Distance measuring system and method using physically offset transducers

A mobile device, comprising:

• a chassis;
• a propulsion subsystem having an end section and configured, responsive to a control signal, to propel the chassis in a first direction;
• a first transducer disposed in the end section and configured to transmit a first sonic pulse in a first direction towards an object, to receive a first echo of the first sonic pulse from the object, and to generate a first time-of-flight value A of the first sonic pulse;
• a second transducer disposed in the end section configured to transmit a second sonic pulse in the first direction towards the object, to receive a second echo of the second sonic pulse from the object, and to generate a second time-of-flight value B of the second sonic pulse, wherein the second transducer is physically offset from the first transducer by an offset distance Δd along the first direction;
• and
• a processor including code executed therein configured to receive the first time-of-flight value A and the second time-of-flight value B, to generate a speed-of-sound value S, and to determine a distance value D of the object from at least one of the first and second transducers using the speed-of-sound value S and at least one of the first time-of-flight value A and the second time-of-flight value B, respectively,
• wherein a controller is configured to receive the distance value D, and is responsive to the distance value D to generate the control signal to control movement of a mobile device by the propulsion subsystem.

A method, comprising:

• providing a processor, a first transducer, and a second transducer physically offset from the first transducer by an offset distance Δd along a first direction;
• transmitting a first sonic pulse in the first direction towards an object using the first transducer;
• receiving a first echo of the first sonic pulse from the object at the first transducer;
• generating a first time-of-flight value A of the first sonic pulse using the first transducer;
• transmitting the first time-of-flight value A to the processor;
• transmitting a second sonic pulse in the first direction towards the object using the second transducer;
• receiving a second echo of the second sonic pulse from the object at the second transducer;
• generating a second time-of-flight value B of the second sonic pulse using the second transducer;
• transmitting the second time-of-flight value B to the processor;
• receiving the first time-of-flight value A and the second time-of-flight value B at the processor;
• generating a speed-of-sound value S from the first time-of-flight value A, the second time-of-flight value B, and the offset distance Δd;
• determining a distance value D of the object from at least one of the first and second transducers using the speed-of-sound value S and at least one of the first time-of-flight value A and the second time-of-flight value B, respectively;
• receiving the distance value D at a controller;
• responsive to the distance value D, generating a control signal using the controller;
• and
• responsive to the control signal, controlling movement of a mobile device.