JP2000041964A - Portable electronic data collecting device for monitoring musculoskeletal stress - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect many kinds of musculoskeletal stress data simultaneously by providing a visual display that displays simultaneously the digital values of channels selected by a user as a function of time, and depicts them graphically in real time. SOLUTION: The measuring unit 2 communicates with a portable computer 17 through a cable 19 connected between a serial port 15 located in the measuring unit 2 and a serial port 20 located in the computer 17. The measuring unit 2 includes eight force sensors 11, two four-direction angle gauges 10 as individual input ports to four groups of EMG sensors 9. All of a plurality of sensors or the number of sensors selected by a user can be used in each data collection period. The number of specified sensors corresponding to the measurement of forces, angular positions, and EMG, related to each of the sensors 9, 10, 11, is displayed in real time on the liquid crystal display 3 of the measuring unit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates generally to portable biofeedback units and, more particularly, to some types of human musculoskeletal stress.
The present invention relates to a portable electronic biofeedback device and method for collecting and simultaneously displaying information on the level of tal stresses.

[0002]

2. Description of the Related Art In recent years, (Repeated stress damage (Repet
active Stress Injuries: RSI
s)) Cumulative trauma disorder (Cumul)
active Trauma Diorders: CT
The number of reported musculoskeletal disorders related to work such as Ds) is increasing. Some risk factors that contribute to the development of RSIs include work repetition rate, speed, acceleration, and applied force. A common RSI is carpal tunnel syndrome, a condition characterized by a thickened protective sheath surrounding each key of the wrist that controls finger movement. Carpal tunnel syndrome can be caused by repeated bending and stretching of the wrist.

[0003] Workers are susceptible to obstacles from ongoing repetitive tasks. Striking is an example of a task that requires a person to perform every few seconds the same exercise pattern as a task that requires the use of vibrating equipment or a task that workers repeatedly handle heavy objects.

Increasingly, employers are using RSIs and RSIs
These jobs and products with risk factors for RSIs are being investigated to determine the extent to which the potential exists. Therefore, identify exercise and stress within each task or product that can provide patterns of harmful physical stress, and quantify the level of physical stress while performing potentially harmful tasks It is desirable to perform measurement analysis.

Various biofeedback devices are available to assist in collecting data related to musculoskeletal stress. For example, an electromyograph sensor (Electrom
yologic Sensors and Force Sensing Resistors
Measures muscle activity and muscle strength, respectively, and the position sensor measures posture. Typically, a biofeedback unit utilizes one type of device to translate a particular physical activity of a person into an electrical signal and displays a signal representation in a form understandable to the person whose activity is being monitored.

[0006] Certain known biofeedback units use an electrode placed on the skin on one or a group of muscles to be monitored to provide electromyography (EMG) activity, ie, the electrical conduction of the muscle during contraction. Measure activity. Another type of biofeedback unit, a goniometer, provides feedback on the angular position, or posture, of a human body joint. Further, sensing vibration by attaching a vibration accelerometer to a body part, and a variable force sensing resistor (FSR)
It is well known to use s) to sense the level of force between a part of the human body, such as a fingertip, and another object, such as a keyboard. EMG electrodes, goniometers, vibration accelerometers and FSRs
Are off-the-shelf products, all available from various sources.

[0007]

However, a portable biofeedback system capable of simultaneously collecting various types of musculoskeletal stress data has not been available at present. For example, a biofeedback unit that measures pressure, muscle activity, and posture at the same time provides the muscle force (Ef) needed to maintain a certain force during work.
It offers the advantage that researchers can determine the position and attitude at a glance.

[0008] Also, utilizing separate portable devices to measure one or more types of activity is tedious and time consuming, and many biofeedback systems require the user to have a large and complex calibration procedure prior to each use. Request to do. Therefore, such systems are not generally suitable for use in the measurement of musculoskeletal stress on the job at work, and they are ergonomic in product design and / or
Or it is not useful to immediately check the efficacy.

[0009]

SUMMARY OF THE INVENTION The features and novel features of the invention will be set forth in the description which follows, and it will be obvious to those skilled in the art that the following experiments will make them partly apparent or will be learned through practice of the invention. I can do it. The features of the invention may be realized and attained by means of the instruments and combinations particularly pointed out in the appended claims.

