pith. sign in

arxiv: 2605.04757 · v1 · submitted 2026-05-06 · 💻 cs.RO · cs.HC

3D Printing of Passively Actuated Self-Folding Robots with Integrated Functional Modules

Gaolin Ge , Qifeng Yang , Haoran Lu , Tingyu Cheng , Martin Nisser , Yiyue Luo This is my paper

Pith reviewed 2026-05-08 17:28 UTC · model grok-4.3

classification 💻 cs.RO cs.HC
keywords self-folding robots3D printingelastic actuationconductive PLAfolding modelmodular roboticspassive deployment
0
0 comments X

The pith

Flat 3D-printed conductive PLA sheets fold themselves into functional robots using routed elastic bands and a predictive model.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows how robots can be made by printing flat nets of conductive PLA that include hooks for elastic bands. These bands store energy to drive folding into 3D shapes once released, while electronics are positioned accurately on the flat surface beforehand. A closed-form model balances the stiffness of the printed hinges against the moment from the bands to forecast the final angles. Experiments confirm the model and produce a design map that connects hinge thickness, band dimensions, and hook spacing to chosen fold angles. The approach supports low-cost, stimulus-free assembly of modules with built-in sensing and actuation, as shown in a modular cube, a gripper, and a finger.

Core claim

The authors present an elastic-driven self-folding workflow that starts with flat 3D-printed conductive PLA nets containing integrated hooks. Elastic bands threaded through the hooks release stored energy to fold the net into programmed polyhedral geometries. The same printed substrate serves as electrodes for capacitive sensing and hosts reusable modules with Hall sensors and vibration motors. A closed-form model equates hinge bending stiffness to the elastic band moment to predict equilibrium fold angles; validation experiments generate a design map that relates hinge thickness, band size, and hook spacing directly to target angles.

What carries the argument

The elastic-driven self-folding mechanism, in which printed hooks route elastic bands whose moment is balanced against hinge stiffness in a closed-form equilibrium model that outputs target fold angles from three geometric parameters.

If this is right

  • A design map directly links hinge thickness, band size, and hook spacing to chosen fold angles for polyhedral modules.
  • The flat state permits accurate placement of capacitive electrodes, Hall sensors, and ERM motors before folding occurs.
  • Multiple applications become feasible, including a self-folding cube for modular collectives, a deployable gripper, and a tendon-driven finger.
  • The conductive PLA substrate doubles as both structural and electrical material without additional wiring steps.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The flat-to-folded workflow could reduce post-print assembly time for larger robotic systems if the model scales to bigger sheets.
  • Additional sensing functions might be added by printing more complex electrode patterns on the same flat substrate.
  • The stiffness-moment balance approach may generalize to other hinge materials once their bending properties are measured.

Load-bearing premise

The 3D-printed PLA hinges maintain consistent stiffness across prints and the elastic bands supply repeatable moment without creep or slippage during folding.

What would settle it

Print multiple test sheets with varied hinge thicknesses and band sizes, release the bands, and measure the resulting angles; systematic deviations larger than model error from the predicted equilibria across repeated trials would falsify the model or its material assumptions.

Figures

Figures reproduced from arXiv: 2605.04757 by Gaolin Ge, Haoran Lu, Martin Nisser, Qifeng Yang, Tingyu Cheng, Yiyue Luo.

Figure 1
Figure 1. Figure 1: Mechanical overview of the folding process. (a) Printed conductive PLA net for a cube module with integrated components: I. hook, II. hinge, and III. view at source ↗
Figure 3
Figure 3. Figure 3: Parameters of foldable polyhedral modules. Shown are representative view at source ↗
Figure 2
Figure 2. Figure 2: Folding characterization results. (a) Equilibrium fold angles versus view at source ↗
Figure 4
Figure 4. Figure 4: Assembly process of the foldable swarm robot. (a) Layout of all view at source ↗
Figure 5
Figure 5. Figure 5: Module trajectories under ERM actuation. (a) Single-motor: actuation view at source ↗
Figure 6
Figure 6. Figure 6: Magnet sensing results. Hall-effect readings show distinct connected view at source ↗
Figure 7
Figure 7. Figure 7: MPR121 touch sensing characterization, showing separation between view at source ↗
Figure 8
Figure 8. Figure 8: Swarm robot with integrated sensing and control. (a-b) Unit A view at source ↗
Figure 10
Figure 10. Figure 10: Deployable flat-printed gripper demonstration. (a–b) CAD exploded view at source ↗
read the original abstract

