Reducing the undesirable effects of joints clearance on the behavior of the planar 3-RRR parallel manipulators

Clearance imposes some uncontrollable degrees of freedom to a manipulator. Therefore, poor dynamic performance, low accuracy, reduction in components lifetime and generation of undesirable vibrations result in the impacts of mating parts in a clearance joint. In this study, the effects of clearance on the dynamics of a planar 3-RRR parallel manipulator are investigated. Then, an optimization algorithm for simultaneously kinematic and dynamic synthesis has been carried out to reduce these effects and improve the performance and the accuracy of the manipulator. The algorithm is based on changing the lengths and the mass distribution of the links. By combining the Lagrange equations with Lankarani–Nikravesh contact force model, a series of dynamic equations are established. Then, the highly nonlinear optimization problem is tackled via a PSO method. The last but not the least, the efficiency of the algorithm and its superiority have been demonstrated by a numerical example. We claim that the linear and angular accelerations of the links and the contact forces in the joints are bounded and evolve very smoothly in the optimal design. Finally, to verify the validity of the optimization algorithm, the planar 3-RRR parallel manipulator is modeled in MSC.ADAMS software and the simulation results are compared for the original and the optimal manipulators.

[1]  S. Rahmanian,et al.  Bifurcation in planar slider–crank mechanism with revolute clearance joint , 2015 .

[2]  Hamid M. Daniali,et al.  Pick and place trajectory planning of planar 3-RRR parallel manipulator in the presence of joint clearance , 2017, Robotica.

[3]  N. Morita,et al.  A New Optimization Method for Dynamic Design of Planar Linkage With Clearances at Joints—Optimizing the Mass Distribution of Links to Reduce the Change of Joint Forces , 2002 .

[4]  Sukhan Lee,et al.  Statistical representation and computation of tolerance and clearance for assemblability evaluation , 1998, Robotica.

[5]  Ming-June Tsai,et al.  Kinematic sensitivity analysis of linkage with joint clearance based on transmission quality , 2004 .

[6]  S. M. Varedi,et al.  Optimal dynamic design of a planar slider-crank mechanism with a joint clearance , 2015 .

[7]  C. Liu,et al.  ElastoHydroDynamic lubricated cylindrical joints for rigid-flexible multibody dynamics , 2013 .

[8]  Ming-June Tsai,et al.  Accuracy analysis of a multi-loop linkage with joint clearances , 2008 .

[9]  Jorge Ambrósio,et al.  A study on dynamics of mechanical systems including joints with clearance and lubrication , 2006 .

[10]  Jun Wu,et al.  Dynamic load-carrying capacity of a novel redundantly actuated parallel conveyor , 2014 .

[11]  Jun Wu,et al.  Dynamics and control of a planar 3-DOF parallel manipulator with actuation redundancy , 2009 .

[12]  Selçuk Erkaya,et al.  A neural–genetic (NN–GA) approach for optimising mechanisms having joints with clearance , 2008 .

[13]  Jorge Ambrósio,et al.  Impact of Rigid and Flexible Multibody Systems: Deformation Description and Contact Models , 2003 .

[14]  Romdhane Lotfi,et al.  Analytical modeling and analysis of the clearance induced orientation error of the RAF translational parallel manipulator , 2016, Robotica.

[15]  S. M. Varedi,et al.  Dynamic synthesis of a planar slider–crank mechanism with clearances , 2015 .

[16]  Hamid M. Daniali,et al.  The effects of joint clearance on the dynamics of the 3RRR planar parallel manipulator , 2017, Robotica.

[17]  Jun Wu,et al.  A Control Strategy of a Two Degrees-of-Freedom Heavy Duty Parallel Manipulator , 2015 .

[18]  Brian Birge,et al.  PSOt - a particle swarm optimization toolbox for use with Matlab , 2003, Proceedings of the 2003 IEEE Swarm Intelligence Symposium. SIS'03 (Cat. No.03EX706).

[19]  H. P. Jawale,et al.  Investigation of Positional Error in Two Degree of Freedom Mechanism With Joint Clearance , 2012 .

[20]  Christoph Glocker,et al.  Modeling and analysis of rigid multibody systems with translational clearance joints based on the nonsmooth dynamics approach , 2010 .

[21]  Selçuk Erkaya,et al.  Investigation on effect of joint clearance on dynamics of four-bar mechanism , 2009 .

[22]  S. M. Varedi,et al.  Optimal free-defect synthesis of four-bar linkage with joint clearance using PSO algorithm , 2013 .

[23]  Jorge Ambrósio,et al.  Revolute joints with clearance in multibody systems , 2004 .

[24]  Hamid M. Lankarani,et al.  A Contact Force Model With Hysteresis Damping for Impact Analysis of Multibody Systems , 1989 .

[25]  Alireza Fathi,et al.  A novel algorithm for kinematic and dynamic optimal synthesis of planar four-bar mechanisms with joint clearance , 2015 .

[26]  Jun Wu,et al.  Stiffness and natural frequency of a 3-DOF parallel manipulator with consideration of additional leg candidates , 2013, Robotics Auton. Syst..

[27]  Oscar Altuzarra,et al.  Workspace analysis of positioning discontinuities due to clearances in parallel manipulators , 2011 .

[28]  Vincenzo Parenti-Castelli,et al.  Clearance influence analysis on mechanisms , 2005 .

[29]  Arend L. Schwab,et al.  A comparison of revolute joint clearance models in the dynamic analysis of rigid and elastic mechanical systems , 2002 .

[30]  Jean-Pierre Merlet,et al.  Parallel Robots , 2000 .

[31]  Yang Zhao,et al.  Dynamic behaviour analysis of planar mechanical systems with clearance in revolute joints using a new hybrid contact force model , 2012 .

[32]  Xu Li-Xin,et al.  Investigation of joint clearance effects on the dynamic performance of a planar 2-DOF pick-and-place parallel manipulator , 2014 .