CA1308218C - Liquid contractility actuator - Google Patents
Liquid contractility actuatorInfo
- Publication number
- CA1308218C CA1308218C CA000561044A CA561044A CA1308218C CA 1308218 C CA1308218 C CA 1308218C CA 000561044 A CA000561044 A CA 000561044A CA 561044 A CA561044 A CA 561044A CA 1308218 C CA1308218 C CA 1308218C
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- Prior art keywords
- cylindrical
- anchor points
- bladder
- platform
- array
- Prior art date
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Abstract
ABSTRACT
A contractility actuator includes a longitudinal quadrilateral mesh of relatively inelastic segments with anchor points at either end, an expandable bladder confined within the mesh and means for introducing and inflating the bladder with a liquid for generating a contractile force between the anchor points mechanically analogous to a muscle but of much greater magnitude. Two or more of the contractile actuators are arranged in a system for precisely articulating one or more arms pivotally secured at the distal ends of a structural member.
A contractility actuator includes a longitudinal quadrilateral mesh of relatively inelastic segments with anchor points at either end, an expandable bladder confined within the mesh and means for introducing and inflating the bladder with a liquid for generating a contractile force between the anchor points mechanically analogous to a muscle but of much greater magnitude. Two or more of the contractile actuators are arranged in a system for precisely articulating one or more arms pivotally secured at the distal ends of a structural member.
Description
~ 308? ~ 8 2 DOCKET NO. 171~.03 ~ACKGROVND OF TH~ INVENTION
Field of the Invention:
The invention relates to mechanisms of contractility, and to systems utilizing "McKibben" muscles.
Description of the Prior Art:
Contractility describes the fundamental mechanism by which motion or movement is accomplished by living matter.
Contractility is thought to result from the interaction of various fibrillar (contractile) proteins within the living cell. The contractile properties of ~uch proteins are thought to primarily result from chemical interactions.
Accordingly, investigations of the contractile properties of muscle cells primarily focus on the chemical aspects (reactions), rather than the mechanical aspects of contraction.
It is generally believed that two types of filament structures form the contractile machine in a muscle, ie, a "thick" filament composed primarily of myosin and a "thin"
filament which contains actin. It has been discovered that the filaments, whether thick or thin, do not change in length as a muscle cell contracts from its relaxed state.
It is also known that "thin" filaments are attached at either end of the muscle cell and that the "thick" fil2ments bind to the "thin" filaments. It has been hypothesized that the "thin" filaments mechan~cally slide by the "thick"
filaments.
The magnitude of the change in the overall length of the muscle cell during contraction is t~pically less than 3 microns. In ~act the sarcomere length of ome ~keletal muscles is only about 2.5 microns indicating that cuch 1 308?~1 8 3 DOCKET NO. 1717.03 skeletal muscles do not signifigantly shorten during contraction.
Summarizing, muscle cells and muscles have the capability of producing very large forces upon contraction.
Muscles also tend to increase in diameter as they contract.
However, the mechanical aspects of the contractility mechanism of a muscle cell are not well understood.
Mechanical systems simulating the action of a muscle described in the literature typically include an expandable bladder confined and/or co~strained to expand radially when pressurized with a gas. For example, a Brevet D' Invention published October 15, 19~1 in the Republic of France, No. 2.076.768 describes a device for converting fluid pressure into contractile force and includes an ovoidal rubber envelope reinforced with relatively inelastic longitudinal filaments. The ends of the ovoidal envelope are anchored between two points and the envelope pressurized wlth a gaseous fluid causing the ovoidal envelope to expand diametrically and contract longitudinally pulling the anchor points together.
Similarly, United States Patent No. 3,645,1~3, Yarlott, describes an ovoidal envelope defined by an expandable bladder confined within relatively inelastic longitudinal strands such that the bladder can expand diametrically but not longitudinally when pressurized with a gaseous fluid.
The earlist k~own mechanical system which simulated the action of a muscle known as the "McKibben S~nthetic Muscle" comprised a cylindrical sheath woven ~rom helical strands of an inGlastic material surrounding a gas inflatable bladder, and was designed to articula~e orthopedic and prosthetic appliances for polio victims.
~ hile ga~ has advantages as a med~um ~or pressurizing and expanding "McKibben" type contractile ac~uators or muscles, i~s primary disadvantage is that it is compres~ible which dictates an "21astic" contractile 4 1 3 0 8 - 1DOCKET NO. 1~1~,03 response. Elastic contractile responses are not always desirable. For example, an elastic contractile mechanism can not establish or maintain a reference position ~7here load varies.
Also, as explained infra, the contractile force generated by a "McKibben" type contractile device as it inflates is not linear, and when a gas is utilized to inflate or "energize" the muscle, the contractile position of the muscle will vary with ~as pressure and tensile load.
Accordingly, any system utilizing gas inflatable "McKibben"
type contractile devices requires complex electromechanical or other type of servomechanisms both for adjusting position, and for metering the gas for inflating and deflating under conditions of varying pressure.
Still another significant disadvantage of using a gas for inflating and contracting a "McKibben" muscle relates to the property of gas to expand filling the available volume. This means that the degree of contraction (or extension) of the muscle is determined by the tensile force between the anchor points of the muscle resisting contraction.
The above reasons, among others have discouraged commercial acceptance of the "McKibben" muscle as a contractile force generating mechanism/actuator.
Summarizing, gas energized contractile force mechanisms have three variables, position (volume), pressure and tension. Temperature also af~ects the response of such gas energized systems. For the "McKibben" type contractile force mechanisms to achieve commercial acceptance , it i5 necessary to eliminate or minimize the above variables affecting its re~ponse.
SUMMARY 0~ THE INV~NTION
A contractility actuator i5 described which includes a ~ylindrical array formed by a network o~ open two dimensional guadrilateral segments, and expandable bladder 1 308~ 1 8 DOCKET NO. 1~1~.03 located within the cylindrical network and meahs introducing and expanding the bladder with a liquid for generating a very large magnitude contractile force aligned with the axis of the array. Two or more of the described contractility actuators may be arranged in a system for precisely articulating one or more arms pivotally secured at the distal end of a ridged structure.
Th~ principal aspect of the invented contractility actuator relates to the incompressible properties of liquids which reduces the number of variables allowing the actuator to precisely respo~d relative to both position and tension.
Accordingly, two or more such actuators working in opposition acro~s a fulcrum establish a dynamic equilibrium which can be incremently altered by simultaneously inputting liquid into actuators on one side of the fulcrum and allowing liquid to exhaust from the actuators on the other side of the fulcru~ to establish a new dynamic equilibrium position without oscillation.
Another aspect of the invention relates to utilization of a combination of liguid and gas inflated contractility actuators for pivoting arms at the di6tal ends of structure member~ providing a combination of the elastic positional response characteristics of a gas inflated contractility actuator with the positional precision and accuracy charact~ristics of the liquid energized contractility actuator.
Other a5pect5, f~atures and objects of the present invention involve both methods and apparatus for control-ling a plurality of such contractility actuators for articulating an arm in a solid angle about a pivot point.
1 30~2 1 ~
6 DOCKET NO. 171~ 03 Still other advantages, objects, features and aspects of the invented liguid energized contractility actuators and systems utilizing ~uch actuators are more fully described and will become apparent with reference to the following descriptions and drawings of preferred and exemplary embodiments of both the actuator and of systems utilizing the invented actuator.
D~SCRIPTION OF THE DR~KINGS
Fig. 1 illustrates the essential components of a "McKibben" type contractility mechanism.
Fig. 2 is a schematic of a rhombus responding to an impressed force for illustrating an aspect of "McKibben"
type contractility actuators.
Fig. 3 is a simple vector diagram for illus~rating the relative magnitude of the respective forces with respect to an ideal rhombus.
Fig. 4 is a perspective schematic illustrating a cylindrical segment of a "McKibben" type contractility actuator.
Fig. 5 illustrates the constructor of a general conical array beginning with a cone axi5 line AA and a cone generation line BB line in a plane.
Fig. 6 is a ~chematic illustrating a "McKibben"
actuator in a relaxed configuration.
Fig. 7 is a 6chematic illustrating a t'McKibben"
contractility actuator in a contracted confi~uration.
1 308~ 1 8 7 DOCKET NO. 1717.03 Fig. 8 is a graph illustrating the cotangent dependency of the contractile force generated by "McKibben"
type contractility actuators.
Fig. 9 is a graph illustrating the change in length as a function as a change in volume for a "McKibben" type contractile ~echanism and for a piston-cylinder contractile mechanism.
Fig. 10 is a partial cut-away illustration of a pivoting mechanism where invented liquid contracti1ity actuators articulate platorms secured at either end of a longitudinal arm.
Fig. 11 is an enlarged cross section of the coupling ~ecuring one end of the contractility actuators to the shank of the longitudinal arm of the pivoting mechanism shown in Fi~ure 10.
Figs. 12, 12a, and 12b illustrate the ~eatures of the embodiment of the arm a~d platform shown in Figure 10.
Fig. 13 illustrates the essential features of another embodiment for the arm and platforms of Fig. 10.
Figs. 14 and 15 present block diagrams of an exemplary control system inflating and deflating contractility actuators for articulating the respective platforms at the distal ends of a pivoting mechanism of the type shown in Figure 10.
Fig. 16 presents a schematic dia~ram of a plurallty of pivoting mechanisms of the type illustrated in Fig. 10.
1,308'21~
8 DOCKET NO. 171~.03 DESCRIPTION OF PRæFERR~D AND EXEMPLARY ~MBODIM~NT5 As shown in Fig. 1 the basic "McKibben" type fluid contractile actuator includes a cylindrical sheath 11 formed from a flexible mesh 12 secured to connectors 13 at either end of the sheath 11. A bladder 14 composed of a strong ~xpandable material is disposed within the sheath 11.
~onnected to the bladder i8 an inflation line 16 through which a pressurizing ~luid 17 may be introduced for purpose of expanding the bladder 14 within the cylindrical sheath 11. Appropriate valves 18 on the inflation line 16 direct fluid from a pressurizing source 1~ into the bladder for inflation (oontraction) and allow fluid to escape from the bladderfor deflation (extension~.
