Velocity detection, position detection and navigation system

• US 20070067137A1
• Filed: 08/28/2006
• Published: 03/22/2007
• Est. Priority Date: 09/06/2005
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takaoka, Tomohisa, Ohkubo, Masashi
• Granted Patent: US 7,505,865 B2
• Time in Patent Office: Days
• US Class Current: 702/142
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01P 3/62 Devices characterised by the determination or the variation of atmospheric pressure with height to measure the vertical components of speed measuring pressure in general G01L
• CPC Class Codes: G01P 7/00 Measuring speed by integrating acceleration measuring travelled distance by double integration of acceleration G01C21/16

Abstract

As an embodiment of the present invention, in a navigation system using an acceleration sensor, when position information cannot be obtained from a GPS processing section, a velocity detecting unit performs an operation using detected acceleration αG, a measurement time mt, a velocity V0 at a time t0, gravity acceleration g and an amount of height change Dh, according to Expression (11). By using the relationship among a gravity acceleration component gf, the gravity acceleration g, the amount of height change Dh and distance Dm shown in Expression (4), the gravity acceleration component gf can be offset by the amount of height change Dh. Therefore, velocity V can be calculated with high accuracy without receiving the effect of the gravity acceleration component gf.

Claims

1. A velocity detecting system comprising:

an acceleration sensor for obtaining detected acceleration corresponding to the result of that mobile body acceleration in a forward direction in a predetermined mobile body was added to the component of said forward direction being gravity acceleration operating on the above mobile body;

amount of height change calculating means for calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor; and

velocity calculating means for obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration corresponds to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at a measurement finish point by using the above mobile body acceleration, based on the known velocity of said mobile body at a measurement start point.

2. The velocity detecting system according to claim 1, wherein;

said velocity calculating means calculates the velocity of said mobile body at said measurement finish point according to the following expression;

$V<br><br>\text{\hspace{1em}<br><br>}<br><br>1=\frac{\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>G·<br><br>\mathrm{mt}}{2}+\sqrt{{\left(\frac{\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>G·<br><br>\mathrm{mt}}{2}+V<br><br>\text{\hspace{1em}<br><br>}<br><br>0\right)}^2-2<br><br>\mathrm{Dh}·<br><br>g}$

however,

V1;

velocity at the finish point of measurement time

aG;

detected acceleration

mt;

measurement time

V0;

velocity at the finish point of measurement time

Dh;

amount of height change

g;

gravity acceleration

3. The velocity detecting system according to claim 1, wherein;

said amount of height change calculating means converts the pressure at said measurement start point and said measurement finish point into the height of said mobile body respectively, by height converting means for converting from pressure into height, and sets a difference value between them as said amount of height change.

4. The velocity detecting system according to claim 3, wherein;

said height converting means converts from said pressure into said height based on a correspondence table between pressure and height previously made.

5. The velocity detecting system according to claim 3, wherein;

said height converting means converts from said pressure into said height according to the following expression;

$h=153.8\times <br><br>\left(t_z+273.2\right)\times <br><br>\left(1-{\left(\frac{\mathrm{PR}}{{\mathrm{PR}}_z}\right)}^{0.1902}\right)$

however,

h;

height

t_z;

temperature at h=0 m

PR;

pressure

PR_z;

pressure at h=0 m

6. The velocity detecting system according to claim 1, wherein;

said velocity calculating means calculates the velocity of said mobile body at said measurement finish point, using the velocity of said mobile body at the start point of said measurement time, and said detected acceleration and said amount of height change at said measurement start point.

7. The velocity detecting system according to claim 1, wherein;

said velocity calculating means calculates the velocity of said mobile body at said measurement finish point, using the velocity of said mobile body at said measurement start point, and the mean value of said detected acceleration at said measurement start point and said measurement finish point, and said amount of height change.

8. The velocity detecting system according to claim 1, wherein;

when the variance of detected acceleration obtained by said acceleration sensor is a predetermined threshold value or less, said velocity calculating means sets the velocity of said mobile body at the start point of said measurement time as zero.

9. The velocity detecting system according to claim 1, including:

an angular velocity sensor for detecting an angular velocity in the shaft revolution vertical to the horizontal direction in said mobile body;

wherein when the variance of angular velocities obtained by said angular velocity sensor is a predetermined threshold value or less, said velocity calculating means sets the velocity of said mobile body at the start point of said measurement time as zero.

10. The velocity detecting system according to claim 1, wherein;

said velocity calculating means obtains the velocity of said mobile body at the start point of said measurement time by predetermined satellite positioning signal receiving and positioning means.

11. The velocity detecting system according to claim 1, wherein;

when said amount of height change is not within a predetermined range of height change, said amount of height change calculating means corrects said amount of height change to be within the above range of height change.

12. The velocity detecting system according to claim 11, wherein;

said amount of height change calculating means determines whether or not said amount of height change is within said range of height change, based on a maximum slope angle being the maximum value of a slope angle to be obtained from said amount of height change.

