JP2010054374A - Mobile sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply install, on a fixed object, a motion sensor capable of detecting movement of the fixed object, when it is moved. <P>SOLUTION: The motion sensor includes an accelerator for respectively detecting acceleration in three-axial directions and a control part for detecting the movement from the acceleration in the three-axial directions detected by the accelerator. The control part acquires an acceleration detection signal from the accelerator, obtains an acceleration measurement value of each axis, determines whether the motion sensor stands still or is moving, based on the acceleration measurement value, and calculates a posture angle of the motion sensor using the acceleration measurement value of each axis when the sensor is determined to stand still. Meanwhile, when the motion sensor is determined to be moving, horizontal acceleration is calculated by means of the posture angle of the motion sensor, which is calculated when the sensor is determined as being stationary so as to determine whether the sensor is moving, based on the horizontal acceleration. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a movement detection device that detects movement when a fixed object is moved.

  In recent years, theft of fixed objects used in a fixed state such as large machine tools and ATMs has become a problem.

A device described in Patent Document 1 is known as a device for detecting such theft. In the anti-theft damper function module device with a theft detection function described in Patent Document 1, the acceleration, velocity, and displacement in the horizontal direction are calculated from the acceleration data from the X-axis acceleration sensor and the Y-axis acceleration sensor arranged along the horizontal direction. Furthermore, the horizontal displacement is subjected to fast Fourier transform to obtain the Fourier amplitude power spectrum, which is stored as log data. When the acceleration exceeds a predetermined value, the speed duration, displacement time, displacement According to the quantity and the Fourier vibration power spectrum, it is identified whether the movement of the device is due to theft or an earthquake other than theft.
JP 2006-277400 A

  However, in the configuration of Patent Document 1, there is a problem that the acceleration sensor must be correctly installed along the horizontal direction, and when the user himself / herself installs the acceleration sensor on a fixed object, the installation is difficult.

  Further, in Patent Document 1, in order to identify whether the movement of the device is due to theft or an earthquake, not only the acceleration and speed but also the displacement of the device and the power spectrum of the displacement are obtained, and the calculation process is complicated. There's a problem.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a movement detection device capable of easily installing the device. A further object of the present invention is to provide a movement detection device that can identify movement and other movements with simple arithmetic processing.

  In order to solve the above-mentioned problem, the present invention according to claim 1 is a movement detection device installed on a fixed object, the accelerometer for detecting acceleration in three axial directions, respectively, and detected by the accelerometer. A control unit for detecting movement from triaxial acceleration, the control unit taking in an acceleration detection signal from the accelerometer and obtaining a triaxial acceleration measurement value, and moving based on the acceleration measurement value A movement determination means for determining whether the detection apparatus is stationary or exercising, and movement detection using the three-axis acceleration measurement value when the movement determination means determines that the apparatus is stationary. An attitude angle calculating means for calculating an attitude angle of the apparatus, and the attitude angle when the movement detecting apparatus determines that the movement detecting apparatus is stationary when the movement determining means determines that the movement detecting apparatus is moving. Calculate with calculation means And a horizontal acceleration calculating means for calculating horizontal acceleration using the attitude angle of the movement detecting device, and determining whether or not the vehicle is moving based on the horizontal acceleration calculated by the horizontal acceleration calculating means. To do.

  According to a second aspect of the present invention, the control unit according to the first aspect further includes an acceleration threshold determination unit that determines whether the horizontal acceleration calculated by the horizontal acceleration calculation unit exceeds a predetermined acceleration threshold, and the acceleration threshold determination A speed calculation unit that calculates a speed from the acceleration measurement value, and a speed threshold that determines whether the speed calculated by the speed calculation unit exceeds a predetermined speed threshold The apparatus further comprises: a determination unit; and an output unit that outputs a movement signal when the speed threshold determination unit determines that a predetermined speed threshold is exceeded.

  According to a third aspect of the present invention, the control unit according to the first or second aspect includes a movement variance calculation unit that calculates a movement variance of an acceleration measurement value obtained by the acceleration measurement unit, and the motion determination unit includes a movement When the variance exceeds a predetermined threshold, it is determined that the movement detection device is moving.

  According to a fourth aspect of the present invention, when the control unit according to any one of the first to third aspects determines that the movement detection device is stationary by the motion determination unit, a series of the units is provided. This process is performed intermittently.

  According to the present invention, when it is determined that the movement detection device is moving, the posture angle calculated using the acceleration measurement value of each axis is used when it is determined that the movement detection device is stationary. Since the horizontal acceleration is obtained and the movement is determined based on the horizontal acceleration, the horizontal acceleration can be obtained regardless of the posture of the movement detection device installed on the fixed object. it can. Therefore, when installing the movement detection device on a fixed object, it is not necessary to consider its posture, and the movement detection device can be easily installed.

