0001] This application claims priority to U.S. Provisional Appl. No. 62/01 2,744,
entitled TORQUE MONITORING FEEDBACK DEVICE, filed June 16, 2014, and
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Many types of systems include a rotating shaft. For example, electric motors
and internal combustion engines drive shafts and/or transmissions of vehicles, crafts,
manufacturing systems, and other devices. While a rotating shaft may be exposed
to normally occurring resistive loads, cyclic and intermittent forces may be fed back
into the shafts and transmissions from other components and loads. Combined with
the normally occurring forces, such additional forces may reduce the service life of
the rotating shaft. Further, such abnormal forces and vibrations may result in a
failure of the shaft that may damage other components as well.
SUMMARY
[0003] In one embodiment, a torque monitoring system includes a rotatable
measurement interface and a stationary data receiver. The measurement interface is
configured to be attached to a rotatable shaft. The measurement interface includes
a strain gauge, a processor, and a near field communication (NFC) transceiver coil.
The stationary data receiver is stationary with respect to the rotating shaft. The
stationary data receiver includes a processor and an NFC transceiver coil. The
rotatable measurement interface receives operating power via its NFC transceiver
coil that is derived from a radio signal wirelessly transmitted by the NFC transceiver
coil in the stationary data receiver. The processor in the rotatable measurement
interface is configured to receive strain gauge signals from the strain gauge
indicative of torque on the rotatable shaft and wirelessly transmit digital data
indicative of the strain gauge signals through the NFC transceiver coils to the
processor in the stationary data receiver.
[0004] In another embodiment, a torque monitoring and feedback system includes
a rotatable drive shaft, a rotatable measurement interface, a stationary data receiver,
and an electronics control unit (ECU). The rotatable measurement interface is
attached to the rotatable drive shaft so as to rotate in unison with rotatable drive
shaft. The measurement interface including a strain gauge, a processor, and a
transceiver coil. The stationary data receiver is contained in a housing and
stationary with respect to the rotating drive shaft. The stationary data receiver
includes a processor and a transceiver coil. The ECU is configured to communicate
with the stationary data receiver. The rotatable measurement interface receives
operating power via its transceiver coil that is derived from a radio signal wirelessly
transmitted by the transceiver coil in the stationary data receiver. The processor in
the rotatable measurement interface is configured to receive strain gauge
measurement data from the strain gauge and wirelessly transmit data indicative of
the measurement data through the transceiver coils to the processor in the stationary
data receiver.
[0005] In yet another embodiment, a system includes a main drive shaft, a parallel
drive shaft, and a transmission mechanically linking the main drive shaft to the
parallel drive shaft. A first rotatable measurement interface is attached to the main
drive shaft so as to rotate in unison with main drive shaft. The first measurement
interface includes a strain gauge and a transceiver coil. A first stationary data
receiver is contained in a housing and stationary with respect to the main drive shaft.
The first stationary data receiver includes a transceiver coil for wireless
communication with the transceiver coil of the first rotatable measurement device. A
second rotatable measurement interface is attached to the parallel drive shaft so as
to rotate in unison with parallel drive shaft. The second measurement interface
includes a strain gauge and a transceiver coil. A second stationary data receiver is
contained in a housing and stationary with respect to the parallel drive shaft. The
second stationary data receiver includes a transceiver coil for wireless
communication with the transceiver coil of the second rotatable measurement
device. The first and second rotatable measurement interfaces receive power from
and provide data communications to their respective first and second stationary data
receivers via the corresponding transceiver coils.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Fig. 1 illustrates a torque monitoring and feedback system in accordance
with various embodiments.
[0007] Fig. 2 illustrates a rotatable measurement interface in accordance with
various embodiments.
[0008] Fig. 3 illustrates a stationary data receiver in accordance with various
embodiments.
[0009] Fig. 4 illustrates an embodiment of the torque monitoring and feedback
system including switched reactance element in accordance with various examples.
[0010] Fig. 5 shows an example of a capacitive divider network usable for data
communications in accordance with various embodiments.