In operation, the "McKibben" type fluidic contractility actuator or "muscle" is connected between two fixed points using connector 13 with the bladder 14 deflated. Ideally the cylindrical sheath formed from the flexible mesh when connected between two flexible points should experience a very slight tensile stress in order to ensure that the sheath 11 when connected in its extended "relaxed" position between the two points is at a minimum diameter. The in~lation line 16 is then connected to the source of pressurizing ~luid 1~. m e fluid may be compressible, i.e., a gas, or incompressible, i.e., a liquid. The fluid when introduced into the bladder 14 expands it against the enclosing mesh sheath 11 causing it to expand diametrically and contract longitudinally generating an extremely large contractile force between the connectors ~3.
The two dimensional diagram of Fig. 2 illustrates the basic principles of a "McKibben" muscle. In particular, rhombu~ 21 is defined by four inextensible seyments or rods 3 DOCKET NO. 1~1~.03 22 each having a length L. The ends of the segments 22 are pivotally secured together allowing the adjacent segments to rotate relative to one another. In the extended position, the rhombus 21 has an initial half angle eO between the respective segments as shown. If a force is impressed in the vertical direction (along the Y-axis) the rhombus 21 is disturbed increasing ~ts diagonal width along the Y axis and decreasing its diagonal width along the X axis according to a differential relationship:
dx = dy cotan ~;
where 0 is the half angle of ~he disturbed rhombus (shown in phantom in Fig. 2).
As illustrated in Figure 2, the pivot points 23 between the segments 22 of the rhombus are not fixed. Now assume that the pivot points 23 lying along the X-axis of Fig. 2 are fixed, and using vector analysis, the magnitude of the contractile force between those two pivot points resulting when a force is impressed in the Y direction can be determined. In particular referring to Figures 2 & 3, a relatively small magnitude force Fy along the Y-axis can generate a relatively large magnitude contractile force Fx along the X-axis between the fixed pivot points of the rhombus 21, particularly for small half-angles e. The ratio of the contractile force along the X axis, Fx to that of the force impressed in the Y direction, Fy varies as a cotangent of the half angle 3 between the connected segments 22, i.e.;
Fx = Py cotan e Fig. 8 illustrates the magnitude of the force magnification factor as the half angle e approaches O.
Now consider a three-dimensional connected network of rhombi 21 in the form of right cylinder 24, a segment of 1 30~ 1 8 DOC~ET NO. 1717.03 which is illustrated in Fig. 4. Each rhombus 21 is formed o~ ~our inextensible segments 22 pivotally coupled together at their respective ends. The inextensible segments 22 of the rhombi laterally combined to form a mesh of the lnextensible helical cords which terminate at the respective ends of the cylindri~al sheath formed by the rhombi.
Similarly, the sum of the respective diagonai widths of the rhombi along the Y axis will equal the circumference of the cylindrical sheath and the sum of the diagonal length of the rhombi along the X axi5 will equal the length of the cylindrical sheath. More generally, the right cylinder of Fig. 4 can be supplanted by a general array formed b~ a connected network of rhombi or other quadrilaterals as shown in Fig. 5.
In particular, as shown in Fig. 5, two smooth curvilinear lines AA and BB lie in substantially in a plane P. Assuming that the lines AA and BB do not intersect, then line AA can be designated as an axis and the line BB can be connoted the generator of a conical array. For each point on line AA construct a line segment La perpendicular to AA
within the plane P. The line segment La terminates at its intersection with the generator line BB at a point Ba~
distance Pa from point a on the axis line M . Now rotate the line segment La about the point a in a plane containing it and perpendicular to the plane P. The locus of the end points of the rotated line segment La defines a circle Ca with its ceDter at a and havi~g a radius Pa. The locus of points Ca for al~ points a on th~ axis AA defines a eneral conical arrav which is a 2-dimensional surface that includes ~ost or all of the cone generator BB for a.
For any point, a on M , the circle CA i5 called a circumference line for the array. It should be appreciated that utilizin~ generally descriptive terms for describing 11 DOCKET NO. 1~1~.03 the sheath 11 enclosing the bladder 14 allows for mathematical analysis of changes in configuration of th~
rhomboidal array as the sheath expands.
In particular, referring now to Figs. 6 and 7, a general conical array 26 is shown in a relaxed or collapsed configuration (Fig. 6), and in ~ contracted or inflated configuration (Fig. 7). ~ith reference to the diagrams presented in Figs. 6 and ~, the following definitions may be utilized for the purpose of gaining an analytical insight a5 to how a "McKibben" muscle operates:
St is the parabolic length of the conical array;
Li is the relaxed length of the actuator between the termination points;
Lf is a contracted length of the actuator between the termination points;
Df is the maximum diameter of the array in the contracted position;
Di is the minimal diameter of the conical array in the relaxed configuration;
Vf i5 the internal volume of the conical array in the contracted configuration;
Vi is the i~ternal volume of the conical array in the relaxed configuration;
TH is the horizontal tension along the axis of the conical array;
P is the f~uid pressure within the bladder;
D is the average diameter assumed equal to 2/3 (Di +
Df); and R e~uals (~f - Di3/Lf (The horizontal f~rce component due to pressurization of the bladder within the general conical array is assumed to be O predicated on an assumption of symmetry.) 1 30~1 8 12 DOCKET N0. 171~.03 Based on the above assumptions and definitions, the ~ollowing equations approximately describe the response of a "Mc~ibben" muscle assuming that the materlal composing the general conical array is inextensible:
st= Li= Lf[l+(2/3)R2-(2/5~R4~(4/7)R6 - ...]; (eq.l) Vf - ( /15)Lf[2D2f+VfDi~(3/4)D2i]; (eq.2) Vi = ( /4)D2iLi; (e~-3) T = ( /6)(PLf2)[(Di~Df~/Df-D~ /2) PDLf(cotan e); (eq.4) L~ - [l-(cosarcsiD(Di/2)-cosarcsin(Dj/2))]2/3[Li]; (eq.5) The above equations illustrate the magnitude of the horizontal contractile tensile force that can be generated by a "McKibben Muscle." For example, from equation 4 it can be ~een that the contractile force component due to the pressurizing fluid theoretically increases asymptot~cally approaching infinity as e approaches 0. (See the graph of Fig. 8.) The graph presented in Fig. 9 plots the change in length of a McKibben Muæcle, ~L, along the horizontal axis for a corresponding change in volume, ~V, along the vertical axis based upvn the relationship obtained using a 5/8 in. HD
EXPANDO cylindrical he}ical weave sheath ~anufactured by Bently Harris Corporation.
The solid line presents data points for a sheath having a initial l~ngth Li of 9~76 in. The dashed line presents data points for a sheath having a initial len~t~ Li of 9.20 in. The third line presents the same data $or a cylinder hRving an internal diameter of 1.125 in. and an initial length Li of 10 in.
1 30~2 1 8 13 DOC~ET NO. 1717.03 From Fig. 9, it can be seen that for that particular "Mckibben Muscle", the ratio of the rate of changP in length to the rate of change of volume, ~L/~V, is substantial less than the same ratio for a comparable cylinder (by a factor of 4)-It can also be observed from the relationshipsexpressed in ~quations 1-5 and from the graphs of Figures 8 and 9 that the spring constant of a "McKibben Muscle" has a significant dependanc~ on the natur~ of the fluid inflating the bladder 14. In particular, w~ere a ~as i5 utilized to inflate the internal bladder 14, a "McKibben Muscle" is highly ela.~tic with a correspondingly low spring constant since a gas is compressible, and accordingly does not have the capacity to maintain a reference position under conditions of varying load. However, using an incompressible fluid or a liquid to inflate the internal bladder 14 converts the "McKibben Muscle" into an inelastic contractile mechanism having a correspondingly high spring constant which accordingly has the capacity to establish and maintain a reference position under conditions of varying load in addition to capacity for generating contractile forces of very high magnitude.
Turning now to Fig. 10, a pivoting mechanism 39 includes plurality of "McKibben" type contractile actuators ~1 each with one end secured by a coupler 42 to a shank of a longitudinal arm 43 and its remaining end secured by an eyelet fastener 64 to an articulating platform 44 by U-bolts 46. The platforms 44 each include a hemispherical socket 4~
receiving a spherical head at the distal ends of the ar~ 43.
In the p*rspectiv~ illustrated, the contractile ~ctuator 41A i~ contracted while contractile actuator 4~B ls extended. A contractile actuator is also secured be~ween a coupling point 45 on the arm 43 and the platform ~4 [not '` ? 1 8 14 DOCKET NO. 1717.03 shown). Liquid is introduced into the respective contractile actuators 41 via inlet ports 49 which connect to conduits 50 (not shown) communicating through the interior of the arm 43 and up through a central shaft 51 at each coupling point 45 on the shank of the longitudinal arm 43.
In more detail, referring to Fig. 11 the coupler 42 includes a central housing 54 with cylindrical passageway 56 dimensioned to a receive the shaft 51 integrally extending out of the shank of the arm 43. The liquid sonduit 50 through the interior of the arm 43 and through the shaft 51 at each coupling point 45 communicates with an annular plenum 57 cut radially into the passageway 56. A threaded tube 58 forming the mouth of the bladder 14 screws into a threaded port 52 communicating through the housing 54 to the plenum 57. Liquid flows via the passageway 50 and plenum 5~
and out the outlet port 52 for inflating or expanding the bladderl4. Suitable seals 61 are compressed between the annular shoulders 62 on either side of the houslng 54 and a mounting nut 63 and a corresponding annular ~houlder of the shaft 51. The mounting nut 63 and the shaft 51 are suitably threaded for compressing the seals 61 to render the coupling 42 liquid tight.
The mechanism illustrated in Fig. 11 for introducing liquid into bladders 14 for inflating the actuators 41 is exemplary. In fact, provlded there is sufficient space between the quadrilateral segments forming the mesh sheath 11, the connection to the bladder 14 can be made through a nozzle communicating to the interior of the bladder extending centrally between the quadrilateral mesh 6egm~nts forming the sheath.
1 3()P,~ 1 ~
DOCKET NO. 171~.03 In the preferred ~mbodiment, again referring to Fig.
