GB2411472A

GB2411472A - Industrial vibration monitor attached to body of operator

Info

Publication number: GB2411472A
Application number: GB0404247A
Authority: GB
Inventors: Roy Wyatt
Original assignee: South West Highways Ltd
Current assignee: South West Highways Ltd
Priority date: 2004-02-26
Filing date: 2004-02-26
Publication date: 2005-08-31
Anticipated expiration: 2024-02-26
Also published as: GB0404247D0; GB2411472B

Abstract

A vibration monitor 1 for monitoring the exposure of an operator to vibration (eg caused by power tools, pneumatic cutting tools, machinery) can be attached to the operator's arm, wrist or leg (eg by a strap 16). A sensor measures the magnitude and frequency of the vibration and stores time and date stamepd data in flash memory. Data may be downloaded to an external unit (eg PC) via a serial communications link for analysis. A spectrograph is generated and the exposure of the user over a period of time is determined. The monitor may also include a temperature sensor.

Description

241 1 472 Vibration exposure monitoring device and method This invention

concerns a vibration monitor for monitoring the exposure of an operator to vibration, and a method of monitoring exposure to such vibration. s

Power tools, for example pneumatic cutting tools, can produce large vibrations in an operator's hands and arms. These vibrations can induce industrial diseases such as Hand and Arm Vibration Syndrome (HAVS).

If power tools or machinery are likely to produce vibrations of a level and frequency that may cause industrial diseases then there is a duty on the employer to monitor the exposure of the employee to these vibrations and record these levels. This is normally carried out by the employee who is expected to keep a log of times of exposure, the type of tool used and other factors required to identify the cause, level and duration of vibration. This can be very inaccurate and time-consuming.

It is an object of the present invention to provide an automatic means for logging the vibration exposure levels, frequency and duration.

In accordance with a first aspect of the present invention there is provided a vibration monitor for monitoring the exposure of an operator to vibration, comprising attachment means for attaching the monitor to the body of the operator, a vibration sensor for detecting vibration and which produces in use data indicative of the vibration and data storage means for storing the vibration data.

Advantageously, the sensor in use detects the magnitude and or frequency of the vibration.

Preferably, the vibration is sampled intermittently.

Processing means may be provided to process the data from the sensor, which may then be stored in the storage means.

Communications means may be provided to allow stored data to be passed to an external device.

In a preferred embodiment, the attachment means, in use, attaches the monitor to a wrist of the operator. Alternatively, it may be attached to a leg of the operator.

A temperature sensor may be provided for measuring the body temperature of the operator.

According to a second aspect of the present invention, there is provided a method of monitoring the exposure of an operator to vibration, comprising the steps of: a) attaching a monitor to the body of the operator, b) sensing the vibration of the monitor, c) producing data indicative of the vibration, d) storing the data.

Advantageously, the magnitude and or frequency of the vibration is sensed.

Preferably, the vibration is sampled intermittently.

The data may be processed before being stored.

The stored data may be communicated to an external device.

Preferably, at least one spectrograph is constructed from the data. This may be analysed to produce vibration magnitude and or frequency values. A series of spectrographs may be analysed to determine the exposure level for the operator over a period of time.

The invention will now be described by way of example with reference to the following figures, in which: Figure 1 shows a schematic diagram of the components of the inventive monitor; Figure 2 shows a schematic sectional plan view of the monitor; and Figure 3 shows a schematic sectional side view of the monitor.

Figure l shows in schematic form the main components of a vibration monitor l according to an S embodiment of the present invention. The monitor l is a discrete "package" that may be worn by an operator e.g. of a power tool that produces vibration, for example on the arm, wrist or leg.

There are essentially three parts to the monitor l: a sensor arrangement 2, microprocessor 3, and memory section 4. The sensor arrangement 2 includes a sensor 5 that can measure both the magnitude of vibration and its frequency. Various sensors suitable for this purpose are well l O known in the art. Data relating to the magnitude and frequency of the vibration are produced by the sensor 5 and passed, via interface 6, to an input buffer and filter 7 of the microprocessor 3.

Here, the data are filtered and the size of the data sample is controlled. The frequency that the sample is taken at may also be controlled. The filtered data are sent to an analogue to digital converter 8 to produce digital data, the sampling rate being controlled by timer 9. The digital data are passed to a further buffer l O. Time information is added to the data in the form of a time and date stamp 1 1. The data set is stored in the flash memory 12, from where it may be retrieved as required, so as to be downloaded to an external device via a serial communication link 13.

The whole device is powered by a battery 14.

