Sensor fusion of motion data obtained from portable electronic devices

A portable electronic device, comprising:

• at least first and second inertial sensors for sensing motion of the device;
• one or more processors for executing computer-executable instructions;
• and
• one or more computer-readable storage media for storing the machine-executable instructions, the instructions when executed by the one more processors implementing processing logic that, based on motion data derived from the first inertial sensor in response to physical movement of the electronic device, is capable of tracking an orientation of the device, said tracked orientation having an error associated therewith such that the processing logic periodically reduces the error using a feedback control signal of a PID control process based on additional motion data obtained from the second inertial sensor, wherein, if said processing logic determines that the rotational motion data obtained from the first inertial sensor is invalid or unavailable while tracking the orientation of the device, the processing logic is capable of suppressing an integral function and causing a proportional function of the PID control process to increase its response rate until the rotational motion data is again available and valid.