Patent Publication Number: US-6911012-B2

Title: Apparatus and method for applying a friction massage stroke

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
   Not Applicable 
   REFERENCE TO MICROFICHE APPENDIX 
   Not Applicable 
   FIELD OF THE INVENTION 
   The present invention generally relates to an apparatus and method for applying pressure to a desired portion of a person&#39;s body and, more particularly, to such an apparatus and method for applying a selected friction or shear force on the desired portion of the person&#39;s body. 
   BACKGROUND OF THE INVENTION 
   The benefits of massage and acupressure have been known for centuries. There are many different kinds of massage styles in existence, and each style has some unique massage stroke. An important Swedish massage stroke is known as the friction or shear stroke. The friction stroke is the deepest of Swedish massage strokes. In applying a friction stroke, the masseur&#39;s hands move with the skin instead of gliding across the skin. There are many varieties of the friction stroke such as, for example, this stroke can be done parallel to the deeper muscle fibers (longitudinal friction), in a circular motion over the deeper muscle fibers (circular friction), or across the deeper muscle fibers (cross fiber or transverse friction). Cross fiber friction strokes, in particular, are believed to reduce fibrosis and encourage formation of strong, pliable scar tissue at a healing site of injuries. Cross fiber friction strokes are further believed to reduce crystalline roughness that forms between tendons and their sheaths that can result in painful tendonitis and to prevent or soften myofascial adhesions. 
   There are three modes of friction that can be utilized in a massage stroke: static friction; sliding friction; and rolling friction. Static friction is characteristic of acupressure and Shiatsu where static friction keeps the acupressure contact from sliding across the massage recipient&#39;s body but the primary form of therapy is a force normal to the user&#39;s body. Sliding friction is characteristic of Swedish massage where sliding friction provides a shear force applied to the recipient&#39;s body which is equal in importance to the normal force applied to the recipient&#39;s body. Rolling friction is rarely characteristic of massage by hand but is frequently used by automatic massage systems having massage rollers. 
   Due to static friction, a static friction force is produced which keeps an object, such as a massaging manipulator, at rest while an external force is applied to the massaging manipulator which is less than a static limit. The static friction force is a reaction force, that is, its value depends on the direction and magnitude of the applied external force trying to move the massaging manipulator along the recipient&#39;s skin. The static limit is determined by a coefficient of static friction μ static  multiplied by the normal component of the applied external force. As the applied external force increases, the massaging manipulator “breaks loose” and begins to move relative to the recipient&#39;s skin once the applied external force is above the static limit. The magnitude of the applied external force which overcomes the static friction force is called the starting force. It should be appreciated that, due to static friction, the manipulator can produce a shear force on the recipient prior to movement of the manipulator relative to the recipient. 
   Due to sliding friction (also referred to as dynamic or kinetic friction), a sliding friction force is produced which resists sliding movement of the manipulator when the static limit is overcome and the manipulator is sliding relative to the recipient&#39;s skin. The sliding friction force is less then the maximum static friction force but still has some gripping force on the recipient&#39;s skin. Typically, sliding friction produces heat as the manipulator is moved along the recipient&#39;s skin. 
   Rolling friction is a much more complex. Due to rolling friction, two primary forces are produced which oppose rolling motion of a massage roller, one acts at the roller&#39;s center and the other acts at the area of contact on the user&#39;s skin. The force at the roller&#39;s center is created by rubbing contact at an axle supporting the roller. The force at the contact zone is created by contact between the roller and the recipient and enables the roller to have traction so that the roller rolls along the recipient rather than slips Another important factor is rolling resistance. Rolling resistance is a loss due to roller/skin deformation or compression and not due to drag between the two surfaces. In rolling friction, the molecules on the wheel&#39;s circumference execute cycloidal motion so the molecules in the wheel&#39;s contact area hop along the ground as one molecule lifts off the ground another descends to replace it. Because rolling motion does not theoretically involve sliding, the coefficient of static friction applies in rolling friction as well as in static friction. This static friction is combined with the rolling resistance to create the total skin friction of the roller. This skin friction and the axle friction react with an applied force to allow rolling until a certain limit is reached. A state of skidding or slipping occurs when the limiting force is exceeded. 
   There is a multiplicity of massage devices known in the prior art. These devices range from handheld blocks or immobile probes to automatic massaging chairs and tables having massage rollers. A Backknobber or Jacknobber manufactured by Pressure Positive Company is an example of a typical immobile probe. The probe is used in a stationary fashion as with an acupressure stroke or in a sliding fashion across the recipient&#39;s back. When sliding, the probe generates a large amount of shear or friction force which is useful for cross fiber friction strokes as well as other types of strokes. 