[0011] Fig. 6 shows a cutaway view of a portion of the torque monitoring and
feedback system in accordance with various embodiments.
[0012] Fig. 7 illustrates a transmission include multiple pairs of rotatable
measurement interfaces and stationary data receivers in accordance with an
embodiment.
DETAILED DESCRIPTION
[0013] This disclosure relates to systems and methods for monitoring the torque of
one or more rotatable shafts for use in any of a variety of systems. Examples of
such systems include manufacturing systems and drive systems. One non-limiting
example of a drive system is a drive rotor of a helicopter. In some systems, cyclic
and/or intermittent forces and/or vibrations may feed back to the shaft and/or
transmission from other components so that the shaft and/or transmission not only
experience the normally anticipated forces of driving resistive rotation loads but also
cyclic and/or intermittent variations in rotational loading. In some systems, as
components such as bearings wear or otherwise degrade, the forces required to
rotate the shaft may gradually increase. The systems and methods disclosed herein
monitor the effect of the forces applied to the shafts and the transmissions in a
manner configured to provide notice and/or information regarding changes in cyclic,
transient, or gradually changing of torque loads so that the monitoring and collection
of data regarding loading of a shaft and/or transmission may be utilized to mitigate
cyclic fatigue failures, resonant loading failures, inefficient operation, or other types
of undesirable outcome related to an undesirable torque loading of a shaft.
Accordingly, a torque monitoring and feedback system is disclosed below that may
be operated according to a variety of methods and embodiments described herein.
[0014] Fig. 1 illustrates a torque monitoring and feedback system 100 in
accordance with various embodiments. In the non-limiting example shown, the
torque monitoring and feedback system 100 includes a rotatable measurement
interface 102 attached to a rotatable shaft 90. The rotatable shaft may be any type
of rotating shaft, such as a drive shaft usable in, for example, a vehicle or a
manufacturing system. The rotatable measurement interface 102 is rigidly attached
to the shaft 90 so that the rotatable measurement interface rotates with the shaft.
The rotatable measurement interface 90 may include a variety of components such
as a strain gauge, a processor, and a transceiver coil. In some embodiments, the
components of the rotatable measurement interface 102 may be distributed radially
about shaft 90 to minimize unbalancing forces that may be generated by rotation of
the rotatable measurement interface 102 along with the shaft.
[0015] The system 100 also includes a stationary data transceiver 104, which may
surround a circumference of shaft 90 but is not rigidly attached to the shaft. Thus, as
the shaft 90 rotates, the stationary data transceiver does not rotate. The stationary
data transceiver 104 may be contained in a housing that is separate and apart from
the rotatable shaft 90. The stationary data transceiver 104 may include various
components such as a processor and a transceiver coil.
[0016] The stationary data transceiver 104 remains in a fixed position longitudinally
relative to the rotatable measurement interface 102 so that the spacing L 1 between
the stationary data transceiver and the rotatable measurement interface generally is
constant despite the rotation of the shaft and rotatable measurement interface
relative to the stationary data transceiver.
[0017] The transceivers coils of the stationary data transceiver 104 and the
rotatable measurement interface 102 are used to transfer power from the stationary
data transceiver to the rotatable measurement interface to provided operating power
for the components of the rotatable measurement interface. The transceiver coils
are also used as a wireless data communication link between rotatable
measurement interface and stationary data transceiver. For example, the rotatable
measurement interface 102 may transmit digital data encoding information of the
strain gauge to the stationary data receiver 104.
