System for multi-dimensional stiffness control of surfaces

Abstract

An elastic device providing means of controlling its stiffness by controlling the tension of the string or group of springs resulting in adjustable transverse stiffness of it, arranged in matrix to enable the control of spatial stiffness of a 2D matrix in unlimited resolution.

Claims

1. An elastic device comprising: a matrix of loading points, each of said loading points being attached to one or more strings in two or more directions, wherein each of said strings is coupled to a tension mechanism independently of the other strings, and wherein a transverse stiffness of a particular one of said loading points is proportional to tensions of said strings that are coupled to said particular one of said loading points, and wherein each of said strings is coupled with a connecting spring to said tension mechanism, wherein said tension mechanism is configured to adjust the tension of each of said strings.

2. The elastic device according to claim 1, wherein said two or more directions are longitudinal and transverse to define rows and columns.

3. The elastic device according to claim 1, wherein said loading points are arranged in rows and columns.

4. The elastic device according to claim 1, further comprising an additional supporting layer of foam next to said loading points.

5. The elastic device according to claim 1, wherein each of said strings is attached directly to said tension mechanism.

6. The elastic device according to claim 1, further comprising a pressure sensor configured to sense pressure at at least one of said loading points.

7. The elastic device according to claim 1, further comprising a biasing device to adjust a height of at least one of said loading points.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an isometric view of a 5×5 matrix.

(2) FIG. 2 is an isometric view of a single point of load (junction), isolated from all other points of load with a sample 4 strings support.

(3) FIG. 3 is a top view of a 5×5 matrix (25 points resolution) of a support surface.

(4) FIG. 4 is a top view of a single point of a matrix, isolated from all other points.

(5) FIG. 5 is a scheme presenting an n×m matrix with related stiffness calculation in each point.

(6) FIG. 6 is a top view of a simplified 2×2 matrix with the related strings and tension forces on each point enabling the control of the point stiffness.

(7) FIG. 7 is a side view of a single point in a matrix connected with four strings in a junction (2 in a column and 2 in a row).

(8) FIG. 8 is an isometric view of a full matrix with supporting frame and upper cushioning layer.

(9) FIG. 9 is a side view of a single string with additional spring.

(10) FIG. 10 is a side view of a single point in a matrix connected with four strings in a junction (2 in a column and 2 in a row) preloaded, to provide means to control the height position of a junction.

DETAILED DESCRIPTION

(11) The present invention provides a supporting device for, such as but not limited to, mattresses, trampolines, treatment beds, anti-bedsore-systems, emergency patients beds, etc. The invention is an elastic element that consists of a string or strings system, or strings integrated with another elastic element. Since the string's longitudinal tension influences its transverse firmness, hence by adjusting the string's longitudinal tension, one can control its transverse stiffness. This can be applied on a plurality of strings, each pair or more, supporting each point in a 2D matrix configuration to enable 2D stiffness control with unlimited resolution.

(12) Loading points or junctions (1) are distributed in a matrix of rows and columns or any other arrangement. Each of the junctions 1 are attached to one or more strings (2) in two or more directions, usually longitudinal and transverse, set as a rows and columns, although any other arrangement is valid. Each of the strings is tensioned to a different value using a tension mechanism (3). This results in an assembly of which each junction is independent from the other junctions, so each junction can be separately and independently controlled.

(13) The string arrangement to each loading point can be one string, two strings or more, and each string contributes to the transverse stiffness of the loading point. String tension is T.sub.1, T.sub.2, T.sub.3, . . . T.sub.a where a is the total number of strings supporting a loading point. Since the transverse stiffness of a loading point is proportional to the tension of the string, the stiffness of a loading point supported by a single string is C.Math.T.sub.1, the stiffness of a loading point supported by two strings is C.Math.(T.sub.1+T.sub.2) and so on. Thus, in general, the transverse stiffness of a loading point is C.Math.(T.sub.1+T.sub.2+T.sub.3+ . . . +T.sub.a), where C is a multiplication factor, which may be different for every junction depending on the junction parameters. Moreover, C may be different for each string; for example, if the strings are not identical, the total stiffness of a loading point is (C.sub.1T.sub.1+C.sub.2T.sub.2+C.sub.3T.sub.3+ . . . +C.sub.aT.sub.a).

(14) FIG. 5 describes a general possible matrix configuration. c.sub.1-c.sub.m represents the columns numbers (total of m columns), r.sub.1-r.sub.n represents the rows number (total of n rows). P.sub.11-P.sub.nm represents the junction's numbers (total junctions are n.Math.m). In this figure, each junction is connected to 2 strings—column string and row string. For example, junction P.sub.11 is connected to string c.sub.11 and r.sub.11, P.sub.12 is connected to string c.sub.21 and r.sub.12, etc., so the general junction P.sub.nm is connected to string c.sub.nm and r.sub.mn. The stiffness of each junction is a function of its related string tension (T); therefore, in general, junction P.sub.nm stiffness (S) is equal to c.sub.nm.Math.(Tc.sub.mn+Tr.sub.nm) where Tc.sub.mn is the tension of string c.sub.mn and Tr.sub.nm is the tension of string r.sub.nm.

(15) FIG. 6 describes an example of a 2×2 matrix of loading points P.sub.11, P.sub.12, P.sub.21 and P.sub.22. Each loading point is supported by 2 strings in this example, but it is not limited to two and can be connected to more than 2 strings in any configuration. Loading point P.sub.11 is supported by strings (16) and (14) having tensions Tc.sub.1 and Tr.sub.4 respectively. Loading point P.sub.12 is supported by strings (18) and (13) having tensions Tc.sub.3 and Tr.sub.3 respectively. Loading point P.sub.21 is supported by strings (15) and (12) having tensions Tc.sub.2 and Tr.sub.2 respectively. Loading point P.sub.22 is supported by strings (17) and (11) having tensions Tc.sub.4 and Tr.sub.1 respectively. This exemplary arrangement of 2×2 results in 4 different stiffnesses for each of the loading points as follows: Stiffness of loading point P.sub.11 is C.sub.11.Math.(Tc.sub.1+Tr.sub.4); stiffness of loading point P.sub.12 is C.sub.12.Math.(Tc.sub.3+Tr.sub.3); stiffness of loading point P.sub.21 is C.sub.21*(TC.sub.2+Tr.sub.2); stiffness of loading point P.sub.22 is C.sub.22.Math.(Tc.sub.4+Tr.sub.1). C represents a general constant or parameter and is not necessarily the same for each of the loading points.

(16) On top or in the volume of the points of load there may or may not exist an additional supporting layer of foam or any other type of material or structure which assists in averaging the stiffness. The support layer may be added on top of the points of loads.

(17) Tensioning mechanism (3), either manual, pneumatic, electrical or any other external energy source may or may not be connected to the string or a group of strings to control the string/s tensioning and thus control the transverse stiffness of every point of load.

(18) A pressure sensing sensor or any other sensing mechanism may be installed on the surface, or cover the whole upper surface of the point of load or on top of the supporting layer to sense the pressure on every point over the 2D surface to feedback to the tensioning mechanisms and by using a dedicated algorithm to control each supporting point or a group of points stiffness.

(19) The strings may or may not be attached to the tension mechanism (3) directly. For example, they may be coupled with a connecting spring (6) which provides additional flexibility to the string.

(20) Each or some of the junctions can be preloaded transversely with a biasing device such as a spring or another element (11) to adjust or lower the initial height, thereby controlling the height of each junction.