In this paper, different approaches for friction estimation and compensation in an inverted pendulum are compared. The Coulomb, static, and viscous frictions are estimated using data only from a closed-loop operation. A control law using linear state feedback is designed to stabilize the pendulum, but limit cycles appear due to friction. Methods based on fitting an ellipse to the input-output plot and using least squares with the Karnopp friction model are employed to estimate the friction parameters to be used with the frictionmodels considered. The values are then compared to those obtained in open-loop tests, obtained via application of a ramp of current to the motor of the cart. Friction compensation is carried out using the friction values in two strategies:model based compensation using theKarnopp and LuGre friction models and non-model based compensation using the knocker and constant reinforcement techniques. While model-based methods use the sign of the velocity to change the sign of the compensation, the non-model- based methods use the sign of the control signal for this decision, with an anticipatory action. Both strategies are compared through their application to a simulation model and to a real inverted pendulum, using the IAE and variance of position and angle for performance measurement. This comparison and the analysis about the difficulty for estimating the parameters to be used for each compensation indicate the best scheme for estimation and compensation method to be used for this benchmark. © Brazilian Society for Automatics-SBA 2013.246794805Campbell, S.A., Crawfoord, S., Morris, K., Friction and the inverted pendulum (2008) Journal of Dynamic Systems, Measurement and Control, 130, pp. 54502-54509Choudhury, M.A.A.S., Shah, S.L., Thornhill, N.F., Shook, D.S., Automatic detection and quantification of stiction in control valves (2006) Control Engineering Practice, 14, pp. 1395-1412Cuadros, M.A.S.L., Munaro, C.J., Munareto, S., An improved algorithm for automatic quantification of valve stiction in flow control loops (2010) Proceedings of the IEEE International Conference on Industrial Technology, pp. 135-140Cuadros, M.A.S.L., Munaro, C.J., Munareto, S., A novel model free approach for stiction compensation in control valves (2012) Industrial and EngineeringChemistry Research, 51 (25), pp. 8465-8476De Wit, C.C., Olsson, H., Aström, K.J., A new model of control of systems with friction (1995) IEEE Transactions on Automatic Control, 40 (3), pp. 419-425Fang, L., Chen, W.J., Cheang, S.U., Friction compensation for a double inverted pendulum (2001) IEEE International Conference on Control Applications, 5 (7), pp. 908-913Garcia, C., Comparison of friction models applied to a control valve (2008) Control Engineering Practice, 31 (78), pp. 1231-1243Gäfvert, M., Dynamicmodel based friction compensation on the furuta pendulum (1999) IEEE International Conference on Control Applications, 22 (27), pp. 1260-1265Hägglund, T., A friction compensator for pneumatic control valves (2002) Journal of Process Control, 12, pp. 897-904Hägglund, T., Automatic on-line estimation of backlash in control loops (2007) Journal of Process Control, 17, pp. 489-499Ivan, L.Z.X., Lakshminarayanan, S.A., A new approach to valve stiction quantification and compensation (2009) Industrial & Engineering Chemistry Research, 48, pp. 3474-3483Olsson, H., (1996) Control Systems with Friction, , PhD Thesis, Lund Institute of Technology, LundOlsson, H., Aström, K.J., Friction models and friction compensation (1998) European Journal of Control, 3 (4), pp. 176-195Olsson, H., Aström, K.J., Friction generated limit cycles (2001) IEEE Transactions on Control Systems Technology, 9 (4), pp. 629-636Park, D., Chwa, D., Hong, S.K., An estimation and compensation of the friction in an inverted pendulum (2006) SICE-ICASE International Joint Conference, 18 (21), pp. 779-783Ravanbod-Shirazi, L., Besançon-Voda, A., Robust friction compensation based on Karnopp model (2001) Proceedings of the European Control Conference, pp. 2558-2563Romano, R.A., Garcia, C., Karnopp friction model identification for a real control valve (2008) Proceedings of the 17th World Congress the International Federation O Automatic ControlRomano, R.A., Garcia, C., Valve friction and nonlinear process model closed-loop identification (2011) Journal of Process Control, 21, pp. 667-677Srinivasan, R., Rengaswamy, R., Stiction compensation in process control loops: A framework for integrating stiction measure and compensation (2005) Industrial & Engineering Chemistry Research, 44, pp. 9164-9174Thornhill, N.F., Huang, B., Zhang, H., Detection of multiple oscillations in control loops (2003) Journal of Process Control, 13, pp. 91-100Vidyasagar, M., (2002) Nonlinear Systems Analysis, , Philadelphia, PA, USA: Society for Industrial and Applied Mathematics