One-Piece Gravity Compensation Mechanism Using Cam Mechanism and Compression Spring

  • Giuk Lee
  • Donggun Lee
  • Yonghwan OhEmail author
Regular Paper


In this paper, we propose a one-piece gravity compensation mechanism (OGCM), which improves energy efficiency by compensating for the gravity torque of the target structure using a combination of a cam mechanism and a compression spring. First, the gravity compensation methodology of the OGCM is explained. Next, an analysis of how to design cam mechanisms as a function of the design variables of other mechanical parts is presented. Finally, the gravity compensation performance of the OGCM is verified through experiments by comparing the designed and actual gravity compensation torques. In addition, we simply evaluate the gravity compensation performance of the OGCM visually by testing it on an actual target structure. Both the verification tests show that the OGCM provides decent performance as a gravity compensation mechanism. The proposed OGCM has many advantages. Because it can be constructed as an independent one-piece structure, it can be easily installed on the target platform without many modifications. Moreover, because of its compactness, the size and inertia of the target platform do not increase considerably after installation. The OGCM can also be operated in the entire 360° range, so it does not interfere with the existing workspace of the target platform after installation. Because of these advantages, the OGCM can be used effectively on a variety of platforms and structures.


Gravity compensation Counterbalancing Cam mechanism Compression spring 



Degree of freedom


Center of mass


Center of rotation


Weight of target structure


Distance between CoR and CoM of target structure


Rotation angle of target structure from horizontal basement


Total length of compression spring


Length of compression spring between CoR of one-piece gravity compensation mechanism (OGCM) and fixed end at stator


