Kaman KD-5100 User manual

Copyright © 2015 Kaman Precision Products
PART NO: 860029-001 A Division of Kaman Aerospace Corporation
Last Revised: 01/06/15 217 Smith Street
Middletown, CT 06457
www.kamansensors.com
KD-5100
Differential Measuring System
User’s Manual
TABLE OF CONTENTS

www.kamansensors.com 2 PART NO: 860029-001
Last Revised 01/06/15
1.0 INTRODUCTION...................................................................................................... 4
2.0 THEORY OF OPERATION...................................................................................... 5
3.0 OPTIMUM PERFORMANCE ................................................................................... 6
4.0 APPLICATION INFORMATION............................................................................... 7
5.0 TARGETS................................................................................................................ 8
5.1 Material................................................................................................................. 8 
5.2 Thickness ............................................................................................................. 9
5.3 Size....................................................................................................................... 9
6.0 SPECIAL HANDLING CAUTIONS.......................................................................... 9
6.1 Sensors ................................................................................................................ 9
6.2 Mounting Surface................................................................................................ 10
7.0 FIXTURING............................................................................................................ 11
7.1 Factors that degrade performance:...................................................................... 11
7.2 Pivot point requirements: ..................................................................................... 11
7.3 Sensor mounting considerations:......................................................................... 13
8.0 CROSS-AXIS SENSITIVITY.................................................................................. 14
8.1 Cross-axis sensitivity may occur under the following conditions:......................... 14
8.2 Additional points of emphasis about cross-axis sensitivity:.................................. 14
9.0 PIN OUT and CONNECTOR ASSIGNMENTS...................................................... 15
10.0 USER’S ABBREVIATED FUNCTIONAL TEST................................................... 16
11.0 SENSOR INSTALLATION GUIDELINES AND PROCEDURE............................. 17
11.1 Guidelines.......................................................................................................... 17
11.2 Procedure .......................................................................................................... 17
12.0 CALIBRATION..................................................................................................... 19
12.1 Equipment Required .......................................................................................... 20
12.2 Calibration Procedure Overview ........................................................................ 20
12.3 Calibration Steps ............................................................................................... 21
13.0 TROUBLESHOOTING......................................................................................... 23
14.0 TERMINOLOGY................................................................................................... 24
15.0 CUSTOMER SERVICE INFORMATION.............................................................. 25
APPENDIX A: Total System Specifications*(sensor, cable, and electronics) .............. 26
APPENDIX B: Measuring Range and Performance Tradeoffs .................................... 27
APPENDIX C: Output Filter Characteristics of the KD-5100........................................ 35

www.kamansensors.com 3 PART NO: 860029-001
Last Revised 01/06/15
ILLUSTRATIONS
Figure 1 Block Diagram: Differential Measuring System ............................................... 5
Figure 2 Sensor and Target Geometry........................................................................... 6
Figure 3 Differential Target Configurations..................................................................... 7
Figure 4 x-y Mirror Alignment Configuration................................................................... 8
Figure 5 Aluminum Targets on Invar .............................................................................. 8
Figure 6 Mounting/Cover Plate Dimensions ................................................................. 10
Figure 7 15N Sensor Dimensions ................................................................................ 12
Figure 8 20N Sensor Dimensions ............................................................................... 12
Figure 9 Sensor Coil Dimensions................................................................................. 13
Figure 10 Sensor Cable Connections........................................................................... 15
Figure 11 Power & Output Connections ....................................................................... 15
Figure 12 Sensor Field ................................................................................................. 17
Figure 13 Calibration Cover Dimensions...................................................................... 20
Figure 14 Zero & Gain Control Location Case Dimensions.......................................... 21
Figure 15 Null Gap, Offset, Measuring Range ............................................................. 24

