Good Vibrations Engineering Ltd.

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This simulation is based on the next prototype design we expect to build, test and evaluate. It has been developed based on a combination of finite element modelling - static & normal modes modes, augmented with in-house matlab simulations. The non-linear influences have been modelled and evaluated in matlab, against test results of earlier prototypes.

This 1st simulation does not include temperature influence, nor does it include the algorithm to translate between frequency and load. We know from earlier testing that the configuration has minor thermal distortions. We will be building the temperature effects and frequency transduction algorithm into the upgraded simulation. We have done enough work to be able to analytically isolate and predict the temperature mechanisms.

Design ParameterMaximumMinimum
Measureable force90 lb0.4 lb
Measureable moment 250 ft-lb0.6 in-lb Nm
Allowable Drift (10% of measurement)8 hoursn/a
Rotational Stiffness25.4e4 lb-in/rad27.e3 lb-in/rad
Surviveable Force150 lbn/a
Surviveable Moment370 ft-lbn/a
mass, excluding electronics3.5 lb n/a
dimensionsdiameter: 9 1/8"height: 2 1/4"
1st resonancen/a617 Hz

If you're interested trying out the sim, as part of your control program, you can download the matlab and sample files fms simulation , the matlab code. Of course, its still just a design and analysis. No consideration of temperature yet.

The mass properties are taken as linear, without cabling. The table was taken from Nastran output file. Mass units are lb f- sec 2/inch. RIGID BODY MASS MATRIX AT ORIGIN
9.130E-03 0.000E+00 0.000E+00 0.000E+00 7.840E-03 7.522E-19
0.000E+00 9.130E-03 0.000E+00 -7.840E-03 0.000E+00 1.613E-18
0.000E+00 0.000E+00 9.130E-03 -7.522E-19-1.613E-18 0.000E+00
0.000E+00 -7.840E-03 -7.522E-19 6.190E-02 -3.226E-18 5.557E-18
7.840E-03 0.000E+00 -1.613E-18 -3.226E-18 6.190E-02 -1.152E-18
7.522E-19 1.613E-18 0.000E+00 5.448E-18 -5.014E-19 9.877E-02

US Patent No 5,033,314: expired

US Patent No 9,513,179 B2 Dec 6, 2016

Input and Output

Initially the required input is the time identifier & 6 dof forces between the end effector to fms interface. But the h/w FMS will use accelerometers, and these will be used to extract shape information. Eventually, we will need temperature, so temperature and low frequency acceleration of the robot will be required.

The coordinate system for the fms is Z along the longitudinal direction of the end effector. The origin is taken as the end effector to wrist roll joint interface (roll assumed as joint adjacent to end effector)

Axes system: right hand coordinate system. The unloaded fms X and Y flexibilities are the same, because the the unloaded sensor is axi-symmetric.

The unit system for the applied forces is pounds, inches and seconds. The output flexibility units are: in/lb, & rad/in-lb.

sample input file: ldinput.txt . Time series, 6 dof load input

sample output load file loadout.txt . Time series, 6 dof load output

sample output flexibility file flexout.txt Time series, triangular portion of 6x6