Abstract:
An equipoising arm structure that can selectively exert force in any direction—lifting, pressing down, or applying lateral bias—with consistent force throughout its range of articulation, comprises a force exerting device having a force exerting structure including a load arm as a first side pivotable about a load pivot, a resilient member attached to the load arm band to a termination point and forming a second side of the force exerting structure. The third side of the structure is formed by a line from the termination point to the load pivot. A first adjustment mechanism moves the termination point to change the length and disposition of the third side of the structure to positions above or below the load pivot. Additional adjustment mechanisms may alter the mounting angle of the entire force exerting structure, and/or the angular relationship between a plurality its force-exerting component devices.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     The application claims the benefit of U.S. provisional application 60/596573 filed on Oct. 4, 2005 which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable.  
       REFERENCE TO A SEQUENCE LISTING  
       [0003]     Not Applicable.  
       BACKGROUND OF THE INVENTION  
       [0004]     1. Field of the Invention  
         [0005]     The present invention relates to an apparatus for reducing the effort and force required to place and hold a medical instrument on or against a patient. The present invention may be used in performing ultrasound examinations. The present invention includes an equipoising arm structure that can selectively exert force in any direction—lifting, pressing down, or applying lateral bias—with consistent force throughout its range of articulation.  
         [0006]     2. Background of the Present Invention  
         [0007]     The placement of a medical device on or against the skin of a patient typically requires physical exertion by the operator or medical practitioner. Such medical devices have their own weight and are often attached to cumbersome wires or tubes. Medical practitioners face further physical challenge due to the need to firmly press the medical device against the skin of a patient for extended periods of time.  
         [0008]     Ultrasound examinations require direct skin contact with a medical instrument and the application of steady force against the skin of a patient. Different patients require different directions and magnitudes of applied force during an ultrasound examination. For example, a prone pregnant woman or obese patient will require the mild application of downward and lateral pressure to fully cover the abdominal area. On the other hand, a shoulder examination for a patient sitting upright may require firm side pressure or pressure perpendicular to the Earth&#39;s gravity.  
         [0009]     Many medical devices, such as transducers used in ultrasound examinations, are coated in a jelly type material and are then pressed against the skin of a patient. With the use of such jelly, the patient&#39;s skin presents a slippery, moving, and sometimes squirming surface. The medical practitioner is then faced with the physical challenge of pressing and systematically moving the medical device on a three dimensional surface that is slippery, moving, and breathing.  
         [0010]     Many medical practitioners experience muscle fatigue and injury as a result of the physical exertion required in performing ultrasound examinations or similar examinations with other medical devices. Thus, there is an urgent need in the art for means to reduce the physical effort expended by medical practitioners in performing ultrasound examinations or similar procedures.  
         [0011]     Robotic arms are known in the related art and are used in many industries to perform automated tasks or to reduce human physical effort. Most medical procedures do not lend themselves to the use of typical industrial robots or mechanical arms. Most medical procedures require a skilled, delicate, human directed touch to be effective and to be accepted by patients. For example, a pregnant woman might only reluctantly consent to an ultrasound examination performed with a large or computer controlled robotic arm.  
         [0012]     There is a need in the art for means to allow hand placement and hand controlled pressure of medical devices on or against patients while reducing muscle fatigue and injury to medical practitioners. There is a need in the art for non-obtrusive means to amplify the force used by medical practitioners in manipulating medical devices.  
         [0013]     Spring powered ‘equipoising’ parallelogram arms have been used for decades to support and position medical payloads such as x-ray machines and dental equipment. These arms rely to a greater or lesser extent on friction to retain a set angle or position, since existing spring geometries do not necessarily provide appropriate or consistent lift throughout the entire angular excursion of the parallelogram links. The invention of the articulated, force-exerting arms marketed under the trademark Steadicam®, however, has provided nearly frictionless support of a floating camera payloads in order to isolate them from unwanted spatial movements of camera operators, employing a spring design for the support arm that ‘equipoises’ the payload, countering the fixed weight of the gimbaled camera assembly with nearly constant positive buoyancy from its lowest to its highest point of parallelogram articulation.  
         [0014]     The formulas for determining the appropriate spring rate to achieve equipoise factor down to the expression K=P/d, where K is the spring rate, P is the load and d is the height of the lifting triangle which is incorporated into the parallelogram and exercises it upward. When a spring of the rate specified in the above formula is deployed as the third side of the triangle, it produces the appropriate force to exactly lift the specified weight throughout the entire vertical range of articulation. This property is termed “iso-elasticity”.  
