Haptic Rendering of Fractional-Order Viscoelasticity: Passivity and Rendering Fidelity
Pith reviewed 2026-05-20 21:40 UTC · model grok-4.3
The pith
Closed-form passivity conditions allow stable haptic rendering of fractional-order viscoelastic models.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We derive closed-form expressions to ensure the passivity of haptic rendering with a fractional-order (FO) standard linear solid (SLS) model based on Grunwald-Letnikov derivative under short-memory discretization. The resulting passivity conditions constitute a unified framework that generalizes previously reported results for integer-order Kelvin-Voigt, Maxwell, and SLS models, since these results are special cases of the newly derived condition. We also provide symbolic expressions for the effective stiffness and damping of such FO-SLS models.
What carries the argument
The closed-form passivity conditions obtained from applying short-memory discretization to the Grunwald-Letnikov derivative of the fractional-order standard linear solid model.
If this is right
- The passivity conditions unify previous results by treating integer-order models as special cases of the fractional-order framework.
- Symbolic expressions for effective stiffness and damping support analysis of rendering performance.
- Experimental validations demonstrate that the theoretical passivity bounds are achievable in practice.
- Human-subject evaluations confirm that the FO-SLS models provide realistic haptic sensations.
Where Pith is reading between the lines
- This method could be extended to haptic rendering of other fractional-order dynamics beyond the standard linear solid.
- Applications in virtual reality medical training may benefit from more accurate modeling of tissue viscoelasticity.
- Further studies could examine how varying the memory length affects both stability and computational efficiency.
Load-bearing premise
The short-memory truncation of the Grunwald-Letnikov derivative remains sufficiently accurate for the sampling rates and interaction frequencies typical in haptic rendering without introducing significant energy injection or loss of fidelity.
What would settle it
A test that measures the energy exchanged between the haptic device and the virtual FO-SLS model to check if it remains non-positive when the derived passivity condition is satisfied.
Figures
read the original abstract
Haptic rendering of viscoelastic materials that exhibit creep and stress relaxation is crucial for many applications, such as medical training with realistic biological tissue models. Fractional-order viscoelastic models provide an effective means of describing intrinsically time-dependent dynamics with few parameters, as these models can naturally capture memory effects. In this study, we present analyses of passivity and rendering performance for fractional-order viscoelastic models under finite-memory discretization. We derive closed-form expressions to ensure the passivity of haptic rendering with a fractional-order (FO) standard linear solid (SLS) model based on Grunwald-Letnikov derivative under short-memory discretization. We also provide symbolic expressions for the effective stiffness and damping of such FO-SLS models. The resulting passivity conditions constitute a unified framework that generalizes previously reported results for integer-order Kelvin-Voigt, Maxwell, and SLS models, since these results are special cases of the newly derived condition. Furthermore, we provide experimental validations of the theoretical passivity bounds and human-subject evaluations of perceived realism of FO-SLS models. Overall, this study establishes a unified theoretical framework and experimental evaluations for FO viscoelastic rendering under short-memory discretization.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript derives closed-form passivity conditions for haptic rendering of a fractional-order standard linear solid (FO-SLS) model discretized via the short-memory Grunwald-Letnikov derivative. It supplies symbolic expressions for effective stiffness and damping, demonstrates algebraic generalization of the conditions to integer-order Kelvin-Voigt, Maxwell, and SLS models, and reports experimental validation of the passivity bounds together with human-subject evaluations of perceived realism.
Significance. If the passivity bounds remain valid under the finite-history truncation, the work supplies a unified theoretical framework that extends existing integer-order results to fractional-order viscoelastic rendering. This is relevant for high-fidelity haptic simulation of biological tissues. The algebraic unification and provision of closed-form effective parameters constitute clear strengths; the experimental component further supports practical utility.
major comments (2)
- [§3] §3 (Passivity analysis): the derivation of the discrete passivity condition does not supply an explicit bound on the energy contribution of the truncation remainder of the Grunwald-Letnikov sum. Because the binomial coefficients for α ∈ (0,1) decay only polynomially, the omitted tail can accumulate net positive energy over multiple cycles at 1 kHz haptic rates, undermining the guarantee that the stated inequality ensures passivity.
