Small size apparatus for measuring and recording acceleration

• US 5,541,860 A
• Filed: 07/10/1995
• Issued: 07/30/1996
• Est. Priority Date: 06/22/1988
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Suzuki, Hiroaki, Fujita, Shozo, Takei, Fumio, Asano, Koji, Hashitani, Takafumi, Sugama, Akio, Kojima, Naomi
• Primary Examiner(s): Trammell, James P.
• Assistant Examiner(s): CHOI, KYLE JAEHUN
• Application Number:
  US08/500,113
• Time in Patent Office: 386 Days
• Field of Search: 364/424.02, 364/424.06, 364/550, 364/551.01, 364/556, 364/566, 73/489, 73/491, 73/492, 73/503, 73/510, 73/517 R, 340/429, 360/5, 360/6
• US Class Current: 702/141
• CPC Class Codes: G01P 1/127 for acceleration values

Abstract

A small size apparatus for measuring and recording acceleration comprises an acceleration sensor, an A/D converter which converts the output signal of the acceleration sensor to a digital signal, a control element which processes the digital signal, a detachable external memory device which stores data of a change in acceleration and, a battery for supplying electric power to the sensor, the A/D converter, the control element and the external memory device. The small size apparatus is mounted on a moving body to be measured and the entire small size apparatus is driven by the battery. The correct attachment of the external memory device is detected by steps of writing data into a special address, reading the data out thereafter, and comparing the written data and read data. When the read data coincides with the written data, it is judged that the external memory device is correctly attached.

Claims

1. A small size apparatus applied to a moving body for measuring and recording acceleration with time, comprising:

a servo-type acceleration sensor producing an analog signal;

a variable gain amplifier connected to said acceleration sensor to receive the analog signal and amplify the analog signal by a suitable factor;

a sample and hold circuit connected to said variable gain amplifier to sample and hold the amplified analog signal;

an A/D converter, having an analog portion and a digital portion, the analog portion being connected to said sample and hold circuit, for converting a sampled and held analog signal by the sample and hold circuit into a digital signal when the sample and hold circuit is actuated;

a control element, connected to said digital portion of the A/D converter, for processing the digital signal, said control element comprising;

a central processing unit;

a read only memory connected to said central processing unit;

a random access memory connected to said central processing unit;

a programmable timer connected to said central processing unit;

a programmable gain amplifier interface connected to said central processing unit;

a peripheral interface adapter connected to said central processing unit; and

a memory cassette interface connected to said central processing unit;

a detachable external memory device, connectable to said control element, having no mechanical movement, for storing data regarding a change in acceleration as time sequential data;

an I/O unit operatively connected to said control element; and

a battery for supplying electric power to said sensor, said A/D converter, said control means, said detachable external memory device, said variable gain amplifier and said sample and hold circuit, said central processing unit performing, in accordance with a program stored in said ROM, suitability of sensor signal amplification factor, generation of a sampling signal, management of said detachable external memory device, display of input commands and operation situation to said I/O unit, and controlling said variable gain amplifier to always be set to an optimum amplification factor, said small size apparatus being mounted on a moving body to be measured and the entire small size apparatus being driven by said battery.

2. An apparatus according to claim 1, wherein said detachable external memory device has a recording medium selected from one of a semiconductor memory, a bubble memory and similar memories having no mechanical movement.

3. An apparatus according to claim 2, wherein said detachable external memory device is formed by four 256k bit static RAMs, detachable from a main body via a multi-pole connector.

4. A small size apparatus according to claim 1, wherein said small size apparatus begins measuring and recording acceleration at the instant the acceleration changes from high to low and goes below a first predetermined value, and wherein said small size apparatus stops measuring and recording acceleration at the instant the acceleration changes from low to high and goes above a second predetermined value.

5. An apparatus according to claim 1, wherein a sampling time interval of a sampling signal for said sample and hold circuit is 10 ms˜

100 ms.

6. An apparatus according to claim 5, wherein the sampling time interval is less than 1/30 second.

7. An apparatus according to claim 1, further comprising three acceleration sensors connected at right angles along three dimensional axes for measuring fine changes in acceleration with respect to time in three dimensional directions.

8. An apparatus according to claim 1, wherein said memory cassette interface comprises:

a latch for specifying the address for writing or reading said detachable external memory device;

a data bus transceiver for controlling the direction of the data in said memory cassette interface between a personal computer and the data of said detachable external memory device;

a one-shot multivibrator for controlling the timing of the write and read operations; and

address decoders for selecting an address of said personal computer.