www.kamansensors.com 4 PART NO: 860029-001
Last Revised 01/06/15
KD-5100 SERIES
DIFFERENTIAL MEASURING SYSTEMS
SYSTEM SPECIFICATIONS:
Sensor Type __________ Null Gap __________
Offset __________ Measuring Range __________
Full Scale Output __________ Scale Factor __________
Target Material __________
1.0 INTRODUCTION
This manual describes installation and use of the KD-5100, theory of operation, ways to
optimize performance, special handling cautions, functional tests, and guidelines for fixturing
and targets, and calibration procedures.
Calibration
Though there is a section on calibration, these systems are shipped from the factory calibrated
for a user specified target, sensitivity, and measuring range. We calibrate these systems in a
controlled environment using a precision laser as a primary dimensional standard. Since it is
difficult for users to duplicate our calibration conditions, call us before attempting any
adjustments of your KD-5100. On the other hand, it is equally difficult for Kaman to duplicate
your actual application conditions, so special circumstances may dictate come calibration.
Again, coordinate with a Kaman engineer first.
Maintainability
The KD-5100 is designed so that scheduled maintenance and adjustments are not required.
The unit can be removed and replaced without special tools.
Environment
The KD-5100 provides specified performance after exposure to all natural and/or induced
environments encountered during manufacture, test, transportation, handling, storage,
installation, and removal operations.

www.kamansensors.com 5 PART NO: 860029-001
Last Revised 01/06/15
2.0 THEORY OF OPERATION
The KD-5100 Differential Measuring System uses advanced inductive measurement technology
to detect the aligned or centered position of a conductive target. Two matched sensors are
positioned relative to the target so that as it moves away from one sensor it moves toward the
other an equal amount.
The transducer operates on the principle of impedance variation caused by eddy currents
induced in a conductive target located within range of each sensor. The coil in the sensor is
energized with an AC current, causing a magnetic coupling between the sensor coil and the
target. The strength of this coupling depends upon the gap between them and changes in gap
cause an impedance variation in the coil.
In the KD-5100, the coils of a pair of sensors form the opposite legs of a balanced bridge circuit
(Figure 1).
VOLTAGE
REGULATOR
+15 Vdc
COMMON
-15 Vdc
Figure 1 Block Diagram: Differential Measuring System
When the target is electrically centered between the two sensors at the nominal null gap for
each, the system output is zero. As the target moves away from one sensor and toward
another, the coupling between each sensor and target is no longer equal causing an impedance
imbalance between the sensors. The bridge detects this imbalance and its output is amplified,
demodulated, and presented as a linear analog signal directly proportional to the targets
position. This is a bipolar signal that provides both magnitude and direction of misalignment.
Only the differential output is available.

www.kamansensors.com 6 PART NO: 860029-001
Last Revised 01/06/15
This differential configuration achieves its high resolution by eliminating the noise and drift any
intervening summation and Log amplifiers normally add to the system.
Maximum performance depends upon advanced sensor technology. Factors critical to the high
resolution of the KD-5100 are tighter manufacturing control, using significantly larger coils for a
given range of operation, and electrically matching the sensors.
By using electrically matched sensors on opposing legs of the same bridge, temperature effects
common to the sensors and cabling of a differential sensor pair tend to be cancelled. This is
true for the mechanical aspects of the sensor/target system also. Assuming the thermal
characteristics of each sensor track together, slight changes in sensor length due to
temperature tend to be cancelled.
3.0 OPTIMUM PERFORMANCE
To optimize the performance of a KD-5100 system, a high (d) to (s) ratio is desired: (d) is the
sensor coil diameter and (s) includes: the null gap, the positive measuring range, and ½ of the
coil depth (Figure 2).
Figure 2 Sensor and Target Geometry