   U.S. Pat. No. 6,283,928 discloses a typical massage apparatus incorporating rollers. The massage rollers are “roller-blade” type wheels that are mounted on a fixed bracket and engage a recipient. As the bracket translates up and down the user&#39;s back the rollers spin freely as they roll along the recipient&#39;s back. The free spinning or rolling motion of the rollers generate only a small amount of shear or friction force. 
   There are massaging roller-type devices which include braking mechanisms but the devices do not transfer a shear force to the user. For example, U.S. Pat. No. 6,213,962 discloses a massage device having two massage rollers mounted on a driven shaft which are rotatable relative to each other. Although the disclosure indicates that “braking means be provided for applying a frictional resistance against the rotation of [one of the rollers relative to the other]” and that a second brake means be provided to prevent the overall shaft from rotating when pressed by the user, both of these brakes do not allow the device to apply shear force to the user. In all embodiments of the device, the rollers are mounted behind a membrane which must be designed to slide freely relative to the rollers. In fact, the inventor notes that “it is preferred that the pair of right and left massaging rollers are coupled to the rotary shaft so as to be rotatable relative to the rotary shaft for preventing unnecessary friction against the affected part and the cover member.” See column 3, line 57. 
   There are also massaging devices with friction brakes which are fixed in the degree of friction which they apply. For example, see U.S. Pat. No. 6,071,253 which discloses a spinal column flexing fixture which has a roller with a friction brake. The brake applies a constant friction force which only applies a predetermined and fixed level of rolling resistance. The level of shear resistance cannot be adjusted without disassembling the device and replacing components. However, the roller does not have means of sensing or dynamically controlling shear forces applied to the user. 
   While each of these prior massaging devices may adequately perform a specific type of massage stroke or other manipulation, they are each limited in the types of massage strokes which they can perform. Accordingly, there is a need in the art for a massage device which is adjustable to selectively produce different magnitudes of shear force so that a larger number of different types of massage strokes can be produces by a single massage manipulator. 
   SUMMARY OF THE INVENTION 
   The present invention provides a massage device which overcomes at least some of the above-noted problems of the related art. According to the present invention, a massage device for manipulating a user includes, in combination, a support member and a manipulator carried by the support member. The manipulator is adapted to engage the user and to apply a shear force to the user when the manipulator is moved relative to the user. The manipulator is rotatable about at least one axis relative to the support member. A brake operably connected to the manipulator selectively adjusts rotation of the manipulator about the at least one axis whereby the shear force applied to the user by the manipulator is adjusted. 
   From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of massage devices. Particularly significant in this regard is the potential the invention affords for providing a high quality, reliable, low cost assembly which can apply an adjustable shear force to a user. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and further features of the present invention will be apparent with reference to the following description and drawing, wherein: 
       FIG. 1  is an elevational view of a device for applying a frictional massage stroke according to a first embodiment of the present invention; 
       FIG. 2  is an elevational view of a device according to a variation of the device of  FIG. 1  wherein a manual control device is utilized to selectively apply a brake; 
       FIG. 3  is an elevational view of a device according to another variation of the device of  FIG. 1  wherein an optical sensor is utilized to detect slippage; 
       FIG. 4  is an elevational view of a device according to another variation of the device of  FIG. 1  wherein an optical sensor is utilized to detect slippage; 
       FIG. 5  is an elevational view of a device according to yet another variation of the device of  FIG. 1  wherein a roller is provided with a drive mechanism; 
       FIG. 6  is an elevational view of an automatic massage chair incorporating the device of  FIG. 1 ; 
       FIG. 7  is an elevational view of an chiropractic therapy table incorporating the device of  FIG. 1 ; 
       FIG. 8  is an elevational view of a device for applying a frictional massage stroke according to a second embodiment of the present invention; 
       FIG. 9  is an elevational view of a device for applying a frictional massage stroke according to a third embodiment of the present invention; 
       FIG. 10  is an elevational view of a device for applying a frictional massage stroke according to a fourth embodiment of the present invention; 
       FIG. 11  is an elevational view of a device for applying a frictional massage stroke according to a fifth embodiment of the present invention; and 
       FIG. 12  is an elevational view of a device for applying a frictional massage stroke according to a sixth embodiment of the present invention. 
