simplified one-diode models is p…

Pricing and hedging GDP-linked bonds in incomplete markets

2018

Abstract We model the super-replication of payoffs linked to a country’s GDP as a stochastic linear program on a discrete time and state-space scenario tree to price GDP-linked bonds. As a byproduct of the model we obtain a hedging portfolio. Using linear programming duality we compute also the risk premium. The model applies to coupon-indexed and principal-indexed bonds, and allows the analysis of bonds with different design parameters (coupon, target GDP growth rate, and maturity). We calibrate for UK and US instruments, and carry out sensitivity analysis of prices and risk premia to the risk factors and bond design parameters. We also compare coupon-indexed and principal-indexed bonds. F…

Competition and inflation differentials in EMU

2008

In a monetary union, inflation rate differentials may be substantial over the business cycle. This paper parameterizes a two-country monetary union in which different economic structures in the two countries generate temporary inflation differentials. Cross-country differences are introduced in (i) the elasticity of demand in the goods markets, which cause producers to discriminate prices, (ii) the degree of price inertia and (iii) the degree of openness or preference for foreign goods in consumption. The model is calibrated to reproduce two average large EMU countries and it is able to generate such inflation differentials. We find the mechanism of price discrimination quantitatively more …

Inflation anchoring and growth: The role of credit constraints

2022

Abstract Can inflation anchoring foster growth? To answer this question, we use panel data on sectoral growth for 22 manufacturing industries from 39 advanced and emerging market economies over 1990–2014 and employ a difference-in-differences strategy based on the theoretical prediction that higher inflation uncertainty particularly depresses investment in industries that are more credit constrained. Industries characterized by high external financial dependence, liquidity needs, and R&D intensity, and low asset tangibility, tend to grow faster in countries with well-anchored inflation expectations. The results, based on an IV approach—using indicators of monetary policy transparency and ce…

A Naïve Sticky Information Model of Households’ Inflation Expectations

2009

This paper provides a simple epidemiology model where households, when forming their inflation expectations, rationally adopt the past release of inflation with certain probability rather than the forward-looking newspaper forecast as suggested in Carroll [2003, Macroeconomic Expectations of Households and Professional Forecasters, Quarterly Journal of Economics, 118, 269-298]. The posterior model probabilities based on the Michigan survey data strongly support the proposed model. We also extend the agent-based epidemiology model by deriving for it a simple adaptation, which is suitable for estimation. Our results show that this model is able to capture the heterogeneity in households’ expe…