  Moreover, since it can be determined whether it moved only with the accelerometer which each detects the acceleration of a triaxial direction as a sensor, it can comprise at low cost.

  According to the second aspect of the present invention, the movement signal is output when the horizontal acceleration exceeds the predetermined acceleration threshold and the speed exceeds the predetermined speed threshold. , Posture change, low-speed movement, and the like can be distinguished from movement.

  According to the third aspect of the present invention, the determination condition of the motion determination means is that the movement variance of each acceleration component obtained from the accelerometer exceeds a predetermined threshold value, so that it is not affected by gravitational acceleration. It is possible to correctly determine whether or not exercise is occurring.

  According to invention of Claim 4, when it determines with the exercise | movement not having generate | occur | produced, power consumption can be suppressed by making operation | movement of a control part into intermittent operation | movement.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram showing the configuration of a movement detection apparatus according to the present invention. In the figure, a movement detection device 10 includes an accelerometer 12X, 12Y, 12Z that detects accelerations in three orthogonal axes, a control unit 14, a non-volatile memory 16 that stores data indicating normality or movement, and a battery. 18 and a power source 20 that generates power for driving the control unit 14 from power supplied from the outside and charges the battery 18.

  This movement detection device 10 is installed in an arbitrary part of a fixed object for monitoring movement, and its installation posture is arbitrary, and three axes (X, Y, Z) of the coordinate system of the apparatus and three unique items of the fixed object. It does not have to coincide with the axis, nor does it need to coincide with the local coordinate system in which the fixed object is installed. Here, the three axes of the local coordinate system are a right-handed coordinate system that includes the XY axes on the horizontal plane and the Z axis is vertically downward.

  The control unit 14 takes in the acceleration detection signals of the accelerometers 12X, 12Y, and 12Z, and outputs the movement signal when the movement is detected. The detection signals of the accelerometers 12X, 12Y, and 12Z are A / D. An A / D conversion circuit 30 for conversion, a CPU 32, a ROM 34, a RAM 36, an I / O driver 38, and a connector 40 are provided.

  As functions executed by the CPU 32, as shown in FIG. 2, an acceleration measuring unit 142 that takes in an acceleration detection signal and obtains a measured value of acceleration of each axis, and a moving variance calculating unit 144 that calculates a moving variance of the measured acceleration value , The movement determination means 146 for determining whether the apparatus 10 and the fixed object are stationary or moving based on the calculation by the movement dispersion calculation means 144, and the apparatus and the fixed object are stationary by the movement determination means 146. When it is determined that the apparatus 10 and the fixed object are moving, the attitude angle calculating means 148 that calculates the attitude angle of the apparatus 10 and the horizontal acceleration that calculates the horizontal acceleration when the apparatus 10 and the fixed object are determined to be moving. A calculation unit 150; an acceleration threshold determination unit 152 for determining whether the acceleration calculated by the horizontal acceleration calculation unit 150 is equal to or greater than an acceleration threshold; and an acceleration threshold determination unit. When the determination result is yes in 152, the speed calculation means 154 for calculating the speed, the speed threshold determination means 156 for determining whether the speed calculated by the speed calculation means 154 is equal to or higher than the speed threshold, and the normal signal or the movement signal Output means 158 for outputting is provided.

  Hereinafter, the operation of the control unit 14 will be described based on the flowchart of FIG.

  When the control unit 14 starts a task, the acceleration measuring unit 142 takes in an acceleration detection signal obtained from each acceleration and calculates the acceleration (step S01). The acceleration measured by the accelerometers 12X, 12Y, and 12Z is a combination of gravitational acceleration input according to the law of universal gravitation and motion acceleration input according to the motion of the device. In the normal state in which the device 10 and the fixed object are completely stationary, only the gravitational acceleration is input. However, when the device 10 and the fixed object move, a motion acceleration is applied.

  The moving variance calculating unit 144 obtains a moving average and a moving variance from the time series values of the accelerations of the respective axes calculated by the acceleration measuring unit 142 (step S02).

  The motion determination unit 146 determines whether or not the movement variance of the acceleration of each axis calculated by the movement variance calculation unit 144 is within a predetermined variance threshold range. If all the axes are within the predetermined dispersion threshold range, it is determined that the apparatus is stationary. If at least one axis is outside the predetermined threshold range, it is determined that the apparatus is moving (step S03).

