perm filename FORCAL.DAT[1,VDS]2 blob
sn#217348 filedate 1976-05-23 generic text, type C, neo UTF8
COMMENT ⊗ VALID 00005 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00002 00002 JPL FORCE BALANCE - FOR CURV MANIPULATOR
C00006 00003 ELECTRICAL DETAILS
C00008 00004 CALIBRATION MATRIX: CURRENT TIME AND DATE: 14:07 22MAY76
C00011 00005 CALIBRATION DATA FOR JPL FORCE WRIST - CURV MANIPULATOR
C00024 ENDMK
C⊗;
JPL FORCE BALANCE - FOR CURV MANIPULATOR
USEFUL INFORMATION
Load range.
Direction force (lb) Torque (in-lbs)
X 30 72
Y 30 72
Z 50 120
Construction Details
The force sensing element is a single aluminum piece, characterized
by four square beams cantelevered from a central hub simply supported
at their outer end. All forces and torques are supported by beam
bending. Tensile and compressive strains are less than 2% of bending
strain at the gages. Torsional strain is less than 15% of bending
strain.
Eight pairs of semiconductor strain gages are mounted on the
sides of these beams near the built in ends. These matched pairs of
gages have gage factors of about 120. All gage leads are brought out
to a terminal board where they are paired and power supply leads are
commoned. The gages are powered with a +- 2.5 vdc supply. Ten wires
are required- + 2.5 vdc, - 2.5 vdc, and the 8 signal leads.
The force balance has been designed to that maximum strains
will be about 1200 microinches per inch. Thus with a gage factor of
120 the output will be about +- .36 volts.
The amplifiers supplied by JPL have been set up to have a
uniform gain of 10. This gives a maximum output of +- 3.6 vdc. As
the peak strains are not uniform, this peak output varies from +- 2.0
vdc to +- 6 vdc depending on axis. It is suggested that amplifier
gains be left where they are for the time being.
Overload protection is provided by a plate mounted between
the force beams and the hand. This plate has a small gap in it and
four pins. The gap sets Z-force and X and Y moment limits, while the
pins set Z moment and X and Y force limits.
The calibration matrix has been derived by putting test loads
on the force sensor. The hand was in place while this was done. All
measurements were made on a relative basis. This means that the
unloaded output was recorded, and then the loaded output recorded.
The differences were used in the matrix solution. All units are in
pounds and inch-pounds. As the amplifiers were not zeroed for each
bridge, unloaded offsets exist. All measurements must be made on a
relative basis. It is suggested that each operation be started with
a base measurement.
ELECTRICAL DETAILS
SIGNALS
GAGE NAME LEAD COLOR CHANNEL # JPL #
1X RED 0 8
1Y BROWN 1 7
2X PURPLE 2 6
2Y GREEN 3 5
3X WHITE 4 4
3Y GREY 5 3
4X YELLOW 6 2
4Y ORANGE 7 1
--------------------------
| |
--- Y ---
| --- |
| X | | X | SIDE VIEW OF FLEXURE UNIT
| | | | END VIEW OF A BEAM
--- --- ---
| Y |
--------------------------
All gages are paired. Thus gage pair 1X consistes of the two X gages on beam #1.
___ ___
Gages are wired this way. +2.5---| X |--.--| X |--- -2.5
--- | ---
|
OUT
Principal gage pairs are:
Force Principal gages Sign of signal
+X 3X(+),1X(-)
+Y 2X(+),4X(-)
+Z 1Y,2Y,3Y,4Y (+ towards wrist and arm)
Moment about axis
+MX 1Y(+),3Y(-)
+MY 2Y(+),4Y(-)
+MZ 1X,2X,3X,4X (+)
CALIBRATION MATRIX: CURRENT TIME AND DATE: 14:07 22MAY76
FORCES GIVEN IN LBS. AND MOMENTS IN UNITS OF INCH-LBS.