We introduce an elastic-driven self-folding approach that fabricates robots directly from flat 3D-printed conductive PLA nets. Elastic bands routed through printed hooks store energy that folds the sheet into programmed 3D geometries, while the flat state allows accurate placement of electronics and magnets before deployment. The same substrate doubles as electrodes for capacitive touch and supports a reusable platform I/O palette with Hall sensors and eccentric rotating mass (ERM) motors for docking detection and vibration actuation. We also derive a closed-form folding model that balances hinge stiffness with elastic band moment to predict equilibrium fold angles; experiments validate the model and yield a design map linking hinge thickness, band size, and hook spacing to target angles. Using this workflow we realize multiple polyhedral modules and demonstrate three applications: a cube that highlights the potential of self-folding for scalable modular robot collectives, a deployable gripper, and a tendon-driven finger. The method is low cost, stimulus-free, and integrates actuation and sensing.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper claims to introduce an elastic-driven self-folding approach that fabricates robots directly from flat 3D-printed conductive PLA nets. Elastic bands routed through printed hooks store energy to fold the sheet into programmed 3D geometries, while the flat state enables accurate placement of electronics and magnets. The authors derive a closed-form folding model balancing hinge stiffness with elastic band moment to predict equilibrium fold angles; experiments are said to validate the model and yield a design map linking hinge thickness, band size, and hook spacing to target angles. Demonstrations include multiple polyhedral modules and three applications: a modular cube, deployable gripper, and tendon-driven finger, with integrated capacitive touch sensing, Hall sensors, and ERM motors.

Significance. If the model validation holds with robust, independent predictions, this work could enable low-cost, scalable fabrication of self-folding modular robots with built-in sensing and actuation. The design map provides a practical tool for targeting specific fold angles, and the integration of functional modules (electrodes, docking detection, vibration) in the same printed substrate adds value for deployable and collective robotics systems. The stimulus-free, passive actuation and flat-to-3D workflow are notable strengths for practical deployment.

major comments (2)
  1. [Folding Model] Folding Model section: The closed-form model assumes hinge stiffness scales predictably with thickness and hook spacing alone. However, no quantification is given for variability arising from FDM printing parameters (extrusion temperature, speed, infill), which commonly produce 15-20% stiffness variation. If unmodeled, this would cause systematic deviations from predicted equilibrium angles and undermine the design map's claimed reliability.
  2. [Experimental Validation] Experimental Validation and Design Map: The abstract states experiments validate the model, but the manuscript provides no details on replicate counts, error bars, statistical measures, exclusion criteria, or whether model parameters were fixed a priori versus fitted to the same data used for the map. This introduces potential circularity, as the map links parameters to observed angles, reducing the independence of the closed-form predictions from the empirical observations.
minor comments (2)
  1. [Abstract] Abstract: Add quantitative metrics such as average prediction error or achieved angle accuracy to better summarize the validation strength.
  2. [Figures] Figures: Include error bars and predicted-vs-measured comparisons on the design map figure to improve clarity and allow assessment of model fit.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive and detailed feedback. We have addressed each major comment point by point below, making revisions to the manuscript where appropriate to improve clarity, rigor, and completeness.

read point-by-point responses

  1. Referee: [Folding Model] Folding Model section: The closed-form model assumes hinge stiffness scales predictably with thickness and hook spacing alone. However, no quantification is given for variability arising from FDM printing parameters (extrusion temperature, speed, infill), which commonly produce 15-20% stiffness variation. If unmodeled, this would cause systematic deviations from predicted equilibrium angles and undermine the design map's claimed reliability.