www.kamansensors.com 7 PART NO: 860029-001
Last Revised 01/06/15
The 15N sensor used over the specified ±0.009” measuring range provides a d/s ratio of 3.08.
The ratio for the 20N is 10.68. Therefore, if mounting space and target size permit, the 20N
offers better performance over the specified measuring range.
For either sensor model, performance can be improved by decreasing the one variable, the
measuring range. Significant reduction can provide a d/s ratio up to 35. This effectively lowers
the noise floor and improves resolution, linearity, and thermal stability.
The temperature of the mounting surface and the environment for the electronics should not
exceed the specified –20oC to 60oC (-4oF to +140oF). For optimum performance, stabilize the
temperature for the mounting surface/electronics at a constant temperature within this range,
preferably 25oC.
4.0 APPLICATION INFORMATION
For differential measurement applications, the two electronically matched sensors are
positioned on opposite sides or ends of the target (Figure 3). The sensor to target relationship
is such that as the target moves away from one sensor, it moves toward the other an equal
amount.
Figure 3 Differential Target Configurations
A standard system comes with two measurement axes (four sensors – two per axis) and can
therefore be fixtured a number of ways to provide precise x-y alignment. Figure 4 illustrates
target configuration for x-y alignment of an image stabilization mirror for an electro-optical
application.
DO NOT MAKE ANY MODIFICATIONS TO CABLE LENGTH, SENSOR OR
CALIBRATED TARGET MATERIALS WITHOUT CONSULTATING A
KAMAN APPLICATION ENGINEER

www.kamansensors.com 8 PART NO: 860029-001
Last Revised 01/06/15
Figure 4 x-y Mirror Alignment Configuration
5.0 TARGETS
5.1 Material
Iron, nickel, and many of their alloys (magnetic targets) are not acceptable for use with the KD-
5100.
Aluminum is preferred as the most practical target material. Aluminum targets can be mounted
on materials with more stable temperature characteristics such as Invar or other substrates as
long as target thickness guidelines are observed (Figure 5).
Figure 5 Aluminum Targets on Invar
These systems are set up to work with other nonmagnetic conductive targets on a special order
basis. If you purchased a system for use with a target material other than aluminum, it has
been calibrated (with selected component values) at the factory using that target material. An
arbitrary change in target material may, at a minimum, require calibration or, not work at all.

www.kamansensors.com 9 PART NO: 860029-001
Last Revised 01/06/15
5.2 Thickness
The RF field developed by the sensor is at a maximum on the target surface. There is
penetration below the surface and the extent of penetration is a function of target resistivity and
permeability. The RF field will penetrate aluminum to a depth of 0.022”, a little more than three
“skin depths” (at one skin depth the field density is only 36% of surface density and at two skin
depths it is 13%). To avoid variations caused by temperature changes of the target, the
minimum thickness should be at least three skin depths.
The depth of penetration depends on the actual target material used. In cases where the
sensors are opposing each other, aluminum target thickness must be at least 0.050” to prevent
sensor interaction.
Material Thickness in mils
Silver and Copper 22
Gold and Aluminum 22
Beryllium 25
Magnesium, Brass, Bronze, Lead 58
300 Series Stainless 110
Inconel 110
Recommended minimum target thickness in mils.
5.3 Size
The minimum target size is at least 2 times sensor diameter.
6.0 SPECIAL HANDLING CAUTIONS
6.1 Sensors
Due to design requirements, the sensor coil is exposed. The sensors are shipped with
protective caps. Keep them in place until installation of the sensors.
CAUTION: If any sharp object comes in contact with the coil face or edge and damages it in
any way, this could short a number of turns in the coil, alter its impedance, and render the
sensor useless.

www.kamansensors.com 10 PART NO: 860029-001
Last Revised 01/06/15
6.2 Mounting Surface
The base plate of the electronics module has a smooth surface to enhance thermal conduction
away from the electronics. Mounting the base plate flush with another surface will enhance
thermal dissipation (assuming a mount surface with a temperature below 60oC). Base plate
dimensions and mounting hole spacing are shown in Figure 6.
Figure 6 Mounting/Cover Plate Dimensions