11, each strand 66 of the mesh sheath 11 forms a closed loop which encircles both the eyelet fastener 64 and the coupler 42 In this fashion, any limitation on the magnitude of the tensile load which can be born by the actuator 41 ls determined by the strengths of the strands 66, the shaft 51 and the U-bolts 46. In fact, the primary criteria for selecting a mechanism or means for coupling the mesh sheath 11 to the eyelet ~astener 64 and coupler 42 is that it must be able to withstand the maximum e~pect~d tensile load between the connection points of the actuator 41.
Referring back to Fig. 10, the platform 44 pivoted by the actuators 41 about the spherical heads 48 at either end of the arm 43 each include connector means 67 (at the top) and 68 ~at the bottom). The connectors 67 and 68 simply define receiving receptacles 69 for receiving correspondingly shaped male or female protrusions or receptacles ~not shown) dimensioned to receive the connectors 6~ & 68. Accordingly, the pivoting mechanism 3g can be secured to a stationary surface or the pivoting platform 44 of an adjacent plvoting mechanism 39. (See Figure 16.) As illustrated, the connector 68 is inclined with respect to the longitudinal axis o~ the arm 43 to provide an additional dimension to the articulating range and capacity of a machine formed by two or more pivoting mechanisms 39.
The actuators 41 w~rk in opposition as illustrated by actuators 41A and ~lB ( Fi~. 10). Referring to Figures 12, 12A & 12B each arm 43 lncludes four (4) contractile actuators 41, for articulating the top platform 44A and ~our (4) for articulating the bottom platform 44B. The re p~ctive fastening positions of the actuators articulating the top platform 44, indicated by the U-bolts 46 in Figure 12A, are rotated 4~ degrees with respect to the coupling 1 30~2~ ~
16 DOCKET NO . 1717.03 points 45 on the shank of the arm 43 of the actuator.s 41 articu~ating the bottom platform 44b. Similarly with reference to Figure 12B, the U-bolts 46 securing the eyelet fasteners 64 of the latter actuators 41 to the bottom platform are rotated at an angle of 45 degrees with respect to the coupling points 45 of the former actuators 41 articulating the upper platform 44A.
As illustrated in Figures 12 the articulating mechanism formed by the co~bination of the arm 43, the platforms 44 A ~ B and the contractil~ actuators 41 (Figure 10) can tilt a particular platform through a solid angle of approximat~ly 90 degrees as illus~rated in phantom ~or the top platform 44 A in Figure 12. Such tilting of the platform 44 is accomplished by relative contraction of the respective actuators articulating a particular platform. In the example illustrated in Figures 10, 12, 12A and 12B, contraction of a particular actuator tilts the particular platform in a plane determined by the positional relationship of the U-bolt receiving the eyelet fastener 6~
of the particular actuator 41 and its coupling point45 on the shank of the arm 43.
As illustrated in Figures 12A and 12B. The U-bolts 46 of the platform and coupling points 45 on the arm 43 are oriented in the same plane. It should be appreciated however, that the platform 44 can rotate relative to the arm 43 such that contraction of a particular actuator secured between its coupling point 45 on the arm 43 and the U-bolt 46 of the platform 44 provides a twisting or torque ~oment in addition to tilting the platform.
Figure 13 schematically illustrates the relationship between fastening points ~1 on a platform 72 and coupling po~nts ~3 on the shaft 74 of an embodiment of a pivotin~
mechanism ~O ~or three contractile actuators (not ~hown).
Such f astening points 71 on the platform 72 and coupling 1 30~2 1 ~3 17 DOCKET NO. 1717.03 points 73 on the shaft 74 for the platform 72 at the other end are rotated ~O degrees with respect to each other.
Again, a cylindrical head indicated at 76 is received in a corresponding socket is (not shown) on the platform, and it should be realized that the platform 72 can be rotated such that a contracting actuator imparts a twisting as well as a tilting moment to the platform as it contracts.
Referring now to Figure 14, a control system for controlling an articulating or pivoting mechanism ~O of the type depicted in Figure 10, ~hould include a master control system (section A) which may comprise a computer or other type of programmable data processor system. The master control system inputs commands and r~ceives data via address bus 81, a data bus 82, and a control signal bus 83.
The control system should also include a work station controller (section B) for implementing subprograms unique to particular articulating mechanisms for accomplishing such tasks as parts handling, tool manipulation, measurement and the like. The work station basically insludes a micro-controller 84 which accepts commands from the master control and contains memory and microprograming for implementing device-level action. The work station should also include an energizing source such as pump 85 and manifold gl for inflating the contractlle actuators making up the system with a suitable high pressure liquid (water or hydraulic oil).
At the device level (section C~ control processing is provided via an address decoder B6 for interpretin~ signals directed to a particular articulating mechanism, and a data multiplexing system for interpreting directional data coming ~rom the micro-controller 84. A read only memory IROM) and a data latch indicated at 8B, the heart of the device level oontrol processing subqystem, ~ets the sub-routines for opening an~ closin~ valves psr instructions from either or 1 3(~8~ 1 8 18 DOCKET NO. 1~17.03 both the master control and micro-controller 84 subsystems to inflate or deflate a particular artiçulating mechanis~
(section D).
In particular, an amplifier 89 receives and amplifies output signals from the ROM/data latch 88 opening and closing hiyh speed valves 90: i.) controlling flow of a liquid Prom the high pressure side of the manifold 91 into line(s) for inflating particular contractile actuator(s) inducing contraction and il.~ controlling flow of the liquid from line~s) into the low pressure side of the manifold 91 for deflating particular contractile actuator(s) allowing extension.
At the articulating mechanism (section D), feedback signal generators 92 receiving input from pressure sensors 94 located between the valves 90 and the contractile actuators 95 and from one or more relative motion/displacement sensors 93 located on an articulating structure 96 provide data signals to both the master control and work station contol subsystems indicative of displacement relative to contraction and extension of the respective contractile actuators 95.
Figure 15 presents a block diagram schematically illustrating a simple control circuit (Fig. 14, section C) for controlling two contractile actuators wor~ing in opposition including an address decoder 101, and a data latch 102. The data latch 102 receives inpu~ from the micro-controller 84, and the master control subsystems via a data bus (the address bus 81, data bus 82 and control 8ignal bus 83 of Fig. 14) and a clocking pulse from a clock 97. The data latch 102 outputs signals directed .Por particular values. ~n amplifier 103 receiv~s the output from the data latch 102 and amplifys it for ~witching (opening and closlng) ~olenoid, diaphragm and/or shaped~
memory-alloy actuated high speed valves 90. Suitable valves 1 30~2 1 ~
l9 DOCKET NO. 171~.03 include Model 8225 made BY AUTOMATIC SWITCH VALVE CO. (ASCO) Florham Park, New Jersey, and Model Nos. EV2-12 and ETO-3 made by CLIPPARD Cincinnati, Ohio.
Although the preferred and exemplary embodiments of the invented liquid inflated contractility actuator and systems for utilizing same are described in context of representative, schematic, and computational embodiments, many variations and modifications of the invention including those suggestcd by the computational and schematic models utilized for describing and understanding the invention maybe made without departing from ~he scope of the invention as defined and set forth in the following claims ~e clain:
Field of the Invention:
The invention relates to mechanisms of contractility, and to systems utilizing "McKibben" muscles.
Description of the Prior Art:
Contractility describes the fundamental mechanism by which motion or movement is accomplished by living matter.
Contractility is thought to result from the interaction of various fibrillar (contractile) proteins within the living cell. The contractile properties of ~uch proteins are thought to primarily result from chemical interactions.
Accordingly, investigations of the contractile properties of muscle cells primarily focus on the chemical aspects (reactions), rather than the mechanical aspects of contraction.
It is generally believed that two types of filament structures form the contractile machine in a muscle, ie, a "thick" filament composed primarily of myosin and a "thin"
filament which contains actin. It has been discovered that the filaments, whether thick or thin, do not change in length as a muscle cell contracts from its relaxed state.
It is also known that "thin" filaments are attached at either end of the muscle cell and that the "thick" fil2ments bind to the "thin" filaments. It has been hypothesized that the "thin" filaments mechan~cally slide by the "thick"
filaments.
The magnitude of the change in the overall length of the muscle cell during contraction is t~pically less than 3 microns. In ~act the sarcomere length of ome ~keletal muscles is only about 2.5 microns indicating that cuch 1 308?~1 8 3 DOCKET NO. 1717.03 skeletal muscles do not signifigantly shorten during contraction.
Summarizing, muscle cells and muscles have the capability of producing very large forces upon contraction.
Muscles also tend to increase in diameter as they contract.
However, the mechanical aspects of the contractility mechanism of a muscle cell are not well understood.
Mechanical systems simulating the action of a muscle described in the literature typically include an expandable bladder confined and/or co~strained to expand radially when pressurized with a gas. For example, a Brevet D' Invention published October 15, 19~1 in the Republic of France, No. 2.076.768 describes a device for converting fluid pressure into contractile force and includes an ovoidal rubber envelope reinforced with relatively inelastic longitudinal filaments. The ends of the ovoidal envelope are anchored between two points and the envelope pressurized wlth a gaseous fluid causing the ovoidal envelope to expand diametrically and contract longitudinally pulling the anchor points together.
Similarly, United States Patent No. 3,645,1~3, Yarlott, describes an ovoidal envelope defined by an expandable bladder confined within relatively inelastic longitudinal strands such that the bladder can expand diametrically but not longitudinally when pressurized with a gaseous fluid.
The earlist k~own mechanical system which simulated the action of a muscle known as the "McKibben S~nthetic Muscle" comprised a cylindrical sheath woven ~rom helical strands of an inGlastic material surrounding a gas inflatable bladder, and was designed to articula~e orthopedic and prosthetic appliances for polio victims.
~ hile ga~ has advantages as a med~um ~or pressurizing and expanding "McKibben" type contractile ac~uators or muscles, i~s primary disadvantage is that it is compres~ible which dictates an "21astic" contractile 4 1 3 0 8 - 1DOCKET NO. 1~1~,03 response. Elastic contractile responses are not always desirable. For example, an elastic contractile mechanism can not establish or maintain a reference position ~7here load varies.
