0
Research Papers: Design of Mechanisms and Robotic Systems

Design of Three New Cam-Based Constant-Force Mechanisms

[+] Author and Article Information
Javier López-Martínez

Department of Engineering,
University of Almería,
Almería 04120, Spain
e-mail: javier.lopez@ual.es

Daniel García-Vallejo

Department of Mechanical Engineering
and Manufacturing,
University of Seville,
Seville 41092, Spain
e-mail: dgvallejo@us.es

Francisco Manuel Arrabal-Campos

Department of Engineering,
University of Almería,
Almería 04120, Spain
e-mail: fmarrabal@ual.es

Jose Manuel Garcia-Manrique

Department of Civil Engineering,
Materials and Manufacturing,
University of Málaga,
Málaga 29071, Spain
e-mail: josegmo@uma.es

Contributed by the Mechanisms and Robotics Committee of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received January 18, 2018; final manuscript received April 26, 2018; published online May 28, 2018. Assoc. Editor: Massimo Callegari.

J. Mech. Des 140(8), 082302 (May 28, 2018) (14 pages) Paper No: MD-18-1052; doi: 10.1115/1.4040174 History: Received January 18, 2018; Revised April 26, 2018

Constant-force mechanisms are designed to keep a constant or nearly constant input force along a prescribed stroke of the mechanism. The implementation of this kind of mechanisms has been approached in literature using compliant mechanisms or through a certain combination of springs and nonlinear transmissions. In this work, three new constant-force mechanisms based on the use of springs, rollers, and cams are presented and analyzed. The rolling friction forces between the rollers and the cam are included in the force equilibrium equations and considered in the integration of the cam profile. The influence of the friction force on the input force as well as the design parameters involved is studied based on numerical techniques and simulations. In fact, the results evidence that to obtain a precise constant-force mechanism, rolling friction forces must be considered in the cam profile definition. The main design guidelines for the three constant-force mechanisms proposed are described.

Copyright © 2018 by ASME
Your Session has timed out. Please sign back in to continue.