In accordance with the present invention, these and other objects are ameliorated by a portable electronic data acquisition device that includes dissimilar sensors that convert musculoskeletal activity into electrical signals, each sensor being input to a channel. The A / D converter samples the electrical signal from the channel selected by the user at a predetermined rate, and as a result, obtains the digital value of the electrical signal. A processor centrally controls the collection and display of digital data. A memory in communication with the processor receives and stores the digital values. Some general features of the preferred embodiment include a first visual display, which may be a computer monitor that simultaneously graphs the magnitude of the digital value of the channel selected by the user as a function of time.

[0011] A second visual display, which may be a liquid crystal display, can show a real-time numerical representation of the level of musculoskeletal activity being monitored to the user of the unit.

The memory may be a cable, a radio frequency connection, or a portable computer manufacturer's computer interface association (Personal Computer Manufacturer) that is accepted by both the memory and the processor.
cturers computer interface
The processor can be contacted via an eAssociation (PCMCIA) card. The stored signals can be analyzed to identify potentially deleterious patterns of repetitive stress.

In a preferred embodiment, the different sensors of the present invention include an EMG surface electrode that measures electrical muscle activity, which can be passive (non-amplified) or amplified, and a portion of the human body contacting the subject. It has variable force-sensing resistors (FSRs) for measuring the force applied and a goniometer for measuring the angular position, velocity and acceleration of the body joint. The variable force sensing resistor may be replaced by a vibration accelerometer that measures vibration activity.

In a further embodiment, the unit can be calibrated by adjusting the output level of the unit to substantially match the sampled maximum and minimum values of the various signals being measured. Provide all output information as percentages of maximum and minimum values.

According to another aspect of the present invention, a method for simultaneously collecting data on several different types of musculoskeletal stress includes a method for measuring muscle activity, which is a force signal associated with a portion of a human body in contact with a subject. And an EM associated with at least two of the angular position signals associated with the body joint position.
Simultaneously sensing the G signal and sampling the signal at a predetermined rate to obtain a digital value of the signal at discrete points in time, the sampling rate of the signal being selectively adjusted by a person using the unit; Storing the digital values and graphing the magnitude of the different digital signals simultaneously and in real time as a function of time.

Still other objects and features of the present invention will become readily apparent to those skilled in the art from the following description. In the following description, only the preferred embodiments of the invention are illustrated and described, by merely denoting what appears to be the best mode for practicing the invention. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting.

[0017]

1 shows a portable electronic data acquisition system 1 constructed in accordance with a preferred embodiment of the present invention. The measurement unit 2 communicates with the portable computer 17 via a cable 19 connected between a serial boat 15 located on the measurement unit 2 and a serial port 20 located on the computer 17.

A force sensor 13, a goniometer 12, an electromyograph (EM)
G) Multiple dissimilar sensors, such as sensor 7, convert musculoskeletal activity into electrical signals. The force sensor 13 is a force sensing resistor (FSR) and measures an external force of a body part with respect to a target. The resistance of the FSR varies inversely with the amount of force applied to the FSR.

When the goniometer 12 is placed on the body joint surface,
The angular deviation of the joint from the neutral position in two mutually perpendicular directions is measured, and the degree of rotation of the joint is also measured. The electrical signal changes as a function of joint position. Location measurements can be integrated to determine velocity or acceleration values that, in addition to location, are also potential risk factors for repetitive stress disorders (RSIs).

The EMG sensor 7 is a surface electrode that measures the electrical activity generated by muscles when placed on the skin above the muscles of a person. The electrical signal is proportional to the amount of muscle exercise. The surface electrode 7 may be of a passive type (ie, non-amplified) or an amplified type. The three electrodes 7 are used to measure the activity of one muscle. Muscle contraction creates a potential difference between the two electrodes 7a, 7c, and the third electrode 7b is maintained at a reference potential and is preferably grounded. Typically, two electrodes are placed on the muscle when activity is measured, and a third is located at a distance from the muscle, for example at a bony prominence such as an elbow. Each electrode 7a, 7b, 7c is coupled to a connector, for example, an alligator clip 8.