9. An apparatus according to claim 1, wherein said acceleration measurement is between 10 G-10 μ

G.

10. An apparatus according to claim 1, further comprising a power source circuit, said power source circuit is formed by power regulators and a DC--DC converter.

11. An apparatus according to claim 10, wherein said power source circuit supplies +5 V for a digital IC, ±

15 V for an analog signal processing system, +5 V is delivered by one of said power regulators and ±

15 V is provided by said DC--DC converter.

12. An apparatus according to claim 1, wherein said gain control of said variable gain amplifier is determined by said central processing unit of said control element and automatically calculates the measured value for a full scale value.

13. An apparatus according to claim 1, wherein an analog output signal of said acceleration sensor is stored in said sample and hold circuit synchronized with the sampling signal.

14. An apparatus according to claim 1, wherein a sampling interval of a sampling signal for said sample and hold circuit and start and end points of the acceleration measurement are inputted by external switches.

15. An apparatus according to claim 1, wherein volume and weight of said apparatus is below 4000 cc and below 4 kg, respectively.

16. An apparatus according to claim 1, wherein the data recorded in said external memory device can be read out and processed by other apparatus after the experiment is completed.

17. An apparatus according to claim 1, wherein the measurement range of the X and Y axes acceleration sensors is ±

1 G, and that of Z axis is ±

4 G.

18. An apparatus according to claim 1, wherein the capacity of said detachable external memory device is 128k bits in one cassette, and continuous measurement becomes possible for 210-2100 sec. (3.5-35 min.) at a sampling interval of 10-100 ms.

19. An apparatus according to claim 1, wherein said detachable external memory device is a large capacity static or dynamic type Random Access Memory (RAM) backed up by battery.

20. An apparatus according to claim 1, wherein a sampling interval of a sampling signal for said sample and hold circuit and the start and end points of the acceleration measurement are automatically determined by a trigger obtained from the output signal from said acceleration sensor.

21. An apparatus according to claim 20, wherein the trigger obtained from the output signal from said acceleration sensor, changes in accordance with a trajectory or parabolic flight of an airplane.

22. An apparatus according to claim 21, wherein the trigger is obtained in accordance with, at a first instant, an acceleration in a Z direction (vertical) changes from high to low and goes below a first predetermine value, and, at a second instant, the acceleration changes from low to high and goes above a second predetermined value, and the apparatus begins measuring and recording acceleration at the first instant, and stops measuring and recording acceleration at the second instant.

23. A small size apparatus applied to a moving body for measuring and recording changes in acceleration in three axes with respect to time, comprising:

three acceleration sensors located at right angles along three dimensional axes for measuring fine time changes in X, Y and Z axis accelerations, respectively, each of the three acceleration sensors producing an analog signal corresponding to the X, Y and Z axis accelerations, respectively;

three variable gain amplifiers each connected to each of said three acceleration sensors respectively, to receive the analog signal from each of said acceleration sensors and to amplify each analog signal by a suitable factor, respectively;

three sample and hold circuits each connected to a respective one of said three variable gain amplifiers to sample and hold each of the amplified analog signals of each of the three variable gain amplifiers;

an A/D converter having an analog portion and a digital portion, the analog portion connected to each of said three sample and hold circuits, for converting sampled and held analog signals from each of said three sample and hold circuits, into digital signals, respectively, when each of said three sample and hold circuits are actuated;

a control element connected to said digital portion of said A/D converter, for processing the digital signal, said control element comprising;

a random access memory connected to said central processing unit;

a programmable timer connected to said central processing unit;

a programmable gain amplifier interface connected to said central processing unit;

a peripheral interface adapter connected to said central processing unit; and

a memory cassette interface connected to said central processing unit;

a detachable external memory device having no mechanical movement, operatively connected to said control element, for storing data regarding changes in X, Y and Z axis accelerations as time sequential data;

an I/O unit connected to said control element; and

a battery for supplying electric power to said sensors, said variable gain amplifier, said sample and hold circuit, said A/D converter, said control element, said detachable external memory device, and said I/O unit, said central processing unit performing, in accordance with a program stored in said ROM, suitability of a sensor signal amplification factor, generation of a sampling signal, management of said detachable external memory device, display of input commands and operation situations to said I/O unit, and controlling the variable gain amplifier to always be set at an optimum amplification factor, said apparatus being mounted on said moving body to be measured, and the entire small size apparatus being driven by said battery.