Individuals may experience reduced range of motion of body members as a result of physical injury or other infirmity. The increase or loss of range of motion is relevant to evaluation of recovery or disability and therefore accurate measurement of the range of motion is critical. The present measurement of the range of motion of body members is performed by a goniometer method which is operated by hand. Such goniometer consists of two metal rules pivoted together at the center of a graduated semicircle protractor type device. The instrument is placed and held by hand on some strategic portion of the body such as the Cervical, thoracic or

Lumbar spine, shoulder, hip, knee and the operator of the goniometer moves the flexible part of the goniometer to correspond with the patient moving the body member through the range of motion permitted by his condition.

In this manner, the operator is measuring the angle of motion. Such method has been used for years in the medical profession but has several accuracy limitations because there is no reference point and the hand-held and operated unit can easily make an error by the movement of the operator's hand or the patient and therefore all results are inaccurate and an error of 10° or more is not uncommon. This deficiency therefore makes the evaluation of the range of motion and corresponding disability with high accuracy, practically impossible.

In order to assist in evaluating or rating permanent disability the American Medical Association has published Guides to the Eva luat ion of Permanent Impairment . 1977, hereinafter Guides. Copies of certain pertinent pages of Guides are attached hereto as Annex A

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and are incorporated, herein by reference. One of the shortcomings of the method set forth is determination of the neutral point. This can be alleviated by the ability of the microprocessor to "zero set" the angular displacement device at any point in time and to make subsequent measurement thereafter. This also assists in use when the patient is in pain or discomfort. As shown on page 42 of Guides the method for measurement of the cervical region is extremely subjective, both in the measuring technique and evaluation. Measurements such as this will be greatly improved by the use of the bevel gear assembly which can translate movement 90°. Therefore, there exists a need for a more accurate instrument or instruments which would reduce the error to 1° or less. This increase in accuracy would be beneficial not only for the treating and evaluating doctors but would be of equal importance to other medical fields such as physical therapy, rehabilitation, insurance claims, etc. and have also other commercial applications in sports, industrial hiring practice, the military, arbitration and litigation.

Several new devices described in this disclosure have been invented to accomplish this desired result and use. All of the devices are measuring the range of motion in degrees but utilize different methods of approach and sophistication.

BRIEF DESCRIPTION OF THE INVENTION

A rang e of mot ion measur ing devic e is provided to increase accuracy in the measurement o f the range of movement of body members. In one embod iment , a movement s en s it ive g ear sy st em i s u s e d in c onj unct ion w ith an infrared l ight syst em to s ens e movement , react to that

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movement and measure with increased accuracy the amount of movement. The gear system uses a counterweight in the form of a pendulum to establish a fixed reference direction relative to the direction of gravity. Subsequent movement of the gear system which is attached to the body member will result in the measurement of the movement of the body member from the reference point. This measurement is accomplished by utilizing a infrared light system to measure the rotation of a gear which results from the gear system responding to the movement of the body member from the reference point. The sensings of the infrared light system are converted into encoded data.

In a similar device, a po entiom ter is utilized which is dependent upon the same pendulum weight theory for continued reference to the vertical plane by gravity.

In another embodiment, a shaft encoder is used to determine the absolute angle. This device also has a pendulum attached to its shaft inside a case attached to the body. The shaft encoder's shaft is rotated and the encoder outputs a binary encoded data work, which changes in value to agree with the new position after the movement of the body member.

The microcomputer accepts the encoded data from either the pot, encoder or gear system, and calculates an absolute difference between the current position and the gravity reference (beginning point) position. The absolute difference may then be displayed on the digital readout and preserved in the internal storage for subsequent printing upon the paper at the time of exam completion.

STITUTE SHEET

DESCRIPTION OF THE DRAWINGS

Figure 1 is a partial cut away view of the gear train of an embodiment of the present invention.

Figure 2 is a side elevation view of either the gear train, potentiometer, or the shaft encoder assembly embodiment attached to a body member.

Figure 3 is a side elevational view of either the gear train, potentiometer or the shaft encoder assembly embodiment attached to another body member. Figure 4 is a perspective/blow-up view of the potentiometer/pendulum angular displacement transducer.

Figure 5 is a side perspective view of the bevel gear assembly.

Figure 6 is a front elevational view of a r presentative microcomputer with visual display and printer.

Figure 7 is a block diagram of inputs and outputs in a representative microcomputer for the range of motion instrument. Figure 8 is a flow chart for the microcomputer with the gear assembly used as the angular displacement transducer .

Figure 9 is a flow chart for the microcomputer- with the shaft encoder used as the angular displacement transducer.

