Platform Balance
In one aspect, a platform balance includes a frame support, and at least three spaced-apart transducer bodies coupled to the frame support. Each transducer body includes a support having clevis halves. The sensor body includes a generally rigid peripheral member disposed about a spaced-apart central hub joined to each of the clevis halves. At least three flexure components couple the peripheral member to the hub. The flexure components are spaced-apart from each other at generally equal angle intervals about the hub; the sensor body further including a flexure assembly for some flexure components joining the flexure component to at least one of the hub and the peripheral member, the flexure assembly being compliant for forces in a radial direction from the hub to the peripheral member. Each flexure assembly is configured such that forces transferred concentrate strain at a midpoint along the length of each corresponding flexure component.
1 . A platform balance suitable for transmitting forces and moments in a plurality of directions, the platform balance comprising:
a frame support; and
at least three spaced-apart transducer bodies coupled to the frame support, each transducer body comprising:
a support comprising a pair of clevis halves; and
a sensor body coupled to each of the clevis halves, wherein the sensor body is disposed between the clevis halves and configured to deflect with forces along two orthogonal axes, wherein the sensor body includes a generally rigid peripheral member disposed about a spaced-apart central hub, the central hub being joined to each of the clevis halves with the peripheral member spaced apart from each clevis half, wherein at least three flexure components couple the peripheral member to the central hub, and wherein the flexure components are spaced-apart from each other at generally equal angle intervals about the central hub; the sensor body further including a flexure assembly for each of said at least some flexure components joining the flexure component to at least one of the central hub and the peripheral member, the flexure assembly being compliant for forces in a radial direction from the central hub through the flexure component and to the peripheral member, wherein each flexure assembly is configured such that forces transferred between central hub and the peripheral member concentrate strain at a midpoint along the length of each corresponding flexure component.
2 . The platform balance of claim 1 wherein each flexure assembly is configured such that forces transferred between central hub and the peripheral member cause a first force at the connection of the flexure component to the central hub to be equal and opposite to a second force at the connection of the flexure component to the peripheral member, wherein the first and second force are tangential to the radial direction of each corresponding flexure component.
3 . The platform balance of claim 1 wherein said at least some of the flexure components are configured to concentrate strain in shear.
4 . The platform balance of claim 1 wherein said at least some of the flexure components are configured to concentrate strain in bending.
5 . The platform balance of claim 1 wherein said at least some of the flexure components are configured with a pair of beams.
6 . The platform balance of claim 5 wherein the pair of beams of each flexure component of at least some of the flexure components is formed by an aperture.
7 . The platform balance of claim 1 , and further comprising:
a biasing assembly connected between the support and the sensor body and configured to provide a bias force between the sensor body and the support.
8 . The platform balance of claim 7 wherein the biasing assembly comprises a bias connector configured to operate in tension to provide the bias force.
9 . The platform balance of claim 8 wherein the bias connecter comprises an elongated strap having a width of the strap greater than a thickness of the strap.
10 . The platform balance of claim 9 wherein the biasing assembly comprises a pair of straps provided on opposite portions of the transducer body that are symmetrical.
11 . The platform balance of claim 10 wherein the biasing connector comprises a flexible member fixedly connected to one of the sensor body or the support.
12 . The platform balance of claim 11 wherein the flexible member is integrally formed from a single unitary body of one of the sensor body or the support.
13 . The platform balance of claim 9 wherein the biasing assembly comprises a pair of biasing connectors wherein a biasing connector is provided each of opposite portions of the transducer body that are symmetrical.
14 . The platform balance of claim 13 wherein the biasing structure comprises flexible members, a flexible member being fixedly connected to one of the sensor body or the support.
15 . The platform balance of claim 14 wherein the flexible members are integrally formed from a single unitary body of one of the sensor body or the support.
16 . The platform balance of claim 11 wherein each flexible member comprises a cantilevered beam with one of the biasing connectors connected to one of the flexible members.
17 . The platform balance of claim 12 wherein the flexible member is provided on the support.