   

   It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of a massage device as disclosed herein, including, for example, specific manipulator shapes and specific types of slippage detectors, will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the massage device illustrated in the drawings. In general, up or upward refers to an upward direction within the plane of the paper in FIG.  1  and down or downward refers to a downward direction within the plane of the paper in FIG.  1 . 
   DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS 
   It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the improved massage devices disclosed herein. The following detailed discussion of various alternative and preferred embodiments illustrate the general principles of the invention with reference to several specific embodiments of the present invention. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure. 
     FIG. 1  illustrates a massage device  10  for manipulating and/or massaging a recipient or user  12  according to a first embodiment of the present invention. The illustrated massage device  10  includes a support member  14 , a rotatable manipulator  16  adapted to engage and to apply a shear force to the user  12 , and a brake  18  operably connected to the manipulator  16  to selectively adjust rotation of the manipulator  16  whereby a magnitude of the shear force applied to the user  12  by the manipulator  16  is adjusted. 
   The manipulator  16  is preferably carried by the support member  14  at an end thereof and is rotatable relative to the support member  14  about a rotational axis  20 . The illustrated rotational axis  20  is substantially parallel to the surface of the user  12  which is to be massaged by the manipulator  16 . The illustrated manipulator  16  is a roller  22 , that is, a manipulator  16  which rotates about a single fixed axis to roll along the user  12 . The illustrated roller  22  is cylindrically-shaped but other suitable shapes can be utilized such as, for example, a spherical shape. It is noted that other types of manipulators  16  can be utilized within the scope of the present invention such as, for example, casters. 
   The illustrated brake  18  is mounted adjacent the support member and the roller  22  and includes a piston and cylinder assembly  24  having a brake or friction pad  26  located at the end of the piston. The piston and cylinder assembly  24  is arranged to extend and retract the brake pad  26  into and out of engagement with the roller  22 . When the brake  18  is actuated, the piston linearly extends from the cylinder to engage the brake pad  26  with the roller  22  to resist rotation of the roller  22  about the rotational axis  20 . When the brake  18  is released, the piston linearly retracts toward the cylinder to space the brake pad  26  away from the roller  22  so that the roller  22  is free spinning about the rotational axis  20 . The brake pad  26  is preferably provided with a surface having a relatively high coefficient of friction. The engagement of the brake pad  26  applies a frictional or braking force to the roller  22  to resist rotation of the roller  22 . The piston cylinder assembly  24  can be actuated in any suitable manner such as, for example, a hydraulic actuator, a pneumatic actuator, and/or electric actuator. It is noted that while the illustrated brake  18  is of a linear-action friction type, the brake can be of any suitable type such as, for example, pivoting type, a caliper type, or drum type. 
   The illustrated embodiment includes a translator  28  for moving the manipulator  16  along at least one axis relative to the user  12 . The illustrated translation axis is substantially parallel to the surface of the user  12  to be massaged by the manipulator  16 . The illustrated translator  28  includes a movable carriage  30  upon which the support member  14  and the brake  18  are carried to move the manipulator  16  along a translation path relative to the user  12 . The translator  28  can be of any suitable type such as, for example, a single axis linear translator, an X-Y or two-axis translator, or an X-Y-Z or three axis translator. The translator  28  can be also driven in any suitable manner such as, for example, an electric motor, a pneumatic drive system, a hydraulic drive system, and/or a manual drive system. It is noted that means for providing dynamic intensity control can also be provided such as those disclosed in U.S. Pat. No. 6,752,772, the disclosure of which is expressly incorporated herein in its entirety by reference. 
   The illustrated massage device  10  includes a control system  32  for automatically adjusting the brake  18  to obtain a desired resistance to rotation of the manipulator  16  whereby a magnitude of the shear force applied to the user  12  by the manipulator  16  is automatically adjusted. The control system  32  includes a detector  34  operably connected to the manipulator  16  for detecting or indicating a magnitude or degree of slippage of the roller  22  relative to the user  12  and a controller  36  for automatically operating the brake  18  in response to signals from the detector  34 . The illustrated detector  34  is a strain gauge  38  mounted between the support member  14  and a base  40  to which the support member is secured. The detector  34  is in communication with the controller  36  for providing signals thereto. Another detector  34  may be attached bilaterally to allow motion in either direction. 