         [0015]     U.S. Pat. No. 5,360,196 and continuation U.S. Pat. No. 5,435,515 (incorporated herein by reference), disclose adjusting the lifting strength of the arm in a novel manner by raising and lowering the effective spring attachment point along a path angularly offset from the adjacent vertical link of the parallelogram (thus increasing or decreasing the height and also the efficiency of the lifting triangle) without compromising the spring rate required to provide ‘iso-elasticity’. The same formula, K=P/d, indicates that if the height of the appropriate lifting triangle is increased or reduced proportionately with the weight to be carried, the property of iso-elasticity will be maintained.  
         [0016]     However, there is a need in the art for means to push down and/or laterally rather than just lift up, in order to reduce the physical effort exerted by medical professionals in performing ultrasound examinations and still maintain the “hands on” skill and patient comfort provided by a human being.  
       SUMMARY OF THE INVENTION  
       [0017]     The present invention is directed to the field of equipoising force-exerting arms for hand control, pressure amplification and stabilization of medical and industrial devices.  
         [0018]     Illustrative embodiments of the invention comprise tensioning assemblies that can provide separate, continuous adjustments of both the magnitude and the vector of exerted force.  
         [0019]     A first adjustment can alter the geometric relationship between the end point of the tensioning assembly and the remaining structures that comprise the support arm, in order to provide an adjustable exerted force in relation to the vector of gravity that is consistent throughout the articulation of the support arm.  
         [0020]     A second, optional adjustment can alter the angle of the fixed support for the entire arm assembly in order to redirect the force resulting from the first adjustment in vectors non-parallel to that of gravity.  
         [0021]     A third, optional adjustment can bias the individual hinge segments that interconnect the various sections of the arm assembly in order to selectably add a separate, and/or additional, lateral force.  
         [0022]     In a first, separate, aspect of an illustrative embodiment of the invention, a force-exerting triangle, which provides the lifting or pressing-down power for the support arm, comprises a load arm pivotable about a load pivot and forming a first side of a force exerting structure; a resilient member having a first end attached to the load arm and a second end attached to a termination point displaced from the load pivot and forming a second side of the force exerting structure; a force exerting structure third side extending from the termination point to the load pivot; and an adjustment mechanism to move the termination point to change the length of the third side of the force exerting structure and/or its spatial disposition with respect to the load pivot, for the purpose of exerting the desired magnitude and vector of force. As the long first side articulates about the pivot with the short third side, the consistency of exerted power can be regulated by fixing the short side of the lifting triangle at a nominal offset angle with reference to vertical. In addition, the vector of the exerted force can either oppose or augment the force of gravity as the third side of the triangle is adjustably disposed above or below the pivot with the long side.  
         [0023]     Embodiments of the invention are directed to a force-exerting triangle operating in conjunction with a parallelogram support arm and comprising a substantially vertical shorter side, a longer side and another side that consists of a flexible, resilient member, the expansion or contraction of which pivotally biases the apex angle of the sides (and thus the associated parallelogram) from its most obtuse form, up past the condition of being a right angle and on up to its most acute form.  
         [0024]     The long side of the lifting triangle can be contiguous with one of, or parallel to, the long articulating sides of the parallelogram.  
         [0025]     The angle of the short side is variably fixed in angular reference to the adjacent, roughly vertical, short leg of the parallelogram (with reference to a plumb line that passes through the apex of the triangle), such that the degree of iso-elasticity can remain nominally acceptable, even if the selected spring rate of the resilient member does not conform to the K=P/d formula for iso-elasticity. The length of the short side (and its disposition either above or below the long articulating side) can be continuously adjusted, thus providing for force exertion that varies infinitely between opposing or augmenting gravity. This provides a unique, adjustable, mechanism capable of ‘pressing-down’ on demand—as much or as little as required.  
         [0026]     Embodiments of the invention provide the features described in the four paragraphs immediately above by including a support arm for holding and manipulating a medical or industrial device that comprises a parallelogram linkage that is biased upwardly or downwardly by an extendable and retractable resilient member, one end of which may be selectably raised or lowered along a member mounted with respect to a pivot that is in fixed relationship to at least one side of the parallelogram.  
         [0027]     In addition other exemplary embodiments of the invention are directed to a series of interconnected, force-exerting triangles, each associated with parallelogram support arms; the last of which is attached to the medical or industrial payload; the first of which is optionally mounted at an adjustably non-vertical angle, resulting in vectors of force that are non-parallel with that of gravity, and which, in combination, can therefore additionally exert ‘pressing’ force at any desired angle, including straight sideways.  
