Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1999-09-23
2003-04-08
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S207000, C701S216000, C701S217000
Reexamination Certificate
active
06546336
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a portable position detector and a position management system, and more particularly to a portable position detector capable of estimating the moved position of a walking body (e.g., a person) by self-contained navigation (number of steps×length of a step) and a position management system capable of managing the positions of a plurality of portable position detectors.
DESCRIPTION OF THE RELATED ART
A variety of vehicle navigational systems have been developed. At the beginning, self-contained navigation was used to provide information about the location of a vehicle. Later, self-contained navigation and a global positioning system (GPS) were combined into a hybrid system. The self-contained navigation employs an integration system. That is, the outputs from a speed sensor are integrated to detect the traveled distance of a vehicle, and the direction of the vehicle is detected from a direction sensor such as a gyro. The direction detected for each predetermined distance or time and the distance traveled during that period are cumulatively added to the starting point to detect the current position.
On the other hand, portable position detectors utilizing the GPS have recently been developed in order to render the measurement of the position of a walker possible. However, in the GPS, the position of a walker cannot be calculated unless information is received from 4 satellites (or 3 satellites although measurement accuracy is reduced). Since walkers walk on mountains and valleys and, even in a city, walk on a sidewalk that is easily shaded by buildings, the portable position detector is considerably disadvantageous in the above-mentioned reception, compared with vehicle navigational systems that are employed in vehicles traveling on a roadway in the central portion between buildings. In addition, a speed sensor cannot be simply applied to a walker, as in vehicle navigational systems.
Hence, the ideas of self-contained navigation for walkers, which employ a pedometer, have hitherto been proposed in Japanese Laid-Open Patent Publication Nos. HEI 2-216011, HEI 5-172579, HEI 8-68643, and HEI 9-89584.
However, the above-mentioned conventional methods have the following disadvantages when measuring the position of a walker. That is, the direction of a walker can always be detected at any point, while a pedometer can detect only whether or not a single step of a walk has been made. For example, the pedometer cannot continuously detect the moved distance of the center of gravity of a walker's body, which is continuously moved during a single step of a walk. Therefore, unlike vehicle navigational systems, at what point a moved distance and a moved direction are detected and used as a base of the calculation of the position of a walker is considerably important for the position detection of a walker based on self-contained navigation, because particularly when a walk involves a curve, the direction of the body easily changes even during movement of a single step of a walk.
In the above-mentioned 4 publications, Japanese Laid-Open Patent Publication No. HEI 9-89584 has no description of how a moved distance and a moved direction are determined.
On the other hand, the aforementioned Japanese Laid-Open Patent Publication No. HEI 8-68643 discloses that when a cantilever vibration meter (pedometer) with a weight outputs a pulse signal, the direction at that time is employed to calculate a moved distance. However, in this vibration meter (pedometer), a pulse signal is generated by the vertical movement of the center of gravity of a walker when the vibration meter strikes the weight that attempts to keep its position by inertia. Note that all pedometers are uniformly set so that a pulse signal is generated when the aforementioned gravity of center rises by a predetermined distance (about 15 mm). Also, since there is a great shock when a walker lands on a surface such as a road, the output of the vibration meter gives rise to hunting. For this reason, this vibration meter is constructed so that an electric circuit cuts the hunting (i.e., a signal at the time of landing is not used). Therefore, if a moved direction is detected at the time of the generation of this output pulse, the moved direction will often be detected when a walker begins to change a direction. As a result, it cannot be expected to select an optimal moved direction, and a measured position is often departed from the moved position.
Japanese Laid-Open Patent Publication Nos. HEI 2-216011 and HEI 5-172579 disclose that the direction of a walker is constantly detected and that it is judged whether or not the direction has been changed. If it is judged that the direction has been changed, the direction and distance up to this point are stored in order. As occasion demands, a position and a walked route are calculated from the stored data. This method judges a change in a moved direction by whether or not a measured direction has exceeded a reference range of direction that becomes a predetermined change of direction. However, when a measured direction exceeds the reference range of direction, there is no description of which direction of the moved directions being changed up to that time within the reference range of direction is employed in the measurement of a moved position.
In the aforementioned case, if the range of a reference value is narrow, the direction of a walker will constantly change and become complicated. At the same time, the information will be too much for the storage capacity, so the reference value must be set wide to some degree. If the reference value is set wide, the dispersion will become increasingly great, depending on the direction used before change of direction. Particularly, in a long and gentle curve or an inclined road, an error will be cumulated.
Also, in many cases, pedometers are constructed so that they count the number of steps and cumulate a value obtained by multiplying the number of steps by the length of a step, thereby displaying a walked distance. However, in practice, the step length of a walker is not constant. For this reason, this method has the disadvantage that the calculation accuracy of a walked distance is insufficient. For example, it is general that the length of a step varies between when the walker is hurried and when the walker walks slowly. However, in the conventional method, since a walked distance is calculated without giving consideration to variations in the length of a step due to a difference in a walking state, the accuracy of the walked distance is insufficient.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a portable position detector and a position management system that are capable of enhancing the accuracy of the position of a walking body detected by self-contained navigation, by accurately detecting the direction of the walking body even when GPS signals cannot be received or even when no GPS signals are received and also changing the length of a step in accordance with the walking state.
To achieve this end and in accordance with a first preferred form of the present invention, there is provided a portable position detector for detecting a moved position of a walking body. The portable position detector comprises: (1) walking-motion detection means for measuring a value related to a walking motion caused by movement of the walking body; (2) acceleration detection means for detecting acceleration of the value related to the walking motion caused by movement of the walking body; (3) moved-distance estimation means for estimating the moved distance of the walking body, based on both a number of steps detected from an output of the walking-motion detection means and a step length changed according to horizontal acceleration of the walking body or the magnitude of a change in the horizontal acceleration detected by acceleration detection means; (4) moved-direction detection means for detecting a direction or direction of movement of the walking body caused by movem
Matsuoka Yoshio
Yamamoto Akito
Blank Rome Comisky & McCauley LLP
Broadhead Brian J.
Jatco Corporation
Louis-Jacques Jacques H.
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