13. The velocity detecting system according to claim 11, wherein;

said amount of height change calculating means determines whether or not said amount of height change is within said range of height change, based on a maximum slope change rate being the maximum value of a slope change rate under per unit time of a slope angle to be obtained from said amount of height change.

14. A method for detecting velocity comprising the steps of:

obtaining detected acceleration corresponding to the result of that mobile body acceleration in a forward direction in a predetermined mobile body was added to the component of said forward direction being gravity acceleration operating on the above mobile body, by an acceleration sensor;

calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor; and

obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration corresponds to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at a measurement finish point by using the above mobile body acceleration, based on the known velocity of said mobile body at a measurement start point.

15. A velocity detecting program for making a velocity detecting system execute the steps of:

obtaining detected acceleration corresponding to the result of that mobile body acceleration in a forward direction in a predetermined mobile body was added to the component of said forward direction being gravity acceleration operating on the above mobile body, by an acceleration sensor;

calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor; and

obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration corresponds to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at a measurement finish point by using the above mobile body acceleration, based on the known velocity of said mobile body at a measurement start point.

16. A position detecting system comprising:

an acceleration sensor for obtaining detected acceleration including mobile body acceleration in a forward direction in a predetermined mobile body and the component of said forward direction being gravity acceleration operating on the above mobile body;

an angular velocity sensor for detecting an angular velocity in the shaft revolution vertical to the horizontal direction in said mobile body;

amount of height change calculating means for calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor;

velocity calculating means for offsetting said forward direction component included in said detected acceleration by the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration is equal to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at the finish point of said measurement time, based on the velocity of said mobile body at the start point of said measurement time; and

position information calculating means for calculating the position information of said mobile body at the finish point of said measurement time, based on the position information of said mobile body at the start point of said measurement time, and said calculated velocity and angular velocity of said mobile body.

17. The position detecting system according to claim 16 including;

angular velocity correcting means for correcting said angular velocity, based on the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, wherein said position information calculating means calculates the position information of said mobile body at the finish point of said measurement time, using said angular velocity after said correction.

18. A method for detecting a position comprising the steps of:

obtaining detected acceleration including mobile body acceleration in a forward direction in a predetermined mobile body and the component of said forward direction being gravity acceleration operating on the above mobile body, by an acceleration sensor;

detecting an angular velocity in the shaft revolution vertical to the horizontal direction in said mobile body, by an angular velocity sensor;

calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor;

offsetting said forward direction component included in said detected acceleration by the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration is equal to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at the finish point of said measurement time, based on the velocity of said mobile body at the start point of said measurement time; and

calculating the position information of said mobile body at the finish point of said measurement time, based on the position information of said mobile body at the start point of said measurement time, and said calculated velocity and angular velocity of said mobile body.

19. A position detecting program for making a position detecting system execute the steps of:

obtaining detected acceleration including mobile body acceleration in a forward direction in a predetermined mobile body and the component of said forward direction being gravity acceleration operating on the above mobile body, by an acceleration sensor;

detecting an angular velocity in the shaft revolution vertical to the horizontal direction in said mobile body, by an angular velocity sensor;

calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor;

offsetting said forward direction component included in said detected acceleration by the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration is equal to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at the finish point of said measurement time, based on the velocity of said mobile body at the start point of said measurement time; and

calculating the position information of said mobile body at the finish point of said measurement time, based on the position information of said mobile body at the start point of said measurement time, and said calculated velocity and angular velocity of said mobile body.

20. A navigation system comprising:

present position calculating means for receiving a positioning signal from a predetermined satellite positioning system, and calculating the present position of a predetermined mobile body;

an acceleration sensor for obtaining detected acceleration corresponding to the result of that mobile body acceleration in a forward direction in said mobile body was added to the component of said forward direction being gravity acceleration operating on the above mobile body;

amount of height change calculating means for calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor;

velocity calculating means for obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration corresponds to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at a measurement finish point by using the above mobile body acceleration, based on the known velocity of said mobile body at a measurement start point; and

information display means for displaying information on the position of said mobile body, based on the velocity of said mobile body calculated by said velocity calculating means.

21. A velocity detecting system comprising:

an acceleration sensor for obtaining detected acceleration corresponding to the result of that mobile body acceleration in a forward direction in a predetermined mobile body was added to the component of said forward direction being gravity acceleration operating on the above mobile body;

a mechanism calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor; and

a mechanism obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration corresponds to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at a measurement finish point by using the above mobile body acceleration, based on the known velocity of said mobile body at a measurement start point.

22. The velocity detecting system according to claim 21, wherein;

said velocity calculating mechanism calculates the velocity of said mobile body at said measurement finish point according to the following expression;

$v<br><br>\text{\hspace{1em}<br><br>}<br><br>1=\frac{\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>G·<br><br>\mathrm{mt}}{2}+\sqrt{{\left(\frac{\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>G·<br><br>\mathrm{mt}}{2}+v<br><br>\text{\hspace{1em}<br><br>}<br><br>0\right)}^2-2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Dh}·<br><br>g}$

however,

V1;

velocity at the finish point of measurement time

aG;

detected acceleration

mt;

measurement time

V0;

velocity at the finish point of measurement time

Dh;

amount of height change

g;

gravity acceleration

23. The velocity detecting system according to claim 21, wherein;

said amount of height change calculating mechanism converts the pressure at said measurement start point and said measurement finish point into the height of said mobile body respectively, by a mechanism converting from pressure into height, and sets a difference value between them as said amount of height change.