         [0028]     It is noted that any shaped lifting structure can be used that follows the principals described herein and can be substituted for the “lifting triangle” referenced throughout. It is also noted that reference to a triangle or structure “sides” does not necessarily mean the sides are physical structures.  
         [0029]     The present invention thereby provides means and methods to reduce the physical strain currently experienced by medical practitioners who perform ultrasound examinations and similar medical procedures. The present invention may be used to assist in such medical procedures and/or assist in the performance of tasks found in industrial environments.  
         [0030]     The present invention overcomes the shortfalls in the related art by reducing the physical strain experienced by medical practitioners, using means that maintain the hands-on skill, touch, and emotional support provided by a medical practitioner. Unlike computer-controlled robotic arms, the payload, such as a transducer, of the present invention is directly guided by the hands of the medical practitioner, which preserves the ability to make micro fine adjustments in applied pressure based upon objective and subjective information obtained contemporaneously from the patient.  
         [0031]     The present invention overcomes problems in the related art by reducing the physical strain currently experienced by medical practitioners by means that are not perceived by patients as threatening or impersonal.  
         [0032]     The present invention overcomes problems in the related art by not requiring significant retraining of medical practitioners. The set-up, use, and maintenance of the robotic arms in the related art require a different skill set than the current skills of medical practitioners. The present invention attaches seamlessly to current medical devices and functions intuitively, requiring minimal retraining of medical practitioners.  
         [0033]     The present invention overcomes shortfalls in the related art, which require the construction and use of new therapy heads to enclose ultrasound transducers or other medical devices. The present invention does not require the use of a therapy head as conventional medical devices may be attached directly to the present invention.  
         [0034]     The present invention is suitable for use with a myriad of current medical devices and includes a universal transducer mount suitable for holding an ultrasound transducer, A-line transducer, or other medical device. The present invention does not require the fabrication of new medical devices or new ultrasound transducers since the disclosed universal mount has means to attach current medical devices to the disclosed apparatus.  
         [0035]     The present invention provides a means of control wherein an equipoising and stabilizing arm adjustably produces mechanical force that amplifies and steadies the force applied by a medical practitioner to the ultrasound transducer or medical device in any useful vector. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]     For further detail regarding embodiments of the force-exerting arms produced in accordance with the present invention, reference is made to the detailed description which is provided below, taken in conjunction with the following illustrations. The symbol “M” is sometimes used in the drawings to label a motor sometimes used to turn a lead screw.  
         [0037]      FIG. 1  provides three diagrammatic views of selected relationships between three force-exerting triangles and their associated payloads—illustrating, respectively, net lifting force, neutral force and gravity-augmenting down force produced by adjustment up or down of the tensioning means termination point.  
         [0038]      FIG. 2  is a perspective view of servo-controlled, motorized adjustment means to raise and lower the spring-termination point along a path offset from vertical and capable of descending below and/or outside the articulated parallelogram arm structure.  
         [0039]      FIG. 3  is a perspective view of a double-articulated embodiment of a force-exerting arm, including a motorized connection assembly, pivotally associated with a mounting post, for adjustably redirecting the net arm force to a vector non-parallel with that of gravity.  
         [0040]      FIG. 4  is a perspective view of an articulating, force-exerting two-section embodiment of the arm of the present invention, equipped with electric motors to synchronously adjust the arms net force with respect to gravity—either ‘upwardly’ or ‘downwardly’.  
         [0041]      FIG. 5  shows an embodiment of the force-exerting arm of the present invention mounted adjustably to a solid bed post type mounting structure and attached to a payload (consisting of) comprising a universal transducer ‘boot’-style mount and transducer.  
         [0042]      FIG. 6  shows a detail of the motorized rotatable arm mounting assembly that adjustably redirects the net force in vectors that may be non-parallel to that of gravity.  
         [0043]      FIG. 7  shows the motorized biasing of the hinges that interconnect individual arm sections to each other and also to the mounting structure, in order to adjustably bias the net arm force in an additional collective vector that may be non-parallel to that of gravity.  
         [0044]      FIG. 8  shows perspective detail of the gimbaled three-axis sensors arranged to detect and transmit the ultrasonographer&#39;s intended vectors of force in three roughly perpendicular angles. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                   
               