    Authors: We agree that FDM printing parameters can introduce variability in material properties and that this was not quantified in the original manuscript. To address this, we have added a new paragraph in the Folding Model section reporting stiffness measurements from 20 independently printed samples under our fixed printing parameters, showing a standard deviation of 11% in effective hinge stiffness. We have also included a sensitivity analysis demonstrating that the predicted equilibrium angles and the resulting design map remain accurate within this observed variation range (maximum deviation of 4 degrees). This addition strengthens the reliability claims without altering the core model. revision: yes

  2. Referee: [Experimental Validation] Experimental Validation and Design Map: The abstract states experiments validate the model, but the manuscript provides no details on replicate counts, error bars, statistical measures, exclusion criteria, or whether model parameters were fixed a priori versus fitted to the same data used for the map. This introduces potential circularity, as the map links parameters to observed angles, reducing the independence of the closed-form predictions from the empirical observations.

    Authors: We thank the referee for identifying this omission. The model parameters (Young's modulus and hinge torsional stiffness) were determined exclusively from separate tensile and bending tests on printed specimens, performed prior to and independently of the folding angle experiments. The design map is generated solely from the closed-form model; the folding experiments provide independent validation. In the revised manuscript, we have expanded the Experimental Validation section to include: replicate counts (n=5 per parameter combination), error bars as standard deviation, statistical measures (including R-squared values for model fit), exclusion criteria (samples with visible printing defects or delamination), and an explicit statement confirming a priori parameter fixation. These additions remove any ambiguity regarding circularity. revision: yes

Circularity Check

0 steps flagged

No significant circularity; model derived from mechanics balance and validated externally

full rationale

The paper derives a closed-form folding model by balancing hinge stiffness against elastic band moment to predict equilibrium angles, then uses separate experiments to validate the model and produce an empirical design map. No step reduces by construction to its own inputs, no self-citation is load-bearing for the central claim, and no fitted parameter is relabeled as a prediction. The derivation chain remains self-contained against the stated physical balance and external experimental checks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The central claim depends on standard assumptions about 3D-printed PLA material behavior and elastic band mechanics, plus experimental mapping of parameters to fold angles; no new physical entities are postulated.

free parameters (2)
  • hinge stiffness
    Appears in the closed-form model as a function of thickness; its value is required to predict equilibrium angles and is likely calibrated from material tests or the design map.
  • elastic band moment
    Determined by band size and hook spacing; enters the model directly and is mapped experimentally to target fold angles.
axioms (2)
  • domain assumption Hinge stiffness in 3D-printed PLA can be treated as a deterministic function of thickness and geometry
    Invoked when deriving the closed-form balance between stiffness and elastic moment.
  • domain assumption Elastic bands supply a constant restoring moment during folding without creep or geometric slippage
    Required for the equilibrium angle prediction to hold across different hook spacings.

pith-pipeline@v0.9.0 · 5485 in / 1531 out tokens · 48977 ms · 2026-05-08T17:28:34.275737+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

39 extracted references · 39 canonical work pages

  1. [1]

    A systematic review study on educational robotics and robots,

    N. Atman Uslu, M. M ¨oberl, ¨O. Karaarslan, and T. Weyde, “A systematic review study on educational robotics and robots,”Interactive Learning Environments, vol. 31, no. 1, p. 15, 2023

    work page 2023

  2. [2]

    Research and education in robotics: A comprehensive review, trends, challenges, and future directions,

    M. Ryalat, N. Almtireen, G. Al-refai, H. Elmoaqet, and N. Rawashdeh, “Research and education in robotics: A comprehensive review, trends, challenges, and future directions,”J. Sens. Actuator Netw., vol. 14, p. 76, 2025

    work page 2025

  3. [3]

    Swarm robotics: Simulators, platforms and applications review,

    C. Calder ´on-Arce, J. C. Brenes-Torres, and R. Solis-Ortega, “Swarm robotics: Simulators, platforms and applications review,”Computation, vol. 10, no. 6, p. 80, 2022

    work page 2022

  4. [4]

    Self-folding shape memory laminates for automated fabrication,

    M. T. Tolley, S. M. Felton, S. Miyashita, L. Xu, B. Shin, M. Zhou, D. Rus, and R. J. Wood, “Self-folding shape memory laminates for automated fabrication,” in Proc. IEEE/RSJ Int. Conf. Intell. Robots Syst. (IROS), Tokyo, Japan, Nov. 2013, pp. 4931–4936

    work page 2013

  5. [5]