Also, as explained infra, the contractile force generated by a "McKibben" type contractile device as it inflates is not linear, and when a gas is utilized to inflate or "energize" the muscle, the contractile position of the muscle will vary with ~as pressure and tensile load.
Accordingly, any system utilizing gas inflatable "McKibben"
type contractile devices requires complex electromechanical or other type of servomechanisms both for adjusting position, and for metering the gas for inflating and deflating under conditions of varying pressure.
Still another significant disadvantage of using a gas for inflating and contracting a "McKibben" muscle relates to the property of gas to expand filling the available volume. This means that the degree of contraction (or extension) of the muscle is determined by the tensile force between the anchor points of the muscle resisting contraction.
The above reasons, among others have discouraged commercial acceptance of the "McKibben" muscle as a contractile force generating mechanism/actuator.
Summarizing, gas energized contractile force mechanisms have three variables, position (volume), pressure and tension. Temperature also af~ects the response of such gas energized systems. For the "McKibben" type contractile force mechanisms to achieve commercial acceptance , it i5 necessary to eliminate or minimize the above variables affecting its re~ponse.
SUMMARY 0~ THE INV~NTION
A contractility actuator i5 described which includes a ~ylindrical array formed by a network o~ open two dimensional guadrilateral segments, and expandable bladder 1 308~ 1 8 DOCKET NO. 1~1~.03 located within the cylindrical network and meahs introducing and expanding the bladder with a liquid for generating a very large magnitude contractile force aligned with the axis of the array. Two or more of the described contractility actuators may be arranged in a system for precisely articulating one or more arms pivotally secured at the distal end of a ridged structure.
Th~ principal aspect of the invented contractility actuator relates to the incompressible properties of liquids which reduces the number of variables allowing the actuator to precisely respo~d relative to both position and tension.
Accordingly, two or more such actuators working in opposition acro~s a fulcrum establish a dynamic equilibrium which can be incremently altered by simultaneously inputting liquid into actuators on one side of the fulcrum and allowing liquid to exhaust from the actuators on the other side of the fulcru~ to establish a new dynamic equilibrium position without oscillation.
Another aspect of the invention relates to utilization of a combination of liguid and gas inflated contractility actuators for pivoting arms at the di6tal ends of structure member~ providing a combination of the elastic positional response characteristics of a gas inflated contractility actuator with the positional precision and accuracy charact~ristics of the liquid energized contractility actuator.
Other a5pect5, f~atures and objects of the present invention involve both methods and apparatus for control-ling a plurality of such contractility actuators for articulating an arm in a solid angle about a pivot point.
1 30~2 1 ~
6 DOCKET NO. 171~ 03 Still other advantages, objects, features and aspects of the invented liguid energized contractility actuators and systems utilizing ~uch actuators are more fully described and will become apparent with reference to the following descriptions and drawings of preferred and exemplary embodiments of both the actuator and of systems utilizing the invented actuator.
D~SCRIPTION OF THE DR~KINGS
Fig. 1 illustrates the essential components of a "McKibben" type contractility mechanism.
Fig. 2 is a schematic of a rhombus responding to an impressed force for illustrating an aspect of "McKibben"
type contractility actuators.
Fig. 3 is a simple vector diagram for illus~rating the relative magnitude of the respective forces with respect to an ideal rhombus.
Fig. 4 is a perspective schematic illustrating a cylindrical segment of a "McKibben" type contractility actuator.
Fig. 5 illustrates the constructor of a general conical array beginning with a cone axi5 line AA and a cone generation line BB line in a plane.
Fig. 6 is a ~chematic illustrating a "McKibben"
actuator in a relaxed configuration.
Fig. 7 is a 6chematic illustrating a t'McKibben"
contractility actuator in a contracted confi~uration.
1 308~ 1 8 7 DOCKET NO. 1717.03 Fig. 8 is a graph illustrating the cotangent dependency of the contractile force generated by "McKibben"
type contractility actuators.
Fig. 9 is a graph illustrating the change in length as a function as a change in volume for a "McKibben" type contractile ~echanism and for a piston-cylinder contractile mechanism.
Fig. 10 is a partial cut-away illustration of a pivoting mechanism where invented liquid contracti1ity actuators articulate platorms secured at either end of a longitudinal arm.
Fig. 11 is an enlarged cross section of the coupling ~ecuring one end of the contractility actuators to the shank of the longitudinal arm of the pivoting mechanism shown in Fi~ure 10.
Figs. 12, 12a, and 12b illustrate the ~eatures of the embodiment of the arm a~d platform shown in Figure 10.
Fig. 13 illustrates the essential features of another embodiment for the arm and platforms of Fig. 10.
Figs. 14 and 15 present block diagrams of an exemplary control system inflating and deflating contractility actuators for articulating the respective platforms at the distal ends of a pivoting mechanism of the type shown in Figure 10.
Fig. 16 presents a schematic dia~ram of a plurallty of pivoting mechanisms of the type illustrated in Fig. 10.
1,308'21~
8 DOCKET NO. 171~.03 DESCRIPTION OF PRæFERR~D AND EXEMPLARY ~MBODIM~NT5 As shown in Fig. 1 the basic "McKibben" type fluid contractile actuator includes a cylindrical sheath 11 formed from a flexible mesh 12 secured to connectors 13 at either end of the sheath 11. A bladder 14 composed of a strong ~xpandable material is disposed within the sheath 11.
~onnected to the bladder i8 an inflation line 16 through which a pressurizing ~luid 17 may be introduced for purpose of expanding the bladder 14 within the cylindrical sheath 11. Appropriate valves 18 on the inflation line 16 direct fluid from a pressurizing source 1~ into the bladder for inflation (oontraction) and allow fluid to escape from the bladderfor deflation (extension~.
In operation, the "McKibben" type fluidic contractility actuator or "muscle" is connected between two fixed points using connector 13 with the bladder 14 deflated. Ideally the cylindrical sheath formed from the flexible mesh when connected between two flexible points should experience a very slight tensile stress in order to ensure that the sheath 11 when connected in its extended "relaxed" position between the two points is at a minimum diameter. The in~lation line 16 is then connected to the source of pressurizing ~luid 1~. m e fluid may be compressible, i.e., a gas, or incompressible, i.e., a liquid. The fluid when introduced into the bladder 14 expands it against the enclosing mesh sheath 11 causing it to expand diametrically and contract longitudinally generating an extremely large contractile force between the connectors ~3.
The two dimensional diagram of Fig. 2 illustrates the basic principles of a "McKibben" muscle. In particular, rhombu~ 21 is defined by four inextensible seyments or rods 3 DOCKET NO. 1~1~.03 22 each having a length L. The ends of the segments 22 are pivotally secured together allowing the adjacent segments to rotate relative to one another. In the extended position, the rhombus 21 has an initial half angle eO between the respective segments as shown. If a force is impressed in the vertical direction (along the Y-axis) the rhombus 21 is disturbed increasing ~ts diagonal width along the Y axis and decreasing its diagonal width along the X axis according to a differential relationship:
dx = dy cotan ~;
where 0 is the half angle of ~he disturbed rhombus (shown in phantom in Fig. 2).
As illustrated in Figure 2, the pivot points 23 between the segments 22 of the rhombus are not fixed. Now assume that the pivot points 23 lying along the X-axis of Fig. 2 are fixed, and using vector analysis, the magnitude of the contractile force between those two pivot points resulting when a force is impressed in the Y direction can be determined. In particular referring to Figures 2 & 3, a relatively small magnitude force Fy along the Y-axis can generate a relatively large magnitude contractile force Fx along the X-axis between the fixed pivot points of the rhombus 21, particularly for small half-angles e. The ratio of the contractile force along the X axis, Fx to that of the force impressed in the Y direction, Fy varies as a cotangent of the half angle 3 between the connected segments 22, i.e.;
Fx = Py cotan e Fig. 8 illustrates the magnitude of the force magnification factor as the half angle e approaches O.
Now consider a three-dimensional connected network of rhombi 21 in the form of right cylinder 24, a segment of 1 30~ 1 8 DOC~ET NO. 1717.03 which is illustrated in Fig. 4. Each rhombus 21 is formed o~ ~our inextensible segments 22 pivotally coupled together at their respective ends. The inextensible segments 22 of the rhombi laterally combined to form a mesh of the lnextensible helical cords which terminate at the respective ends of the cylindri~al sheath formed by the rhombi.
Similarly, the sum of the respective diagonai widths of the rhombi along the Y axis will equal the circumference of the cylindrical sheath and the sum of the diagonal length of the rhombi along the X axi5 will equal the length of the cylindrical sheath. More generally, the right cylinder of Fig. 4 can be supplanted by a general array formed b~ a connected network of rhombi or other quadrilaterals as shown in Fig. 5.
In particular, as shown in Fig. 5, two smooth curvilinear lines AA and BB lie in substantially in a plane P. Assuming that the lines AA and BB do not intersect, then line AA can be designated as an axis and the line BB can be connoted the generator of a conical array. For each point on line AA construct a line segment La perpendicular to AA
within the plane P. The line segment La terminates at its intersection with the generator line BB at a point Ba~
distance Pa from point a on the axis line M . Now rotate the line segment La about the point a in a plane containing it and perpendicular to the plane P. The locus of the end points of the rotated line segment La defines a circle Ca with its ceDter at a and havi~g a radius Pa. The locus of points Ca for al~ points a on th~ axis AA defines a eneral conical arrav which is a 2-dimensional surface that includes ~ost or all of the cone generator BB for a.
For any point, a on M , the circle CA i5 called a circumference line for the array. It should be appreciated that utilizin~ generally descriptive terms for describing 11 DOCKET NO. 1~1~.03 the sheath 11 enclosing the bladder 14 allows for mathematical analysis of changes in configuration of th~
rhomboidal array as the sheath expands.