References

Wall, A. , 1963, Mechanical Springs, 2nd ed., McGraw-Hill, New York.
Wang, P. , and Xu, Q. , 2018, “ Design and Modeling of Constant-Force Mechanisms: A Survey,” Mech. Mach. Theory, 119, pp. 1–21. [CrossRef]
Bidgoly, H. , Ahmadabadi, M. , and Zakerzadeh, M. , 2016, “ Design and Modeling of a Compact Rotational Nonlinear Spring,” IEEE International Conference on Intelligent Robots and Systems (IROS), Daejeon, South Korea, Oct. 9–14, pp. 4356–4361.
Howell, L. , and Midha, A. , 1995, “ Parametric Deflection Approximations for End-Loaded, Large-Deflection Beams in Compliant Mechanisms,” ASME J. Mech. Des., 117(1), pp. 156–165. [CrossRef]
Howell, L. , 2001, Comliant Mechanisms, Wiley, New York.
Gallego, J. , and Herder, J. , 2010, “ Classification for Literature on Compliant Mechanisms: A Design Methodology Based Approach,” ASME Paper No. DETC2009-87334.
Tolman, K. , Merriam, E. , and Howell, L. , 2016, “ Compliant Constant-Force Linear-Motion Mechanism,” Mech. Mach. Theory, 106, pp. 68–79. [CrossRef]
Lamers, A. , Gallego Snchez, J. , and Herder, J. , 2015, “ Design of a Statically Balanced Fully Compliant Grasper,” Mech. Mach. Theory, 92, pp. 230–239. [CrossRef]
Boyle, C. , Howell, L. , Magleby, S. , and Evans, M. , 2003, “ Dynamic Modeling of Compliant Constant-Force Compression Mechanisms,” Mech. Mach. Theory, 38(12), pp. 1469–1487. [CrossRef]
Pham, H.-T. , and Wang, D.-A. , 2011, “ A Constant-Force Bistable Mechanism for Force Regulation and Overload Protection,” Mech. Mach. Theory, 46(7), pp. 899–909. [CrossRef]
Meaders, J. , and Mattson, C. , 2010, “ Optimization of Near-Constant Force Springs Subject to Mating Uncertainty,” Struct. Multidiscip. Optim., 41(1), pp. 1–15. [CrossRef]
Prakashah, H. , and Zhou, H. , 2016, “ Synthesis of Constant Torque Compliant Mechanisms,” ASME J. Mech. Rob., 8(6), p. 064503. [CrossRef]
Pedersen, C. , Fleck, N. , and Ananthasuresh, G. , 2006, “ Design of a Compliant Mechanism to Modify an Actuator Characteristic to Deliver a Constant Output Force,” ASME J. Mech. Des., 128(5), pp. 1101–1112. [CrossRef]
Chen, Y.-H. , and Lan, C.-C. , 2012, “ An Adjustable Constant-Force Mechanism for Adaptive End-Effector Operations,” ASME J. Mech. Des., 134(3), p. 031005.
Liu, Y. , Zhang, Y. , and Xu, Q. , 2017, “ Design and Control of a Novel Compliant Constant-Force Gripper Based on Buckled Fixed-Guided Beams,” IEEE/ASME Trans. Mechatronics, 22(1), pp. 476–486. [CrossRef]
Wang, P. , and Xu, Q. , 2017, “ Design of a Flexure-Based Constant-Force Xy Precision Positioning Stage,” Mech. Mach. Theory, 108, pp. 1–13. [CrossRef]
Xu, Q. , 2017, “ Design of a Large-Stroke Bistable Mechanism for the Application in Constant-Force Micropositioning Stage,” ASME J. Mech. Rob., 9(1), p. 011006. [CrossRef]
Qiu, J. , Lang, J. , and Slocum, A. , 2004, “ A Curved-Beam Bistable Mechanism,” J. Microelectromech. Syst., 13(2), pp. 137–146. [CrossRef]
Chen, G. , Gou, Y. , and Zhang, A. , 2011, “ Synthesis of Compliant Multistable Mechanisms Through Use of a Single Bistable Mechanism,” ASME J. Mech. Des., 133(8), p. 081007. [CrossRef]
Starostin, E. , 1987, “ Calculating a Cam Profile for a Constant-Force Mechanism,” Sov. Mach. Sci., 4, pp. 69–76. https://www.researchgate.net/publication/257505307_Calculating_a_cam_profile_for_a_constant-force_mechanism
Duval, E. , 2010, “ Dual Pulley Constant Force Mechanism,” U.S. Patent No. 7,677,540. https://patents.google.com/patent/US7677540
Riley, R. , and Carey, D. , 1980, “ Exercise Machine With Spring-Cam Arrangement for Equalizing the Force Required Through the Exercise Stroke,” U.S. Patent No. 4,231,568.