   The controller or computer  36  is preferably of the programmable type and is operably connected to the brake  18  for adjustment thereof. During operation, the controller  36  actuates the brake  18  so that a desired shear force is provided to the user  12  by the roller  22 . The controller  36  receive signals from the detector  34  and when the controller  36  determines that the roller  22  is in a slipping condition, the controller  36  automatically varies the braking action of the brake  18  until the slipping condition is eliminated. The braking action can be varied in any suitable manner such as, for example, short alternating pulses of full braking force and no braking force (similar to an automobile ABS brake system) and/or gradual or proportional easing of the braking force. 
     FIG. 2  illustrates a variation of the massage device of  FIG. 1  wherein the control system includes a manual control device  42 . The illustrated manual control device  42  is a push button switch but alternatively can any suitable type of switch. The manual control device  42  is operably connected to the controller  36  so that the user can selectively adjust the braking force applied by the brake  18 . It is noted that the manual control device  42  can be in addition to or in place of the automatic control system  32  described hereinabove. 
     FIG. 3  illustrates another variation of the massage device  10  of  FIG. 1  wherein the detector  34  is an optical sensor  44 . The optical sensor  44  is mounted adjacent the roller  22  and the user  12  to sense movement of the roller  22  and/or the user  12 . The optical sensor  44  provides signals to the controller  36  regarding movement of the roller  22 . The controller  36 , which is in communication with the translator  28  and/or has signals indicating movement of the translator  28 , determines whether the roller  22  is in a slip condition. 
     FIG. 4  illustrates another variation of the massage device  10  of  FIG. 1  wherein the detector  34  is a linear position sensor  46 . The linear position sensor  46  is mounted adjacent the translator  28  to sense movement of the carriage  30 . The position sensor  46  provides signals to the controller  36  regarding movement of the carriage  30 . The controller  36  determines whether there the roller  22  is in or likely to be in a slip condition. It is noted that the linear position sensor  46  is preferably utilized in conjunction with the optical sensor  44  as discussed hereinabove. 
     FIG. 5  illustrates yet another variation of the massage device  10  of  FIG. 1  wherein the roller  22  is provided with a drive mechanism  48  for the roller  22 . The illustrated drive mechanism  48  includes an electric motor  50  operatively connected to the roller  22  with a drive belt  52  to selectively directly drive or rotate the roller  22 . The drive motor  50  is operably connected to the controller  36  so that the shear force of the roller  22  can be controlled directly without translating or moving the translator carriage  30 . The motor  50  rotates the roller  22  until the controller  36  determines from signals of the detector  34  that a desired frictional or shear force is obtained. The motor  50  may provide the controller  36  with torque or current information which are indicative of shear force. 
   The drive mechanism  48  is particularly advantageous when a flexible interface material or membrane  54  is provided between the roller  22  and the user  12  such as, for example, in a massaging chair. The drive mechanism can also function as a take-up or gathering mechanism  56 . This is particularly true when it is desirable to apply friction strokes to the user  12  and the interface material  54  is a non-elastic material. In order to apply friction strokes to the user  12 , the interface material  54  must stick to both the user  12  and the roller  22 , that is, move with the roller  22  without sliding there between. When slipping occurs, the friction stroke is not applied to the user  12 . Therefore, the membrane  54  preferably has a coefficient of friction which substantially prevents sliding of the manipulator relative to the membrane  54 . The driven roller  22  can be used to move the interface material  54  and collect the interface material  54  in a series of pleats  58  before the roller  22  is locked against rotation by the brake  18  for application of a friction stroke to the user  12 . The excess material in the pleats  58  is then utilized to move the material  54  along with the roller  22  when a friction stroke is applied to the user  12 . 
     FIG. 6  illustrates an automatic massage chair  60  incorporating the massage device  10  of FIG.  1 . When incorporated into an automatic massage chair  60 , the braking force is preferably automatically controlled by the controller  36 . The controller  36  is preferably preprogrammed to automatically vary or adjust the braking force applied to the roller  22  by the brake  18  depending on the location on the user  12  being massaged, the preferences of the user  12 , and may ramp up from a small amount of braking force at the beginning of a particular massage session to a larger amount of braking force in the middle of the session, and then back down to a small amount of braking force at the end of the session. 
     FIG. 7  illustrates a chiropractic therapy table  62  incorporating the massage device  10  of FIG.  1 . When incorporated into the chiropractic therapy table  62 , the friction strokes are likely to travel along an inferior to superior user axis. Preferably there are a plurality of wide rollers  22  (collectively spanning the width of the user). At least one of these rollers  22  moves along the user&#39;s inferior to superior axis relative to the other rollers  22 . When the roller  22  moves in one direction for a friction stroke, a braking force is applied to the roller  22  by the brake  18  to increase the friction stroke force to whatever shear force is therapeutic without slipping against the user&#39;s skin or clothing. When the roller  22  moves back in the other direction for a recovery stroke, the roller  22  is preferably permitted to rotate or spin freely without a braking force applied thereto. 