- [§5] §5 (Experimental validation): the reported human-subject study quantifies neither statistical significance of realism differences nor the precise exclusion criteria for outlier trials, making it impossible to assess whether the fidelity results actually corroborate the passivity conditions under realistic interaction frequencies.
minor comments (2)
- [§2.2] The relation between the short-memory length L, the fractional order α, and the sampling interval T should be stated as an explicit equation rather than left implicit in the discretization description.
- [Figure 4] Figure 4 caption should clarify whether the plotted force trajectories include or exclude the truncation tail so that readers can reproduce the energy-balance check.
Simulated Author's Rebuttal
We thank the referee for the constructive and detailed feedback. We address each major comment below and indicate the revisions planned for the next version of the manuscript.
read point-by-point responses
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Referee: [§3] §3 (Passivity analysis): the derivation of the discrete passivity condition does not supply an explicit bound on the energy contribution of the truncation remainder of the Grunwald-Letnikov sum. Because the binomial coefficients for α ∈ (0,1) decay only polynomially, the omitted tail can accumulate net positive energy over multiple cycles at 1 kHz haptic rates, undermining the guarantee that the stated inequality ensures passivity.
Authors: We acknowledge that the current derivation of the discrete passivity condition for the short-memory Grunwald-Letnikov approximation does not include an explicit bound on the energy injected by the omitted tail of the infinite sum. While the short-memory principle is standard in real-time haptic implementations and the chosen memory lengths are typical for 1 kHz rendering, the referee correctly notes that polynomial decay of the binomial coefficients leaves open the possibility of net energy accumulation over repeated cycles. In the revised manuscript we will add a supplementary analysis that bounds the remainder term’s contribution to the discrete energy balance. Specifically, we will derive an upper estimate on the tail energy using the asymptotic behavior of the binomial coefficients for α ∈ (0,1) and show that, for the memory lengths and interaction durations used in our experiments, the accumulated remainder remains strictly dissipative, thereby preserving the passivity guarantee. This bound will be stated as a function of memory length L, sampling period T, and fractional order α. revision: yes
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Referee: [§5] §5 (Experimental validation): the reported human-subject study quantifies neither statistical significance of realism differences nor the precise exclusion criteria for outlier trials, making it impossible to assess whether the fidelity results actually corroborate the passivity conditions under realistic interaction frequencies.
Authors: We agree that the experimental section would benefit from explicit statistical reporting and clearer description of data handling. In the revision we will add the results of paired t-tests (or repeated-measures ANOVA where appropriate) comparing perceived realism scores across the integer-order and fractional-order models, including p-values and effect sizes. We will also document the precise exclusion criteria applied to trials (e.g., incomplete force data, participant-reported device malfunction, or trials exceeding a pre-defined interaction-duration threshold) together with the number of trials excluded and the final sample size. These additions will allow readers to evaluate whether the fidelity results are consistent with the passivity bounds at the interaction frequencies tested. revision: yes
Circularity Check
Derivation of passivity conditions proceeds algebraically from model equations without reduction to inputs
full rationale
The paper derives closed-form passivity conditions for the FO-SLS model under short-memory GL discretization directly from the discrete energy balance of the fractional operator. Generalization to integer-order Kelvin-Voigt, Maxwell, and SLS models occurs by algebraic substitution of the fractional order parameter, not by re-fitting or self-citation. No load-bearing step equates a derived bound to a fitted quantity or renames an input as a prediction. The short-memory truncation is treated as an explicit modeling assumption whose accuracy is validated experimentally rather than assumed by construction. The central result therefore remains independent of its own fitted values or prior author outputs.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Short-memory truncation of the Grunwald-Letnikov derivative is accurate enough for typical haptic sampling rates and interaction frequencies.