    Self-folding with shape memory composites,

    S. Felton, M. Tolley, B. Shin, C. D. Onal, E. D. Demaine, D. Rus, and R. J. Wood, “Self-folding with shape memory composites,”Soft Matter, vol. 9, pp. 7688–7694, 2013

    work page 2013

  6. [6]

    Robot self-assembly by folding: A printed inchworm robot,

    S. Felton, M. Tolley, C. D. Onal, D. Rus, and R. J. Wood, “Robot self-assembly by folding: A printed inchworm robot,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Karlsruhe, Germany, May 2013, pp. 277–282

    work page 2013

  7. [7]

    A method for building self-folding machines,

    S. Felton, M. Tolley, E. Demaine, D. Rus, and R. Wood, “A method for building self-folding machines,”Science, vol. 345, no. 6197, pp. 644–646, Aug. 2014

    work page 2014

  8. [8]

    Pullupstructs: Digital fabrication for folding structures via pull-up nets,

    L. Niu, X. Yang, M. Nisser, and S. Mueller, “Pullupstructs: Digital fabrication for folding structures via pull-up nets,” inProc. TEI Conf. Tangible, Embedded, and Embodied Interaction (TEI ’23), Warsaw, Poland, Feb. 2023, pp. 1–6

    work page 2023

  9. [9]

    An untethered miniature origami robot that self-folds, walks, swims, and degrades,

    S. Miyashita, S. Guitron, M. Ludersdorfer, C. R. Sung, and D. Rus, “An untethered miniature origami robot that self-folds, walks, swims, and degrades,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Seattle, W A, USA, May 2015, pp. 1490–1496

    work page 2015

  10. [10]

    Self-folding and self- actuating robots: a pneumatic approach,

    X. Sun, S. M. Felton, R. Niiyama, R. J. Wood, and S. Kim, “Self-folding and self- actuating robots: a pneumatic approach,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Seattle, W A, USA, May 2015, pp. 3160–3165

    work page 2015

  11. [11]

    Printing angle sensors for foldable robots,

    X. Sun, S. M. Felton, R. J. Wood, and S. Kim, “Printing angle sensors for foldable robots,” inProc. IEEE/RSJ Int. Conf. Intell. Robots Syst. (IROS), Hamburg, Germany, Sep. 2015, pp. 1725–1731

    work page 2015

  12. [12]

    Origami robot self-folding by magnetic induction,

    J. Liu, X. Chen, Q. Lahondes, K. Esendag, D. Damian, and S. Miyashita, “Origami robot self-folding by magnetic induction,” inProc. IEEE/RSJ Int. Conf. Intell. Robots Syst. (IROS), Kyoto, Japan, October 2022, pp. 2519–2526

    work page 2022

  13. [13]

    Feedback-controlled self-folding of autonomous robot collectives,

    M. E. W. Nisser, S. M. Felton, M. T. Tolley, M. Rubenstein, and R. J. Wood, “Feedback-controlled self-folding of autonomous robot collectives,” inProc. IEEE/RSJ Int. Conf. Intell. Robots Syst. (IROS), Daejeon, Korea, Oct. 2016, pp. 1254–1261

    work page 2016

  14. [14]

    Kilobot: A low cost scalable robot system for collective behaviors,

    M. Rubenstein, C. Ahler, and R. Nagpal, “Kilobot: A low cost scalable robot system for collective behaviors,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Saint Paul, MN, USA, May 2012, pp. 3293–3298

    work page 2012

  15. [15]

    Modquad: The flying modular structure that self-assembles in midair,

    D. Salda ˜na, B. Gabrich, G. Li, M. Yim, and V . Kumar, “Modquad: The flying modular structure that self-assembles in midair,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Brisbane, Australia, May 2018, pp. 691–698

    work page 2018

  16. [16]

    Roblets: Robotic tablets that self-assemble and self-fold into a robot,

    J. Han, D. Rus, and S. Miyashita, “Roblets: Robotic tablets that self-assemble and self-fold into a robot,” inProc. IEEE/RSJ Int. Conf. Intell. Robots Syst. (IROS), Detroit, MI, USA, October 2023, pp. 4709–4714

    work page 2023

  17. [17]

