Contact-free measurement of respiratory rate using infrared and vibration sensors

•A multi-modal system for respiratory rate measurement is described.•The multi-modal system consists of two PIR sensors and a vibration sensor.•An error of less than 2breathings/min is achieved for different lying positions.•Fusion of the data of different types of sensors provides a robust respiratory monitoring.•The multi-modal system is capable of detecting sleep apnea as well.