Figures 2 and 3 respectively show schematic plan and sectional views of the physical assembly of the monitor. The monitor 1 includes an outer case 15 in which components are housed. The case 15 is mounted onto a strap 16 which enables the monitor to be secured to the arm, wrist or leg of an operator as desired. The case contains battery 14 and a circuit board 17 on which the electrical components 18 are mounted. The circuit board / components are advantageously surrounded by a potting compound 19 to improve the durability and electrical isolation of the components. It is important aspect of the invention that the monitor is small enough to be worn by an operator without discomfort, and the monitor shown in the figures would typically have a diameter of about 33mm and a thickness of about 8mm.

In use, an operator, for example a power-tool operator, would attach the monitor to their arm, wrist or leg prior to working the tool. This allows the vibration at various positions to be assessed. The sensor detects the magnitude and frequency of the vibration at the place of attachment. The microprocessor unit processes the data from the sensor which is stored in the flash memory. At a later date the monitor can be interrogated and the data downloaded to an external unit, for example a personal computer (PC). From the downloaded data the exposure levels and times are derived. This information can then be used to update personnel records.

Typically, the monitor samples the vibration magnitude and frequency at a regular rate during the day, for example at ten second intervals. At these regular intervals a small sample of vibration is measured. The duration of the sample is proportional to the frequency range of interest, and typically a one second sample is taken. This mode of operation reduces the memory required such that many working days of data can be held within the memory of the device. The sample is converted to a digital format and stored with a time / date stamp in the memory of the device.

IS The stored data can be accessed via a communications port on the device and serial communication link 13. The data is downloaded and filtered and a spectrograph generated for each sample. By assessing the spectrograph the magnitude and frequency of the vibration is determined, and by integrating a series of spectrographs the exposure level for the operator over a working period is determined. Examination of the spectrograph also indicates the condition and operating performance of the tool.

The stored data may also be used to identify the type of tool being used and identify changes in the nature of its vibrations such that any increases in vibration level can result in the tool being removed from use.

Although the invention has been described with reference to the embodiments above, there are many other modifications and alternatives possible within the scope of the claims.

For example, rather than merely storing data for assessment at a later date, the monitor may communicate the vibration to an external device in real time, for example using a radio communication link. This set-up allows the vibration level of the tool to be automatically adjusted during use, for example by adjusting the power supply, whether electric, pneumatic or hydraulic, to the tool.

In addition, the monitor may comprise a plurality of sensors, so that vibration can be measured in various components of direction. This embodiment enables a more detailed assessment ofthe tool's performance, and may indicate if the operator is using the tool incorrectly.

A temperature sensor may also be connected to the device, which may be housed in the monitor or separately attached to the body of the operator. This allows temperature measurements to be taken concurrently with the vibration measurements, so that the body temperature ofthe operator may be monitored, providing a direct indication of the physical well-being of the operator.

Claims

Claims 1. A vibration monitor for monitoring the exposure of an operator

to vibration, comprising attachment means for attaching the monitor to the body of the operator, a vibration sensor for detecting vibration and which produces in use data indicative of the vibration and data storage means for storing the vibration data.
2. A vibration monitor according to claim 1, wherein the sensor in use detects the magnitude of the vibration.
3. A vibration monitor according to either of claims 1 and 2, wherein the sensor in use detects the frequency of the vibration.
4. A vibration monitor according to any preceding claim which samples the vibration 1 5 intermittently.
5. A vibration monitor according to any preceding claim including processing means to process the data from the sensor.
6. A vibration monitor according to claim 5, wherein data storage means stores the processed data.
7. A vibration monitor according to any preceding claim, comprising communications means to allow stored data to be passed to an external device.
8. A vibration monitor according to any preceding claim, wherein in use the attachment means attaches the monitor to a wrist of the operator.
9. A vibration monitor according to any of claims 1 to 7, wherein in use the attachment means attaches the monitor to a leg of the operator.
10. A vibration monitor according to any preceding claim, comprising a temperature sensor for measuring the body temperature of the operator.
A method of monitoring the exposure of an operator to vibration, comprising the steps of: a) attaching a monitor to the body of the operator, b) sensing the vibration of the monitor, c) producing data indicative of the vibration, ] O d) storing the data.
12. A method according to claim 11, wherein the magnitude of the vibration is sensed.
13. A method according either of claims 1 1 and 12, wherein the frequency of the vibration is sensed.
14. A method according to any of claims 11 to 13, wherein the vibration is sampled intermittently.
15. A method according to any of claims 1 1 to 14, wherein the data is processed before being stored.
16. A method according to any of claims 1 1 to 15, wherein the stored data is communicated to an external device.
17. A method according to any of claims 11 to 16, wherein at least one spectrograph is constructed from the data.
18. A method according to claim 17, wherein the at least one spectrograph is analysed to produce vibration magnitude and or frequency values.
19. A method according to claim 18, wherein a series of spectrographs is analysed to determine the exposure level for the operator over a period of time.
20. A vibration monitor as herein described with reference to accompanying Figures 1 to 3.
21. A method for monitoring exposure to vibration as herein described with reference to accompanying Figures 1 to 3.