The measuring unit 2 comprises eight force sensors 11
, Two 4-directional goniometers 10, and four groups of EMs
A separate input port for the G sensor 9 is included. All of the plurality of sensors or a number selected by the user can be utilized during each data collection period. The force, angular position, and number corresponding to the EMG measurement associated with each of the sensors 9, 10, 11 of the particular group are displayed in real time on the liquid crystal display 3 on the face of the measurement unit 2. The increase button 6 allows the user to enter the sensors 9, 10,
Eleven groups can be selected, which are displayed on the liquid crystal display 3. The unit has a power on / off button 5 for controlling the battery 14 and the battery 1
4 has an A / C power adapter 50 for changing the A / C power adapter.

A portable computer 17, preferably an IBM compatible machine, provides a force, angular position or E measured by each sensor and grouped by sensor type.
Receive and store data corresponding to MG activity. Instantaneous Measurement (Instantaneous Measurement)
In addition to the ents), the time-weighted average and peak point values are continuously updated by the computer 17 and all data is simultaneously displayed graphically in real time on the computer monitor 16. A system application program (not shown) provides a user-friendly interface for scaling and data acquisition (described below). Further, the program may analyze the stored data to identify potentially deleterious patterns and / or levels of repetitive stress. In the preferred embodiment, the system application program runs on Dos Windows.

As shown in FIG. 2a, the system application program allows the user to calibrate the channel 72, collect data while displaying the data in a graphical format 74 or a numeric format 76, and convert the binary data file into an ASCII text format 78. To provide a main menu screen 70 with options to change the data acquisition rate 79.

The system application program also supports a scaling program. FIG. 2b shows, through a simple routine, the user of the system, the EMG sensor 82, the FSR sensor 8 used during the measurement period.
4 shows a sampling screen 80 for guiding initialization of the goniometer 86. Each channel shown corresponds to one measurement input. The calibration screen is used to select the channel to be used. The user supplies a minimum and maximum level of input to each sensor, and the calibration program adjusts these measurements to the system output level such that all output information is provided as a percentage of the sampled minimum and maximum values. Used for Software programs that perform the above are well known to those skilled in the art.

FIG. 3 is an electrical diagram of the feedback unit shown in FIG. Multiplexers receive electrical signals from force sensing resistor 13, EMG electrode 7 and goniometer 12. The outputs 22, 23 of the two multiplexers 21a, 21b associated with the EMG electrode 7 are
4 is input. The operational amplifier 24 has a filter amplification signal 25 representing the contraction level of the muscle where the EMG electrode 7 is located.
I will provide a.

Filter EMG signal 25 and force sensing resistor 1
The output 26 of the multiplexer 21 associated with 3
Is a first A / D converter 2 that alternately samples signals 25, 26 at an adjustable rate up to 1000 Hz.
7 is input.

The second A / D converter 29 includes a goniometer 1
2 from the multiplexer 21 associated with
0 is received and the signal 30 is sampled at an adjustable rate up to 124 Hz.

The processor 32 receives the digital signal 28 from the first A / D converter and the digital signal 31 from the second A / D converter and provides a numerical representation of the base 10 of the digital signal of the selected channel. Are simultaneously displayed on the liquid crystal display 3, and the signal is transmitted to the portable computer via the RS-232 cable 19.

The digital signal can also be transmitted to a portable computer via a radio frequency link.
In addition, the unit can be configured to accept a removable personal computer manufacturer's computer interface association (PCMCIA) card that fits into the memory slot of a portable computer, eliminating the need for a direct link to the computer during the data collection phase. It is.

The processor 32 includes an A / D converter 2
7. Supply control signals 33, for example, clock signals and various reference voltages, to components such as 7, 29 and auxiliary amplifier 24. A power supply 14 such as a battery supplies power to the processor 32.