ROW 1:
-.3842216@-1 .7738081@-3 -.1980125@-3 .2643359@-2
.3910925@-1 .9296865@-3 .2450492@-3 .1941004@-2
ROW 2:
-.2212931@-3 .2937272@-3 .3921106@-1 -.6701423@-3
.1410366@-2 .4863639@-3 -.3878679@-1 .1571425@-2
ROW 3:
-.1230674@-2 .2637714@-1 .1738579@-2 .2676672@-1
.1623723@-2 .2664726@-1 .2004941@-3 .2645674@-1
ROW 4:
.1823379@-2 .4318801@-1 -.8740230@-4 .1541083@-2
.1055043@-2 -.3885803@-1 -.2136039@-2 .1147877@-2
ROW 5:
.2132998@-2 -.1207303@-2 .4674648@-3 -.4275645@-1
-.2940330@-2 -.1396479@-2 .5432162@-3 .3994823@-1
ROW 6:
.3111507@-1 -.3894525@-2 .4818625@-1 .1130393@-3
.4628459@-1 .3162766@-2 .2960590@-1 .1115819@-2
THE FOLLOWING MATRIX EQUATION TOGETHER WITH THE CALIBRATION MATRIX
GIVEN ABOVE CAN BE USED TO RESOLVE THE FORCES AND MOMENTS:
F ← M * ε
where
T
F = (FX,FY,FZ,MX,MY,MZ)
= force/moment vector
M = calibration matrix shown above
T
ε = (ε1,ε2,ε3,ε4,ε5,ε6,ε7,ε8)
= difference in strain gage readings
CALIBRATION DATA FOR JPL FORCE WRIST - CURV MANIPULATOR
FORCE/MOMENT OF 0 4.4 0 3.3 0 0
CURRENT TIME AND DATE: 13:35 22MAY76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
-9.00 52.60 100.00 24.00 37.00 -12.00 -19.00 58.00
-4.00 38.60 50.00 -1.00 -3.00 -39.00 -63.20 -1.00
.00 .52 .00 .00 .00 .00 .00 .00
FORCE/MOMENT OF 0 0 4.4 0 0 0
CURRENT TIME AND DATE: 13:38 22MAY76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
-2.30 52.00 50.00 64.00 36.00 72.00 46.00 103.00
2.70 38.00 .00 39.00 -4.00 45.00 1.80 44.00
.48 .00 .00 .00 .00 .00 .00 .00
FORCE/MOMENT OF 0 4.4 0 30.58 0 0
CURRENT TIME AND DATE: 13:44 22MAY76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
16.00 388.00 104.00 22.00 63.00 -339.80 -15.00 54.00
21.00 374.00 55.00 -3.00 23.00 -366.80 -59.00 -4.00
.00 .00 .00 .00 .00 .42 .00 .00
FORCE/MOMENT OF 4.4 0 0 0 -30.58 0
CURRENT TIME AND DATE: 13:49 22MAY76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
-58.30 9.00 51.00 391.00 93.00 25.00 26.00 -309.00
-53.30 -5.00 1.00 365.00 54.00 -2.00 -18.00 -368.00
.48 .00 .00 .00 .00 .00 .00 .00
FORCE/MOMENT OF 4.4 0 0 0 -3.3 0
CURRENT TIME AND DATE: 13:55 22MAY76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
-66.10 12.00 44.00 62.00 91.00 24.00 38.00 22.00
-61.10 -2.00 -6.00 36.00 52.00 -3.00 -6.00 -37.00
.32 .00 .00 .00 .00 .00 .00 .00
FORCE/MOMENT OF O 4.4 0 4.62 0 18.48
CURRENT TIME AND DATE: 14:02 22MAY76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
-128.00 73.00 -17.00 26.00 -81.00 -25.00 -141.00 60.00
-123.00 59.00 -67.00 .00 -120.00 -52.00 -185.00 1.00
.00 .00 .00 .00 .00 .00 .00 .00