Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Comparison of the simulated model with measurement results: (a) measured piston position sp,m; (b) measured oil pressure po,m; (c) calculated inlet oil flow qo,c from actual pump data and inlet oil flow qo,ND, obtained from the measured piston position; and (d) gas temperature Tg,s of the sensor model, calculated gas temperature Tg,c using Eq. (3), measured gas temperature Tg,m, and measured ambient temperature Ta,m.

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Schematic of the gas charged hydraulic piston-type accumulator

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Concept of the signal-based estimator

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Comparison of the estimator results and measurement data for nominal parameters: (a) measured gas volume Vg,m and estimated gas volumes V∧g,SB and V∧g,KF; (b) estimation errors of the two approaches; and (c) estimated oil leakage flow of the EKF Δq∧o,KF compared to the result of the numerical differentiation Δqo,ND.

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Comparison of alternative calculation methods based on an ideal adiabatic (index ad) and isothermal (index is) process with different initial conditions, based on the initial fill (index if) and on V∧g,0 (index V∧g,0): (a) measured gas volume Vg,m and estimated gas volumes V∧g,• and (b) estimation errors.

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Study of the influence of a reduced (simulation) gas mass of m˜g=0.95mg: (a) measured gas volume Vg,m and estimated gas volumes V∧g,•; (b) estimation errors; and (c) estimated oil leakage flow Δq∧o,KF,m˜g compared to the results of the numerical differentiation Δqo,ND,m˜g.

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Comparison of the Extended Kalman-filters with constant gas mass m˜g = 0.95mg (index KF,m˜g) and with an augmented gas mass model (index KF,m∧g), where the initial gas mass is set to m∧g,0 = 0.75mg: (a) measured gas volume Vg,m and estimated gas volumes V∧g,•; (b) estimation errors; (c) gas mass mg and estimated gas mass m∧g; and (d) estimated oil leakage flow Δq∧o,KF,m∧g and Δq∧o,KF,m˜g compared to the results of the numerical differentiation Δqo,ND,m˜g.

Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: State of Charge Estimator Design for a Gas Charged Hydraulic Accumulator J. Dyn. Sys., Meas., Control. 2015;137(6):061014-061014-9. doi:10.1115/1.4029407 Figure Legend: Comparison of the estimation results of the Extended Kalman-filter with nominal ambient temperature (index KF) and with an error in the ambient temperature of −5 K (index KF,T˜a5) and −15 K (index KF,T˜a15): (a) measured gas volume Vg,m and estimated gas volumes V∧g,•; (b) estimation errors; and (c) estimated oil leakage flows Δq∧o,• compared to the results of the numerical differentiation Δqo,ND.