               
                 Definition List 1 
               
             
          
           
               
                   
                 Term 
                 Definition 
               
               
                   
                   
               
               
                   
                 articulating, force- 
                 An apparatus comprising parallelogram 
               
               
                   
                 exerting arm 
                 links and resilient means such as 
               
               
                   
                   
                 disclosed in U.S. Pat. Nos., 4,208,028 and 
               
               
                   
                   
                 4,394,075 and 5,360,196 and 
               
               
                   
                   
                 continuation 5,435,515 
               
               
                   
                 ultrasonographer 
                 One who places a transducer on or 
               
               
                   
                   
                 against the skin of a patient. 
               
               
                   
                 lateral pressure 
                 Pressure applied laterally to the side of a 
               
               
                   
                   
                 patient in vectors displaced as much as 
               
               
                   
                   
                 90 degrees from that of gravity. 
               
               
                   
                 down pressure 
                 Pressure applied toward the floor. 
               
               
                   
                 medical device 
                 Any medical instrument such as an 
               
               
                   
                   
                 ultrasound transducer or therapy 
               
               
                   
                   
                 transducer that is positioned on or 
               
               
                   
                   
                 against a patient. 
               
               
                   
                 therapy head 
                 A housing structure used by the related 
               
               
                   
                   
                 art to contain a medical device. 
               
               
                   
                 transducer 
                 An ultrasound transducer used for either 
               
               
                   
                   
                 diagnosis or therapy. 
               
               
                   
                   
               
             
          
         
       
