Time Delay Sliding Mode Control of nonholonomic wheeled mobile robot: Experimental validation

In this endeavor, a hybrid control strategy has been proposed for composite path tracking control of a nonholonomic wheeled mobile robotic (WMR) system under parametric and nonparametric uncertainties. A WMR, often in practical circumstances, undergoes through various parametric changes. Moreover, modeling of WMR in presence of friction, slip or skid, backlash etc. is very difficult. These factors, which make the system model more cumbersome, are normally ignored but their effects are compensated through appropriate control methods. Conventional Sliding Mode Control (SMC) is such a method but it is susceptible to chattering due to high switching gains and reasonable tracking accuracy is sacrificed to avoid chattering. On the other hand, Time Delay Control (TDC) technique is highly efficient to assure robustness against unknown dynamics but it is unable to eliminate approximation errors that arise due to introduced delay. Considering the aforesaid difficulties of SM and TD controllers a hybrid control methodology christened as Time Delay Sliding Mode Control (SMC-TD) is adopted in this work for accurate path tracking of nonholonomic WMR. The SMC-TD is absolutely a judicious blending of SMC and TDC strategies aiming at elimination of the individual shortcomings while retaining the positive advantages. Detail features and advantages of the proposed controller are presented in greater length along with the experimental results, which are very promising.