FIG. 4 is a side view of a human hand having three types of sensors connected to the unit 2 of the present invention and to which they are fixed. Five force sensing resistors 13 attached to the fingertip 40 measure the force at which the fingertip 40 contacts an object, for example, a keyboard (not shown). One goniometer 12, which is arranged on the back of the wrist 41, measures the angular deviation of the wrist from the neutral position in two mutually perpendicular directions (up and down and left and right) as the wrist rotates. One set of three EMG sensors 7, 8 arranged on the forearm 42 (although only one sensor is shown)
Detects the underlying muscle contraction.

FIG. 5 shows a real-time graphical visual display of the computer monitor 16, which represents the magnitude of the force and EMG measurements associated with each sensor in a particular group of sensors 90, 91 as a function of time. I have. The graphical display shows two channels of EMG data 90 and FSR data 91
Feature two channels. Software modules that accomplish the graphical display are well known to those skilled in the art.

The data shown in FIG. 5 was collected when the operator was holding an electric drill trigger with four short pulses. One EMG electrode was mounted on the extensor digitorum and the other was positioned on the flexor muscle. One FSR was on the drill trigger and the other was on the handle under the palm and facing the trigger.

With the simultaneous graph display, the operator can
The correlation between MG and FSR measurements can be observed immediately, allowing a complete analysis of the muscle effort required to maintain a specified force over a period of time. Such an analysis
This is not possible if each measurement is performed and / or displayed individually.

As will be appreciated by those skilled in the art, the present invention can be implemented with multiple sensors. EMG sensors and angle measurements may help to identify the physical cause of dangerous muscle stress, but for example, to quickly determine the effect of passing a certain time in a dangerous posture while experiencing the use of force. FSRs and angle measurements can be used to analyze.

[0036]

According to the portable electronic data collection device for monitoring musculoskeletal stress of the present invention, since various kinds of musculoskeletal stress data can be collected simultaneously, it is necessary to maintain a specific force during work. The researchers can determine at a glance the force and posture of the muscles. Further, it is convenient because it is not necessary to use a plurality of devices as in the related art.

[Brief description of the drawings]

FIG. 1 is a biofeedback unit configured in accordance with a preferred embodiment of the present invention.

FIG. 2a is a visual display providing a main menu to a user of the biofeedback unit.

FIG. 2b is a visual display that guides the user of the biofeedback unit through a calibrating process.

FIG. 3 is a schematic electrical diagram of the unit of FIG. 1;

FIG. 4 is a side view of a human hand secured to a biofeedback unit of the present invention having three dissimilar sensors connected thereto.

FIG. 5 is a visual display that graphically displays the magnitude of an electromyograph and a force signal as a function of time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable electronic data collection system 2 Measuring unit 3 Liquid crystal display 7 EMG sensor 9 EMG sensor 10 Angle meter 11 Force sensor 12 Angle meter 13 Force sensor 17 Portable computer 19 Cable

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Cynthia Ross Massapeake, New York, USA Hampton Boulevard 118 (72) Inventor, Dennis A. Mitchell Huntington, Oakwood Road 40, New York, United States F Room No. 3 (Reference) 4C027 AA04 BB03 CC00 EE03 FF01 FF02 HH04 HH11 JJ00 KK00 KK03 KK05 4C038 VA20 VB11 VB12 VB13 VB22 VC09 VC20

Claims (19)

