Adaptive gravity compensation of decoupled parallel and serial manipulators using a passive hydraulic transmission

Abstract

This article addresses the gravity compensation of decoupled or partially decoupled parallel and serial manipulators. The proposed technique applies to manipulators in which the vertical motion is decoupled from other Cartesian degrees of freedom (DOFs). In the latter situation, only one DOF needs to be gravity compensated in order to eliminate actuator torques due to the weight of the moving parts. First, a passive hydraulic transmission consisting of two cylinders connected by hoses is introduced in order to perform gravity compensation using a remote counterweight (CW) affecting only the inertia of the equilibrated DOF. A complete system is then shown using a set of CWs, cylinders, and valves allowing to adapt rapidly and effectively to a variety of payloads. Finally, two experimental implementations using, respectively, hydraulic and pneumatic cylinders filled with water are presented and the practical limitations of the approach are discussed.

Keywords

gravity compensation hydraulic transmission counterweights decoupled manipulator static balancing

Get full access to this article

View all access options for this article.

References

Herder

, Energy-free systems. Theory, conception and design of statically balanced spring mechanisms. PhD Thesis, Delft University of Technology, Delft, The Netherlands, 2001).

French

M. J.

Widden

M. B.

, The spring-and-lever balancing mechanism, George Carwardine and the Anglepoise lamp. Proc. IMechE, Part C: J. Mechanical Engineering Science, 2000, 214(C3), 501–508. DOI: 10.1243/0954406001523137.

van Dorsser

W. D.

Barents

Wisse

B. M.

Herder

J. L.

, Energy-free adjustment of gravity equilibrators, with application in a mobile arm support. In Proceedings of the ASME 2006 International Design Engineering Technical Conference, Philadelphia, PA, paper number: DETC2006-99745, 10–13 September, Philadelphia, PA 2006.

Rahman

Ramanathan

Seliktar

Harwin

, A simple technique to passively gravity-balance articulated mechanisms. J. Mech. Des., 1995, 117(4), 655–658.

Wisse

B. M.

van Dorsser

W. D.

Barents

Herder

J. L.

, Energy-free adjustment of gravity equilibrators using the virtual spring concept. In Proceedings of the IEEE 10th International Conference on Rehabilitation robotics 2007, ICORR 2007, pp. 742–750.

Laliberte

Gosselin

C. M.

Jean

, Static balancing of 3-DOF planar parallel mechanisms. IEEE/ASME Trans. Mechatronics, 1999, 4(4), 363–377.

Russo

Sinatra

, Static balancing of parallel robots. Mech. Mach. Theory, 2005, 40(2), 191–202.

Wyrobek

K. A.

Berger

E. H.

Van der Loos

H. F. M.

Salisbury

J. K.

, Towards a personal robotics development platform: Rationale and design of an intrinsically safe personal robot. In Proceedings of the IEEE International Conference on Robotics and automation, ICRA 2008, Pasadena, CA, 19–23 May 2008.

Tremblay

Gosselin

C. M.

, Static balancing with a Torsional Elastic Bar. In Proceedings of CCToMM Symposium on Mechanisms, machines, and mechatronics, Montreal, Quebec, Canada, 2007.

10.

Fattah

Agrawal

S. K.

Catlin

Hamnett

, Design of a passive gravity-balanced assistive device for sit-to-stand tasks. J. Mech. Des., 2006, 128(5), 1122–1129.

11.

Gosselin

Wang

, Static balancing of spatial six-degree-of-freedom parallel mechanisms with revolute actuators. J. Robot. Syst., 2000, 17(3), 159–170.

12.

Kong

Gosselin

, Type synthesis of parallel mechanisms. Tracts in advanced robotics, vol. 33, 2007 (Springer).

13.

Foucault

Gosselin

Kong

Bonev

, A fully decoupled 3-DOF translational parallel mechanism. In Proceedings of the 4th Chemnitz Parallel Kinematics Seminar/2004 Parallel Kinematic Machines International Conference, 2004, pp. 595–610.

14.

Gosselin

Richard

P.-L.

Kong

, Kinematic analysis and prototyping of a partially decoupled 4-DOF 3tlr parallel manipulator. ASME J. Mech. Des., 2007, 129(6), 611–616.

15.

Tremblay

, Equilibrage statique adaptatif d'un manipulateur sériel à 4 degrés de liberté. Master's Thesis, Université Laval, 2008.

16.

Lakkonen

Koskinen

K. T.

Vilenius

, Lowpressure water hydraulics makes its move. Hydraul. Pneum., 2005, 58(3), 40–42.

17.

Krutz

G. W.

Chua

P. S.

, Water hydraulics–-theory and applications 2004’. In Proceedings of the Workshop on Water Hydraulics, Agricultural Equipment Technology Conference (AETC'04), Louisville, Kentucky, pp. 1–33, 2004.