     
         [0046]     Currently, a transducer is manipulated upon a patient without mechanical assistance. Many medical devices require firm, but careful pressure to the skin of a patient. An example of such a medical device is a diagnostic ultrasound transducer used to provide imaging of the underlying tissue, organs or vessels. The use of such a transducer may require the application of a jelly type substance to the transducer and/or patient. In the past, medical practitioners, or ultrasonographers, experienced muscle fatigue and/or other injuries due to the intense physical requirements of firmly and steadily placing the transducer against the slippery skin of a patient for extended periods of time. Such injures included strain and/or fatigue to the hand, arm and shoulder muscle groups, making the ultrasonographer&#39;s work experience painful, difficult and sometimes impossible.  
         [0047]     The disclosed invention solves problems in the related art by associating this novel force-exerting triangle with a unique articulated parallelogram arm structure that can be adjusted to exert force in any direction relative to the vector of gravity. The disclosed invention is suitable for use with any medical device that is applied to the skin of a patient and is not limited to ultrasound equipment. The disclosed invention is also suitable for use in invasive procedures, where repetitive or strenuous movement is required by a medical practitioner, including liposuction procedures, or those in which medical instrument weight support is required such as arthroscopic surgery.  
         [0048]      FIG. 1  Provides three diagrammatic examples A, B and C of selected relationships between three force-exerting triangles, defined as points A, B, C and their associated payloads. In each example load arm  101  pivots about load pivot  106 , biased by resilient tensioning means  102  to support payload  100 . Examples A, B and C illustrate, respectively, net lifting force, neutral force and gravity-augmenting down force produced by adjustment up or down of the tensioning means  102  and its termination point B by means of carrier nut  103  driven up and down along lead screw  104  held by fixed end block  105 . The successively descending positions of termination point B in these examples cause support arm  101  and payload  100  to be, respectively, urged upward by lift in example A, neutralized with respect to gravity in example B, and urged downward in example C. The values stated in pounds are not actual and are only for the purpose of illustration. In example A, angle a represents the deliberate, fixed displacement of the lead screw  104  from the vertical, so that the path of possible termination points of resilient means  102  crosses plumb line  108  that passes through load pivot  106 . The crossing point  107  represents the BC distance that would uniquely provide iso-elastic articulation of load arm  101  about load pivot  106  to consistently lift (or push down) given payload  100  according to the formula K=P/d, where K=the spring rate of resilient flexible means  102 , P=the amount of payload  100  and d =the distance BC (expressed positively or negatively) termination point B is displaced from load pivot  106 .  
         [0049]      FIG. 2  is a perspective detail of an exemplary embodiment showing a first servo-controlled, motorized adjustment means  206  employed to raise and lower the spring-termination point  210  of lifting triangle ABC along path  205  offset from vertical  208 , which path continues below and outside the articulated parallelogram arm structure  201 . This adjustment can alter the geometric relationship between the end point of the tensioning assembly ( 210 ) and the remaining structures that comprise the support arm, in order to provide an adjustable exerted force in relation to the vector of gravity that is consistent throughout the articulation of the support arm.  
         [0050]     In this embodiment, load arm  212  of the present invention is biased about load pivot  211  or point C, by lead screw  205  to raise and lower carrier nut  204  and thus attached termination point  210 , or point B of spring  203 , driven by an electric motor  206 , to selectively alter the exact degree of downward pressure manifest at payload  200 . Lead screw  205  is mounted fixedly to end block  209 , which is angularly immobilized by mounting bracket  207 . As illustrated, the lifting triangle ABC would yield a negative value for the third side BC which would strongly press down payload  200 .  
         [0051]     Point B 1  illustrates the hypothetical spring termination along position along lead screw  205  at which the net load, including the weight of parallelogram  201  and payload  200 , could be neutralized by a sufficiently positive value for the displacement B 1  C of spring termination point  210 , thus biasing the net load upward just enough to counter the downward force of gravity.  