When the movement determination unit 146 determines that the apparatus is stationary, the posture angle calculation unit 148 calculates a posture angle from the triaxial acceleration measurement values (step S04). The posture angle is represented by a pitch angle and a roll angle of the apparatus coordinate system with respect to the local coordinate system. Now, assuming that the coordinate system of the device is rotated about the Y axis with respect to the local coordinate system by the pitch angle θ and further rotated about the X axis by the roll angle ψ, the accelerometer 12X, the accelerometer 12Y, and the acceleration The accelerations a _x , a _y and a _z detected by the total 12Z are determined by the pitch angle θ and the roll angle ψ.
a _x = g · sinθ
a _y = -g · cosθ · sinψ
a _z = -g · cosθ · cosψ
It becomes. Here, g is a gravitational acceleration at a place installed in the apparatus. From these, θ, ψ, and g are obtained and stored in the control unit 14.

  Then, the output means 158 determines that it is normal, that is, has not moved, and outputs a normal signal to the outside via the I / O driver 38 and the connector 40 (step S05). At the same time, “normal data” is stored in the nonvolatile memory 16.

  On the other hand, when it is determined by the movement determination means 146 that the apparatus 10 is moving, the horizontal acceleration calculation means 150 calculates the horizontal acceleration (step S06).

When horizontal acceleration a _h and vertical acceleration a _v including gravitational acceleration are applied, the acceleration detected by each accelerometer is:
a _x = −a _v · sin θ + a _h · cos θ · cos ξ
a _y = a _v · cos θ · sinψ + a _h · (sinθ · sinψ · cosξ + cosψ · sinξ)
a _z = a _v · cos θ · cosψ + a _h · (sinθ · cosψ · cosξ−sinψ · sinξ)
It becomes. Here, ξ is an angle formed between the input direction of the horizontal acceleration and the X axis of the local coordinate system.

By solving the above equation, the horizontal acceleration a _h can be obtained. Here, the latest values calculated by the attitude angle calculation means 148 are used for the pitch angle θ and the roll angle ψ.

Then, the acceleration threshold determination unit 152 determines whether the horizontal acceleration a _h calculated by the horizontal acceleration calculating means 150 is equal to or acceleration threshold exceeds the acceleration threshold (step S07).

  This acceleration threshold removes acceleration at normal levels such as accelerometer error, vibration due to normal operation of the fixed object with the device 10 or its surroundings, and the natural vibration of the building where the fixed object is installed. Set it to a value that you can do. This makes it possible to distinguish between movement and non-movement movement.

  If the determination result by the acceleration threshold determination unit 152 is No, it is determined that the movement is not a movement, and the process proceeds to step S05.

  On the other hand, when the determination result by the acceleration threshold value determination unit 152 is Yes, the speed calculation unit 154 obtains a speed equivalent amount corresponding to the speed by time-integrating the horizontal acceleration (step S08). However, the speed equivalent amount may be a time integral of the motion acceleration from which the gravitational acceleration is removed.

  Next, the speed threshold determination unit 156 determines whether or not the speed equivalent amount calculated by the speed calculation unit 154 exceeds the speed threshold or is equal to the speed threshold (step S09).

  This speed threshold is set, for example, to distinguish a low-speed movement of a fixed object due to an earthquake having a predetermined seismic intensity or less (for example, seismic intensity 6 or less), a large vibration, a layout change, etc. as a movement. Is set to a value corresponding to an inappropriate slow speed. This makes it possible to distinguish between movement and non-movement movement.

  When the determination result by the speed threshold determination unit 156 is No, it is determined that the movement is not performed, and the process proceeds to step S05.

  On the other hand, when the determination result by the speed threshold determination unit 156 is Yes, it is determined that the movement is performed, and the output unit 158 sends the movement signal to the I / O driver 38 and the connector 40 in response to an external request or regardless of the request. To the outside (step S10). At the same time, “movement data” is stored in the nonvolatile memory 16. Thereafter, the task activation of the control unit 14 is stopped.

  This movement signal is input to a control circuit that controls a fixed object, for example, as a trigger signal for any crime prevention operation that disables the operation of the fixed object or erases electronic data stored in the fixed object. Can be used.

  As described above, in this embodiment, when it is determined that the apparatus 10 is stationary, the posture angle is calculated and stored using the acceleration measurement value of each axis, and using this posture angle, When it is determined that the device is moving, the horizontal acceleration is obtained, and since the movement is determined based on the horizontal acceleration, the device 10 is installed in a fixed object in any posture. Even if it is, horizontal acceleration can be calculated | required. Therefore, when the apparatus 10 is installed on a fixed object, it is not necessary to consider its posture, so that the apparatus can be installed easily.

