Abstract: An improved transducer for a proximity sensing system using a sonar transmitter is disclosed. An autonomous device provided with a number of motor-driven wheels further comprises a number of elements for the proximity navigation and guiding of the device such as a microprocessor system and a proximity ultrasonic sensing system comprising at least one transmitting member and one receiving member. The transmitting member is formed by the ultrasound transducer (11), which is positioned behind a wire mesh at the front of the device. The device transmits ultrasonic waves from a first strip-shaped device (21) with a narrow vertical distribution within a wide horizontal sector, and a second strip-shaped device (22) providing a wider vertical distribution within a similarly wide horizontal sector in front of the autonomous device.