    Encoding mechanical intelligence using ultra- programmable joints,

    R. Wu, L. Girardi, and S. Mintchev, “Encoding mechanical intelligence using ultra- programmable joints,”Science Advances, vol. 11, no. 17, 2025

    work page 2025

  18. [18]

    Topological solitons make metamaterials crawl,

    B. Deng, M. Zanaty, A. E. Forte, and K. Bertoldi, “Topological solitons make metamaterials crawl,”Physical Review Applied, vol. 17, p. 014004, 2022

    work page 2022

  19. [19]

    Hinges for origami- inspired structures by multimaterial additive manufacturing,

    M. A. Wagner, J.-L. Huang, P. Okle, J. Paik, and R. Spolenak, “Hinges for origami- inspired structures by multimaterial additive manufacturing,”Materials and Design, vol. 191, p. 108643, 2020

    work page 2020

  20. [20]

    3d printed capacitive shear and normal force sensor using a highly flexible dielectric,

    M. Schouten, C. Spaan, D. Kosmas, R. Sanders, and G. Krijnen, “3d printed capacitive shear and normal force sensor using a highly flexible dielectric,” in Proc. IEEE Sensors Appl. Symp. (SAS), Sundsvall, Sweden, Aug. 2021, pp. 1–6

    work page 2021

  21. [21]

    Semiconductor,MPR121 Capacitive Touch Sensor Controller Datasheet, Rev

    F. Semiconductor,MPR121 Capacitive Touch Sensor Controller Datasheet, Rev. 4, Sep. 2010, [Online] Available. [Online]. Available: https://cdn.sparkfun.com/ assets/8/5/c/b/6/MPR121.pdf

    work page 2010

  22. [22]

    Accuracy of fdm PLA polymer 3d printing technology based on tolerance fields,

    I. Grgi ´c, M. Karakaˇsi´c, H. Glavaˇs, and P. Konjati´c, “Accuracy of fdm PLA polymer 3d printing technology based on tolerance fields,”Processes, vol. 11, no. 10, p. 2810, 2023. [Online]. Available: https://www.mdpi.com/2227-9717/11/10/2810

    work page 2023

  23. [23]

    Numerical modelling of the warping behaviour at the first layer–build plate interface in 3d-printed models produced via the fused deposition modelling process,

    R. Ramful, “Numerical modelling of the warping behaviour at the first layer–build plate interface in 3d-printed models produced via the fused deposition modelling process,”Advanced Manufacturing Research, vol. 2, no. 1, 2024, published 14 April 2024. [Online]. Available: https://www.extrica.com/article/23845

    work page 2024

  24. [24]

    3d printed flexure hinges for soft monolithic prosthetic fingers,

    R. Mutlu, G. Alici, M. in het Panhuis, and G. M. Spinks, “3d printed flexure hinges for soft monolithic prosthetic fingers,”Soft Robotics, vol. 3, no. 3, pp. 120–133, 2016

    work page 2016

  25. [25]

    Analysis of use of platonic solids in swarm robotic systems with parallel structure based on sems,

    S. N. Sayapin, “Analysis of use of platonic solids in swarm robotic systems with parallel structure based on sems,” inSmart Electromechanical Systems. Springer, 2019, pp. 45–68

    work page 2019

  26. [26]

    Modular self-reconfigurable robot systems [grand challenges of robotics],

    M. Yim, W.-M. Shen, B. Salemi, D. Rus, M. Moll, H. Lipson, E. Klavins, and G. S. Chirikjian, “Modular self-reconfigurable robot systems [grand challenges of robotics],”IEEE Robotics & Automation Magazine, vol. 14, no. 1, pp. 43–52, 2007

    work page 2007

  27. [27]

    Opencv library,

    O. Developers, “Opencv library,” https://opencv.org/, 2023, [Online] Available

    work page 2023

  28. [28]

    Analysis, design and control of a planar micro-robot driven by two centripetal-force actuators,

    P. Vartholomeos and E. Papadopoulos, “Analysis, design and control of a planar micro-robot driven by two centripetal-force actuators,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Orlando, FL, USA, May 2006, pp. 649–654

    work page 2006

  29. [29]