[0018] An electronics control unit (ECU) 110 also is shown in communication with
the stationary data receiver 104. The stationary data receiver 104 may forward to
the ECU 110 data, alerts, etc. related to the operation of and events detected by the
stationary data receiver and/or the rotatable measurement interface 102. Examples
of such detected events include one or more of a vibration event, a tension event, a
compression event, a bending event, a resonance event, and a torque event. The
rotatable measurement interface 102 may include multiple strain gauges and other
types of sensors to be able to detect such events. These various events may be a
vibration, tension, compression, bending, resonance, or torque level detected in
excess of a corresponding threshold. For example, a strain gauge may output a
voltage proportional the strain detected by the gauge. The voltage can then be
translated by processor 126, 136 to a strain measurement. This measurement can
then be compared against a user-specified threshold strain level. As a result of the
wireless communication between the rotatable measurement interface 102 and
stationary data receiver 104 which in turn is coupled to the ECU 110, any of these
events may be determined to exist by the processor 126 in the rotatable
measurement interface 102, the processor 136 in the stationary data receiver 104,
and/or the ECU 110. The threshold value may be determined by the system
designer and can be loaded into memory in the stationary data receiver 104 and/or
rotatable measurement interface 102 (e.g., loaded into storage integrated in the
processors 126, 136). Strain on a shaft can be caused by any of the events
(vibration, tension, etc.) described above. Depending on gauge configuration (e.g.,
how the gauge is mounted to the shaft 90), different events can be measured. The
voltage output from the gauge will be proportional to the amplitude of the event and
this output voltage will be translated into a strain measurement.
[0019] For example, the processor 126 in the rotatable measurement interface 102
may process the strain gauge signal and determine that a mechanical event has
occurred, or is occurring. The processor 126 in the rotatable measurement interface
102 can then transmit a signal through the NFC interface to the stationary data
receiver 104 that a mechanical event has occurred or is occurring. Through the ECU
110, the stationary data receiver 104 can then cause the drive unit 115 to adjust the
torque and/or speed of a motor driving the shaft 90 (in the example in which the shaft
is actively driven). Alternatively, the stationary data receiver 104 sends a signal to
other system logic that a mechanical event has occurred and such system logic will
take appropriate action commensurate with the specifics of the particular system. In
other embodiments, the rotatable measurement interface 102 sends digital data
indicative of the strain gauge signal across the NFC interface to the stationary data
receiver 104, and the stationary data receiver 104 processes such data to determine
that a mechanical event has occurred or is occurring. Further still, the digital data
indicative of the strain gauge signal may be transmitted from the rotatable
measurement interface to the stationary data receiver and on to the ECU 110 (or
other system logic) for the ECU 110 to process and determine whether a mechanical
event has occurred or is occurring.
[0020] A drive unit 115 is provided to actively turn the shaft 90 in embodiments in
which the shaft 90 is desired to be actively rotated. In other embodiments, the shaft
90 is not actively rotated and thus the drive unit 115 may not be included in such
embodiments. For the example of an actively driven shaft 90, upon detection of any
of the events listed above, the ECU 110 may cause the drive unit 115 to control the
speed of rotation of the shaft 90 and/or the torque on the shaft. For example, the
shaft 90 can be stopped completely upon detection of an excessive vibration,
tension, etc. on the shaft, rather then risk damage to the shaft 90 and other
components in the vicinity of the shaft. The latency between receiving a signal from
a strain gauge, to detecting a problem with the shaft, to adjusting the speed and/or
torque of the shaft is relatively small with this system, particular because of the
speed of processors 126 and 136 coupled with the NFC interface. In some
implementations, the latency is in the range of 1-20 ms. As such, the latency is
small enough that the operation of the shaft can be adjusted in real time, or near
real-time. As such, the system can react quickly enough to provide, for example,
minute adjustments in the timing feed and part synchronization to avoid the costly
jams and misfeeds.
[0021] Fig. 2 shows a block diagram of the rotatable measurement interface 102 in
accordance with various embodiments. As shown in the example of Fig. 2, the
rotatable measurement interface 102 includes a strain gauge, am amplifier (AMP)
122, an analog-to-digital converter (ADC) 124, a processor 126, a rectifier 128, and a
transceiver coil 130. The strain gauge 120 may be a torsional strain gauge. More
than one strain gauge may be included in the rotatable measurement interface 102
and a separate amplifier 122 may be provided for each strain gauge to increase the
magnitude of the signal from the corresponding strain gauge. The ADC 124
converts the analog signal from the strain gauge 120 to a digital equivalent value and
provides the digital equivalent value to the processor 126.
