Abstract:In order to improve the accuracy of robot joints model,a modeling approach is proposed,in which the friction, backlash and hysteresis characteristics are included in an integrated model.The proposed model is built upon dividing a robot joint into high-speed and low-speed axes respectively.The friction model of high-/low-speed axes are set up based on the GMS(generalized Maxwell-slip) model.Preisach model is utilized to describe the linear behaviors of the high-/low-speed axes of the hysteresis model,and the polynomial method is used to describe nonlinear stiffness in the hysteresis behavior to meet the actual conditions of the reducers' nonlinearity.A simple and effective method is developed to model the backlash behavior in which the speed difference of input and output axes is regarded as the state variable.Finally,an integrated robot joint model is established and simulated in the environment of Matlab/Simulink.Simulation results show that the proposed approach reflects the nonlinear features of robot joints effectively,and thereby can be used in robot joints modeling for describing characteristics and improving accuracy.
[1] Canudas de Wit C C,Olsson H,Astrom K J,et al.A new model for control of systems with friction[J].IEEE Transactions on Automatic Control,1995,40(3):419-425.
[2] Al-Bender F,Lampaert V,Swevers J.The generalized Maxwellslip model:A novel model for friction simulation and compensation[J].IEEE Transactions on Automatic Control,2005,50(1 1):1883-1887.
[3] Astrom K J,Canudas de Wit C.Revisiting the LuGre friction model[J].IEEE Control Systems Magazine,2008,28(6):101-114.
[4] Lagerberg A,Egardt B.Backlash estimation with application to automotive powertrains[J].IEEE Transactions on Control Systems Technology,2007,15(3):483-493.
[5] Villwock S,Pacas M.Time-domain identification method for detecting mechanical backlash in electrical drives[J].IEEE Transactions on Industrial Electronics,2009,56(2):568-573.
[6] Dhaouadi R,Ghorbel F H,Gandhi P S.A new dynamic model of hysteresis in harmonic drives[J].IEEE Transactions on Industrial Electronics,2003,50(6):1165-1171.
[7] Ruderman M,Hoffmann F,Bertram T.Preisach model of non-linear transmission at low velocities in robot joints[C]//10th IEEE International Workshop on Advanced Motion Control.Piscataway,NJ,USA:IEEE,2008:721-726.
[8] Kircanski N M,Goldenberg A A,Jia S.An experimental study of nonlinear stiffness,hysteresis,and friction effects in robot joints with harmonic drives and torque sensors[J].The International Journal of Robotics Research,1997,16(2):214-239.
[9] Albu-Schaffer A,Hirzinger G.Parameter identification and passivity based joint control for a 7 DOF torque controlled light weight robot[C]//IEEE International Conference on Robotics and Automation.Piscataway,NJ,USA,IEEE,2001:2852-2858.
[10] Ruderman M,Hoffmann F,Bertram T.Modeling and identification of elastic robot joints with hysteresis and backlash[J].IEEE Transactions on Industrial Electronics,2009,56(10):3840-3847.
[11] Parlitz U,Homstein A,Engster D,et al.Identification of presliding friction dynamics[J].Chaos,2004,14(2):420-430.
[12] Mayergoyz I D.Mathematical models of hysteresis and their application[M].2nd ed.Kidlington,UK:Elsevier Science,2003:28-76.
[13] Nabtesco Precision group Europe GmbH.RV series features[EB/OLl.(2009-09)/[2010-10-07].http://www.nabtescoprecision.de:Nabtesco Precision.