www.kamansensors.com 11 PART NO: 860029-001
Last Revised 01/06/15
7.0 FIXTURING
The user provides fixturing for the KD-5100 electronics and sensors. The following information
establishes fixturing requirements for optimum system performance. The quality of the
measurement is both a function of Kaman’s system and your Fixturing.
Both the sensor and target fixturing must be structurally sound and repeatable.
7.1 Factors that degrade performance:
Unequal Loading: This refers to an unequal amount of conductive material within the field of
one sensor of a pair as opposed to another (the sensor’s field is approximately three times its
diameter). Unequal loading causes asymmetrical output from the sensor, which induces non-
linearity in the system output. Ideally, no conductive material other than the target should be in
the sensor’s field. Some loading may be acceptable if it is equal and the sensors are calibrated
in place. Even then, sensor loading may cause non-linearity. If unable to calibrate – loading is
too great.
Unequal Displacement: For targets using a pivot point mount (examples, Figures 3 & 4) the
system should “see” equal displacement: i.e., the pivot point of the target is perfectly centered
between the sensors. If the pivot point is a fraction of a mil off it can introduce non-linearity into
the system.
7.2 Pivot point requirements:
The pivot point must be a common line between the centerline of a pair of sensors.
The axis of tilt must be a perpendicular bisector of a line between the centerlines of a sensor
pair.
The pivot point must be positioned on the target so as not to introduce a translation error. This
error, a function of angle, is caused by slight changes in the effective null gap as the target
moves about the pivot. This results in non-linearity.
The pivot point must not change or move with time.

www.kamansensors.com 12 PART NO: 860029-001
Last Revised 01/06/15
Figure 7 15N Sensor Dimensions
Figure 8 20N Sensor Dimensions

www.kamansensors.com 13 PART NO: 860029-001
Last Revised 01/06/15
7.3 Sensor mounting considerations:
The sensors must be securely clamped. Sensor dimensions are shown in Figures 7 & 8.
The target must not strike the sensor face. The system has a null gap and a specified full
measuring range. The difference between the null gap and measuring range is the offset
distance for the sensors. This offset is necessary both to optimize performance and to keep the
target from contacting and possibly damaging the coils in the sensor face.
The sensor coil is mounted at the face of both types of sensor. For purposes of mechanical
nulling, measure distance from the sensor face. (For electrical nulling, the most accurate
method, the null gap is referenced to the electrical centerline, which is one half of the coil depth
– ½D, Figure 9.)
If the face of the sensor and the target surface are not parallel (if the sensor centerline is not
perpendicular to the target) more than 2oto 3o, it will introduce error to the measurement.
15N 20N
Figure 9 Sensor Coil Dimensions

www.kamansensors.com 14 PART NO: 860029-001
Last Revised 01/06/15
8.0 CROSS-AXIS SENSITIVITY
Assuming you have stable and repeatable fixturing, and have followed all of the rules for target
mounting, pivot points, etc., under certain conditions the system may exhibit signs of error we
classify as cross-axis sensitivity.
8.1 Cross-axis sensitivity may occur under the following conditions:
The target must be one with x and y axes of tilt moving about a central pivot point (see Figure
4). When the target tilts full range in its x axis, it should be able to tilt full range in its y axis
without any change in the indicated output of the x axis (or vice versa). This may not be the
case. Cross-axis tilt can increase the coupling between the sensor and target, which causes a
slight change in output, though there is no change in the actual distance between the sensor
and target. This is a definition of error.
This error manifests itself as increased non-linearity of the output at the extreme end points of
target travel only. (This non-linearity can change overall linearity from the specified 0.1% to
about 0.3%.)
8.2 Additional points of emphasis about cross-axis sensitivity:
Again, the error manifests itself only at the end points of target travel (the last 20%) when the
target tilts fully in both x and y axes.
The degree of error is related to the angle between the sensor and target face. As a general
rule, for angles ± 1oor less, there is virtually no problem with cross-axis sensitivity.
Sensor/target angle is a function of the distance between the sensor and target pivot, and the
measuring range. A sensor with a range of ± 10 mils mounted 10 mils from the pivot will
experience 45oof tilt at the end points. This is an extreme example but suffices to illustrate the
point. A sensor with a ± 10 mil range must be mounted approximately 550 mils (13.9 mm – a
little over ½ inch) from the pivot to achieve a 1oangle between sensor and target.
This phenomenon is related to basic physics and is stable, repeatable, small in magnitude, and
can therefore be characterized. If necessary, users can provide a computer correction scheme.
Cross-axis sensitivity is not a problem for the majority of applications. If you anticipate or
experience the problem, contact Kaman Precision Products for test data, which specifies under
which conditions and to what degree cross-axis sensitivity exists.