In particular, referring now to Figs. 6 and 7, a general conical array 26 is shown in a relaxed or collapsed configuration (Fig. 6), and in ~ contracted or inflated configuration (Fig. 7). ~ith reference to the diagrams presented in Figs. 6 and ~, the following definitions may be utilized for the purpose of gaining an analytical insight a5 to how a "McKibben" muscle operates:
St is the parabolic length of the conical array;
Li is the relaxed length of the actuator between the termination points;
Lf is a contracted length of the actuator between the termination points;
Df is the maximum diameter of the array in the contracted position;
Di is the minimal diameter of the conical array in the relaxed configuration;
Vf i5 the internal volume of the conical array in the contracted configuration;
Vi is the i~ternal volume of the conical array in the relaxed configuration;
TH is the horizontal tension along the axis of the conical array;
P is the f~uid pressure within the bladder;
D is the average diameter assumed equal to 2/3 (Di +
Df); and R e~uals (~f - Di3/Lf (The horizontal f~rce component due to pressurization of the bladder within the general conical array is assumed to be O predicated on an assumption of symmetry.) 1 30~1 8 12 DOCKET N0. 171~.03 Based on the above assumptions and definitions, the ~ollowing equations approximately describe the response of a "Mc~ibben" muscle assuming that the materlal composing the general conical array is inextensible:
st= Li= Lf[l+(2/3)R2-(2/5~R4~(4/7)R6 - ...]; (eq.l) Vf - ( /15)Lf[2D2f+VfDi~(3/4)D2i]; (eq.2) Vi = ( /4)D2iLi; (e~-3) T = ( /6)(PLf2)[(Di~Df~/Df-D~ /2) PDLf(cotan e); (eq.4) L~ - [l-(cosarcsiD(Di/2)-cosarcsin(Dj/2))]2/3[Li]; (eq.5) The above equations illustrate the magnitude of the horizontal contractile tensile force that can be generated by a "McKibben Muscle." For example, from equation 4 it can be ~een that the contractile force component due to the pressurizing fluid theoretically increases asymptot~cally approaching infinity as e approaches 0. (See the graph of Fig. 8.) The graph presented in Fig. 9 plots the change in length of a McKibben Muæcle, ~L, along the horizontal axis for a corresponding change in volume, ~V, along the vertical axis based upvn the relationship obtained using a 5/8 in. HD
EXPANDO cylindrical he}ical weave sheath ~anufactured by Bently Harris Corporation.
The solid line presents data points for a sheath having a initial l~ngth Li of 9~76 in. The dashed line presents data points for a sheath having a initial len~t~ Li of 9.20 in. The third line presents the same data $or a cylinder hRving an internal diameter of 1.125 in. and an initial length Li of 10 in.
1 30~2 1 8 13 DOC~ET NO. 1717.03 From Fig. 9, it can be seen that for that particular "Mckibben Muscle", the ratio of the rate of changP in length to the rate of change of volume, ~L/~V, is substantial less than the same ratio for a comparable cylinder (by a factor of 4)-It can also be observed from the relationshipsexpressed in ~quations 1-5 and from the graphs of Figures 8 and 9 that the spring constant of a "McKibben Muscle" has a significant dependanc~ on the natur~ of the fluid inflating the bladder 14. In particular, w~ere a ~as i5 utilized to inflate the internal bladder 14, a "McKibben Muscle" is highly ela.~tic with a correspondingly low spring constant since a gas is compressible, and accordingly does not have the capacity to maintain a reference position under conditions of varying load. However, using an incompressible fluid or a liquid to inflate the internal bladder 14 converts the "McKibben Muscle" into an inelastic contractile mechanism having a correspondingly high spring constant which accordingly has the capacity to establish and maintain a reference position under conditions of varying load in addition to capacity for generating contractile forces of very high magnitude.
Turning now to Fig. 10, a pivoting mechanism 39 includes plurality of "McKibben" type contractile actuators ~1 each with one end secured by a coupler 42 to a shank of a longitudinal arm 43 and its remaining end secured by an eyelet fastener 64 to an articulating platform 44 by U-bolts 46. The platforms 44 each include a hemispherical socket 4~
receiving a spherical head at the distal ends of the ar~ 43.
In the p*rspectiv~ illustrated, the contractile ~ctuator 41A i~ contracted while contractile actuator 4~B ls extended. A contractile actuator is also secured be~ween a coupling point 45 on the arm 43 and the platform ~4 [not '` ? 1 8 14 DOCKET NO. 1717.03 shown). Liquid is introduced into the respective contractile actuators 41 via inlet ports 49 which connect to conduits 50 (not shown) communicating through the interior of the arm 43 and up through a central shaft 51 at each coupling point 45 on the shank of the longitudinal arm 43.
In more detail, referring to Fig. 11 the coupler 42 includes a central housing 54 with cylindrical passageway 56 dimensioned to a receive the shaft 51 integrally extending out of the shank of the arm 43. The liquid sonduit 50 through the interior of the arm 43 and through the shaft 51 at each coupling point 45 communicates with an annular plenum 57 cut radially into the passageway 56. A threaded tube 58 forming the mouth of the bladder 14 screws into a threaded port 52 communicating through the housing 54 to the plenum 57. Liquid flows via the passageway 50 and plenum 5~
and out the outlet port 52 for inflating or expanding the bladderl4. Suitable seals 61 are compressed between the annular shoulders 62 on either side of the houslng 54 and a mounting nut 63 and a corresponding annular ~houlder of the shaft 51. The mounting nut 63 and the shaft 51 are suitably threaded for compressing the seals 61 to render the coupling 42 liquid tight.
The mechanism illustrated in Fig. 11 for introducing liquid into bladders 14 for inflating the actuators 41 is exemplary. In fact, provlded there is sufficient space between the quadrilateral segments forming the mesh sheath 11, the connection to the bladder 14 can be made through a nozzle communicating to the interior of the bladder extending centrally between the quadrilateral mesh 6egm~nts forming the sheath.
1 3()P,~ 1 ~
DOCKET NO. 171~.03 In the preferred ~mbodiment, again referring to Fig.
11, each strand 66 of the mesh sheath 11 forms a closed loop which encircles both the eyelet fastener 64 and the coupler 42 In this fashion, any limitation on the magnitude of the tensile load which can be born by the actuator 41 ls determined by the strengths of the strands 66, the shaft 51 and the U-bolts 46. In fact, the primary criteria for selecting a mechanism or means for coupling the mesh sheath 11 to the eyelet ~astener 64 and coupler 42 is that it must be able to withstand the maximum e~pect~d tensile load between the connection points of the actuator 41.
Referring back to Fig. 10, the platform 44 pivoted by the actuators 41 about the spherical heads 48 at either end of the arm 43 each include connector means 67 (at the top) and 68 ~at the bottom). The connectors 67 and 68 simply define receiving receptacles 69 for receiving correspondingly shaped male or female protrusions or receptacles ~not shown) dimensioned to receive the connectors 6~ & 68. Accordingly, the pivoting mechanism 3g can be secured to a stationary surface or the pivoting platform 44 of an adjacent plvoting mechanism 39. (See Figure 16.) As illustrated, the connector 68 is inclined with respect to the longitudinal axis o~ the arm 43 to provide an additional dimension to the articulating range and capacity of a machine formed by two or more pivoting mechanisms 39.
The actuators 41 w~rk in opposition as illustrated by actuators 41A and ~lB ( Fi~. 10). Referring to Figures 12, 12A & 12B each arm 43 lncludes four (4) contractile actuators 41, for articulating the top platform 44A and ~our (4) for articulating the bottom platform 44B. The re p~ctive fastening positions of the actuators articulating the top platform 44, indicated by the U-bolts 46 in Figure 12A, are rotated 4~ degrees with respect to the coupling 1 30~2~ ~
16 DOCKET NO . 1717.03 points 45 on the shank of the arm 43 of the actuator.s 41 articu~ating the bottom platform 44b. Similarly with reference to Figure 12B, the U-bolts 46 securing the eyelet fasteners 64 of the latter actuators 41 to the bottom platform are rotated at an angle of 45 degrees with respect to the coupling points 45 of the former actuators 41 articulating the upper platform 44A.
As illustrated in Figures 12 the articulating mechanism formed by the co~bination of the arm 43, the platforms 44 A ~ B and the contractil~ actuators 41 (Figure 10) can tilt a particular platform through a solid angle of approximat~ly 90 degrees as illus~rated in phantom ~or the top platform 44 A in Figure 12. Such tilting of the platform 44 is accomplished by relative contraction of the respective actuators articulating a particular platform. In the example illustrated in Figures 10, 12, 12A and 12B, contraction of a particular actuator tilts the particular platform in a plane determined by the positional relationship of the U-bolt receiving the eyelet fastener 6~
of the particular actuator 41 and its coupling point45 on the shank of the arm 43.
As illustrated in Figures 12A and 12B. The U-bolts 46 of the platform and coupling points 45 on the arm 43 are oriented in the same plane. It should be appreciated however, that the platform 44 can rotate relative to the arm 43 such that contraction of a particular actuator secured between its coupling point 45 on the arm 43 and the U-bolt 46 of the platform 44 provides a twisting or torque ~oment in addition to tilting the platform.
Figure 13 schematically illustrates the relationship between fastening points ~1 on a platform 72 and coupling po~nts ~3 on the shaft 74 of an embodiment of a pivotin~
mechanism ~O ~or three contractile actuators (not ~hown).
Such f astening points 71 on the platform 72 and coupling 1 30~2 1 ~3 17 DOCKET NO. 1717.03 points 73 on the shaft 74 for the platform 72 at the other end are rotated ~O degrees with respect to each other.
Again, a cylindrical head indicated at 76 is received in a corresponding socket is (not shown) on the platform, and it should be realized that the platform 72 can be rotated such that a contracting actuator imparts a twisting as well as a tilting moment to the platform as it contracts.
Referring now to Figure 14, a control system for controlling an articulating or pivoting mechanism ~O of the type depicted in Figure 10, ~hould include a master control system (section A) which may comprise a computer or other type of programmable data processor system. The master control system inputs commands and r~ceives data via address bus 81, a data bus 82, and a control signal bus 83.
The control system should also include a work station controller (section B) for implementing subprograms unique to particular articulating mechanisms for accomplishing such tasks as parts handling, tool manipulation, measurement and the like. The work station basically insludes a micro-controller 84 which accepts commands from the master control and contains memory and microprograming for implementing device-level action. The work station should also include an energizing source such as pump 85 and manifold gl for inflating the contractlle actuators making up the system with a suitable high pressure liquid (water or hydraulic oil).