[0022] The transceiver coil 130 in the rotatable measurement interface 102
receives radiated energy from a corresponding transceiver coil in the stationary data
receiver 102. The rectifier 128 rectifies the alternating current (AC)-received energy
and provides rectified power to those components in the rotatable measurement
interface 102 that are to be actively powered, such as the processor 126. The ADC
124 and amplifier also may receive rectified power for their operation as well as the
strain gauge 120 itself. The rectifier may be a half or full bridge rectifier such as a
diode-based rectifier. A voltage regulator may be included if desired to regulate the
power to the various components of the rotatable measurement interface 102.
[0023] The processor 126 also may transmit data back to the stationary data
receiver 104 through the transceiver coil 130. Thus, the transceiver coil 130
receives radiation from the stationary data receiver 104 for powering the rotatable
measurement interface 102, and transmits data in the opposite direction from the
rotatable measurement interface 102 to the stationary data receiver 104.
[0024] Fig. 3 shows an example of a block diagram of the stationary data receiver
104. As shown, the stationary data receiver 104 includes a processor 136 coupled
to a transceiver coil 140. The processor 136 also includes a data interface for the
ECU 110. The stationary data receiver 104 may be battery-operated, may have a
dedicated power connection, or may be powered through the connection with the
ECU 110.
[0025] In one embodiment, the stationary data receiver 104 and the rotatable
measurement interface 102 wirelessly interface with each other in accordance with
Near Field Communication (NFC). As such, the transceiver coils 130 and 136 are
NFC transceiver coils. Other wireless interface standards can be used as well.
[0026] Fig. 4 illustrates an example of the torque monitoring and feedback system
100. Referring to Fig. 4, the data receiver 104 is shown on the left and the rotatable
measurement interface 102 is shown on the right. The data receiver 104 includes a
processor 136 coupled to the transceiver coil 140. Additional components may be
provided as well.
[0027] The rotatable measurement interface 102 includes the transceiver coil 130
as noted above, as well as the processor 126 and rectifier 128. The ADC 124 (not
specifically shown in Fig. 4) may be included as part of the processor 126 or may be
a separate component. A capacitor C 1 is shown connected in parallel across the
transceiver coil 130. The combination of the transceiver coil 130 and capacitor C 1
forms a tank circuit which functions an electrical resonator storing energy received
from the transceiver coil 140 at the tank circuit's resonant frequency. Power transfer
from stationary data receiver 104 to rotatable measurement interface 102 by having
both transceiver coils 130 and 136 tuned to resonate at the same frequency.
[0028] Communications from the remotely powered rotatable measurement
interface 102 may be accomplished by taking advantage of changes in impedance
with resonant frequency. Shifting the series resonance of transceiver coil 130
toward series resonance or toward parallel resonance provides a substantial change
in power drawn by the transceiver coil 130, which in turn changes the loading on the
transceiver coil 136 in the stationary data receiver 104. When tuned to series
resonance, transceiver coil 130 is in an absorptive state where it places a heavy load
on transceiver coil 140, which reduces the Q of its resonance and reduces the
voltage across transceiver coil 140. When tuned to parallel resonance, transceiver
coil 130 is in a reflective state where it reduces the load on transceiver coil 140 in the
stationary data receiver 104, raising the Q of its resonance, and increase the voltage
across the transceiver coil 140. Thus, by changing the reactance (and consequently
the resonant frequency) of transceiver coil 130 in the rotatable measurement
interface 102 relative to transceiver coil 136 in the stationary data receiver 104, the
voltage across the stationary data receiver's transceiver coil 140 can be made to
vary so as to encode digital data transmitted by the processor 126 of the rotatable
measurement interface 102.