Schepelmann, A. , Geberth, K. , and Geyer, H. , 2014, “ Compact Nonlinear Springs With User Defined Torque-Deflection Profiles for Series Elastic Actuators,” IEEE International Conference on Robotics and Automation (ICRA), Hong Kong, China, May 31–June 7, pp. 3411–3416.
Schmit, N. , and Okada, M. , 2011, “ Synthesis of a Non-Circular Cable Spool to Realize a Nonlinear Rotational Spring,” IEEE International Conference on Intelligent Robots and Systems (IROS), San Francisco, CA, Sept. 25–30, pp. 762–767.
Endo, G. , Yamada, H. , Yajima, A. , Ogata, M. , and Hirose, S. , 2010, “ A Passive Weight Compensation Mechanism With a Non-Circular Pulley and a Spring,” IEEE International Conference on Robotics and Automation (ICRA), Anchorage, AK, May 3–7, pp. 3843–3848.
Liu, Y. , Yu, D.-P. , and Yao, J. , 2016, “ Design of an Adjustable Cam Based Constant Force Mechanism,” Mech. Mach. Theory, 103, pp. 85–97. [CrossRef]
Liu, Y. , Li, D.-J. , Yu, D.-P. , Miao, J.-G. , and Yao, J. , 2017, “ Design of a Curved Surface Constant Force Mechanism,” Mech. Based Des. Struct. Mach., 45(2), pp. 160–172. [CrossRef]
Wang, S. , and Zhao, R. , 2015, “ Constant-Force Cylinder Experiment With Low-Gravity Simulation,” Aircr. Eng. Aerosp. Technol., 87(4), pp. 376–379. [CrossRef]
Berselli, G. , Vertechy, R. , Vassura, G. , and Castelli, V. , 2009, “ Design of a Single-Acting Constant-Force Actuator Based on Dielectric Elastomers,” ASME J. Mech. Rob., 1(3), pp. 1–6. [CrossRef]
Nathan, R. , 1985, “ A Constant Force Generation Mechanism,” ASME J. Mech. Des., 107(4), pp. 508–512.
Howell, L. , and Magleby, S. , 2006, “ Substantially Constant-Force Exercise Machine,” Brigham Young University, Provo, UT, U.S. Patent No. 7,060,012. https://patents.google.com/patent/US7060012B2/en
Smith, D. , 2005, “ Resistive Exercise Device,” National Aeronautics and Space Administration (NASA), Washington, DC, U.S. Patent No. 6,958,032. https://patents.google.com/patent/US6958032B1/en
Colosky, P. , and Ruttley, T. , 2004, “ Gravity-Independent Constant Force Resistive Exercise Unit,” U.S. Patent No. 6,685,602. https://patents.google.com/patent/US6685602
Lan, C.-C. , and Wang, J.-Y. , 2011, “ Design of Adjustable Constant-Force Forceps for Robot-Assisted Surgical Manipulation,” IEEE International Conference on Robotics and Automation (ICRA), Shanghai, China, May 9–13, pp. 386–391.
Wang, J.-Y. , and Lan, C.-C. , 2014, “ A Constant-Force Compliant Gripper for Handling Objects of Various Sizes,” ASME J. Mech. Des., 136(7), p. 071008. [CrossRef]
Wang, P. , and Xu, Q. , 2017, “ Design and Testing of a Flexure-Based Constant-Force Stage for Biological Cell Micromanipulation,” IEEE Trans. Autom. Sci. Eng., in press.
Chen, Y.-H. , and Lan, C.-C. , 2012, “ Design of a Constant-Force Snap-Fit Mechanism for Minimal Mating Uncertainty,” Mech. Mach. Theory, 55, pp. 34–50. [CrossRef]
Li-Jun, Z. , Tao, L. , and Bao-Yu, S. , 2008, “ Optimum Design of Automobile Diaphragm Spring Clutch,” IEEE Vehicle Power and Propulsion Conference (VPPC), Harbin, China, Sept. 3–5, pp. 1–4.
Weight, B. , Mattson, C. , Magleby, S. , and Howell, L. , 2007, “ Configuration Selection, Modeling, and Preliminary Testing in Support of Constant Force Electrical Connectors,” ASME J. Electron. Packag., 129(3), pp. 236–246. [CrossRef]
Committee, A. I. H. , 1992, ASM Handbook, Vol. 18, ASM International, Materials Park, OH.
Stoer, J. , and Bulirsch, R. , 2002, Introduction to Numerical Analysis, 3rd ed., Springer, New York. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Sketches of the three constant-force mechanisms proposed: (a) CFM-1, (b) CFM-2, and (c) CFM-3