18 . The platform balance of claim 13 wherein a flexible member is provided on each clevis half and a bridging block connects the flexible portions together, the bridging block being spaced apart from the sensor body.
19 . The platform balance of claim 12 wherein the flexible portion is provided on the sensor body.
20 . The platform balance of claim 8 wherein the biasing assembly comprises a removable biasing actuator configured to be connected between the sensor body and the support.
21 . The platform balance of claim 1 , and further comprising:
a lockup assembly configured to selectively inhibit movement of the sensor body relative to the clevis halves.
22 . The platform balance of claim 21 wherein the lockup assembly is configured to inhibit movement of the peripheral member relative to the clevis halves.
23 . The platform balance of claim 22 wherein the lockup assembly inhibits movement of the peripheral member by frictional contact.
24 . The platform balance of claim 23 wherein the lockup assembly is configured to selectively move portions having engaging surfaces for frictional contact to contact opposed surfaces of the peripheral member, the engaging surfaces and the opposed surfaces being spaced apart from each other to allow forces to be transferred by the flexure components when the lockup assembly is not engaged.
25 . The platform balance of claim 24 wherein the lockup assembly comprises a first plate member jointed to a first clevis half and a second plate member joined to the second clevis halve, wherein the engaging surfaces are disposed on the plate members.
26 . The platform balance of claim 25 wherein a portion of each plate member is space apart from the associated clevis half.
27 . The platform balance of claim 26 wherein when the engaging surface engage the opposed surfaces, the portion of each plate member frictionally engages the associated clevis half.
28 . The platform balance of claim 27 and further comprising an actuator configured to selectively bring the engaging surfaces in contact with the opposed surfaces and also bring the portions of each plate member into contact with each associated clevis half.
29 . The platform balance of claim 28 wherein major surfaces of the portions of the plate members engage major surfaces of the associated clevis halves.
30 . The platform balance of claim 29 wherein the engaging surfaces are on the plate members, and wherein each plate member comprises a hinges and a link portion between the hinges, the link portion connecting portions of the plate members having the engaging surfaces with portions of the plate members having the major surfaces.
31 . The platform balance of claim 30 wherein the actuator is operably mounted to the portions of the plate members having the engaging surfaces, and wherein the actuator includes a pull rod to selectively pull the pull rod so as to bring the engaging surfaces in contact with the opposed surfaces.
32 . The platform balance of claim 31 wherein the pull rod extends through a bore opening to one of the opposed surfaces, the pull rod being spaced apart from inner surfaces of the bore at least when the actuator is not pulling on the pull rod to bring the engaging surfaces in contact with the opposed surfaces.
33 . A platform balance suitable for transmitting forces and moments in a plurality of directions, the platform balance comprising:
a frame support; and
at least three spaced-apart transducer bodies coupled to the frame support, each transducer body comprising:
a support comprising a pair of clevis halves; and
a sensor body coupled to each of the clevis halves, wherein the sensor body is disposed between the clevis halves and includes a generally rigid peripheral member disposed about a spaced-apart central hub, the central hub being joined to each of the clevis halves with the peripheral member spaced apart from each clevis halve, wherein at least three flexure components couple the peripheral member to the central hub, and wherein the flexure components are spaced-apart from each other at generally equal angle intervals about the central hub;
and a biasing assembly connected between the support and the sensor body and configured to provide a bias force between the sensor body and the support.
34 . A platform balance suitable for transmitting forces and moments in a plurality of directions, the platform balance comprising:
a frame support; and
at least three spaced-apart transducer bodies coupled to the frame support, each transducer body comprising:
a support comprising a pair of clevis halves; and
a sensor body coupled to each of the clevis halves, wherein the sensor body is disposed between the clevis halves and includes a generally rigid peripheral member disposed about a spaced-apart central hub, the central hub being joined to each of the clevis halves with the peripheral member spaced apart from each clevis halve, wherein at least three flexure components couple the peripheral member to the central hub, and wherein the flexure components are spaced-apart from each other at generally equal angle intervals about the central hub; and
a lockup assembly configured to selectively inhibit movement of the sensor body relative to the clevis halves.