PREFERRED EMBODIMENT OF THE INVENTION

Shown in Figure 5 is a bevel gear assembly shown generally as 86 for translating rotational movement of a body member, such as the head, 90° so that the movement may be imparted to a vertical sensing device such as pendulum/pot 72 or 10 gear train or shaft encoder to detect relative movement from a specific relationship such as that established by gravity. The

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device 10, 72 and the shaft encoder and their representative accessory elements are fully disclosed in other figures. The bevel gear assembly 86 provides for the translation of horizontal rotational movement to vertical rotational movement. A bracket 88 with a pair of handles 90 houses a set of bevel gears for translating movement 90" in a direct one to one ratio. Base gear 92 is pivotally connected in a parallel plane to bracket 88 and contacts with the body member (head) 94 by a non-slip pad (not shown) which rests on the head. Bracket 88 is held generally in place, in a horizontal plane when the head is held erect, by grasping handles 90 and pressing down gently so that the pad contacts the head 94. The pad is directly connected to base gear 92. This device may be used to measure the lumbar back by placing the bevel gear device on the head and while holding the head or neck rigid rotate upper body. As head 94 rotates left or right (in a horizontal plane) base gear 92 likewise rotates horizontally left or right about pivot plane 96. The translating assembly consists of a vertical meshing bevel gear 98, turning arm 100, and securing cradle 102. Meshing gear 98 is connected to bracket 88 and provides for one to one proportional horizontal rotation of turning arm 100. Turning arm 100 is connected to cradle 102 which holds device gear 10 (or pot 72). As head 94 turns the bevel gear assembly will impart vertical movement of device 10 or 72 or about the horizontal axis of arm 100 which is proportioned and corrolated to the horizontal rotational movement of the head. The range of this movement shall be calculated as described predominantly by the microcomputer .

Referring now to Figure 4, there is shown an

alternative embodiment of the angular motion transducer assembly shown generally as 72. A low torque, precision, linear resistance potentiometer 74 is housed in housing 20". The potentiometer 74 is available commercially to provide low torque to suit the requirement of sensing fine movements of body members. A pendulum 76 is rigidly attached to a rotational shaft 78 of the potentiometer, by a set screw 80, all of which is enclosed within the assembly housing 20" by back plate 82. The pendulum is provided sufficient space within housing 20" to rotate freely maintain its position relative to gravity. As a result as the assembly 20" is rotated, the pendulum will remain vertical to impart a rotational force to shaft 78 and, which provides a rotational torque within potentiometer 74. The potentiometer is itself a variable resistor. When the shaft 78 is rotated within the potentiometer there is a change in resistance which results in a change in the voltage output of the potentiometer. The changing voltage can be interpreted by the icrocompu er (not shown here) as encoded data. Potentiometer 74 is connected by electrical connection 84 to the microcomputer which functions as set forth in this disclosure. This embodiment represents the most simplistic embodiment of the invention. The pendulum provides a continuous reference base in which to establish start and record points (freeze point) in the desired movement. The simplicity of the components will render the device generally inexpensive and therefore encourage extensive use. As a result of the continuous interaction between the pendulum and gravity continuous values representing the motion of the member will be recorded within the microporcessor for discrimination to determine the true range of motion or a span of values

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for comparison with previous performances. The use of the potentiometer and pendulum eliminates a great many human induced errors in the measurement and calculation of range of motion. This embodiment also eliminates any requirements for external calibration. The gear frame assembly 20, shaft encoder, and potentiometer may be attached to the body member of the patient by several means as shown in Figures 2 and 3. The various means for attaching the assembly 20 to the body member will vary according to the requirement of attachment dictated by the body member. In Figure 2 is shown a band 36 for attachment to the head of the patient. In Figure 3 is shown an attachment strap 38 for attachment to a forearm. It is essential to the utilization of this invention that the attachment means prevent random

^• movement of the assembly 20.

Referring now to the drawings, and specifically to Figures 1 and 2, the instant invention is shown in a preferred embodiment of the gear and infrared transmitter/detector assembly, which are shown generally as 10 comprising the gear system, shown generally as 12, and infrared light system, shown generally at 14, a logic controller, shown generally as

16 and a display 18 of a microprocessor (not shown). The gear assembly 12 is used to determine, in degrees, the angular rotational displacement from an initial angular reference position. The initial angular reference position can be any position relative to gravity. The subsequent rotation of the gear assembly 12 is converted to degrees and displayed by the microcomputer.

