Assembly for converting motion
An assembly for converting motion has a first member; a second member pivotally connected at a first position to a first position on the first member; a third member pivotally connected at a first position to a second position on the first member; and a fourth member pivotally connected at a first position to a second position on the second member and pivotally connected at a second position to a second position on the third member; wherein the distance between the first position on the second member and the second position on the second member is a distance X and the distance between the first position on the fourth member and the second position on the fourth member is a distance Y; wherein X is equal to Y.
1 . An assembly for converting motion, the assembly comprising:
a first member;
a second member pivotally connected at a first position on the second member to a first position on the first member;
a third member pivotally connected at a first position on the third member to a second position on the first member, the second position on the first member being spaced apart from the first position on the first member; and
a fourth member pivotally connected at a first position on the fourth member to a second position on the second member and pivotally connected at a second position on the fourth member to a second position on the third member, the second position on the second member being spaced apart from the first position on the second member and the second position on the third member being spaced apart from the first position on the third member;
wherein the distance between the first position on the second member and the second position on the second member is a distance X and the distance between the first position on the fourth member and the second position on the fourth member is a distance Y;
wherein the distance X is equal to the distance Y; and
wherein the second member extends from the first position on the second member in the direction of the second position of the second member beyond the second position on the second member.
2 . The assembly according to claim 1 , wherein in an extended position the second member extends from the second position on the second member in the direction of the first position on the second member beyond the first position on the second member to or beyond the first member.
3 . The assembly according to claim 1 , wherein the first, second, third and fourth members have the same length.
4 . The assembly according to claim 1 , further comprising:
a fifth member pivotally connected at a first position on the fifth member to the second position on the third member and the second position on the fourth member; and
a sixth member pivotally connected at a first position on the sixth member to a third position on the second member, wherein the third position on the second member is spaced from the second position on the second member in the direction extending from the first position on the second member to the second position on the second member, and a second position on the fifth member, the second position on the fifth member being spaced apart from the first position on the fifth member.
5 . The assembly according to claim 4 , wherein the fifth member is of a sufficient length that a point P on the fifth member spaced from the first and second positions on the fifth member and beyond the second position in the direction from the first to the second position on the fifth member moves in a substantially straight line as the assembly moves between the retracted position and an extended position;
the assembly further comprising:
a seventh member pivotally connected at a first position on the seventh member to the point P on the fifth member; and
an eighth member pivotally connected at a first position on the eighth member to the third position on the second member and pivotally connected at a second position on the eighth member to a second position on the seventh member, the second position on the seventh member being spaced apart from the first position on the seventh member.
6 . The assembly according to claim 1 , wherein the distance between the first and second position on the first member is A and wherein X and Y have a length represented by the following formula (I):
A /(1+ϕ) (I)
where ϕ is as follows:
1ϕ≤2.
7 . The assembly according to claim 6 , wherein ϕ is from 1.1 to ≤2.
8 . The assembly according to claim 6 , wherein an angle α is formed between the first member and the third member when the assembly is in an extended position, the angle α defined by formula (II):
α=arccos(ϕ/2) (II)
and
ϕ has a value to give an angle α of from 5° up to 59°.
9 . The assembly according to claim 6 , wherein ϕ has the value of 1.285, SQRT(2), 1.532, [(SQRT(5)+1)/2], or SQRT(3).
10 . A method for providing an assembly for converting motion, the method comprising:
providing a first member;
providing a second member pivotally connected at a first position on the second member to a first position on the first member;
providing a third member pivotally connected at a first position on the third member to a second position on the first member, the second position on the first member being spaced apart from the first position on the first member; and
providing a fourth member pivotally connected at a first position on the fourth member to a second position on the second member and pivotally connected at a second position on the fourth member to a second position on the third member, the second position on the second member being spaced apart from the first position on the second member and the second position on the third member being spaced apart from the first position on the third member;
wherein the distance between the first position on the second member and the second position on the second member is a distance X and the distance between the first position on the fourth member and the second position on the fourth member is a distance Y;
wherein the distance X is equal to the distance Y; and
wherein the second member extends from the first position on the second member in the direction of the second position of the second member beyond the second position on the second member;
the method further comprising:
determining the extent of straight line motion required to be generated by the assembly and the deviation of this motion from a straight line; and
selecting the value of X and Y to provide the predetermined motion.
11 . The method according to claim 10 , wherein the distance between the first and second position on the first member is A and wherein X and Y have a length represented by the following formula (I):
A /(1+ϕ) (I)
wherein ϕ is as follows:
1<ϕ≤2.
12 . The method according to claim 11 , wherein ϕ is less than 2.
13 . The method according to claim 12 , wherein ϕ is from 1.1 to ≤2.
14 . The method according to claim 11 , wherein ϕ has a value up to 1.95.
15 . The method according to claim 11 , wherein an angle α is formed between the first member and the third member when the assembly is in an extended position, the angle α defined by formula (II):
α=arccos(ϕ/2) (II)
and
ϕ has a value to give an angle α of from 5° up to 59°.
16 . The method according to claim 11 , wherein ϕ has the value of 1.285, SQRT(2), 1.532, [(SQRT(5)+1)/2], or SQRT(3).
17 . An assembly comprising an assembly according to claim 1 , wherein the first member is provided by a fixed structure, operation of the assembly providing movement of the members of the assembly with respect to the fixed structure.
18 . The assembly according to claim 17 , comprising a plurality of assemblies according to claim 1 .
19 . The assembly according to claim 18 , wherein one or more members of a first assembly are directly connected to a member of a second assembly.
20 . The assembly according to claim 18 , wherein one or more members of a first assembly are indirectly connected to a member of a second assembly by way of one or more additional members.