Distance measurement and control using coded sonic signals
US5155983A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1991 |
| Grant date | Oct 20, 1992 |
| Priority date | — |
| Expiry date | Apr 24, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S56/15
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An agricultural harvesting machine having a cutting element movably supported thereon is provided with a height sensor including a transmitter and a receiver mounted for movement with the cutting element. The transmitter directs bursts of sound waves in the range of about 5 KHz toward the ground and echoes of the bursts are picked up by the receiver, the elapsed time between transmission and reception being an indication of the height of the cutting element above the ground. To distinguish between echoes of the bursts and environmental noise picked up by the receiver, the bursts are encoded by transmitting them in pairs, the bursts of a pair being of fixed duration and separated by a fixed interval of time. The duration of each signal and the time spacing between signals is checked and if they are not of the correct duration or are not separated by the fixed interval of time they are rejected as noise. The time between transmission and reception of a burst is measured to provide an indication of the height of the cutting element. The measured height is compared with a reference or desired height and the difference value is used to control movement of the cutting element to the desi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.