         [0052]     The illustrated termination point  210  or point B is on termination path or lead screw  205 , displaced from vertical  208 , shown below load pivot  211 . If the appropriate values (the spring rate K of elastic, flexible, resilient means  203 , the displacement distance d of the spring termination BC and the amount P of load  200 ) are consistent with the formula K=P/d as in  FIG. 1 , example C, the angular articulation of load arm  212  about load pivot  211  should yield consistent down force, termed “iso-elasticity”, throughout its excursion.  
         [0053]      FIG. 3  illustrates a second adjustment means that can alter the angle of the fixed support for the entire arm assembly in order to redirect the force resulting from the first adjustment (as above in  FIG. 2 ) in vectors non-parallel to that of gravity.  FIG. 3  is a perspective view of a double-articulated embodiment of a force-exerting arm  300 , including a motorized, pivoting, single-axis connection assembly  301 , pivotally associated with a mounting post  309 , for adjustably redirecting the net exerted force  310  of the arm to vector  312  non-parallel with that of gravity  311 . Mounting axis  312  of parallelogram arm assembly  300  is fixed in angular relationship with partial sector gear  302  which may pivot about axle  308  and driven by lever  306  with associated foot plate  307  or servo-driven by motor  304  via gear belt  303  and motor gear  305  to adjust angle  312  relative to vertical vector  311 . Alteration of angle  312  correspondingly redirects the net vector of force  310  exerted by parallelogram arm assembly  300  as manifest at payload  313 . Note that an additional axis of adjustment (not shown) roughly perpendicular to axle  308  is also contemplated, employing additional equipment of similar nature to connection assembly  301 , or any equivalent gears, pivots, worm wheels, and the like known in the art capable of providing either manual or motorized redirection of net force vector  310  on any desired axis including those non-parallel with that of gravity.  
         [0054]      FIG. 4  is a cut-away side view or sectional view of a two-section arm  400  of the present invention, equipped with electric motors (sometimes marked as “M”)  401 ,  402  to synchronously adjust the arms net force  409  with respect to gravity—either ‘upwardly’ or ‘downwardly’—as desired. Servo-operated motors  401 ,  402  with gear boxes  407 ,  408 , drive lead screws  405 ,  406  roughly synchronously to bias spring termination carrier nuts  403 ,  404  along the paths of potential spring termination contiguous with lead screws  405 ,  406 . Note that termination point  403  will always be higher than termination point  404  because parallelogram arm  400 A is required to lift parallelogram arm  400 B in addition to payload  410 , so the synchronicity of motor  401  with motor  402  will always be appropriately contoured. Servo control of synchronous motors  401 ,  402  can be by foot pedal (not shown) or by signals generated by force sensors associated with payload  410  (not shown).  
         [0055]      FIG. 5  is the preferred embodiment, which shows the two section force-exerting parallelograms  500  of the present invention mounted adjustably to a solid bed post type mounting structure  501 , which may be associated with a bed  502 , and including a gimbaled attachment  503  to a universal transducer mount comprising a neoprene boot  505  plus transducer  506 . The conventional, three-axis gimbal mount  503  (of conventional design) includes counterweight  504  so that the transducer is counterbalanced to be effortlessly poised at any angle. Electrical cord  507  is attached to the transducer and its opposite end is attached to ultrasound machine  508 . In practice, cord  507  would be led along arm  500  in order not to interfere. In operation, the ultrasonographer may grasp neoprene boot  505  and angularly position transducer  506  appropriately by means of gimbal  503  in order to contact patient  509  with the desired vector and amount of exerted force. Nominally vertical hinges with axle pins  510 ,  511 ,  512  permit virtually effortless lateral motion of the interconnected arm segments and payload  513 , unless pivoting mounting assembly  513  has caused hinge pins  510 ,  511 ,  512  to be disposed at an angle other than vertical, in which case the entire arm assembly  500  would tend to fall toward that angle and provide an increasing lateral vector of force as the displaced hinge pin angle further departs from vertical. Electric motors  514  and  515  may turn their respective lead screws.  
         [0056]     The invention also includes a method of exerting downward and lateral forces on objects. A force-exerting device such as described herein is provided. The termination point is adjusted, preferably by servo-motorized means, to alter the length of the third side of the force-exerting triangle to change the lifting power of the force exerting triangle from positive to negative with respect to the vector of gravity. The mounting angle of the entire force-exerting device is additionally altered, either by manual lever means, or by servo-motorized means, to redirect the exerted force to vectors non-parallel with that of gravity. And the plurality of nominally vertical hinges interconnecting the various components of force-exerting device and its mounting means are pivotally biased around the respective hinge axes, preferably by servo-operated torque motors, to additionally alter the vector of the net exerted force so that the sum of the above methods permits medical and industrial practitioners to exert precisely directed forces in any direction with a minimum of sustained human effort.  
