Abstract: A dual encoder system includes first and second encoders on a single printed circuit board mounted on an electric motor. Each encoder independently generates feedback information used by motor and safety controllers for controlling the motor. A single magnet is mounted on the motor shaft. The first encoder cooperates with the magnet to provide first encoder information to the motor controller regarding magnetic alignment between a rotor and a plurality of stator windings of the motor and regarding real-time position and velocity. The second encoder cooperates with the same magnet to provide second encoder information to a safety controller, wherein the second encoder information should be identical to the first. The safety controller may receive the first encoder information from the motor controller, compare the second encoder information to the first encoder information, and brake the electric motor if the second encoder information is different from the first encoder information.

Abstract: A safety switching system and method for braking an electric motor in a mobile device. A multi-phase shorting system brakes the motor by diverting power from the motor windings. Multiple independent switching units each include a switch control unit controlling multiple normally-closed switches which, in response to a safety controller, close to connect a respective motor winding to electrical ground. An electromechanical brake system mechanically brakes the motor. An independent switching unit includes two normally-open switches which, in response to the safety controller, opens to activate an electromechanical brake. A feedback system communicates to the safety controller a switch failure of any of the switches either as a short circuit fault or an open circuit fault. The feedback system may include an analog and/or a digital feedback system. If a switch failure is detected, the safety controller may activate the multi-phase shorting system and the electromechanical brake system.

Abstract: A dual encoder system includes first and second encoders on a single printed circuit board mounted on an electric motor. Each encoder independently generates feedback information used by motor and safety controllers for controlling the motor. A single magnet is mounted on the motor shaft. The first encoder cooperates with the magnet to provide first encoder information to the motor controller regarding magnetic alignment between a rotor and a plurality of stator windings of the motor and regarding real-time position and velocity. The second encoder cooperates with the same magnet to provide second encoder information to a safety controller, wherein the second encoder information should be identical to the first. The safety controller may receive the first encoder information from the motor controller, compare the second encoder information to the first encoder information, and brake the electric motor if the second encoder information is different from the first encoder information.

Abstract: A safety switching system and method for braking an electric motor in a mobile device. A multi-phase shorting system brakes the motor by diverting power from the motor windings. Multiple independent switching units each include a switch control unit controlling multiple normally-closed switches which, in response to a safety controller, close to connect a respective motor winding to electrical ground. An electromechanical brake system mechanically brakes the motor. An independent switching unit includes two normally-open switches which, in response to the safety controller, opens to activate an electromechanical brake. A feedback system communicates to the safety controller a switch failure of any of the switches either as a short circuit fault or an open circuit fault. The feedback system may include an analog and/or a digital feedback system. If a switch failure is detected, the safety controller may activate the multi-phase shorting system and the electromechanical brake system.