The purpose of this study is to develop a safety feedback control system of a power wheelchair for the improvement of self-reliance in personal ambulation and the reduction of system errors due to operational faults. The core processor is a Texas Instrument TMS320LF2407A DSP (digital signal processor). The DSP reads the signal received from the joystick and carries out computations for the control of driving motors, both in direction and speed. An ultrasound module is used for the detection of obstacles in the rear side for safety. Optical encoders generate feedback signals in order to compensate the speed of the two motors by a PD control algorithm, which makes the speed of the power wheelchair independent of the weight load. This system is designed according to M3S (Multiple Master Multiple Slave) standards for a straightforward integration of additional modules and better expansion of a power wheelchair system.