Mobile robots are used in many critical tasks. In such tasks, it is of great importance to tolerate the faults that the robot may encounter during the operation in order to complete the task successfully. This dissertation focuses on tolerating the faults that occur in the hardware of the mobile robots. To tolerate these faults, it is necessary to be prepared for the faults that the robot may encounter during the operation and to determine an appropriate fault toleration strategy. The mobile robot considered in this dissertation has holonomic motion ability in the plane thanks to its omnidirectional wheels. The types of faults focused on are the slippage of one of the wheels of this mobile robot and the performance degradation in the motor that actuates one of the wheels. To tolerate these two faults, an active fault tolerant control method is developed. A model-based fault diagnosis algorithm is developed for fault diagnosis algorithm, which is one of the two main parts of active fault tolerant control. To obtain the dynamic model of the mobile robot that is used in this algorithm, firstly, the friction between the wheel and the ground used is modeled. The parameters of the friction model are identified via the developed test setup. As a result of the tests performed for fault diagnosis, it is seen that these two types of faults occurring in the holonomic mobile robot can be diagnosed with developed fault diagnosis algorithm. In order to tolerate these faults, two different fault recovery algorithms which make use of kinematic redundancy of the mobile robot are developed, and the developed algorithms are tested. As a result of the fault recovery tests performed for the motor performance degradation, it is observed that the motion performance of the mobile robot improved despite the presence of the fault. Thanks to the developed recovery algorithm in the recovery tests for wheel slippage, it is observed that there is a significant decrease in the amount of slippage occurring on the faulty wheel and accordingly the mobile robot performs the desired motion more accurately.