Grahic Jump Location
Fig. 2

Three-dimensional CAD designs of the three constant-force mechanisms: (a) CFM-1, (b) CFM-2 with four springs arranged in parallel, and (c) CFM-3

Grahic Jump Location
Fig. 3

Forces diagram for the rollers assembly of CFM-1

Grahic Jump Location
Fig. 4

Forces diagram for the roller of CFM-2

Grahic Jump Location
Fig. 5

Forces diagram for the roller of CFM-3

Grahic Jump Location
Fig. 6

Trajectory of the roller center of concept CFM-1 obtained by numerical integration. All curves are generated for a target force of 30 N and a spring with natural length of 180 mm and stiffness constant, K, of 4 N/mm.

Grahic Jump Location
Fig. 7

Convergence of the numerical integration scheme for different step sizes. All curves are generated for a target force of 30 N, a value of the rolling friction, μr of 0.002 and a spring with natural length of 180 mm and stiffness constant, K, of 4N/mm.

Grahic Jump Location
Fig. 8

Trajectory of the roller center of concept CFM-2 obtained by numerical integration. All curves are generated for a target force of 30 N, a cable of length lt, of 250 mm and a spring with natural length of 180 mm and stiffness constant, K, of 4 N/mm.

Grahic Jump Location
Fig. 9

Comparison of the trajectory of the roller center for concept CFM-1 and concept CFM-2 width several values of brace length lt. All curves are generated for a target force of 30 N, a value of the rolling friction, μr of 0.002 and a spring with natural length of 180 mm and stiffness constant, K, of 4 N/mm.

Grahic Jump Location
Fig. 10

Trajectory of the roller center of concept CFM-3 obtained by numerical integration. All curves are generated for a target force of 30 N and a spring with natural length of 180 mm and stiffness constant, K, of 4 N/mm.

Grahic Jump Location
Fig. 11

CFM-1. Ratio of the force without friction F′ and the force with friction F for different values of the rolling friction coefficient, when the rollers moves in positive direction of y-axis (continuous lines) and when the rollers moves in negative direction of y-axis (discontinuous lines).

Grahic Jump Location
Fig. 12

(a) Solid lines show the trajectories of the roller center for a desired constant force F of 30 N, a value of the rolling friction coefficients, μr1 = μr2, of 0.002 and different spring stiffness for concept CFM-1 while dashed lines show the trajectories of the roller center for a desired constant force F of 30 N, a rolling friction value, μr, of 0.002 and different spring stiffness (lt = 250 mm, x0 = 90 mm, X0 = 90 mm) for concept CFM-2 and (b) solid lines show the corresponding ratios of the force without friction F′ and the force with friction F (μr1 = μr2 = 0.002) for concept CFM-1 while dashed lines show the corresponding ratios of the force without friction F′ and the force with friction F (μr = 0.002) for concept CFM-2

Grahic Jump Location
Fig. 13

CFM-2. Ratio of the force without friction F′ and the force with friction F for different brace lengths lt (F = 30 N, K = 4 N/mm, μr = 0.002, x0 = 90 mm, X0 = 90 mm).

Grahic Jump Location
Fig. 14

CFM-3. Ratio of the force without friction F′ and the force with friction F for different coefficients of rolling friction, when the spring rotates counterclockwise (continuous lines) and when the spring rotates clockwise (discontinuous lines).

Grahic Jump Location
Fig. 15

CFM-3: (a) Trajectory of the roller center for a desired constant force F of 30 N, a rolling friction value, μr, of 0.002 and different spring stiffness (r0 = 180 mm, R0 = 180 mm), and (b) the corresponding ratios of the force without friction F′ and the force with friction F for a coefficient of rolling friction μr = 0.002 along the arc length

Grahic Jump Location
Fig. 16

Roller axis trajectory and its equidistant curve that define the cam profile

Grahic Jump Location
Fig. 17

Force hysteresis loops of the three CFMs for rolling friction coefficient μr=0.002. Light color curves have been obtained for μr=0.

Grahic Jump Location
Fig. 18

Force hysteresis loops of CFM-1 for different roller-cam contact stiffness, Kc

Grahic Jump Location
Fig. 19

Force peaks due to the presence of cusps at three points in the cam surface of CFM-1, (a) for two different cusps height, and (b) for two different cams profile with the same desired constant force but different spring stiffness

Grahic Jump Location
Fig. 20

Force hysteresis loops for variations in the spring rest length (CFM-1)

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In