At the device level (section C~ control processing is provided via an address decoder B6 for interpretin~ signals directed to a particular articulating mechanism, and a data multiplexing system for interpreting directional data coming ~rom the micro-controller 84. A read only memory IROM) and a data latch indicated at 8B, the heart of the device level oontrol processing subqystem, ~ets the sub-routines for opening an~ closin~ valves psr instructions from either or 1 3(~8~ 1 8 18 DOCKET NO. 1~17.03 both the master control and micro-controller 84 subsystems to inflate or deflate a particular artiçulating mechanis~
(section D).
In particular, an amplifier 89 receives and amplifies output signals from the ROM/data latch 88 opening and closing hiyh speed valves 90: i.) controlling flow of a liquid Prom the high pressure side of the manifold 91 into line(s) for inflating particular contractile actuator(s) inducing contraction and il.~ controlling flow of the liquid from line~s) into the low pressure side of the manifold 91 for deflating particular contractile actuator(s) allowing extension.
At the articulating mechanism (section D), feedback signal generators 92 receiving input from pressure sensors 94 located between the valves 90 and the contractile actuators 95 and from one or more relative motion/displacement sensors 93 located on an articulating structure 96 provide data signals to both the master control and work station contol subsystems indicative of displacement relative to contraction and extension of the respective contractile actuators 95.
Figure 15 presents a block diagram schematically illustrating a simple control circuit (Fig. 14, section C) for controlling two contractile actuators wor~ing in opposition including an address decoder 101, and a data latch 102. The data latch 102 receives inpu~ from the micro-controller 84, and the master control subsystems via a data bus (the address bus 81, data bus 82 and control 8ignal bus 83 of Fig. 14) and a clocking pulse from a clock 97. The data latch 102 outputs signals directed .Por particular values. ~n amplifier 103 receiv~s the output from the data latch 102 and amplifys it for ~witching (opening and closlng) ~olenoid, diaphragm and/or shaped~
memory-alloy actuated high speed valves 90. Suitable valves 1 30~2 1 ~
l9 DOCKET NO. 171~.03 include Model 8225 made BY AUTOMATIC SWITCH VALVE CO. (ASCO) Florham Park, New Jersey, and Model Nos. EV2-12 and ETO-3 made by CLIPPARD Cincinnati, Ohio.
Although the preferred and exemplary embodiments of the invented liquid inflated contractility actuator and systems for utilizing same are described in context of representative, schematic, and computational embodiments, many variations and modifications of the invention including those suggestcd by the computational and schematic models utilized for describing and understanding the invention maybe made without departing from ~he scope of the invention as defined and set forth in the following claims ~e clain:
Claims (25)
1. A contractility actuator resisting a tensile force between two anchor points comprising in combination, a cylindrical array connecting between the two anchor points formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles both the anchoring points, the array having its axis aligned between the anchor points, an expandable bladder located within the cylindrical network, a liquid, an input means for introducing the liquid into the bladder expanding the cylindrical array to generate contractile forces aligned with the axis of the array of increasing magnitude between the anchor points, and output metering means for exhausting precise volumes of the liquid from the bladder allowing contraction of the cylindrical array responsive to the tensile force tending to separate the anchor points generating contractile forces aligned with the axis of the array of decreasing magnitude between the anchor points.
2. A contractility actuator resisting a tensile force between two anchor points for adjusting distance between the anchor points comprising in combination, a cylindrical array connecting between the two anchor points formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles both the anchoring points, the array having its axis aligned between the anchor points, an expandable bladder located within the cylindrical network, a liquid, input means for introducing the liquid into the bladder expanding the cylindrical array incrementally shortening the distance between the anchor points, and output metering means for exhausting precise volumes of the liquid from the bladder allowing contraction of the cylindrical array responsive to the tensile force tending to separate the anchor points incrementally lengthening the distance between the anchor points.
3. The contractility actuator of claim 1 or 2 and further including in combination therewith:
a longitudinal arm having a shank and a pivotable coupling on at least one of its two distal ends, a platform secured to the pivotable coupling at a distal end of the arm, a first shank anchoring means located on the shank of the arm providing one of the anchor points for securing one end of the cylindrical array, a first platform anchoring means located on the platform providing the remaining anchor point for securing the remaining end of the cylindrical array.
a longitudinal arm having a shank and a pivotable coupling on at least one of its two distal ends, a platform secured to the pivotable coupling at a distal end of the arm, a first shank anchoring means located on the shank of the arm providing one of the anchor points for securing one end of the cylindrical array, a first platform anchoring means located on the platform providing the remaining anchor point for securing the remaining end of the cylindrical array.
4. The mechanism of claim 3 having at least a second set of two anchor points and at least a second contractility actuator including:
a second cylindrical array formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles both the second set of anchoring points;
a second expandable bladder located within the second cylindrical array;
input means for introducing the liquid into the second bladder expanding the cylindrical array, incrementally shortening the distance between its anchor points;
output metering means for exhausting precise volumes of the liquid from the bladder allowing contraction of the cylindrical array responsive to a tensile force tending to separate its anchor points, incrementally lengthening the distance between the anchor points;
and wherein each additional set of two anchor points includes for each additional actuator:
a shank anchoring means located on the shank of the arm in an opposite relationship relative to the first shank anchoring means providing an anchor point for securing one end of the second cylindrical array;
a platform anchoring means located on the platform on the opposite side of the pivoting coupling relative to the first platform anchoring means providing an anchor point for securing the remaining end of the second cylindrical array, whereby each pair of actuators upon contraction tend to pivot the platform in different directions about a fulcrum provided by the pivotable coupling at the distal end of the arm; and a programmable control means for selectively controlling the input means and output metering means enabling the liquid to be simultaneously introduced into one bladder expanding one cylindrical array and exhausted from bladders within cylindrical arrays anchored to the platform across the fulcrum, the expanding cylindrical array providing the tensile force for contracting and extending the cylindrical arrays across the fulcrum.
a second cylindrical array formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles both the second set of anchoring points;
a second expandable bladder located within the second cylindrical array;
input means for introducing the liquid into the second bladder expanding the cylindrical array, incrementally shortening the distance between its anchor points;
output metering means for exhausting precise volumes of the liquid from the bladder allowing contraction of the cylindrical array responsive to a tensile force tending to separate its anchor points, incrementally lengthening the distance between the anchor points;
and wherein each additional set of two anchor points includes for each additional actuator:
a shank anchoring means located on the shank of the arm in an opposite relationship relative to the first shank anchoring means providing an anchor point for securing one end of the second cylindrical array;
a platform anchoring means located on the platform on the opposite side of the pivoting coupling relative to the first platform anchoring means providing an anchor point for securing the remaining end of the second cylindrical array, whereby each pair of actuators upon contraction tend to pivot the platform in different directions about a fulcrum provided by the pivotable coupling at the distal end of the arm; and a programmable control means for selectively controlling the input means and output metering means enabling the liquid to be simultaneously introduced into one bladder expanding one cylindrical array and exhausted from bladders within cylindrical arrays anchored to the platform across the fulcrum, the expanding cylindrical array providing the tensile force for contracting and extending the cylindrical arrays across the fulcrum.
5. The mechanism of claim. 4 and further including:
at least a second longitudinal arm having a shank and a pivotable coupling on at least one of its two distal ends, a pivoting member secured to the pivotable coupling at the distal end of the second arm, a plurality of shank anchoring means located in equal angular intervals around the shank of the second arm each providing an anchor point for securing one end of a cylindrical array, a plurality of pivoting member anchoring means located in equal angular intervals around the pivoting member each providing an anchor point for securing an end of a cylindrical array, means for coupling the platform at the distal end of the longitudinal arm to the pivoting member at the distal end of the second longitudinal arm, and including:
a first plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles an anchor point on the shank of the second arm and an anchor point on the pivoting member;
an expandable bladder located within each cylindrical array of the first plurality of such arrays;
input means for introducing the liquid into each bladder within the first plurality of cylindrical arrays whereby each cylindrical array of the first plurality can be expanded, incrementally shortening the distance between its anchor points;
output metering means for exhausting precise volumes of the liquid from each bladder within the first plurality of cylindrical arrays whereby each cylindrical array of the first plurality can contract responsive to a tensile force tending to separate its anchor points, incrementally lengthening the distance between its anchor points;
the programmable control means also selectively controlling the input means and output metering means for the bladders within the first plurality of cylindrical arrays whereby the platform and pivoting member can be pivoted independently.
at least a second longitudinal arm having a shank and a pivotable coupling on at least one of its two distal ends, a pivoting member secured to the pivotable coupling at the distal end of the second arm, a plurality of shank anchoring means located in equal angular intervals around the shank of the second arm each providing an anchor point for securing one end of a cylindrical array, a plurality of pivoting member anchoring means located in equal angular intervals around the pivoting member each providing an anchor point for securing an end of a cylindrical array, means for coupling the platform at the distal end of the longitudinal arm to the pivoting member at the distal end of the second longitudinal arm, and including:
a first plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles an anchor point on the shank of the second arm and an anchor point on the pivoting member;
an expandable bladder located within each cylindrical array of the first plurality of such arrays;
input means for introducing the liquid into each bladder within the first plurality of cylindrical arrays whereby each cylindrical array of the first plurality can be expanded, incrementally shortening the distance between its anchor points;
output metering means for exhausting precise volumes of the liquid from each bladder within the first plurality of cylindrical arrays whereby each cylindrical array of the first plurality can contract responsive to a tensile force tending to separate its anchor points, incrementally lengthening the distance between its anchor points;
the programmable control means also selectively controlling the input means and output metering means for the bladders within the first plurality of cylindrical arrays whereby the platform and pivoting member can be pivoted independently.