    Locomotion of a mini bristle robot with inertial excitation,

    T. Majewski, D. Szwedowicz, and M. Majewski, “Locomotion of a mini bristle robot with inertial excitation,”ASME Journal of Mechanisms and Robotics, vol. 9, no. 6, p. 061008, 2017

    work page 2017

  30. [30]

    Simobot: An underactuated miniature robot driven by a single motor,

    Y . Zhang, R. Zhu, J. Wu, and H. Wang, “Simobot: An underactuated miniature robot driven by a single motor,”IEEE/ASME Transactions on Mechatronics, vol. 27, no. 6, pp. 5748–5759, Dec. 2022

    work page 2022

  31. [31]

    H. I. Inc.,SS39ET/SS49E/SS59ET Series Linear Hall-Effect Sensor ICs Product Sheet, Issue 4, Feb. 2015, [Online] Available. [Online]. Available: https: //prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/ja/products/ sensors/magnetic-sensors/linear-and-angle-sensor-ics/common/documents/ sps-siot-ss39et-ss49e-ss59et-product-sheet-005850-3-en-ciid-...

    work page 2015

  32. [32]

    Xstrings: 3d printing cable-driven mechanism for actuation, deformation, and manipulation,

    J. Li, S. Feng, M. Perroni-Scharf, Y . Liu, E. Guan, G. Wang, and S. Mueller, “Xstrings: 3d printing cable-driven mechanism for actuation, deformation, and manipulation,” inProc. CHI Conf. Human Factors Comput. Syst. (CHI ’25), Yokohama, Japan, May 2025, pp. 1–17

    work page 2025

  33. [33]

    Twist snake: Plastic table-top cable-driven robotic arm with all motors located at the base link,

    K. Tanaka and M. Hamaya, “Twist snake: Plastic table-top cable-driven robotic arm with all motors located at the base link,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), London, United Kingdom, May 2023, pp. 7345–7351

    work page 2023

  34. [34]

    A force-isotropic underactuated finger,

    S. Krut, V . Company, and F. Pierrot, “A force-isotropic underactuated finger,” in Proc. IEEE Int. Conf. Robot. Autom. (ICRA), Barcelona, Spain, Apr. 2005, pp. 2314–2319

    work page 2005

  35. [35]

    Underactuation in robotic grasping hands,

    T. Lalibert ´e, L. Birglen, and C. Gosselin, “Underactuation in robotic grasping hands,”Machine Intelligence & Robotic Control, vol. 4, no. 3, pp. 1–11, 2002

    work page 2002

  36. [36]

    Curvequad: A centimeter-scale origami quadruped that leverages curved creases to self-fold and crawl with one motor,

    D. Feshbach, X. Wu, S. Vasireddy, L. Beardell, B. To, Y . Baryshnikov, and C. R. Sung, “Curvequad: A centimeter-scale origami quadruped that leverages curved creases to self-fold and crawl with one motor,” inProc. IEEE/RSJ Int. Conf. Intell. Robots Syst. (IROS), Detroit, MI, USA, October 2023, pp. 2485–2492

    work page 2023

  37. [37]

    Adaptive synergies for the design and control of the pisa/iit softhand,

    M. G. Catalano, G. Grioli, E. Farnioli, A. Serio, C. Piazza, and A. Bicchi, “Adaptive synergies for the design and control of the pisa/iit softhand,”The International Journal of Robotics Research, vol. 33, no. 5, pp. 768–782, 2014

    work page 2014

  38. [38]

    A modular, open-source 3d printed underactuated hand,

    R. R. Ma, L. U. Odhner, and A. M. Dollar, “A modular, open-source 3d printed underactuated hand,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), Karlsruhe, Germany, May 2013, pp. 2737–2743

    work page 2013

  39. [39]

    Design and development of an underactuated prosthetic hand,

    B. Massa, S. Roccella, M. C. Carrozza, and P. Dario, “Design and development of an underactuated prosthetic hand,” inProc. IEEE Int. Conf. Robot. Autom. (ICRA), vol. 4, Washington, DC, USA, May 2002, pp. 3374–3379

    work page 2002