www.kamansensors.com 15 PART NO: 860029-001
Last Revised 01/06/15
9.0 PIN OUT and CONNECTOR ASSIGNMENTS
Sensor cable connections (Figure 10):
AXIS CONNECTORS SENSORS
1 J3 J1 S3 S1
2 J4 J2 S4 S2
Figure 10 Sensor Cable Connections
Pin assignments for the Power/Signal line connector J5 (Figure 11):
PIN FUNCTION
1 +15 VDC*
2 - 15 VDC*
3 Power Supply Common
4 Signal Output: Axis 1
5 Return Signal for Pin 4
6 Signal Output: Axis 2
7 Return Signal for Pin 6
8 Not Used
9 Not Used
Power Requirements Tolerance
+15 VDC +1.0, -0.5 VDC
-15 VDC +0.5, -1.0 VDC
Figure 11 Power & Output Connections

www.kamansensors.com 16 PART NO: 860029-001
Last Revised 01/06/15
10.0 USER’S ABBREVIATED FUNCTIONAL TEST
This is not a calibration or installation procedure. This unit is factory calibrated, and installation
guidelines are in the next section. This is simply a check to make sure the system is functioning
upon receipt.
Perform this abbreviated functional test prior to installation of the electronics and sensors in the
application fixture.
Attach the power supply cable to connector J5 and apply power to the system.
While monitoring the system output, place an aluminum target within 0.015” (15N
sensor) or 0.020” (20N sensor) of sensor S3. It is preferable this step be accomplished
using a fixture to hold the sensor and to control target movement. However, carefully
hand holding and moving the sensor or the target will be sufficient for this check. (See
Figure 11 for power and output connections at J5. The output for sensor S3 and S1
[axis 1] is at pin 4.)
Slowly move the target through the sensor’s measuring range to check for a full range of
output for S3: 0 V to +10 V.
Next: Check S1 for 0 V to –10 V.
Note: This will not be a linear output and you may get an output with the sensor as much
as 15 or 20 mils away from its target. That is OK since this check is only to confirm that
the system is working.
Repeat the above test for sensor S4 @ +10 V and S2 @ -10 V. Axis 2 output is pin 6.
If the output does not change during this test:
Verify correct input voltage: +14.5 to 16 V and –14.5 to –16 V.
Verify correct wiring to connector J5 (reference Figure 11).
Verify sensor connection, and output connection to the correct channel for the sensor
being checked:
S3 & S1 = axis 1 (pin 4),
S4 & S2 = axis 2 (pin 6).
Still no change: contact Kaman Precision Products.

www.kamansensors.com 17 PART NO: 860029-001
Last Revised 01/06/15
11.0 SENSOR INSTALLATION GUIDELINES AND PROCEDURE
11.1 Guidelines
The sensors should be positioned at the null gap using the Electrical Nulling Procedure. This
installation procedure is the preferred method. Though both sensors may be positioned
mechanically, this can cause a cumulative error. By electrically positioning the second sensor
of a pair using system output, any existing error is self-canceling.
Install the sensors so that only the target interacts with the sensor’s field. This means no
conductive material other than the target within a circle around the sensor that is three times the
sensor’s diameter. The sensor field radiates in all directions. (Figure 12). Excessive back
loading can also be a problem.
CAUTION:Be careful not to damage the sensor coil during this procedure
Figure 12 Sensor Field
11.2 Procedure
This procedure assumes the electronics are installed in the application fixture.
The sensor coil is mounted at the face of both sensors. For purposes of mechanical nulling,
measure distance from the sensor face. For electrical nulling, the null gap is referenced to the
electrical centerline, which is one half of the coil depth (½D, Figure 9).
11.2.1 Verify the target is in the null position.
11.2.2 Install the first sensor of a pair (start with S3) in the application fixture. Using a
dimensional standard, precisely locate the sensor at the null gap specified at time of
order. Secure the sensor and recheck its position.