     FIG. 8  illustrates a massage device  64  according to a second embodiment of the present invention wherein like reference numbers are used to indicate like structure. The massage device  64  according to the second embodiment of the invention is substantially the same as the massage device  10  according to the first embodiment of the invention except that different types of the manipulator  16  and the detector  34  are utilized. The manipulator  16  is in the form of a captive sphere or trackball  66  which is rotatable about each and every axis. The brake pad  26  is engagable with the bottom of the sphere  66  to selectively provide resistance to rotation in each axis. The detector  34  is in the form of a rotational sensor  68  which is located adjacent to the sphere  66  to sense movement of the sphere  66  and thereby slippage can be detected. This massage device  64  is particularly useful when incorporated in an automatic massage chair  60  where the translator carriage  30  automatically translates the manipulator  16  over the user&#39;s body. Slip condition is detected when the rotational sensor  68  shows less motion of the sphere  66  than should be occurring for the current translation of the manipulator carriage  30 . 
     FIG. 9  illustrates a massage device  70  according to a third embodiment of the present invention wherein like reference numbers are used to indicate like structure. The massage device  70  according to the third embodiment of the invention is substantially the same as the massage device  10  according to the first embodiment of the invention except that different a type of the manipulator  16  is utilized. The manipulator  16  is in the form of a castor  72  which is essentially the roller  22  with a swivel mechanism  74  added thereto. The swivel mechanism  74  allows the roller  22 , along with its support arms, to rotate about a second rotational axis  76  which is perpendicular to the first rotational axis  20 . The castor  72  has the advantage over the plain roller  22  that the swivel mechanism  74  allows the roller  22  to rotate about the second rotational axis  76  to a desired orientation. This ability to change the orientation of the roller  22  avoids slippage when the roller  22  is moved off a main driven massage axis, that is, when the roller  22  is moved along a translation path other than along a straight line aligned with the roller  22 . Due to the swivel mechanism  74 , the roller  22  automatically reorients itself to the direction of the massage stroke so that the roller  22  continues to roll rather than sliding or dragging. 
   The swivel mechanism  74  can be passive but is preferably provided with a control element  78  operably connected to the controller  36 . The control element  78  preferably includes at least one of an encoder, a drive motor, and a lock. When the swivel mechanism  74  is passive, the swivel mechanism  74  is preferably offset from the roller  22 , that is, the second rotational axis  76  is spaced apart or offset from the first rotational axis  20  rather than intersecting the first rotational axis  20 . The offset allows the translator  28  to reorient the roller  22  by driving the roller  22  as one drives a shopping trolley. When the control element  78  includes an encoder, orientation information is provided to the controller  36  so that the controller knows the current orientation of the roller  22 . When the control element  78  includes the drive motor, the swivel mechanism  74  can be driven by the controller  36  to reorient the roller  22  to match the direction of the massage stroke. In some circumstances, it may be desirable to drag the roller  22  sideways or with a sideways component such as, for example, 45 degrees off the roller path. In this case, the control element  78  orients the roller  22  at the desired angle while the translator  28  translates the manipulator  16  along a different translation path. When the control element  78  includes the lock, the controller  38  can selectively engage the lock so that the roller  22  no longer rotates about the second rotational axis  76  and the roller  22  remains in its current orientation until the lock is disengaged. In operation, the controller  36  can translate the carriage  30  to achieve the desired orientation for the roller  22  and then engage the lock so that the roller  22  remains in the desired orientation regardless of the direction of later translations of the carriage  30 . The carriage  30  can translate in an arbitrary direction achieving a component of slippage at the roller  22  without the roller  22  automatically swiveling to the direction of travel. When the control element  78  includes both the drive motor and the lock, the lock can reduce strain on the drive motor during sideways friction strokes. This may be useful if the drive motor reorients the roller  22  when less normal force is applied enabling the use of a low torque and inexpensive drive motor yet allowing the swivel mechanism  74  to drag sideways without reorienting when desired. It is noted that when the swivel mechanism  74  is passive and aligned on the same axis as the roller  22 , that is the second rotational axis  76  intersects the first rotational axis  20 , it is possible to have rolling motion about the first rotational axis  20  during a dragging friction stroke in the transverse direction without the lock and/or the drive motor. 