  Also, an acceleration threshold value and a speed threshold value are set. The acceleration threshold value is a dead zone for horizontal acceleration, and the speed threshold value is a dead zone for speed. By providing this dead zone, as described above, it is possible to distinguish between movements such as earthquakes, errors, vibrations, posture changes, and low-speed movements, and movements.

  Further, as a determination condition of the movement determination unit 146, it is a condition that the movement dispersion of each acceleration component obtained from each accelerometer is within a predetermined dispersion threshold range. Therefore, it is possible to correctly determine whether or not exercise is occurring. However, the present invention is not limited to this, and any determination condition can be adopted. For example, the determination can be made by determining whether or not the change in the magnitude of acceleration (the square root of the sum of squares of each acceleration) is greater than a predetermined threshold.

  Under the situation where the apparatus 10 and the fixed object are likely to be moved, it can be expected that the supply of electric power from the outside will be lost. As described above, when the power supply 20 is not supplied with external power, the power from the battery 18 is supplied to the control unit 14.

  At this time, a sleep mode for saving the power consumption of the battery 18 can be adopted, and the control unit 14 can include a wake-up timer means 160 for that purpose. And the determination result of the exercise | movement determination means 146 can be used as determination of whether it transfers to sleep mode. When it is determined by the motion determination means 146 that the apparatus is stationary, when a normal signal is output from the output means 158, the wake-up timer means 160 starts measuring a predetermined time, and the task activation is stopped. Since the task is activated after a predetermined time has elapsed, a series of processes by each means of the control unit 14 is an intermittent operation.

  On the other hand, if it is determined by the exercise determination unit 146 that the apparatus is exercising, task activation is repeated at the same basic period as when there is an external power supply shorter than the predetermined time, and the exercise determination unit 146 No transition to sleep mode is made until it is determined that the camera is stationary.

  Thus, when it is determined that no movement of the device 10 has occurred, the operation of the control unit 14 is set to an intermittent operation, so that power consumption can be saved. This intermittent operation can also be employed when there is a normal external power supply.

  Once the control unit 14 detects the movement, even if the stationary object is stationary and external power is supplied again, the control unit 14 reads the “movement data” stored in the nonvolatile memory 16, and the output unit 158 In order to output a movement signal, a crime prevention operation of a fixed object can be performed.

It is a schematic block diagram which shows the structure of the movement detection apparatus by this invention. It is a functional block diagram showing the function of the control part of the movement detection apparatus by this invention. It is a flowchart showing the process of the control part by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Movement detection apparatus 12X, 12Y, 12Z Accelerometer 14 Control part 142 Acceleration measurement means 144 Movement dispersion | distribution calculation means 146 Motion determination means 148 Attitude angle calculation means 150 Horizontal acceleration calculation means 152 Acceleration threshold value determination means 154 Speed calculation means 156 Speed threshold value determination Means 158 Output means

Claims (4)

A movement detection device installed on a fixed object,
An accelerometer that detects accelerations in three axial directions,
A control unit that detects movement from three-axis acceleration detected by the accelerometer,
The controller is
Acceleration measurement means for acquiring an acceleration detection signal from the accelerometer and obtaining a triaxial acceleration measurement value;
Movement determination means for determining whether the movement detection device is stationary or exercising based on the acceleration measurement value;
A posture angle calculating means for calculating a posture angle of the movement detecting device using the three-axis acceleration measurement values when the motion determining means determines that the device is stationary;
When it is determined by the motion determination means that the movement detection device is moving, the posture angle of the movement detection device calculated by the posture angle calculation means when the movement detection device is determined to be stationary is used. Horizontal acceleration calculating means for calculating horizontal acceleration,
And a movement detection device for determining whether or not the vehicle is moving based on the horizontal acceleration calculated by the horizontal acceleration calculation means. The controller is
Acceleration threshold determination means for determining whether the horizontal acceleration calculated by the horizontal acceleration calculation means exceeds a predetermined acceleration threshold;
A speed calculation means for calculating a speed from the acceleration measurement value when it is determined by the acceleration threshold value determination means that a predetermined acceleration threshold value is exceeded;
Speed threshold determination means for determining whether the speed calculated by the speed calculation means exceeds a predetermined speed threshold;
An output means for outputting a movement signal when it is determined by the speed threshold determination means that a predetermined speed threshold has been exceeded;
The movement detection apparatus according to claim 1, further comprising: The control unit includes movement variance calculation means for calculating the movement variance of the acceleration measurement value obtained by the acceleration measurement means,
The movement detection apparatus according to claim 1, wherein the movement determination unit determines that the movement detection apparatus is moving when the movement variance exceeds a predetermined threshold value.   The said control part performs a series of processes by each said means intermittently, when it determines with the said movement determination means that a movement detection apparatus is still, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. The movement detection device according to item.

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