Multi-axis load cell
AssigneeMTS Systems Corporation
InventorRichard A. Meyer
Life of this patent
Estimating the term…
Abstract
A load cell body for measuring components of force and moment in plural direction includes an integral assembly having a rigid central hub and a rigid annular ring concentric with the central hub. At least three radial tubes extends radially along corresponding longitudinal axes from the central hub to the annular ring. Flexure members join the radial tubes to the annular ring. Each flexure member is compliant for displacement of each corresponding radial tube along the corresponding longitudinal axis. As a load cell, a strain sensor mounted on each radial tube measures strain therein.
Claims35
A load cell body for transmitting forces and moments in plural directions, the load cell body comprising:
- an integral assembly having:
- a rigid central hub;
- a rigid annular ring concentric with the central hub and having a plurality of apertures;
- at least three radial tubes extending radially along corresponding longitudinal axes from the central hub to the annular ring wherein an aperture of the plurality of apertures is aligned with each bore of the radial tubes;
- and
- a flexure member extending between an end of each radial tube to the annular ring, the flexure member being compliant for displacements of each corresponding radial tube along the corresponding longitudinal axis.
A load cell for measuring selected components of force or moment, the load cell comprising:
- a rigid central hub;
- a rigid annular ring concentric with the central hub;
- a plurality of radial tubes extending radially along corresponding longitudinal axes from the central hub to the annular ring;
- wherein each tube has a non-rectangular outer surface in section perpendicular to the longitudinal axis and includes a plurality of spaced-apart wall portions of reduced thickness to concentrate stress therein, and wherein each wall portion of reduced thickness includes a flat surface;
- a flexure member extending between an end of each radial tube to the annular ring, the flexure member being compliant for displacements of each corresponding radial tube along the corresponding longitudinal axis;
- and
- a plurality of shear sensors mounted on the flat surfaces of each radial tube at the wall portions of reduced thickness to provide output signals indicative of strain therein.
A method of making a load cell body for transmitting forces and moments in plural directions, the method comprising the steps of:
- fabricating from a single block of material an integral assembly with a rigid central hub, a rigid annular ring concentric with the hub, at least three radial members extending from the central hub to the annular ring wherein the flexure member extends between an end of each radial member to the annular ring, the flexure member being compliant for displacements of each corresponding radial member along a corresponding longitudinal axis of each radial member;
- and
- forming a bore within each radial member along the corresponding longitudinal axis, wherein sensitivity of the load cell is a function of the diameters of the bores formed in the radial members.
A load cell body for transmitting forces and moments in plural directions, the load cell body comprising:
- an integral assembly having:
- a rigid central hub;
- a rigid annular ring concentric with the central hub;
- at least three radial tubes extending radially along corresponding longitudinal axes from the central hub to the annular ring, wherein an outer surface of each radial tube includes a plurality of opposed planar surfaces;
- a flexure member extending between an end of each radial tube to the annular ring, the flexure member being compliant for displacements of each corresponding radial tube along the corresponding longitudinal axis;
- and
- a strain sensor mounted on selected radial tubes to measure strain therein, wherein each strain sensor comprises shear sensors mounted to each of the plurality of opposed planar surfaces.
A load cell for measuring selected components of force or moment, the load cell comprising:
- a rigid central hub;
- a rigid annular ring concentric with the central hub;
- a plurality of radial tubes extending radially along corresponding longitudinal axes from the central hub to the annular ring;
- wherein each tube has a non-rectangular outer surface in section perpendicular to the longitudinal axis and includes four spaced-apart wall portions of reduced thickness to concentrate stress therein;
- a flexure member extending between an end of each radial tube to the annular ring, the flexure member being compliant for displacements of each corresponding radial tube along the corresponding longitudinal axis;
- and
- a plurality of shear sensors mounted on each radial tube at the wall portions of reduced thickness to provide output signals indicative of strain therein.
Dependencies are inferred from the claim text.