Reference graph
Works this paper leans on
-
[1]
Haptic rendering: Programming touch interaction with virtual objects,
K. Salisbury, D. Brock, T. Massie, N. Swarup, and C. Zilles, “Haptic rendering: Programming touch interaction with virtual objects,” in Symposium on Interactive 3D Graphics, 1995, pp. 123–130
work page 1995
-
[2]
Characterizing viscoelastic properties of human melanoma tissue using prony series,
S. Park, A. L. Chien, I. D. Brown, and J. Chen, “Characterizing viscoelastic properties of human melanoma tissue using prony series,” Frontiers in Bioeng. and Biotech., vol. 11, p. 1162880, 2023
work page 2023
-
[3]
The fractional viscoelastic response of human breast tissue cells,
B. Carmichael, H. Babahosseini, S. N. Mahmoodi, and M. Agah, “The fractional viscoelastic response of human breast tissue cells,”Physical Biology, vol. 12, no. 4, p. 046001, 2015
work page 2015
-
[4]
M. Zhang, P. Nigwekar, B. Castaneda, K. Hoyt, J. V . Joseph, A. di Sant’Agnese, E. M. Messing, J. G. Strang, D. J. Rubens, and K. J. Parker, “Quantitative characterization of viscoelastic properties of human prostate correlated with histology,”Ultrasound in Medicine & Biology, vol. 34, no. 7, pp. 1033–1042, 2008
work page 2008
-
[5]
D. Klatt, U. Hamhaber, P. Asbach, J. Braun, and I. Sack, “Noninvasive assessment of the rheological behavior of human organs using multi- frequency mr elastography: a study of brain and liver viscoelasticity,” Physics in Medicine & Biology, vol. 52, no. 24, p. 7281, 2007
work page 2007
-
[6]
The fractional viscoelastic response of human breast tissue cells,
B. Carmichael, H. Babahosseini, S. Mahmoodi, and M. Agah, “The fractional viscoelastic response of human breast tissue cells,”Physical Biology, vol. 12, no. 4, p. 046001, 2015
work page 2015
-
[8]
A theoretical basis for the application of fractional calculus to viscoelasticity,
R. Bagley and P. Torvik, “A theoretical basis for the application of fractional calculus to viscoelasticity,”Journal of Rheology, vol. 27, no. 3, pp. 201–210, 1983
work page 1983
-
[9]
An historical perspective on fractional calculus in linear viscoelasticity,
F. Mainardi, “An historical perspective on fractional calculus in linear viscoelasticity,”Fractional Calculus and Applied Analysis, vol. 15, pp. 712–717, 2012
work page 2012
-
[10]
Active Learning of Fractional-Order Viscoelastic Model Parameters for Realistic Haptic Rendering
H. Tolasa, G. Gemalmaz, and V . Patoglu, “Active learning of fractional- order viscoelastic model parameters for realistic haptic rendering,” CoRR, 2025. [Online]. Available: https://arxiv.org/abs/2512.00667
work page internal anchor Pith review Pith/arXiv arXiv 2025
-
[11]
Factors affecting the Z-width of a haptic display,
J. E. Colgate and J. M. Brown, “Factors affecting the Z-width of a haptic display,”IEEE Int. Conf. on Robotics and Automation, no. pt 4, pp. 3205–3210, 1994
work page 1994
-
[12]
Passivity of a class of sampled-data systems: Application to haptic interfaces,
J. Colgate and G. Schenkel, “Passivity of a class of sampled-data systems: Application to haptic interfaces,”Journal of Robotic Systems, vol. 14, pp. 37–47, 1997
work page 1997
-
[13]
Stability of haptic systems with fractional order controllers,
O. Tokatli and V . Patoglu, “Stability of haptic systems with fractional order controllers,” inIEEE/RSJ Int. Conf. on Intelligent Robots and Systems, 2015, pp. 1172–1177
work page 2015
-
[14]
Fractional order control in haptics,
O. Tokatli, “Fractional order control in haptics,” PhD thesis, Sabanci University, 2015
work page 2015
-
[15]
Using fractional order elements for haptic rendering,
O. Tokatli and V . Patoglu, “Using fractional order elements for haptic rendering,”Springer Advanced Robotics Research, pp. 373––388, 2018
work page 2018
-
[16]
Fractional order admittance control for physical human-robot interaction,
Y . Aydin , O. Tokatli, V . Patoglu, and C. Basdogan, “Fractional order admittance control for physical human-robot interaction,” inIEEE World Haptics Conference, 2017, pp. 257–262. 12
work page 2017
-
[17]