The gear system 12 is composed of a plurality of interconnected gears forming a gear train which are mounted internally in a gear frame assembly 20. the

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interconnec ed gears are mounted in axles which are coaxial so that if one gear is rotated the other gears will rotate in accordance with the established gear ratios. The gear frame assembly 20 also mounts internally the infrared transmitter 22 and detector 24. Gear 26 of the gear system has a counterweight 28 attached to it which establishes the reference point relative to gravity which acts upon counterweight 28. upon movement of gear frame 20, the counterweight 28 will continue to maintain a position in relation to the force of gravity thereby causing gear 26 to rotate. Gear 26 will rotate thereby causing the interconnected gears to also rotate resulting in an angular displacement of gear 30. The gear ratios have been calibrated to cause multiple rotations of the final gear 30 for each one degree displacement of the gear frame assembly 20 which has initiated the internal movement of the gear train. The number of rotations of the final gear 30 can be electrically counted and then mathematically converted to degrees for instantaneous display to the operator by the microcomputer. The final gear 30 of the gear train has at least one hole drilled through it. On either side of the final gear 30 are one or more sets of infrared transmitter/detector pairs. The aforesaid pairs consist of the infrared transmitter 22 and detector 24. These transmitter/detector pairs are placed on opposing sides of gear 30 and coaxial and perpendicular to the face of the final gear 30. As the gear 30 spins on its axle, the hole that is drilled through the gear face passes through and by the beam of the infrared transmitter/detector pairs which is being continuously interrupted by the face of the gear except upon instantaneous passage of the hole 32. The infrared

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transmitter 22 emits a finely focused light beam that travels through the hole 32 when it is aligned between the transmitter 22 and detector 24. At this instant the light beam travels through the hole 32 to the detector

24. then as the gear 30 is continually rotated the light beam is interrupted until the hole travels once again around upon the gear 30. This interruption of the light beam as the gear revolves causes the infrared detector

24 to change state electrically. This electric change of state is analogous to a switch being turned on and off.

The associated microprocessor detects the change of the state of the detector and registers counts equal to the amount of times the light beam has been interrupted. The total count of interruptions can then be mathematically converted to degrees for displaying to the operator. By utilizing additional holes in the gear 30 calculation and conversion may be accomplished for providing for fraction of degrees of displacement thereby providinng greater accuracy.

There is no requirement for external mechanical calibration of this unit in that the gear system is a relative measure of the angular displacement of the gear assembly 20 relative to an established reference position. Once having set the reference position the operator may depress the "zero set" switch and the logic unit will clear internal registers in preparation for the input of count pulses that result from the gear assembly being rotated. This "zero set" will establish the reference point resulting from initial placement of the gear assembly 20 and initial fixing of the counterweight 28 with regard to the force of gravity. Once the reference point has been decided the operator conducts the test requesting the patient to

exert himself in order to accomplish the maximum capable range of motion of the body member. Once the patient has achieved this final position, the sensing system of any of the various embodiments of this invention will calculate the difference between the reference position and the final position to determine the range of motion of the body member. This information concerning the reference position and final position may be encoded in several mediums which may be then decoded by the microcomputer. This difference or range of motion may then be displayed on a digital readout or actually printed.

The shaft encoder transducer also works with the pendulum concept and is housed in a case similar to item 20 of Figure 1. It is attached to the body as in Figures 2 and 3.

The pendulum weight under the influence of gravity does not moves as the case, item 20, figure 1, rotates. The body of the shaft encoder is mounted to the case. As the case rotates, the encoded data output changes representing the current angle of displacement. The encoded data is then input to the microcomputer for decoding and interpretation into degrees of displacement from the absolute starting reference. A custom designed icrocomputer is used to interpret the encoded angular displacement electrical signals. The microcomputer and its remote angular displacement transducers, pot/gears/shaft encoder, comprise a total system which with its programmed operating system reads, interprets and displays the results of the af rementioned range of motion operations. The microcomputer incorporates a crystal time base, input/output channels for digital controls

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and one channel of analog signal processing. The microcomputer utilizes a microprocessor with a memory system comprised of both volatile and non-volatile memory. The microcomputer provides a diagnostic interface to facilitate modular testing of the unit to isolate defective components for later repair or replacement .

The operating system software is, itself, a special design for interpreting the encoded input signals of the angle transducer, the custom worded keyboard 126 and the several control pushbutton switches 128 and provides the instantaneous angular readout 130 as well as the permanent recording of examination result s . Figure 6 shows a representative microcomputer shown generally as 116. The microcomputer unit 116 is used to interpret the encoded angular displacement electrical signals provided by the various angular displacement transducer embodiments previously described, provide the continuous and instantaneous display in true degrees of angular displacement from the established null or reference and provide a printout of examination results. The microcomputer 116 and its remote angular displacement transducer embodiments comprises a total system which with its programmed operating system reads, interprets and displays the results of the a orementioned examinations.

