perm filename FORCAL.JPL[1,VDS] blob
sn#255254 filedate 1976-12-23 generic text, type C, neo UTF8
COMMENT ⊗ VALID 00005 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00002 00002 JPL FORCE BALANCE - FOR SEA MANIPULATOR
C00006 00003 ELECTRICAL DETAILS
C00008 00004 CALIBRATION MATRIX: CURRENT TIME AND DATE: 09:16 23DEC76
C00011 00005 CALIBRATION DATA FOR JPL FORCE WRIST - SEA MANIPULATOR
C00018 ENDMK
C⊗;
JPL FORCE BALANCE - FOR SEA MANIPULATOR
USEFUL INFORMATION
Load range.
Direction force (lb) Torque (in-lbs)
X 10 40
Y 10 40
Z 15 50
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 3% of bending
strain at the gages. Torsional strain is less than 10% 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 +- 2.0 vdc supply. Ten wires are required- + 2.0
vdc, - 2.0 vdc, and the 8 signal leads.
The force balance has been designed to that maximum strains will
be about 1500 microinches per inch. Thus with a gage factor of 120 the
output will be about +- .36 volts.
For use with an A/D having a voltage range of +-10vdc, the
amplifiers required by JPL should be set to have a uniform gain of 20.
This gives a typical output of +- 7.2 vdc. As the peak strains are not
uniform, this peak output varies from +- 3.0 vdc to +- 10 vdc depending on
axis.
Overload protection is provided by a plate mounted between the
force beams and the wrist. 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. A test beam in lieu ofthe 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 PAIR LEAD COLOR CHANNEL #
A1 BLACK 0
A2 BROWN 1
B1 RED 2
B2 ORANGE 3
C1 YELLOW 4
C2 GREEN 5
D1 BLUE 6
D2 GREY 7
+Vgg PURPLE
-Vgg WHITE
Hand End (P,C,Board End)
--------------------------
| |
--- 1b ---
| --- |
| 2c | | 2d | SIDE VIEW OF FLEXURE UNIT
| | | | END VIEW OF A BEAM
--- --- ---
| 1a |
--------------------------
Wrist End
All gages are paired. Thus gage pair A1 consistes of the two gages 1a and 1b on beam A.
--- ---
Gages are wired this way. +2.0---| a |--.--| b |--- -2.0
--- | ---
1
Principal gage pairs are: Note: Gage pairs C1,C2,D1,D2 are wired with supply
voltages opposite of gage pairs A1,A2,B1,B2.
Force Principal gages and Sign of signal change for positive force or moment.
+X A2(+),C2(+)
+Y B2(-),D2(-) (between fingers)
+Z A1(+),B1(+),C1(-),D1(-) (+ force towards hand)
Moment about axis
+MX A1(-),C1(-)
+MY B1(+),D1(+)
+MZ A2(-),B2(-),C2(+),D2(+)
CALIBRATION MATRIX: CURRENT TIME AND DATE: 09:16 23DEC76
FORCES GIVEN IN LBS. AND MOMENTS IN UNITS OF INCH-LBS.
ROW 1:
.6369894@-2 .4467295@-1 -.7870717@-2 -.3333210@-1
-.7967604@-2 -.7507269@-2 .8025011@-2 .2060462@-1
ROW 2:
-.4418469 -.1673075@1 .4409424 .2189730@1
.5816041 .1695400@1 -.4391428 -.1325223@1
ROW 3:
-.8846736@-2 -.4908565@-2 -.7481990@-2 .3844385@-2
.9190580@-2 .1695488@-2 .6405012@-2 -.2578483@-2
ROW 4:
-.3192394@1 -.1215341@2 .3201317@1 .1589894@2
.4240662@1 .1231573@2 -.3188098@1 -.9614570@1
ROW 5:
-.6562473@-2 -.2126321@-1 .1480549@-1 .3206922@-1
.8918669@-2 .2798223@-1 .2719153@-2 -.1925375@-1
ROW 6:
.4865433@-2 .1005591@-1 -.5077997@-2 -.3089022@-1
-.6104943@-2 -.1064676@-1 .4661855@-2 .2290803@-1
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 - SEA MANIPULATOR
FORCE/MOMENT IS 0,-2.2,0,-16.06,0,0
CURRENT TIME AND DATE: 08:45 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
5070.00 4120.00 4092.00 3991.00 5085.00 3980.20 4008.00 4228.00
-2.10 .00 2.00 .00 -2.00 -1.80 2.40 -1.00
.00 .00 .00 .47 .67 .00 .00 .00
FORCE/MOMENT IS 0,-4.4,0,-10.12,0,0
CURRENT TIME AND DATE: 08:52 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
4721.90 4108.00 4093.00 4059.10 4731.40 4013.00 4006.00 4284.00
635.90 27.00 -1.00 94.10 636.40 -53.00 -7.00 126.10
.00 .00 .47 .47 .67 .47 .00 .00
FORCE/MOMENT IS -2.2,0,0,0,16.06,0
CURRENT TIME AND DATE: 08:55 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
4004.00 3977.10 5055.00 3954.00 4095.00 4019.00 4996.00 4141.00
-36.00 -76.90 913.00 -11.00 11.00 -54.00 967.00 10.00
.00 .47 .67 .00 .47 .47 .00 .47
FORCE/MOMENT IS -4.4,0,0,0,10.12,0
CURRENT TIME AND DATE: 09:02 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
4024.00 3926.00 4755.00 3957.00 4085.00 3958.00 4659.00 4136.00
-15.00 -128.00 613.10 -7.00 2.00 -114.00 630.90 5.00
.00 .00 .67 .47 .47 .00 .67 .00
FORCE/MOMENT IS 0,0,4.4,0,0,0
CURRENT TIME AND DATE: 09:06 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
3880.10 4068.00 3954.00 3947.00 4217.70 4056.00 4140.00 4137.00
-149.90 -10.00 -141.00 -7.00 127.70 -17.00 131.00 -5.00
.47 .00 .00 .47 .67 .00 .00 .47
FORCE/MOMENT IS 0,-4.4,0,-6.6,0,18.70
CURRENT TIME AND DATE: 09:14 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
4486.00 3507.00 4095.00 3490.00 4479.00 4635.00 3998.00 4873.00
405.00 -573.00 2.30 -474.00 389.00 571.00 -14.00 715.00
.00 .00 .47 .00 .67 .67 .00 .67
FORCE/MOMENT IS 0,0,0,0,0,0
CURRENT TIME AND DATE: 09:18 23DEC76
Strain Gage Readings: Mean, Corrected Mean, Standard Dev.
4080.00 4078.00 4091.00 3962.20 4088.80 4063.00 4010.00 4156.40
-1.00 -2.00 -1.70 -1.80 -1.20 -1.00 -2.00 -1.60
.00 .00 .47 .47 .82 .47 .00 .47