Stable physical human-robot interaction using fractional order admittance control,
Y . Aydin, O. Tokatli, V . Patoglu, and C. Basdogan, “Stable physical human-robot interaction using fractional order admittance control,”IEEE Trans. on Haptics, vol. 11, no. 3, pp. 464–475, 2018
work page 2018
-
[18]
Y . Aydin, O. Tokatli, V . Patoglu, and C. Basdogan, “A computational multicriteria optimization approach to controller design for physical human-robot interaction,”IEEE Trans. on Robotics, vol. 36, no. 6, pp. 1791–1804, 2020
work page 2020
-
[19]
Fractional viscoelastic models for power-law materials,
A. Bonfanti, J. L. Kaplan, G. Charras, and A. Kabla, “Fractional viscoelastic models for power-law materials,”Soft Matter, vol. 16, no. 26, pp. 6002–6020, 2020
work page 2020
-
[20]
On the elasticity and viscosity of metals,
W. Thomson, “On the elasticity and viscosity of metals,”The Royal Society of London, no. 14, pp. 289–297, 1865
-
[21]
Ueber die innere reibung der festen k ¨orper, insbesondere der krystalle
W. V oigt, “Ueber die innere reibung der festen k ¨orper, insbesondere der krystalle.”Abhandlungen der Koeniglichen Gesellschaft der Wis- senschaften in Goettingen, vol. 36, pp. 3–48, 1890
-
[22]
L. B. Eldred, W. P. Baker, and A. N. Palazotto, “Kelvin-V oigt versus fractional derivative model as constitutive relations for viscoelastic materials,”AIAA Journal, vol. 33, no. 3, pp. 547–550, 1995
work page 1995
-
[23]
On the dynamical theory of gases,
J. C. Maxwell, “On the dynamical theory of gases,”Philosophical Trans. of the Royal Society of London, no. 157, pp. 49–88, 1867
-
[24]
Fractional general- izations of Maxwell and Kelvin-V oigt models for biopolymer character- ization,
B. J ´o´zwiak, M. Orczykowska, and M. Dziubi ´nski, “Fractional general- izations of Maxwell and Kelvin-V oigt models for biopolymer character- ization,”PLOS One, vol. 10, no. 11, p. e0143090, 2015
work page 2015
-
[25]
Elasticity and anelasticity of metals
C. M. Zener and S. Siegel, “Elasticity and anelasticity of metals.”The Journal of Physical Chemistry, vol. 53, no. 9, pp. 1468–1468, 1949
work page 1949
-
[26]
Fractional calculus applied to model arterial viscoelasticity,
D. Craiem, F. Rojo, J. Atienza, G. Guinea, and R. L. Armentano, “Fractional calculus applied to model arterial viscoelasticity,”Latin American Applied Research, vol. 38, no. 2, pp. 141–145, 2008
work page 2008
-
[27]
Gesetze der elastischen nachwirkung f ¨ur constante tem- peratur,
E. Wiechert, “Gesetze der elastischen nachwirkung f ¨ur constante tem- peratur,”Annalen der Physik, vol. 286, no. 11, pp. 546–570, 1893
-
[28]
H. Khajehsaeid, “A comparison between fractional-order and integer- order differential finite deformation viscoelastic models: Effects of filler content and loading rate on material parameters,”International Journal of Applied Mechanics, vol. 10, no. 09, p. 1850099, 2018
work page 2018
-
[29]
An equivalence between generalized maxwell model and fractional zener model,
R. Xiao, H. Sun, and W. Chen, “An equivalence between generalized maxwell model and fractional zener model,”Mechanics of Materials, vol. 100, pp. 148–153, 2016
work page 2016
-
[30]
M. Ayyildiz, R. G. Aktas, and C. Basdogan, “Effect of solution and post- mortem time on mechanical and histological properties of liver during cold preservation,”Biorheology, vol. 51, no. 1, pp. 47–70, 2014
work page 2014
-
[31]
Fractional calculus – A different approach to the analysis of viscoelastically damped structures,
R. L. Bagley and P. J. Torvik, “Fractional calculus – A different approach to the analysis of viscoelastically damped structures,”AIAA Journal, vol. 21, no. 5, pp. 741–748, 1983
work page 1983
-
[32]
A. Carpinteri and F. Mainardi,Fractals and fractional calculus in continuum mechanics. Springer, 2014, vol. 378
work page 2014
-
[33]
Assessing and increasing z-width of haptic displays with active electrical damping,
D. D. Weir, “Assessing and increasing z-width of haptic displays with active electrical damping,” PhD thesis, Northwestern University, 2008
work page 2008
-
[34]