[0029] The resonant frequency of the transceiver coil 130 in the rotatable
measurement interface 102 can be tuned by a switched reactive element. In the
embodiment shown in Fig. 4, capacitor C2 is an example of such a switched reactive
element. Capacitor C2 is switched in and out of the tank circuit by switch SW2,
whose state is controlled by processor 126 via control signal 129. When closed
switch SW2 puts capacitor C2 in parallel to tune the coil to the reflective state. When
switch SW2 is open, capacitor C2 is removed from the tank circuit and the tank
circuit is in the absorptive state. Binary data is sent in this manner, and induces
binary encoded amplitude modulation in the stationary data receiver's coil. The
switched reactive element may include at least one of a selectable capacitor (or a
capacitive divider network).
[0030] Fig. 5 shows an example of a capacitive divider network comprising
capacitors C3 and C4 connected in series across transceiver coil 130 and a
capacitor C5 provided as shown. Depending on whether a logic 1 or a logic 0 is to
be transmitted, the processor 126 can select whether or not to include capacitor C5
and thus can vary the capacitance across the transceiver coil. Other techniques
may be implemented as well for varying the impedance across the resonant tank
circuit of transceiver coil 130 and capacitor C 1.
[0031] Fig. 4 also shows the use of multiple selectable taps 66 for impedance
matching. Either tap 66 can be selected by processor 126 asserting a control signal
13 1 to a switch SW1 to provide the selected tap to the rectifier 128. By selecting a
desired tap, the effective length of the transceiver coil 130 can be varied.
[0032] Referring now to Figure 6, a cut-away view is shown showing the rotatable
shaft 90 and a housing 2 10 provided about the shaft. The housing 2 10 includes the
stationary data receiver 104. The rotatable measurement interface 102 is shown
attached to the shaft 90.
[0033] Referring now to Figure 7, a representation of a drive system 300 is shown.
In some embodiments, the drive system 300 may comprise a portion of, for example,
a helicopter. The drive system 300 generally comprises a primary drive shaft 302, a
parallel drive shaft 304 that takes power from the primary drive shaft 302, and a
plurality of intermediate drive shafts 306 that similarly take power to power loads
308. The loads may comprise rotor hub components, electrical generators, fans,
blowers, pumps, or any other rotationally resistive loads. The reference numerals
100 in Fig. 7 represent pairs of rotatable measurement interfaces 102 and
corresponding stationary data receivers 102. The locations at which each rotatable
measurement interface/stationary data receiver 100 are shown indicate non-limiting
possible locations to be utilized with drive system 300 to ensure proper operation of
all the various branches of such a drive system 300. Each stationary data receiver
of each rotatable measurement interface/stationary data receiver pair is
communicatively coupled to an ECU 110 (not shown in Fig. 7). By including multiple
rotatable measurement interface/stationary data receiver pairs, the relative torque
levels of the various branches (e.g., each of drive shaft 302, parallel drive shaft 304,
and intermediate drive shafts 306) of the transmission system can be monitored by
the ECU 110. Such data can provide real-time or near real-time information on a
multitude of driveline parameters including bearing condition, component alignment,
lubrication conditions, improper shaft speeds and/or aging gearboxes. The rotatable
measurement interface/stationary data receiver pairs similarly may be applied to any
other complex machine, automobile, aircraft, production line system and/or power
transmission systems that combine and divide the supplied rotational power at
multiple points through a drive system.
[0034] The efficiency of the transmission system can be computed based on the
signals from the various strain gauges. The transmission efficiency may be
computed by the ECU 110 based on strain gauge data received from at least two
pairs of rotatable measurement interfaces 102 and stationary data receivers 104.
[0035] In some embodiments, the management of operation of system 300 may
comprise operating the system to avoid and/or reduce overlap between ( 1 )
resonant/natural frequencies and/or harmonics of the resonant/natural frequencies of
one or more components of the drive system 300 and (2) the frequencies of
potentially damaging stresses, strains, forces, torques, powers, and the like. In
alternative embodiments, the rotatable measurement interface/stationary data
receiver pairs and associated components may utilize measured strain and
estimated transmitted torque with information about a shaft rotational speed to
estimate a transmitted power of the shaft so that the transmitted power data may be
utilized by operators and/or electronics 106 and/or a computer to evaluate how to
operate the drive system 300 more efficiently, thereby potentially saving fuel and/or
other energy costs of operating the drive system 300.