Length of compression spring between CoR of OGCM and fixed end at cam follower


Radius of cam follower


Stiffness of compression spring


Gravitational potential energy of target structure


Elastic potential energy of OGCM


Sum of total potential energy of Vtarget and VOGCM


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Alling, E. D., “Improvement in Dental Brackets,” US Patent, 218210A, 1879.Google Scholar
  2. 2.
    Lu, Q., Ortega, C., and Ma, O., “Passive Gravity Compensation Mechanisms: Technologies and Applications,” Recent Patents on Engineering, vol. 5, no. 1, pp. 32–44, 2011.CrossRefGoogle Scholar
  3. 3.
    Fattah, A. and Agrawal, S. K., “Gravity-Balancing of Classes of Industrial Robots,” Proc. of IEEE International Conference on Robotics and Automation, pp. 2872–2877, 2006.Google Scholar
  4. 4.
    Moon, Y. and Banks, S. A., “Experimental Study on Stand-Alone Assistive Suspension System to Reduce Load on Small Robot Manipulating Heavy Payload,” International Journal of Precision Engineering and Manufacturing, vol. 16, no. 3, pp. 451–457, 2015.CrossRefGoogle Scholar
  5. 5.
    Kim, B. and Deshpande, A. D., “Design of Nonlinear Rotational Stiffness Using a Noncircular Pulley-Spring Mechanism,” Journal of Mechanisms and Robotics, Vol. 6, No. 4, Paper No. 041009, 2014.Google Scholar
  6. 6.
    Lin, P.-Y., Shieh, W.-B., and Chen, D.-Z., “A Theoretical Study of Weight-Balanced Mechanisms for Design of Spring Assistive Mobile Arm Support (MAS),” Mechanism and Machine Theory, vol. 61, pp. 156–167, 2013.CrossRefGoogle Scholar
  7. 7.
    Agrawal, S. K. and Fattah, A., “Theory and Design of an Orthotic Device for Full or Partial Gravity-Balancing of a Human Leg during Motion,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 12, no. 2, pp. 157–165, 2004.CrossRefGoogle Scholar
  8. 8.
    Wyrobek, K. A., Berger, E. H., Van der Loos, H., and Salisbury, J. K., “Towards a Personal Robotics Development Platform: Rationale and Design of an Intrinsically Safe Personal Robot,” Proc. of the IEEE International Conference on Robotics and Automation, pp. 2165–2170, 2008.Google Scholar
  9. 9.
    Lenzo, B., Fontana, M., Marcheschi, S., Salsedo, F., Frisoli, A., et al., “Trackhold: A Novel Passive Arm-Support Device,” Journal of Mechanisms and Robotics, Vol. 8, No. 2, Paper No. 021007, 2016.Google Scholar
  10. 10.
    Agrawal, A. and Agrawal, S. K., “Design of Gravity Balancing Leg Orthosis Using Non-Zero Free Length Springs,” Mechanism and Machine Theory, vol. 40, no. 6, pp. 693–709, 2005.CrossRefzbMATHGoogle Scholar
  11. 11.
    Rahman, T., Ramanathan, R., Seliktar, R., and Harwin, W., “A Simple Technique to Passively Gravity-Balance Articulated Mechanisms,” Journal of Mechanical Design, vol. 117, no. 4, pp. 655–657, 1995.CrossRefGoogle Scholar
  12. 12.
    Deepak, S. R. and Ananthasuresh, G., “Perfect Static Balance of Linkages by Addition of Springs but Not Auxiliary Bodies,” Journal of Mechanisms and Robotics, Vol. 4, No. 2, Paper No. 021014, 2012.Google Scholar
  13. 13.
    Lenzo, B., Zanotto, D., Vashista, V., Frisoli, A., and Agrawal, S., “A New Constant Pushing Force Device for Human Walking Analysis,” Proc. of the IEEE International Conference on Robotics and Automation, pp. 6174–6179, 2014.Google Scholar
  14. 14.
    Wongratanaphisan, T. and Chew, M., “Gravity Compensation of Spatial Two-DoF Serial Manipulators,” Journal of Robotic Systems, vol. 19, no. 7, pp. 329–347, 2002.CrossRefzbMATHGoogle Scholar
  15. 15.
    Baradat, C., Arakelian, V., Briot, S., and Guegan, S., “Design and Prototyping of a New Balancing Mechanism for Spatial Parallel Manipulators,” Journal of Mechanical Design, Vol. 130, No. 7, Paper No. 072305, 2008.Google Scholar
  16. 16.
    Lin, P.-Y., Shieh, W.-B., and Chen, D.-Z., “Design of a Gravity-Balanced General Spatial Serial-Type Manipulator,” Journal of Mechanisms and Robotics, Vol. 2, No. 3, Paper No. 031003, 2010.Google Scholar
  17. 17.
    Kim, H.-S. and Song, J.-B., “Multi-DoF Counterbalance Mechanism for a Service Robot Arm,” IEEE/ASME Transactions on Mechatronics, vol. 19, no. 6, pp. 1756–1763, 2014.CrossRefGoogle Scholar
  18. 18.
    Cho, C. and Kang, S., “Design of a Static Balancing Mechanism for a Serial Manipulator with an Unconstrained Joint Space Using One-DoF Gravity Compensators,” IEEE Transactions on Robotics, vol. 30, no. 2, pp. 421–431, 2014.CrossRefGoogle Scholar
  19. 19.
    Cho, C. H., Lee, W. S., and Kang, S. C., “Design of a Static Balancer with Space Mapping,” International Journal of Precision Engineering and Manufacturing, vol. 14, no. 1, pp. 61–68, 2013.CrossRefGoogle Scholar
  20. 20.
    Endo, G., Yamada, H., Yajima, A., Ogata, M., and Hirose, S., “A Passive Weight Compensation Mechanism with a Non-Circular Pulley and a Spring,” Proc. of the IEEE International Conference on Robotics and Automation, pp. 3843–3848, 2010.Google Scholar
  21. 21.
    Koser, K., “A Cam Mechanism for Gravity-Balancing,” Mechanics Research Communications, vol. 36, no. 4, pp. 523–530, 2009.CrossRefzbMATHGoogle Scholar

Copyright information

© Korean Society for Precision Engineering 2018

Authors and Affiliations

  1. 1.Mechanical Engineering DepartmentChung-Ang UniversitySeoulRepublic of Korea
  2. 2.Center for Robotics ResearchKorea Institute of Science and Technology, 5SeoulRepublic of Korea
  3. 3.Mechanical Engineering DepartmentUniversity of CaliforniaBerkeleyUSA

Personalised recommendations