www.kamansensors.com 18 PART NO: 860029-001
Last Revised 01/06/15
11.2.3 Now install the second sensor of the pair (S1) in the fixture and position it to
within a few mils of the required null gap. Connect the Power/Signal line to J5 and apply
power to the system. Use the output from the system as a guide in the final positioning
of this sensor (electrical nulling). Slowly move the second sensor toward or away from
the target as necessary until the system output reads 0 VDC (ideally, 0.000 V). This
output means the sensor is positioned correctly.
11.2.4 Repeat steps 11.2.1 through 11.2.3 for sensor S4 and S2.
11.2.5 The system is now ready for use.

www.kamansensors.com 19 PART NO: 860029-001
Last Revised 01/06/15
12.0 CALIBRATION
KD-5100 systems are shipped from the factory pre-calibrated for a user specified measuring
range, sensitivity, and target material. They do not normally require calibration or re-calibration.
However, some applications may require the availability of this option.
The calibration procedure is very simple. However, it requires an accurate dimensional
standard and a stable environment.
Some considerations……
Dimensional Standard: To calibrate, a dimensional standard (micrometer, laser
interferometer, a weight to provide a known deflection, etc.) is required. This should be a
standard known to be accurate and repeatable. Whether measuring in mils, microns, micro-
radians, etc., a means of accurately positioning the target, using the dimensional standard, to
the desired measurement units is required.
Kaman Precision Products uses a laser interferometer as a primary dimensional standard for
calibration.
Recalibration: Recalibration to a sensitivity and/or measuring range significantly different
from the factory calibration may not be possible. For example, if you purchased a standard
system calibrated 0 to 9 volts over a 9 mil measuring range (1V/mil) and attempted to
recalibrate for 9 volts over a 3 mil measuring range (3V/mil) there may not be sufficient gain
adjustment to do this. These units are built with component values selected for each
application. Therefore, changes in measuring range, sensitivity, or target material may not be
possible and will require reconfiguration by Kaman Precision Products.
Thermal Equilibrium: The mounting/cover plate helps maintain thermal equilibrium
inside the module and acts as a heat sink for the hybrid circuit. The hybrid has two watts of
power to it and needs the cover plate for heat sinking. The calibration controls are located
inside the unit and the cover plate must be removed to access them. Removing the cover plate
removes its heat sinking function. Calibrating with the cover off and then reinstalling it will
cause enough of a thermal gradient to throw the calibration off.
Kaman’s solution is to use a cover plate with access holes for the calibration controls. This
plate is available as an accessory from Kaman.
You may either obtain a calibration cover plate from Kaman or fabricate one from 0.062” thick
aluminum. Dimensions and location of the holes are shown in Figure 13.

www.kamansensors.com 20 PART NO: 860029-001
Last Revised 01/06/15
Figure 13 Calibration Cover Dimensions
(see Figure 6 for additional cover plate dimensions)
12.1 Equipment Required
A dimensional standard
A regulated ± 15 VDC power supply
A voltmeter accurate to one millivolt or better
An insulated adjusting tool (“tweaker”) Kaman P/N 823977-T007
A calibration cover plate
NOTE: When performing a system calibration, it is preferable to have the system
installed in the application fixture at normal operating temperatures. This eliminates any
shift in system output caused by moving the system from a calibration fixture to the
application fixture (translation error).
12.2 Calibration Procedure Overview
Calibration involves the following steps:
Null the Target
Monitor the output of axis 1 - Adjust for 0.000 V output
Move the target to full displacement – Adjust for full output voltage
Return the target to the null position and check for an output of 0V±10mV
Repeat for axis 2
The following information details these five steps.