[Claims] 1. A plurality of dissimilar sensors for converting a plurality of musculoskeletal activities into electrical signals, each of the plurality of sensors being a sensor input to a channel, and a digital value of the electrical signal being temporally different. An A / D converter that samples the electrical signal from a channel selected by the user at a predetermined rate so as to be obtained at discrete points, and a processor that collects the digital value of the electrical signal communicating with the A / D converter. A memory for communicating with the processor for receiving and storing the digital value; and a first visual display for communicating with the processor, wherein the magnitude of the digital value of the channel selected by the user is a function of time. A first visual display for simultaneous display and graphical representation in real time Portable electronic data collection device for case stress monitoring. 2. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 1, wherein said first visual display comprises a computer video monitor. 3. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 1, wherein a rate of the sampling of the electric signal by the A / D converter is controlled by a user of the device. 4. The first plurality of dissimilar sensors comprises: a first sensor for measuring an electromyographic signal associated with a muscle activity communicating with a first A / D converter; and the first A / D converter. A second sensor for measuring a force signal associated with a portion of a human body in contact with an object communicating with the converter, and measuring an angular position signal associated with a position of a body joint communicating with the second A / D converter The portable electronic data collection device for monitoring musculoskeletal stress according to claim 1, further comprising a third sensor that performs the measurement. 5. The portable electronic data collection device for musculoskeletal stress monitoring according to claim 4, wherein said first sensor comprises a passive surface electrode placed on the skin of a person on said muscle where the activity is measured. 6. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 4, wherein said first sensor comprises an amplifying surface electrode disposed on the skin of a person on the muscle where the activity is measured. 7. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 4, wherein the second sensor comprises a force sensing resistor. 8. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 7, wherein the force sensing resistor is arranged on a glove arranged in a human hand. 9. The device further comprises means for calibrating the device such that the output level of the device substantially matches the measured maximum and minimum values of the electrical signal from each channel. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 1. 10. The means for calibrating the device,
10. Store the sampled maximum and minimum values of the electrical signal from each channel for a particular person.
A portable electronic data collection device for monitoring musculoskeletal stress according to the above. 11. The memory is a removable PCMC.
The portable electronic data collection device for monitoring musculoskeletal stress according to claim 1, comprising an IA card. 12. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 1, further comprising a cable connecting the memory to the processor and transmitting the digital value from the processor to the memory. 13. The portable electronic data collection device for musculoskeletal stress monitoring according to claim 1, further comprising a radio frequency connection between said processor for transmitting said digital value from said processor to said memory and said memory. 14. The portable electronic data for monitoring musculoskeletal stress according to claim 1, further comprising means for analyzing digital values stored in said memory so that potentially harmful patterns of repetitive stress can be identified. Collection device. 15. The musculoskeletal stress monitoring system according to claim 1, further comprising a second visual display that communicates with the processor and displays a numerical representation of the digital value from each channel on the data collection device in real time. Portable electronic data collection device. 16. The portable electronic data collection device for monitoring musculoskeletal stress according to claim 15, wherein the second visual display comprises a liquid crystal display. 17. A plurality of dissimilar sensors that convert a plurality of musculoskeletal activities into electrical signals, each of the plurality of sensors being an input to a channel, wherein the channels are grouped according to sensor type. A / Sampling at a predetermined rate the electrical signals of at least two channels selected by the user from a group of different sensor types such that the digital values of the electrical signals are obtained at discrete points in time. A D-converter; a processor for collecting the digital value of the electrical signal communicating with the A / D converter; a memory for communicating with the processor and receiving and storing the digital value; Simultaneously display the magnitude of the digital value of the selected channel as a time function A first visual display graphically depicting an image, a second visual in communication with the processor, and displaying a numerical representation of the digital value of the user-selected channel on the data collection device in real time as a function of time. A portable electronic data collection device for monitoring musculoskeletal stress having a display. 18. A means for simultaneously sensing a plurality of musculoskeletal activities and converting the sensed activities to an electrical signal,
Each of the sensing means comprises at least one input to a channel, wherein the channels are grouped according to the type of sensing means, and at a point where the digital value of the electrical signal is temporally discrete from the sensing means. Means for sampling the electrical signal at a predetermined rate to store the digital values from each channel; and means for centrally controlling the collection, sampling, display and storage of the data collected by the device. A portable electronic data collection device for monitoring musculoskeletal stress, comprising: means for simultaneously and in real time graphically displaying the magnitude of a digital value from each channel as a time function. 19. Simultaneously sensing an electromyographic signal associated with muscle activity, a force signal associated with a portion of a human body in contact with the subject, and an angular position signal associated with a position of a body joint. Sampling the electromyography signal, the force signal and the angular position signal at a predetermined speed so that a digital value of the signal is obtained at discrete points in time, and the electromyography signal, Storing the digital values of the force signal and the angular position signal; and graphically displaying the magnitudes of the digital values of the electromyographic signal, the force signal and the angular position signal simultaneously and in real time as a function of time. Collecting information related to musculoskeletal stress using a portable electronic data collection device.