[0036] The embodiments described herein are examples only and are not limiting.
Many variations and modifications of the systems, apparatus, and processes
described herein are possible and are within the scope of the disclosure.
Accordingly, the scope of protection is not limited to the embodiments described
herein, but is only limited by the claims that follow, the scope of which shall include
all equivalents of the subject matter of the claims.

CLAIMS
What is claimed is:
1. A torque monitoring system, comprising:
a rotatable measurement interface configured to be attached to a rotatable shaft
to rotate with the shaft, the measurement interface including a strain
gauge, a processor, a near field communication (NFC) transceiver coil;
and
a stationary data receiver contained in a housing and stationary with respect to
the rotating shaft, the stationary data receiver including a processor and
an NFC transceiver coil;
wherein the rotatable measurement interface receives operating power via its
NFC transceiver coil that is derived from a radio signal wirelessly
transmitted by the NFC transceiver coil in the stationary data receiver; and
wherein the processor in the rotatable measurement interface is configured to
receive strain gauge signals from the strain gauge indicative of torque on
the rotatable shaft and wirelessly transmit digital data indicative of the
strain gauge signals through the NFC transceiver coils to the processor in
the stationary data receiver.
2. The torque monitoring system of claim 1 wherein the rotatable measurement
interface also includes a switched reactance element to encode the digital data during
transmission to the processor in the stationary data receiver.
3. The torque monitoring system of claim 2 wherein the switched reactance element
includes at least one of a selectable capacitive divider network and multiple taps of the
NFC transceiver coil in the rotatable measurement interface.
4 . The torque monitoring system of claim 1 further comprising a control unit coupled
to the stationary data receiver and configured to control a speed and torque of the shaft,
and wherein, based on the digital data, the stationary data receiver is configured to
determine that the shaft is experiencing a mechanical event and to respond to the
determined event by sending a signal to the control unit to adjust at least one of speed
and torque of the shaft.
5. The torque monitoring system of claim 4 wherein the event includes at least one
of: a vibration event, a tension event, compression event, a bending event, a resonance
event, and a torque event.
6. The torque monitoring system of claim 1 further including:
a plurality of rotatable measurement interfaces;
a plurality of stationary data receivers; and
a transmission;
wherein the shaft is a main drive shaft;
wherein the system further includes a parallel drive shaft mechanically coupled to
the main drive shaft through the transmission; and
wherein each of the main and parallel drive shafts includes at least one of the
rotatable measurement interfaces wirelessly coupled to a corresponding
stationary data receiver.
7. The torque monitoring system of claim 6 wherein each stationary data receiver is
configured to communicate with an electronics control unit (ECU), and said ECU is
configured to determine an efficiency value for the transmission based on digital data
received from at least one rotatable measurement interface on the primary drive shaft
and at least one rotatable measurement interface on the parallel drive shaft.
8. The torque monitoring system of claim 1 wherein the processor in the rotatable
measurement system determines whether the strain gauge detects a force in excess of
a threshold.
9. The torque monitoring system of claim 1 wherein the processor in the stationary
data process the digital data to determine whether the strain gauge in the rotatable
measurement interface detects a force in excess of a threshold.
10. The torque monitoring system of claim 1 wherein the processor in the rotatable
measurement interface is configured to wirelessly transmit the digital through the NFC
transceiver coils to the processor in the stationary data receiver even if the shaft is not
rotating.