     FIG. 10  illustrates a massage device  80  according to a fourth embodiment of the present invention wherein like reference numbers are used to indicate like structure. The massage device  80  according to the fourth embodiment of the invention is substantially the same as the massage device  10  according to the first embodiment of the invention except that different types of the manipulator  16  and the brake  18  are utilized. The manipulator  16  is in the form of a tread assembly  82  having a segmented or continuous flexible belt  84  rotatable about spaced apart wheels or sprockets  86 . The illustrated brake  18  is a sprocket brake  88  located at one of the sprockets  86 . 
     FIG. 11  illustrates a massage device  90  according to a fifth embodiment of the present invention wherein like reference numbers are used to indicate like structure. The massage device  90  according to the fifth embodiment of the invention is substantially the same as the massage device  10  according to the first embodiment except that the manipulator  16  and the brake  18  are each manually operated to form a handheld massage device. The illustrated handheld massage device  90  includes a pair of spaced apart wheels or rollers  22  rotatable supported on a common axle  92 . A handle  94  extends from the axle  92  so that the rollers  22  may be manually translated on the surface of a massage recipient. The brake  18  frictionally engages the axle  92  generating resistance to rotation for both rollers  22 . The magnitude of the braking force is controlled by a manually operated brake handle  96  located at the device handle  94 . The illustrated brake handle  96  is operably connected to the brake  18  by a push-pull or Bowden cable  98 . The brake handle  96  is preferably provided with a lock mechanism which when engages holds the brake handle  96  at a location which provides a desired resistance to rotation. The illustrated lock mechanism  100  includes a threaded rod extending through the free end of the brake handle  96  and a pair of jam nuts on the rod at opposite sides of the brake handle  96 . When the brake  18  is fully disengaged, the brake  18  provides no resistance to rotation and the rollers  22  are freely rotatable about the axle  92 . When the brake  18  is fully engaged, the brake  18  preferably provides enough resistance to rotation to lock the rollers  22  against rotation about the axle  92 . When the brake  18  is between fully disengaged and fully engaged, the brake  18  applies a proportional resistance to rotation. For operation, the brake  18  can be locked to a desired friction force or the brake  18  can be manually operated during the massage to dynamically control the friction force applied to the massage recipient. 
     FIG. 12  illustrates a massage device  102  according to a sixth embodiment of the present invention wherein like reference numbers are used to indicate like structure. The massage device  102  according to the sixth embodiment of the invention is substantially the same as the massage device  10  according to the first embodiment of the invention except that the brake  18  is of a different type which provides a fixed amount of mechanical friction which can be manually adjusted between massage sessions or strokes. The illustrated brake  18  includes resiliently flexible arms  104  supporting an axle  106  of the roller  11  on opposite sides of the roller  22 . Wing or butterfly nuts  108  are provided on threaded ends of the axle  106  at the outer sides of the arms. The position of the nuts determines the degree to which the arms engage the sides of the roller  22 . Preferably, the nuts  108  can be positioned so that the arms  104  are disengaged from the roller  22  so that the roller  22  is freely rotatable and can be positioned so that the arms  104  engage the roller  22  with enough resistance to rotation that the roller  22  is locked against rotation. Preferably, engagement surfaces of the arms  104  and/or the sides of the roller  22  are provided with a high coefficient of friction material. 
   It is apparent from the above detailed description that the present invention incorporates the advantages of freely rolling wheels or rollers and fixed probes into a single massage device having an adjustable brake is dynamically adjustable to vary resistance to rotation during movement of the manipulator and thus to vary the shear force. The brake can be either mechanically adjustable or electromechanically adjustable to vary the resistance to rotation. The desired shear forces are provided while preventing the rollers from sliding on the user. It is not desired for the massaging roller to slip on the skin because slipping causes irritation to skin, the pulling of body hair, and/or the bunching of the user&#39;s clothing, amongst other annoyances. The application of the shear forces are successfully applied to a wide variety of skin types and covering or intervening materials. 
   It is noted that each of the disclosed features of the various embodiments and variations can be utilized with each of the other disclosed embodiments and variations. For example, the optical sensor  66  of the second embodiment can be used with the first embodiment and the manual control device  42  of a variation of the first embodiment can be used with the second embodiment. 
   From the foregoing disclosure and detailed description of certain preferred embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the present invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the present invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to which they are fairly, legally, and equitably entitled.