The remote angular displacement transducer provides an input signal to the microcomputer which is conditioned and then processed further by the microprocessor. This encoded data is input into the logic encoder and buffer which accepts the data and calculates the absolute difference between the current

position and the reference position. The absolute difference is then displayed on the digital read-out 130 and preserved in the internal storage for subsequent printing upon the paper in response to the depression of the "point record" switch. Panel switches 128 of the keyboard 126 provide pre-established logic to the logic encoder containing representing words of standard movement body members, such as flexion, extension, and body members such as arm, leg, etc., for printout in conjunction with the range of motion, in angular degrees .

Figures 8 and 9 show the sequence of operation of input and output information initiated by the angular displacement transducer, and interpreted and discriminated by the operation of the microcomputer for ultimate printout and/or visual angular display. As shown in Figure 7 the output of the angular displacement transducer is input into control logic unit 160 whose output is placed into display 176 and printer 182. In the control logic unit 160 the inputs are compared to previous inputs, testing for the largest displacement.

Figure 8 represents the discriminating operation of the software of the microcomputer in the operation of the range of motion system, with the gear system transducer as shown in Figure 1. By use of the microcomputer, the operator is able to instantaneously determine a value with extreme accuracy for the range of motion at a specific point in time while maintaining continuous motion of the body member. In this manner, a specific range of motion could be selected for repetitive and continuous movement for evaluation or rehabilitation. A signaling device could be connected to the logic controller to signal each time the range of

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motion failed to exceed or be limited to a specific value. In this, one could exercise without exceeding or failing to exceed certain limitations. Also the instantaneous evaluation and display allows the operator to continuously check the performance of the patient while he executes continuous movement, or at a specific point in time when pain occurs, motion is restricted or failure of the muscle. The ability to "zero set" the microprocessor prior to movement of the transducer allows a series of related motions to be performed, such as flexing and extending the arm muscle, sequentially and continuously without any further calibration or adjustment of the equipment. In this manner, the evaluation is not restricted to any reference baseline but may select a new one each time the zero set mechanism is activated. The microcomputer also provides the capability to store information and print it at a later time. At step 186, the microprocessor is energized to start the evaluation. At step 188, discrimina ion is made of whether the condition that the reset button has been depressed is satisfied or not. If the result of discrimination is yes, the yes route is followed to step 190. At step 190 the operation of initialize all internal registers to zero is performed. In this manner, a reference baseline is established for subsequent movement of the body member and evaluation by the invention. By initializing all internal registers to zero, the operator may isolate the specific movement of the body member which is desired. Not only is this valuable to evaluating the limitations due to injury but also limitations resulting from muscle development. Undue muscle development may hinder the capabilities of a worker or athlete. By being able to initialize

internal registers to zero, the instant invention is able to measure, record, isolate and store continuous and subsequent movements such as flexion followed by extension. This is an improvement over prior devices which only are calibrated to evaluate a single movement in one direction. At step 192, a discrimination is made of whether the infrared detectors indicate gear motion. If the result is yes, the yes route is followed to steps 195 and 196. If the result is no, the flow takes the no route to return to the beginning of step 192for further discrimination. At step 194, the Increment Revolution counter will count the number of revolutions of the gear wheel by counting the interruptions of the infrared beam. At step 196, discrimination is made of whether the conditions that Revolution Counter = 4 is satisfied or not. If the result of discrimination is yes, the yes route is followed to step 198. If the result is no, the no route is followed returning to the beginning of step 192. At step 198 is obtained the determination of whether the direction pulse is clockwise or not. If the result of the discrimination is yes, the yes route is followed to steps 200 and 202. If the result is no, the flow is followed to step 199. At step 199, the operation of "subtract one degree from storage register" is performed thereafter proceeding onto step 204. If the result is yes, at step 200 the operation of "add one degree to storage register" is performed followed by step 202 where the operation of "store storage register value as max value" is performed. Continuing to follow the yes flow route brings us to step 204 where the operation of "display the current accumulated displacement storage register" is performed. At step 206 is obtained the discrimination of the condition of

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whether the "freeze button is depressed" or not. If the result is yes, the yes route is followed to the output of step 190 (Step B). If the result is no, the no flow is followed to step 208 where the operation of "recall maximum displacement in degrees display" is performed. Following completion of this operation, the program is ended. By use of the Freeze-button operation (step 206) the operator is able to evaluate the range of motion at any point in time of the motion which is unavailable in other models.

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