11. A torque monitoring and feedback system, comprising:
a rotatable drive shaft;
a rotatable measurement interface attached to the rotatable drive shaft so as to
rotate in unison with rotatable drive shaft, the measurement interface
including a strain gauge, a processor, and a transceiver coil;
a stationary data receiver contained in a housing and stationary with respect to
the rotating drive shaft, the stationary data receiver including a processor
and a transceiver coil; and
an electronics control unit (ECU) configured to communicate with the stationary
data receiver;
wherein the rotatable measurement interface receives operating power via its
transceiver coil that is derived from a radio signal wirelessly transmitted by
the transceiver coil in the stationary data receiver; and
wherein the processor in the rotatable measurement interface is configured to
receive strain gauge measurement data from the strain gauge and
wirelessly transmit data indicative of the measurement data through the
transceiver coils to the processor in the stationary data receiver.
12. The system of claim 11 wherein the rotatable measurement interface also
includes a switched reactance element to encode the digital data during transmission to
the processor in the stationary data receiver.
13. The system of claim 11 further comprising a control unit coupled to the stationary
data receiver and configured to control a speed and torque of the shaft, and wherein,
based on the digital, the stationary data receiver is configured to determine that the
shaft is experiencing a mechanical event and to respond to the determined event by
sending a signal to the control unit to adjust at least one of speed and torque of the
shaft, wherein the mechanical event includes at least one of: a vibration event, a tension
event, compression event, a bending event, a resonance event, and a torque event.
14. The system of claim 11 further including:
a plurality of rotatable measurement interfaces;
a plurality of stationary data receivers; and
a transmission;
wherein the shaft is a main drive shaft;
wherein the system further includes a parallel drive shaft mechanically coupled to
the main drive shaft through the transmission;
wherein each of the main and parallel drive shafts includes at least one of the
rotatable measurement interfaces wirelessly coupled to a corresponding
stationary data receiver; and
wherein each stationary data receiver is configured to communicate with an
electronics control unit (ECU), and said ECU is configured to determine an
efficiency value for the transmission based on digital data received from at
least one rotatable measurement interface on the primary drive shaft and
at least one rotatable measurement interface on the parallel drive shaft.
15. The system of claim 11 wherein the processor in the rotatable measurement
system determines whether the strain gauge detects a force in excess of a threshold.
16. The system of claim 11 wherein the processor in the stationary data process the
digital data to determine whether the strain gauge in the rotatable measurement
interface detects a force in excess of a threshold.
17. A system:
a main drive shaft;
a parallel drive shaft;
a transmission mechanically linking the main drive shaft to the parallel drive
shaft;
a first rotatable measurement interface attached to the main drive shaft so as to
rotate in unison with main drive shaft, the first measurement interface
including a strain gauge and a transceiver coil;
a first stationary data receiver contained in a housing and stationary with respect
to the main drive shaft, the first stationary data receiver including a
transceiver coil for wireless communication with the transceiver coil of the
first rotatable measurement device;
a second rotatable measurement interface attached to the parallel drive shaft so
as to rotate in unison with parallel drive shaft, the second measurement
interface including a strain gauge and a transceiver coil; and
a second stationary data receiver contained in a housing and stationary with
respect to the parallel drive shaft, the second stationary data receiver
including a transceiver coil for wireless communication with the transceiver
coil of the second rotatable measurement device;
wherein the first and second rotatable measurement interfaces receive power
from and provide data communications to their respective first and second
stationary data receivers via the corresponding transceiver coils.
18. The system of claim 17 further including an electronics control unit (ECU)
configured to communicate with the first and second stationary data receivers.
19. The system of claim 18 wherein the ECU computes a transmission efficiency
value based on strain gauge data received from the first and second rotatable
measurement interfaces through their corresponding first and second stationary data
receivers.
20. The system of claim 17 further including an intermediate draft shaft mechanically
coupled to the parallel drive shaft and including:
a third rotatable measurement interface attached to the intermediate drive shaft
so as to rotate in unison with intermediate drive shaft, the third
measurement interface including a strain gauge and a transceiver coil;
and
a third stationary data receiver contained in a housing and stationary with respect
to the intermediate drive shaft, the third stationary data receiver including
a transceiver coil for wireless communication with the transceiver coil of
the third rotatable measurement device; and
wherein the ECU receives stain gauge data from the third stationary data
receiver.