A. Haddadi and K. Hashtrudi-Zaad, “Stability analysis of haptic inter- faces for different types of sampled signals and virtual environment implementations,” inIEEE Haptics Symposium, 2010, pp. 293–299
work page 2010
-
[35]
Stability of haptic rendering: Discretization, quantization, time delay, and Coulomb effects,
N. Diolaiti, G. Niemeyer, F. Barbagli, and J. Salisbury, “Stability of haptic rendering: Discretization, quantization, time delay, and Coulomb effects,”IEEE Trans. on Robotics, vol. 22, no. 2, pp. 256–268, 2006
work page 2006
-
[36]
M. Fardad and B. Bamieh, “A necessary and sufficient frequency domain criterion for the passivity of SISO sampled-data systems,”IEEE Trans. on Automatic Control, vol. 54, no. 3, pp. 611–614, 2009
work page 2009
-
[37]
Issues in the haptic display of tool use,
J. Colgate, M. Stanley, and J. Brown, “Issues in the haptic display of tool use,” inInt. Conf. on Intelligent Robots and Systems, vol. 3, 1995, pp. 140–145
work page 1995
-
[38]
Passive implementation of multibody simulations for haptic display,
J. M. Brown and J. E. Colgate, “Passive implementation of multibody simulations for haptic display,” inASME Int. Mechanical Eng. Congress and Exposition, 1997, pp. 85–92
work page 1997
-
[39]
Passive implementation of multibody simulations for haptic display,
J. M. Brown, “Passive implementation of multibody simulations for haptic display,” PhD thesis, Northwestern University, 1998
work page 1998
-
[40]
A two-port framework for the design of unconditionally stable haptic interfaces,
R. Adams and B. Hannaford, “A two-port framework for the design of unconditionally stable haptic interfaces,” inIEEE/RSJ Int. Conf. on Intelligent Robots and Systems, vol. 2, 1998, pp. 1254–1259
work page 1998
-
[41]
Stable haptic interaction with virtual environments,
R. Adams and B. Hannaford, “Stable haptic interaction with virtual environments,”IEEE Trans. on Robotics and Automation, vol. 15, no. 3, pp. 465–474, 1999
work page 1999
-
[42]
A passivity criterion for real-time haptic simulation of viscoelastic soft tissues,
H. I. Son and T. Bhattacharjee, “A passivity criterion for real-time haptic simulation of viscoelastic soft tissues,”The Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, vol. 230, no. 9, pp. 1062–1071, 2016
work page 2016
-
[43]
Fractional order control – A tutorial,
Y . Chen, I. Petras, and D. Xue, “Fractional order control – A tutorial,” inAmerican Control Conference, 2009, pp. 1397–1411
work page 2009
-
[44]
Time-domain evaluation of fractional order controllers’ direct discretization methods,
C. Ma and Y . Hori, “Time-domain evaluation of fractional order controllers’ direct discretization methods,”IEEJ Trans. on Industry Applications, vol. 124, no. 8, pp. 837–842, 2004
work page 2004
-
[45]
G. Gemalmaz, H. Tolasa, and V . Patoglu, “Supplementary document for haptic rendering of fractional-order viscoelasticity: Passivity and rendering fidelity,” Technical Report, 2026, TR-SU-2026-003
work page 2026
-
[46]
Increasing the impedance range of a haptic display by adding electrical damping,
J. S. Mehling, J. E. Colgate, and M. A. Peshkin, “Increasing the impedance range of a haptic display by adding electrical damping,” in World Haptics Conference, 2005, pp. 257–262
work page 2005
-
[47]
Ren- dered and characterized closed-loop accuracy of impedance-type haptic displays,
N. Colonnese, A. F. Siu, C. M. Abbott, and A. M. Okamura, “Ren- dered and characterized closed-loop accuracy of impedance-type haptic displays,”IEEE Trans. on Haptics, vol. 8, no. 4, pp. 434–446, 2015
work page 2015
-
[48]
Closed-loop stiffness and damping accuracy of impedance-type haptic displays,
N. Colonnese, S. M. Sketch, and A. M. Okamura, “Closed-loop stiffness and damping accuracy of impedance-type haptic displays,” inIEEE Haptics Symposium, 2014, pp. 97–102. Gorkem Gemalmazreceived his B.Sc. degree in mechanical engineering from Middle East Technical University (2022). Currently, he is pursuing his Ph.D. degree at Sabanci University. His res...
work page 2014
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