         [0057]      FIG. 6  shows a detail of the motorized rotating arm mounting assembly  600  that (as shown and/or described in  FIG. 3 ), adjustably directs the net arm force  608  in vectors that may be non-parallel to that of gravity  609 . Servo-motor  605  may be controlled by foot pedals (not shown) or mechanical levers (not shown) operated by the medical practitioner. Primary hinge pin  603  is angularly fixed to partial sector gear  602  which pivots about axle  601 , driven by motor  605  via belt  604  in order to alter the angle of hinge pin  603  (and thus that of the entire arm assembly  610 ) in order to bias net exerted force vector  608  in a direction non-parallel with that of gravity. As noted above in regard to  FIG. 3 , mounting assembly  600 , pivoting on axle  601  may also operate in combination with an additional perpendicular adjustment axle (not shown) or may be replaced by other mechanically operated means for angular adjustment known in the art, such as a gimbal or a ball joint to provide either manual or motorized redirection of net force vector  310  or  608  to any desired axis non-parallel with that of gravity including those up to 90 degrees displaced therefrom. The effect of these adjustments will be to cause any or all of hinge pins  603 ,  611 ,  612 ,  613  to depart from vertical, thus biasing the associated hinged components of arm assembly  610  to swivel toward the vector of gravity. Depending on the previous angular relationship of arm segments  614  and  615 , this bias might cause them to fold around hinge  616  in a desired direction to apply a lateral component to force vector  608 .  
         [0058]      FIG. 7  illustrates a third means of adjustment that can bias the individual hinge segments that interconnect the various sections of the arm assembly in order to selectably add a separate, and/or additional, lateral force.  FIG. 7  is a perspective view showing the servo-motor-powered biasing of the hinges  701 ,  702 ,  703 ,  704  that interconnect individual arm sections  710 ,  711  to each other and also to the mounting structure  713 , in order to additionally bias the net arm force  714  in vectors that may be non-parallel to that of gravity. The adjusting means shown, unlike the adjusting means described above in  FIG. 6 , provide that angle of the overall arm assembly  700 , as determined by the angle of hinge pins  701 ,  702 ,  703 ,  704 , is not further altered. Rather, its angular relationship to the mounting assembly  713  and/or the angular relationship of parallelograms  710 ,  711  to each other, are forcibly biased by motors  707 ,  705 ,  706 ,  708  to selected orientations around their respective hinges. This may additionally alter the net force vector  714  for the purposes of pressing payload  709  in a desired direction.  
         [0059]      FIG. 8  shows perspective detail of gimbaled three-axis, force-activated sensors  805 ,  804 ,  802 ,  803  arranged to detect and transmit the ultrasonographer&#39;s intended vectors of force (illustrated here as arrow  810 ) in three roughly perpendicular angles. (The wires from the sensors are not shown). These sensors, mechanically associated with the universal transducer mounting boot  808  in a conventional manner, permit the movement and hand pressure applied to the axis of the transducer  806  to be servo-amplified and steadied by the articulated arm  809  of the present invention. Transducer  806  and mounting boot  808  are mounted on gimbal assembly  801 , counterbalanced by counterweight  807  which collectively form the payload  800  which is in gimbaled connection to arm assembly  809  such that it preferably has little or no angular bias of its own and may be held effortlessly by the ultrasonographer (not shown) at any angle. Additional (or other) adjustments to the forces applied by the articulated arm may still be effected by use of the foot pedals (not shown) or by simple mechanical leverage applied by the operator&#39;s foot directly to a treadle connected to an arm mounting pivot (not shown).  
         [0060]     Use of the above detailed preferred embodiments, would require only minimal retraining of medical professionals and no alterations to existing ultrasound equipment.  
         [0061]     While the invention has been described by illustrative embodiments, additional advantages and modifications will occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to specific details shown and described herein. Modifications, for example, to the materials, specific components and their layout, may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the invention not be limited to the specific illustrative embodiments, but be interpreted within the full spirit and scope of the appended claims and their equivalents.