6. An articulating mechanism comprising in combination, a first plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments, each array being adapted for connection between a set of two anchor points, and each having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array, a liquid, a first longitudinal arm having a shank and a first spherical head on at least one of its two distal ends, a top platform having a hemispherical socket receiving and articulatable about the spherical head at the distal end of the arm, a plurality of lower shank anchoring means located in equal angular intervals around the shank of the arm each providing an anchor point for securing one end of a cylindrical array in the first plurality of such arrays, a plurality top platform anchoring means located in equal angular intervals around the top platform rotated about the longitudinal axis of the first arm relative to the lower shank anchoring means, each top platform anchoring means providing an anchor point for securing a remaining end of a cylindrical array in the first plurality of such arrays, input means for introducing the liquid into each bladder whereby each cylindrical arrays in the first plurality can be expanded generating a contractile force incrementally shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder whereby each cylindrical array of the first plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, and programmable control means for selectively controlling the input means and output metering means whereby the top platform may be simultaneously rotated and articulated in a solid angle around the spherical head at the distal end of the arm.
7. The articulating mechanism of claim 6 and further including:
a second plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments, each array being adapted for connection between a set of two anchor points, and each having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array, a second spherical head on the remaining distal end of the longitudinal arm, a bottom platform having a hemispherical socket receiving and articulatable about the second spherical head at the distal end of the arm, a plurality of upper shank anchoring means located in equal angular intervals around the shank of the arm each providing an anchor point for securing one end of a cylindrical array in the second plurality of such arrays, a plurality bottom platform anchoring means located in equal angular intervals around the bottom platform rotated about the longitudinal axis of the first arm relative to the upper shank anchoring means, each bottom platform anchoring means providing an anchor point for securing a remaining end of a cylindrical array in the second plurality of such arrays, input means for introducing the liquid into each bladder within the second plurality of cylindrical arrays whereby each cylindrical array in the second plurality can be expanded generating a contractile force shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder within the second plurality of cylindrical arrays whereby each cylindrical array of the second plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, the programmable control means also providing selective control of the input means and output metering means for the bladders within the second plurality of cylindrical arrays whereby a modular articulation unit is provided having top and bottom platforms separated by a longitudinal arm, each of which may be simultaneously rotated and articulated in a solid angle around its respective spherical head at the distal ends of the arms independently.
a second plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments, each array being adapted for connection between a set of two anchor points, and each having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array, a second spherical head on the remaining distal end of the longitudinal arm, a bottom platform having a hemispherical socket receiving and articulatable about the second spherical head at the distal end of the arm, a plurality of upper shank anchoring means located in equal angular intervals around the shank of the arm each providing an anchor point for securing one end of a cylindrical array in the second plurality of such arrays, a plurality bottom platform anchoring means located in equal angular intervals around the bottom platform rotated about the longitudinal axis of the first arm relative to the upper shank anchoring means, each bottom platform anchoring means providing an anchor point for securing a remaining end of a cylindrical array in the second plurality of such arrays, input means for introducing the liquid into each bladder within the second plurality of cylindrical arrays whereby each cylindrical array in the second plurality can be expanded generating a contractile force shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder within the second plurality of cylindrical arrays whereby each cylindrical array of the second plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, the programmable control means also providing selective control of the input means and output metering means for the bladders within the second plurality of cylindrical arrays whereby a modular articulation unit is provided having top and bottom platforms separated by a longitudinal arm, each of which may be simultaneously rotated and articulated in a solid angle around its respective spherical head at the distal ends of the arms independently.
8. The articulating mechanism of claim 6 or 7 wherein the input means include:
a high pressure manifold containing the liquid, conduit means for establishing liquid communication between the manifold and each bladder in the respective cylindrical arrays, and pump means for pressurizing the liquid in the high pressure manifold sufficiently to establish liquid flow from the manifold to each bladder, the programmable control means providing electrical signals for opening any electrically energized, normally closed valve means located in each conduit means for isolating each bladder from the high pressure manifold.
a high pressure manifold containing the liquid, conduit means for establishing liquid communication between the manifold and each bladder in the respective cylindrical arrays, and pump means for pressurizing the liquid in the high pressure manifold sufficiently to establish liquid flow from the manifold to each bladder, the programmable control means providing electrical signals for opening any electrically energized, normally closed valve means located in each conduit means for isolating each bladder from the high pressure manifold.
9. The articulating mechanism of claim 7 further including an output metering means comprising in combination therewith:
a low pressure reservoir for receiving the liquid, conduit means for establishing liquid communication between the low pressure reservoir and each bladder within the respective cylindrical arrays, a plurality of electrically energized, normally closed valve means each for interrupting liquid flow from one bladder to the low pressure reservoir, the pump means pumping the liquid from the low pressure reservoir into the high pressure manifold, the programmable control means providing electrical signals for opening the normally closed valve means for precise intervals.
a low pressure reservoir for receiving the liquid, conduit means for establishing liquid communication between the low pressure reservoir and each bladder within the respective cylindrical arrays, a plurality of electrically energized, normally closed valve means each for interrupting liquid flow from one bladder to the low pressure reservoir, the pump means pumping the liquid from the low pressure reservoir into the high pressure manifold, the programmable control means providing electrical signals for opening the normally closed valve means for precise intervals.
10. The articulating mechanism of claim 9 wherein the electrically energized, normally closed valve means comprise high speed solenoid actuated valves interconnected serially into the respective conduit means establishing liquid communication between each bladder and the respective manifold and reservoir.
11. The articulating mechanism of claim 9 wherein the electrically energized, normally closed valve means comprise high speed diaphragm actuated valves interconnected serially into the respective conduit means establishing liquid communication between each bladder and the respective manifold and reservoir.
12. The articulating mechanism of claim 9 wherein the electrically energized, normally closed valve means comprise high speed shaped alloy valves interconnected serially into the respective conduit means establishing liquid communication between each bladder and the respective manifold and reservoir.
13. The articulating mechanism of claim 9 wherein the programmable control means for selectively controlling the electrically energized, normally closed valve means includes: (Fig. 15) a programmable master control subsystem for encoding articulation instructions into digital instruction signals, a micro-controller subsystem receiving and interpreting instruction signals from the master control subsystem for generating digital action signals expressing an algorithm describing desired response parameters for at least two cylindrical arrays oriented and anchored for pivoting the particular platform in opposite directions and the respective normally closed valve means for such arrays a data bus receiving both instruction and action signals from the master control and micro-controller subsystems, a clock means for generating a clocking signal, an address decoder receiving action signals from the micro-controller subsystem, a data latch receiving the digital instruction and action signals from the data bus and the clocking signal from the clocking means for directing output digital signals to particular normally closed valve means, an amplifier for each normally closed valve means receiving the output digital signals directed to the particular valve means by the data latch for supplying an energizing electrical signal to the particular valve means causing the valve means to open for periods corresponding to the output digital pulses received.
14. The articulating mechanism of claim 9 wherein the programmable control means for selectively controlling the electrically energized, normally closed valve means includes: (Fig 14) a programmable data processor (computer) means for inputting commands and receiving data, a work station controller (micro-controller) means for implementing subprograms uniquely tailored to the articulating mechanism, feedback signal generator means receiving input from pressure sensors located between the normally closed valves means and the bladders and from motion/displacement sensors located on the articulating top and bottom platforms for providing data signals to both the computer means and micro-controller means indicative of displacement relative to contraction and extension of the respective cylindrical arrays, and a control processing means including:
an address decoder for interpreting signals directed to particular cylindrical arrays, a data multiplexing system for interpreting directional data coming from the micro-controller, a read only memory (ROM) and a data latch, for (i.) controlling flow of a liquid from the high pressure side of the manifold for inflating particular bladders inducing contraction of the associated cylindrical array and (ii.) controlling flow of the liquid from particular bladders into the low pressure reservoir allowing extension of the associated cylindrical arrays, and an address bus, a data bus and a control signal bus interconnecting between the programmable data processor (computer) means, the work station controller (micro-controller) means, the control processing means, and the feedback signal generator means.
an address decoder for interpreting signals directed to particular cylindrical arrays, a data multiplexing system for interpreting directional data coming from the micro-controller, a read only memory (ROM) and a data latch, for (i.) controlling flow of a liquid from the high pressure side of the manifold for inflating particular bladders inducing contraction of the associated cylindrical array and (ii.) controlling flow of the liquid from particular bladders into the low pressure reservoir allowing extension of the associated cylindrical arrays, and an address bus, a data bus and a control signal bus interconnecting between the programmable data processor (computer) means, the work station controller (micro-controller) means, the control processing means, and the feedback signal generator means.
15. The modular articulation unit of claim 7 wherein the respective top and bottom platforms include interconnecting means for securing each to a respective bottom and top platform of a second such modular articulation unit.
16. The modular articulation unit of claim 7 wherein at least one ofthe platforms includes a second hemispherical socket receiving and articulatable about a first spherical head at a distal end of a second longitudinal arm and further including:
a third plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles a set of two anchor points, and each array having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array of the third plurality, a plurality of upper shank anchoring means located in equal angular intervals around the shank of the second arm each providing an anchor point for securing one end of a cylindrical array in the third plurality of such arrays, a second plurality of platforrn anchoring means located in equal angular intervals around the platform each providing an anchor point for securing a remaining end of a cylindrical array in the third plurality of such arrays, input means for introducing the liquid into each bladder within the third plurality of cylindrical arrays whereby each cylindrical array in the third plurality can be expanded generating a contractile force incrementally shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder within the third plurality of cylindrical arrays, whereby each cylindrical array of the third plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, the programmable control means also providing selective control of the input means and output metering means for the bladders within the third plurality of cylindrical arrays whereby the second longitudinal arm can be articulated in a solid angle relative to the second hemispherical socket of the particular platform independently of articulation of the respective top and bottom platforms at the distal ends of the first longitudinal arm.
a third plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles a set of two anchor points, and each array having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array of the third plurality, a plurality of upper shank anchoring means located in equal angular intervals around the shank of the second arm each providing an anchor point for securing one end of a cylindrical array in the third plurality of such arrays, a second plurality of platforrn anchoring means located in equal angular intervals around the platform each providing an anchor point for securing a remaining end of a cylindrical array in the third plurality of such arrays, input means for introducing the liquid into each bladder within the third plurality of cylindrical arrays whereby each cylindrical array in the third plurality can be expanded generating a contractile force incrementally shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder within the third plurality of cylindrical arrays, whereby each cylindrical array of the third plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, the programmable control means also providing selective control of the input means and output metering means for the bladders within the third plurality of cylindrical arrays whereby the second longitudinal arm can be articulated in a solid angle relative to the second hemispherical socket of the particular platform independently of articulation of the respective top and bottom platforms at the distal ends of the first longitudinal arm.
