Measuring and testing – Speed – velocity – or acceleration – Structural installation or mounting means
Reexamination Certificate
2003-02-03
2004-11-02
Chapman, John E. (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Structural installation or mounting means
C073S504160, C073S514320
Reexamination Certificate
active
06810735
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sensing apparatus and movable body-mountable electronic equipment utilizing such an apparatus, and particularly to a sensing apparatus for detecting a physical quantity having a direction, such as acceleration and the electronic equipment, which utilizes such a sensing apparatus and is to be mounted on a movable body such as a vehicle.
2. Description of the Related Art
There has recently been widely available an apparatus for detecting the current position of a vehicle to facilitate movement of the vehicle, i.e., a so-called navigation apparatus.
The conventional navigation apparatus utilizes a so-called GPS (Global Positioning System) as well as another system for independently obtaining the traveling direction and distance of the vehicle from a predetermined reference point (more specifically, the starting point from which the vehicle travels), so as to detect the current position of the vehicle.
Many of the conventional navigation apparatus are provided with a gyro-sensor and an accelerometer for detecting acceleration applied to the vehicle, in order to obtain the current position, traveling direction and/or change in velocity of the vehicle with the use of the above-mentioned system for independently obtaining the current position thereof.
The conventional sensor such as the gyro-sensor and accelerometer has a detection reference axis along which the direction and amount of acceleration are detected. In actual cases, such a detection reference axis is provided in the form of a physical element or an imaginary element, taking into consideration the direction of acceleration to be detected by means of the sensor. The positional determination of such a detection reference axis relative to the sensor is made without taking into consideration a possibility that the navigation apparatus in which the sensor is mounted, may not be disposed on a horizontal plane. More specifically, these sensors having the predetermined characteristic features are mounted on the navigation apparatus, on the assumption that the respective detection reference axes are in parallel with a ground on which the vehicle drives. In such a case, the navigation apparatus is disposed on the vehicle so as to be also in parallel with the ground.
On the other hand, miniaturization of the navigation apparatus has recently advanced, thus making it possible to dispose the navigation apparatus in a central console of the vehicle.
With respect to an operation for disposing the navigation apparatus in the central console, in many cases, the navigation apparatus is placed so that the front surface of an operation panel of the navigation apparatus, on which a display unit and operation switches such as buttons are placed, is inclined relative to the vertical direction so as to face upward, in view of improvement in viewability of the display unit and operability of the switches. In a case where the navigation apparatus is placed on or under the other audio apparatus in the central console, the navigation apparatus is usually disposed so that the front surface of the operation panel is inclined relative to the vertical direction so as to face upward. Such a positional relationship can be achieved by mounting the navigation apparatus in itself in the central console in a tilted state (more specifically, so that the rear side of the navigation apparatus (which is the front side in the traveling direction of the vehicle) is placed lower than the front side thereof.
The switches such as the buttons of the navigation apparatus are usually operated with lower frequency than those of the other audio apparatus. Such a tendency may lead to a situation that the navigation apparatus is placed under the other audio apparatus in the central console. As a result, there may be a case where the inclination angle of the navigation apparatus as mounted relative to the horizontal plane becomes excessively large (more specifically, over the allowable angle (for example, 30 degrees) as described later.
In the above-described case, the direction of the detection reference axis of the sensor greatly deviates from the direction of acceleration actually applied to the sensor during an actual detection (i.e., the horizontal direction), thus causing an error such as offset in sensitivity of the sensor. As a result, there occur problems of deterioration of accuracy of positioning the current position and velocity of the vehicle.
Now, such problems will be described more in detail with reference to FIG.
8
.
FIG. 8
is a descriptive view illustrating the central console
102
in which the navigation apparatus
100
provided with the accelerometer
101
is mounted.
When the navigation apparatus
100
is inclined relative to the horizontal plane so that the operation panel
103
faces upward so as to be fitted into a receiving space of the central console
102
, as shown in
FIG. 8
, the detection reference axis “G” of the accelerometer
101
is also inclined relative to the horizontal plane by the mounting angle “&THgr;” of the navigation apparatus
100
in accordance with the inclination thereof.
If the assumption is made that the vehicle drives forward to move rightward in
FIG. 8
, the acceleration actually applied to the navigation apparatus
100
during such a forward movement can be expressed by “Ax” having the opposite directional component to the forward movement.
When the acceleration “Ax” actually applied to the navigation apparatus
100
is detected by means of the accelerometer
101
having the detection reference axis, which is inclined by the mounting angle “&THgr;” of the navigation apparatus
100
, the accelerometer
101
outputs the acceleration “Gx (Gx=cos&THgr;×Ax)” as the detection result, which has the smaller value than the actually applied acceleration “Ax”.
On the other hand, acceleration vertically and upwardly applied to the navigation apparatus
100
(i.e., the vertically and upwardly applied thereto due to vibration of the vehicle and an impactive force from the ground) can be expressed by the acceleration “Az”, which is perpendicular to the above-mentioned acceleration “Ax”.
When the acceleration “Az” actually applied to the navigation apparatus
100
is detected by means of the accelerometer
101
in the same manner as the acceleration “Az”, the accelerometer
101
outputs the acceleration “Gz (Gz=sin&THgr;×Az)” as the detection result, which is the sine element of the actually applied acceleration “Az”.
The acceleration “At”, which is detected through vector sum of the accelerations “Gx” and “Gz” as mentioned above by the accelerometer
101
, can be expressed by the following formula:
At=Gx+Gz
=cos&THgr;×
Ax
+sin&THgr;×
Az
The resultant acceleration “At” differs from the acceleration “Ax” to be actually detected. Such a difference causes an error, which deteriorates accuracy of positioning the current position of the vehicle. As the mounting angle “&THgr;” of the navigation apparatus
100
increases, a tendency that the acceleration “Ax” to be actually detected is more remarkably influenced by the vertical acceleration “Az”, rather than the acceleration “Ax” in the traveling direction of the vehicle, becomes more remarkable, thus leading to a noticeable error.
The conventional navigation apparatus has recently made a correction of the detection results obtained by the accelerometer or the gyro-sensor through a processing operation based on software for correcting the error. In addition, there has also been adopted a system for improving the accuracy of correction through a continuous learning process along with the movement of the vehicle.
However, the error correction carried out by the above-mentioned processing operation does not provide sufficient correcting effects, immediately after the navigation apparatus is mounted on the vehicle, thus causing a problem.
In addition, even when the error correction is carried out utilizing the software for correcting the error,
Endo Isao
Kaneko Hitoshi
Okamoto Tatsuya
Chapman John E.
Nixon & Vanderhye PC
Pioneer Corporation
LandOfFree
Sensing apparatus and electronic equipment using the sensing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sensing apparatus and electronic equipment using the sensing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sensing apparatus and electronic equipment using the sensing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3277071