24. The velocity detecting system according to claim 23, wherein;

said height converting mechanism converts from said pressure into said height based on a correspondence table between pressure and height previously made.

25. The velocity detecting system according to claim 23, wherein;

said height converting mechanism converts from said pressure into said height according to the following expression;

$h=153.8\times <br><br>\left(t_z+273.2\right)\times <br><br>\left(1-{\left(\frac{\mathrm{PR}}{{\mathrm{PR}}_z}\right)}^{0.1902}\right)$

however,

h;

height

t_z;

temperature at h=0 m

PR;

pressure

PR_z;

pressure at h=0 m

26. The velocity detecting system according to claim 21, wherein;

said velocity calculating mechanism calculates the velocity of said mobile body at said measurement finish point, using the velocity of said mobile body at the start point of said measurement time, and said detected acceleration and said amount of height change at said measurement start point.

27. The velocity detecting system according to claim 21, wherein;

said velocity calculating mechanism calculates the velocity of said mobile body at said measurement finish point, using the velocity of said mobile body at said measurement start point, and the mean value of said detected acceleration at said measurement start point and said measurement finish point, and said amount of height change.

28. The velocity detecting system according to claim 21, wherein;

when the variance of detected acceleration obtained by said acceleration sensor is a predetermined threshold value or less, said velocity calculating mechanism sets the velocity of said mobile body at the start point of said measurement time as zero.

29. The velocity detecting system according to claim 21, including:

an angular velocity sensor for detecting an angular velocity in the shaft revolution vertical to the horizontal direction in said mobile body;

wherein when the variance of angular velocities obtained by said angular velocity sensor is a predetermined threshold value or less, said velocity calculating mechanism sets the velocity of said mobile body at the start point of said measurement time as zero.

30. The velocity detecting system according to claim 21, wherein;

said velocity calculating mechanism obtains the velocity of said mobile body at the start point of said measurement time by a predetermined satellite positioning signal receiving and positioning mechanism.

31. The velocity detecting system according to claim 21, wherein;

when said amount of height change is not within a predetermined range of height change, said amount of height change calculating mechanism corrects said amount of height change to be within the above range of height change.

32. The velocity detecting system according to claim 31, wherein;

said amount of height change calculating mechanism determines whether or not said amount of height change is within said range of height change, based on a maximum slope angle being the maximum value of a slope angle to be obtained from said amount of height change.

33. The velocity detecting system according to claim 31, wherein;

said amount of height change calculating mechanism determines whether or not said amount of height change is within said range of height change, based on a maximum slope change rate being the maximum value of a slope change rate under per unit time of a slope angle to be obtained from said amount of height change.

34. A position detecting system comprising:

an acceleration sensor for obtaining detected acceleration including mobile body acceleration in a forward direction in a predetermined mobile body and the component of said forward direction being gravity acceleration operating on the above mobile body;

an angular velocity sensor for detecting an angular velocity in the shaft revolution vertical to the horizontal direction in said mobile body;

a mechanism calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor;

a mechanism offsetting said forward direction component included in said detected acceleration by the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration is equal to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at the finish point of said measurement time, based on the velocity of said mobile body at the start point of said measurement time; and

a mechanism calculating the position information of said mobile body at the finish point of said measurement time, based on the position information of said mobile body at the start point of said measurement time, and said calculated velocity and angular velocity of said mobile body.

35. The position detecting system according to claim 34 including;

a mechanism correcting said angular velocity, based on the ratio of said amount of height change to the moving distance of said mobile body in said measurement time,

wherein said position information calculating mechanism calculates the position information of said mobile body at the finish point of said measurement time, using said angular velocity after said correction.

36. A navigation system comprising:

a mechanism receiving a positioning signal from a predetermined satellite positioning system, and calculating the present position of a predetermined mobile body;

an acceleration sensor for obtaining detected acceleration corresponding to the result of that mobile body acceleration in a forward direction in said mobile body was added to the component of said forward direction being gravity acceleration operating on the above mobile body;

a mechanism calculating the amount of height change of said mobile body in a predetermined measurement time, based on the surrounding pressure of said mobile body detected by a predetermined pressure sensor;

a mechanism obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the above amount of height change, by utilizing that the ratio of said forward direction component of said gravity acceleration to the above gravity acceleration corresponds to the ratio of said amount of height change to the moving distance of said mobile body in said measurement time, and calculating the velocity of said mobile body at a measurement finish point by using the above mobile body acceleration, based on the known velocity of said mobile body at a measurement start point; and

a mechanism displaying information on the position of said mobile body, based on the velocity of said mobile body calculated by said velocity calculating mechanism.