17. The modular articulation unit of claim 16 and:
a second spherical head on the remaining distal end of the second longitudinal arm, a third platform having a hemispherical socket receiving and articulatable about the second spherical head on the remaining distal end of the second longitudinal arm, a fourth plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles a set of two anchor points, and each array having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array of the fourth plurality, a plurality of lower shank anchoring means located in equal angular intervals around the shank of the second arm each providing an anchor point for securing one end of a cylindrical array in the fourth plurality of such arrays, a plurality of platform anchoring means located in equal angular intervals around the third platform each providing an anchor point for securing a remaining end of a cylindrical array in the fourth plurality of such arrays, input means for introducing the liquid into each bladder within the fourth plurality of cylindrical arrays whereby each cylindrical array in the fourth plurality can be expanded generating a contractile force incrementally shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder within the fourth plurality of cylindrical arrays whereby each cylindrical array of the fourth plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, the programmable control means also providing selective control of the input means and output metering means for the bladders within the fourth plurality of cylindrical arrays whereby the third platform at the distal end of the second longitudinal arm can be articulated in a solid angle relative to the second spherical head of the second arm independently of articulation of the respective top and bottom platforms at the distal ends of the first longitudinal arm and articulation of the second longitudinal arm.
a second spherical head on the remaining distal end of the second longitudinal arm, a third platform having a hemispherical socket receiving and articulatable about the second spherical head on the remaining distal end of the second longitudinal arm, a fourth plurality of cylindrical arrays each formed by a network of open two dimensional quadrilateral segments provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve wherein each closed loop strand encircles a set of two anchor points, and each array having an axis aligned between its anchor points, an expandable bladder located within each cylindrical array of the fourth plurality, a plurality of lower shank anchoring means located in equal angular intervals around the shank of the second arm each providing an anchor point for securing one end of a cylindrical array in the fourth plurality of such arrays, a plurality of platform anchoring means located in equal angular intervals around the third platform each providing an anchor point for securing a remaining end of a cylindrical array in the fourth plurality of such arrays, input means for introducing the liquid into each bladder within the fourth plurality of cylindrical arrays whereby each cylindrical array in the fourth plurality can be expanded generating a contractile force incrementally shortening the distance between its anchor points, and output metering means for exhausting precise volumes of the liquid from each bladder within the fourth plurality of cylindrical arrays whereby each cylindrical array of the fourth plurality can be allowed to contract responsive to a tensile force tending to separate its anchor points incrementally lengthening the distance between its anchor points, the programmable control means also providing selective control of the input means and output metering means for the bladders within the fourth plurality of cylindrical arrays whereby the third platform at the distal end of the second longitudinal arm can be articulated in a solid angle relative to the second spherical head of the second arm independently of articulation of the respective top and bottom platforms at the distal ends of the first longitudinal arm and articulation of the second longitudinal arm.
18. The mechanism of claim 6 wherein the network of open two dimensional quadrilateral segments of the cylindrical array are provided by a plurality of closed loop strands composed of a relatively inextensible material helically woven into a cylindrical mesh sleeve and wherein each closed loop strand encircles both the shank and the platform anchoring means.
19. The mechanism of claim 18 wherein the input means and output metering means introduce and exhaust liquid from the bladder via a common conduit communicating through the shank of the arm and through the first shank anchoring means.
20. The mechanism of claim 19 wherein the first shank anchoring means comprises in combination:
a cylindrical collar having a coaxial passageway, raised exterior annular shoulders at each distal end, having a port communicating radially from the passageway to the exterior cylindrical surface of the collar at a point located centrally between its distal ends, the closed loop strands at one end of the of the cylindrical mesh sleeve encircling the exterior of the collar between its raised annular shoulders, a structural protrusion extending outwardly from the shank of the arm having an axial conduit communicating from the arm to a radial port drilled into the protrusion and a raised annular shoulder adjacent to the arm, the protrusion being received in the coaxial passageway through the collar for securing that particular end of the cylindrical mesh sleeve, a tube hermetically received in the port through the collar establishing liquid communication with the bladder, means for establishing a liquid tight seal between the raised annular shoulder of the protrusion and the distal end of the collar adjacent thereto, and between the protrusion and the collar in a region proximate the remaining distal end of the collar, whereby a liquid flow path is provided by the conduit through the arm the axial conduit of the protrusion, out the port terminating the axial conduit, and the tube to the bladder.
a cylindrical collar having a coaxial passageway, raised exterior annular shoulders at each distal end, having a port communicating radially from the passageway to the exterior cylindrical surface of the collar at a point located centrally between its distal ends, the closed loop strands at one end of the of the cylindrical mesh sleeve encircling the exterior of the collar between its raised annular shoulders, a structural protrusion extending outwardly from the shank of the arm having an axial conduit communicating from the arm to a radial port drilled into the protrusion and a raised annular shoulder adjacent to the arm, the protrusion being received in the coaxial passageway through the collar for securing that particular end of the cylindrical mesh sleeve, a tube hermetically received in the port through the collar establishing liquid communication with the bladder, means for establishing a liquid tight seal between the raised annular shoulder of the protrusion and the distal end of the collar adjacent thereto, and between the protrusion and the collar in a region proximate the remaining distal end of the collar, whereby a liquid flow path is provided by the conduit through the arm the axial conduit of the protrusion, out the port terminating the axial conduit, and the tube to the bladder.
21. The mechanism of claim 18 wherein the first platform anchoring means provides an articulating anchor for securing one end of the cylindrical mesh sleeve to the platform
22. The mechanism of claim 21 wherein the articulating anchor includes a toroidal sleeve encircled by the closed loop strands at one end of the of the cylindrical mesh, and a U-shaped bale depending from the platform threading the toroidal sleeve.
23 . The articulating mechanism of claim 6 wherein at least one of the cylindrical arrays is secured between a lower shank anchoring means and a top platform anchoring means for rotating the platform relative to the shank in a first direction and the remaining cylindrical arrays are secured between the remaining lower shank and top platform anchoring means for rotating the platform relative to the shank in an opposite direction to the first direction.
24. The articulating mechanism of claim 23 having at least three cylindrical arrays, whereby the anchor points of the arrays define a plane.
25. An articulating mechanism comprising in combination, a first contractility actuator having an inelastic contractile response including:
a cylindrical array connecting between two anchor points formed by a network of open two dimensional quadrilateral segments, having its axis aligned between the anchor points, an expandable bladder located within the cylindrical network, a liquid, an input means for introducing the liquid into the bladder expanding the cylindrical array to generate contractile forces aligned with the axis of the array of increasing magnitude between the anchor points, and output metering means for exhausting precise volumes of the liquid from the bladder allowing contraction of the cylindrical array responsive to the tensile force tending to separate the anchor points generating contractile forces aligned with the axis of the array of decreasing magnitude between the anchor points, a longitudinal arm having a shank and a pivotable coupling on at least one of its two distal ends, a platform secured to the pivotable coupling at the distal end of the arm, a first shank anchoring means located on the shank of the arm providing one of the anchor points for securing one end of the cylindrical array, a first platform anchoring means located on the platform providing the remaining anchor point for securing the remaining end of the cylindrical array; and a second contractility actuator having an elastic contractile response including:
a second cylindrical array formed by a network of open two dimensional quadrilateral segments and having ends for connection between a second set of two anchor points, a second shank anchoring means located on the shank of the arm in an opposite relationship relative to the first shank anchoring means providing an anchor point for securing one end of the second cylindrical array, a second platform anchoring means located on the platform on the opposite side of the pivoting coupling relative to the first platform anchoring means providing an anchor point for securing the remaining end of the second cylindrical array, a second expandable bladder located within the second cylindrical array, a gas, input means for pressurizing the second bladder with the gas expanding the second cylindrical array generating an elastic contractile force tending to pivot the first set of anchor points apart.
a cylindrical array connecting between two anchor points formed by a network of open two dimensional quadrilateral segments, having its axis aligned between the anchor points, an expandable bladder located within the cylindrical network, a liquid, an input means for introducing the liquid into the bladder expanding the cylindrical array to generate contractile forces aligned with the axis of the array of increasing magnitude between the anchor points, and output metering means for exhausting precise volumes of the liquid from the bladder allowing contraction of the cylindrical array responsive to the tensile force tending to separate the anchor points generating contractile forces aligned with the axis of the array of decreasing magnitude between the anchor points, a longitudinal arm having a shank and a pivotable coupling on at least one of its two distal ends, a platform secured to the pivotable coupling at the distal end of the arm, a first shank anchoring means located on the shank of the arm providing one of the anchor points for securing one end of the cylindrical array, a first platform anchoring means located on the platform providing the remaining anchor point for securing the remaining end of the cylindrical array; and a second contractility actuator having an elastic contractile response including:
a second cylindrical array formed by a network of open two dimensional quadrilateral segments and having ends for connection between a second set of two anchor points, a second shank anchoring means located on the shank of the arm in an opposite relationship relative to the first shank anchoring means providing an anchor point for securing one end of the second cylindrical array, a second platform anchoring means located on the platform on the opposite side of the pivoting coupling relative to the first platform anchoring means providing an anchor point for securing the remaining end of the second cylindrical array, a second expandable bladder located within the second cylindrical array, a gas, input means for pressurizing the second bladder with the gas expanding the second cylindrical array generating an elastic contractile force tending to pivot the first set of anchor points apart.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000561044A CA1308218C (en) | 1988-03-10 | 1988-03-10 | Liquid contractility actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000561044A CA1308218C (en) | 1988-03-10 | 1988-03-10 | Liquid contractility actuator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1308218C true CA1308218C (en) | 1992-10-06 |
Family
ID=4137605
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000561044A Expired - Lifetime CA1308218C (en) | 1988-03-10 | 1988-03-10 | Liquid contractility actuator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1308218C (en) |
-
1988
- 1988-03-10 CA CA000561044A patent/CA1308218C/en not_active Expired - Lifetime
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