Vehicle-ground surface measurement system

• US 5,621,413 A
• Filed: 06/29/1995
• Issued: 04/15/1997
• Est. Priority Date: 06/27/1995
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Kitchen, W. J., Lempkowski, Robert B., Ghaem, Sanjar
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/496,512
• Time in Patent Office: 656 Days
• Field of Search: 342/117, 342/188, 342/106, 342/107, 342/109, 342/113, 342/114, 342/115, 342/116
• US Class Current: 342/117
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/60 wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track G01S13/64 takes precedence
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195

Abstract

A measurement device (103) and method determines various metrics between a vehicle (101) and a ground surface (105) using a transmitter-antenna (109) for emitting energy including a portion directed down toward the ground surface. A receiving antenna (115), has a portion oriented facing toward the transmitter-antenna for receiving a portion of the emitting energy along a direct path (117), and a portion oriented facing downwardly toward the ground surface for receiving a portion of the emitting energy reflected from the ground surface along a reflected path (113). A decoder provides separate indications of forward (121) and sideward (123) velocity relative to motion of the vehicle along the ground surface. Furthermore, the decoder comprises means for determining vehicle height (125) dependent on a measured difference in path length, vehicle level (127), or front to rear tilt angle, dependent on polarization elliptical ratio changes, and road surface conditions (129) dependent on amplitude and phase changes that occur versus time.

Claims

1. A device for measurement between a vehicle and a ground surface comprising:

a transmitter-antenna for emitting energy toward the ground surface in a first polarization and a second polarization;

a receiving antenna oriented facing toward the ground surface for receiving energy reflected from the ground surface along a reflected path in both the first and second polarizations, the receiving antenna providing phase and amplitude signals corresponding to energy received along the reflected path for each of the first and second polarizations; and

a decoder for providing separate indications of forward and sideward velocity of the vehicle relative to the ground surface dependent on the provided phase and amplitude signals for each of the first and second polarizations.

2. A device in accordance with claim 1 wherein the second polarization is oriented orthogonally to the first polarization.

3. A device in accordance with claim 1 wherein the decoder further comprises means for determining a vehicle front to rear tilt angle dependent on changes in a polarization elliptical ratio of the phase and amplitude signals received by the receiving antenna.

4. A device in accordance with claim 1 wherein the decoder further comprises means for determining road surface conditions dependent on amplitude and phase changes of the phase and amplitude signals received by the receiving antenna that occur over time.

5. A device in accordance with claim 1 wherein the transmitter-antenna has a structure for emitting energy directly toward the receiving antenna and the receiving antenna has a portion oriented to receive the energy emitted directly from the transmitter-antenna along a direct path, and wherein the decoder further comprises means for indicating a height difference between the vehicle and the ground surface dependent on a measured difference in path length between the direct path and the reflected path.

6. A device in accordance with claim 5 wherein the decoder comprises:

a quadrature receiver for producing separate in-phase and quadrature signal channels;

a phase detector for providing a signal representative of a phase difference between the portion of the emitting energy along the direct path and portion of the emitting energy reflected from the ground surface along the reflected path; and

a Doppler detector connected to the phase detector to measure difference frequencies generated by a difference in path length between the direct and reflected signal paths.

7. A device for measurement between a vehicle and a ground surface comprising:

a transmitter-antenna for emitting energy directed down toward the ground surface and in a second direction, wherein the energy has a first polarization and a second polarization oriented orthogonally to the first polarization;

a receiving antenna, having a portion oriented facing opposing the second direction for receiving a portion of the emitting energy along a direct path, and a portion oriented facing downwardly toward the ground surface for receiving a portion of the emitting energy reflected from the ground surface along a reflected path, the receiving antenna providing phase and amplitude signals corresponding to energy received along the reflected path for each of the first and second polarizations; and

a decoder for providing separate indications of forward and sideward velocity relative to motion of the vehicle along the ground surface dependent on the provided phase and amplitude signals for each of the first and second polarizations, and an indication of height between the vehicle and the ground surface dependent on a measured difference in path length between the direct path and the reflected path.

8. A device in accordance with claim 7 wherein the decoder further comprises means for determining a vehicle front to rear tilt angle dependent on changes in a polarization elliptical ratio of the phase and amplitude signals received by the receiving antenna.

9. A device in accordance with claim 7 wherein the decoder further comprises means for determining road surface conditions dependent on amplitude and phase changes of the phase and amplitude signals received by the receiving antenna that occur over time.

10. A device for measurement between a vehicle and a ground surface comprising:

a transmitter-antenna for emitting energy directed down toward the ground surface and in a second direction, wherein the energy has a first polarization and a second polarization oriented orthogonally to the first polarization;

a receiving antenna having a first polarization, and a second polarization orthogonally oriented to the first polarization, wherein the receiving antenna is oriented to receive a portion of the energy emitted from the transmitter-antenna directed parallel to the ground surface along a direct path, and a portion of the energy emitted from the transmitter-antenna reflected off the ground surface along a reflected path, and wherein the receiving antenna provides a forward Doppler signal corresponding to the direct and reflected signals received by the portion of the receiving antenna oriented with the first polarization, and provides a lateral Doppler signal corresponding to the direct and reflected signal received by the portion of the receiving antenna oriented with the second polarization; and

a decoder for providing separate indications of forward and sideward velocity relative to motion of the vehicle along the ground surface dependent on the received forward and (sideward)lateral Doppler signals.

11. A device in accordance with claim 10 wherein the receiving antenna generates a direct path length signal, dependent on a physical distance between the transmitter-antenna and the receiving antenna along the direct path, and a reflected path length signal, dependent on a physical distance between the transmitter-antenna and the receiving antenna along the reflected path;

and

the decoder provides an indication of height between the vehicle and the ground surface dependent on a measured difference in path length between the direct path and the reflected path in accordance with a first polarization.

12. A device in accordance with claim 11 wherein the decoder further comprises means for determining a vehicle front to rear tilt angle dependent on changes in a polarization elliptical ratio of phase and amplitude signals received by the receiving antenna.

13. A device in accordance with claim 12 wherein the decoder further comprises means for determining road surface conditions dependent on amplitude and phase changes of signals sensed by the receiving antenna that occur over time.

14. A method for measurement between a vehicle and a ground surface comprising the steps of:

emitting energy toward the ground surface in a first polarization and a second polarization;

receiving energy reflected from the ground surface along a reflected path in both the first and second polarizations and providing phase and amplitude signals corresponding to energy received along the reflected path for each of the first and second polarizations; and

providing separate indications of forward and sideward velocity of the vehicle relative to the ground surface dependent on the provided phase and amplitude signals for each of the first and second polarizations.

15. A method in accordance with claim 14 wherein the step of providing separate indications of forward and sideward velocity further comprises a step of determining a vehicle front to rear tilt angle dependent on changes in a polarization elliptical ratio of the phase and amplitude signals received in the step of receiving energy reflected from the ground surface.

16. A method in accordance with claim 14 the step of providing separate indications of forward and sideward velocity further comprises a step of determining road surface conditions dependent on amplitude and phase changes of the phase and amplitude signals received in the step of receiving energy reflected from the ground surface.

17. A method in accordance with claim 14 further comprising the steps of:

emitting energy directly toward a receiving antenna;

receiving the energy emitted directly toward the receiving antenna along a direct path; and

indicating a height difference between the vehicle and the ground surface dependent on a measured difference in path length between the direct path and the reflected path.