Torque sensing system with wireless two-way communication

A torque sensing system which includes a torque sensor capable of wirelessly communicating torque and misalignment data to a smartphone or a tablet using a protocol such as Wi-Fi or Bluetooth technology, and wirelessly communicating commands from the smartphone or table back to the torque sensor. The torque sensor electronics include an rf coil for taking power off of a stationary housing to a rotary shaft and one or more accelerometers for indicating misalignments.

FIELD OF THE INVENTION

The invention described herein is a torque sensing system wherein the torque sensor is capable of two-way wireless communication via Wi-Fi and/or Bluetooth with smartphones and tablets having both data display and command input capabilities. The wireless communication can use Wi-Fi, Bluetooth or other technology. The sensor can provide one-way communication of torque-related data to various conventional devices including laptops and hand-held displays via analog cable connection while, at the same time, providing two-way wireless communication to smartphones and tablets.

BACKGROUND OF THE INVENTION

Electronic torque sensors are used to produce signals carrying data in analog format from the sensor output to conventional display devices via a cable connection. The data communication is one-way; i.e. from the sensor electronics to the display device.

This communication format substantially limits the range or distance between the sensor electronic and the display device; i.e. they must essentially be in the same room. It also prevents the user from instantaneously changing or adjusting parameters such as threshold and/or range values for the monitored metrics, or changing units of measurement. Moreover, state of the art systems do not provide an indication of misalignment of torque transmitting components such as shafts in a rotary torque sensor wherein the misalignments can occur either during installation or in operation or both. Such misalignments can substantially and negatively impact the quality of the data being communicated.

SUMMARY OF THE INVENTION

The torque sensing system disclosed herein provides improvements in torque sensors in which a principal benefit is the capability to provide wireless two-way communication from the sensor electronics to smartphones and/or tablets thereby to enable the user not only to read and record data but also to input commands to the system that can change or adjust metrics such as, but not limited to, threshold values, ranges and units of measurement, in real time; i.e. without the need to shut the system down to reprogram onboard processors and the like. The system can, for example, trigger an alert in the smartphone or tablet when data values exceed pre-established values.

In addition, the system herein described can provide real time indications of torque and other metrics such as rotational speed and system misalignments occurring either during installation or while the system is in operation or both. In general, this capability is provided by mounting various instrumentation on the torque transmitting shafts including strain gages wired into a Wheatstone bridge circuit to provide torque signals, an encoder to provide speed signals, and accelerometers to provide misalignment signals to a processor on the shaft. The signals are then sent by an rf coupling to a processor on the sensor housing. The housing processor, in turn, supplies data to a wireless transmission system using either Wi-Fi or Bluetooth technology by way of an antenna on the sensor housing. This can substantially increase the range, allow real time changes or adjustments in various metrics and also allow data to be transmitted from a smartphone to a receiver location hundreds or even thousands of miles away.

The disclosure herein presumes that the reader is familiar with strain gage technology wherein a foil type variable resistor is mounted on a structural component that exhibits a physical characteristic that allows it to elastically flex. The strain gage, or a set of strain gages, is mounted in a flexure zone in the structural component such that the resistance of the strain gage or gages changes in portion to the degree of flexure experienced while, for example, transmitting torque. The variation in resistance is readily converted by a Wheatstone bridge circuit shown inFIG. 19to a variable voltage that can be processed by known electronics such as analog-to-digital converters and conventional microprocessors.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIG. 1shows a torque sensing system comprising the combination of a modified FUTEK model TRS300 rotary torque sensor10having a strain gage instrumented8connected through a coupling11to an electric motor12and through a coupling13to an Eddy current brake14acting as a load. The motor12supplies mechanical power that is transmitted through the shaft to the brake14. The load flexes the shaft8within the sensor housing in proportion to transmitted torque.

The torque sensor10comprises electronics including suitably located strain gages and processors for producing electrical signals representing various metrics of transmitted torque. These metrics can be coupled from the torque sensor10via a cable connector16directly to one or more of a digital display18, a hand-held display20and/or a laptop computer22by way of a USB port24.

In addition, the metrics produced by the electronics within the torque sensor10can be communicated wirelessly by way of antenna26to smartphone28or a tablet29using Wi-Fi and/or Bluetooth technology. In an implementation, as used throughout this disclosure, wireless communication can refer to a system for communicating data wirelessly between devices, including, without limitation, wireless versions of Internet, intranet, or Ethernet, Wi-Fi, Bluetooth, radio frequency, near field communication, code division multiple access, global system for mobile communications, long-term evolution, or the like. Unless explicitly indicated otherwise, references throughout this disclosure to Wi-Fi and/or Bluetooth can also or instead refer to any one or combination of the foregoing.

While the cable communication from connector16to the devices18,20and22is one-way; i.e. from the torque sensor10to the devices18,20and22, the wireless data communication from the torque sensor10to the smartphone28is two-way in that the smartphone28or the tablet29can communicate commands back to the torque sensor10by way of either a Wi-Fi link or a Bluetooth link to alter the metrics and to perform other functions as hereinafter described.

In summary, the two-way transmission link between the torque sensor10and the smartphone28or tablet29enables the smartphone28or tablet29to receive the sensor output wirelessly via Wi-Fi and/or Bluetooth. After processing the transmitted output by the smartphone/tablet the user will be able see the following data displayed on the smartphone/tablet in real time:1. Torque sensor analog output in VDC;2. Instantaneous torque measured by the torque sensor10in any selected unit of measurement preferred by the user;3. Torque sensor rotational speed in RPM or any other unit of measurement selected by the user;4. Torque sensor rotational angle in degrees or any other unit of measurement selected by the user;5. Temperature inside the torque sensor10in Fahrenheit or Celsius or any other unit of measurement selected by the user;6. Misalignment occurring during installation through an accelerometer imbedded in the torque sensor as hereinafter in reference toFIGS. 7 and 10; and7. Misalignment/instability during operation through the aforementioned accelerometer imbedded in the torque sensor10.

In addition, the user can set threshold and/or range values for any of the above mentioned metrics to trigger an alert on the smartphone28or on a tablet. The user can log the above metrics in any spreadsheet available on the smartphone28or tablet29or in cloud storage.

As a further benefit of having a two-way link between the torque sensor10and the smartphone28or comparable tablet, the user can send commands to the torque sensor10wirelessly through Wi-Fi and/or Bluetooth enabling the user to;1. Modify calibration data points and configuration of the torque sensor10wirelessly;2. Modify the sampling rate or bandwidth of the torque sensor10wirelessly;3. Enable or disable linearization features of the torque sensor10wirelessly, or4. Perform shunt calibration remotely.

As indicated above, the two-way link between the torque sensor10and the smartphone28or tablet29can be established using the Bluetooth platform or, alternatively Wi-Fi can be used to institute the two-way communication link which can be done in any of three different ways:1. Wi-Fi direct; this enables the communication between the torque sensor10and the smartphone28directly; or2. Connection to the same Wi-Fi network; the torque sensor10and the smartphone tablet must be connected to the same Wi-Fi network in order to communicate with each other; or3. Connection through a server; the torque sensor10is connected to a server through a Wi-Fi network. The user can use a different Wi-Fi network to connect to the same server in order to establish the link between the torque sensor10and the smartphone28or any computing device with capabilities of connection to a Wi-Fi network.

In the system ofFIG. 1the torque sensor10is an instrument with “strain gages” or other types of torque sensing elements that generate electrical signals in response to elastic deformation or twist in a flexure section of shaft8within the torque sensor housing. The torque sensor10is designed to send analog signals by way of a cable to the torque sensor connector16for use by any of the electronic systems illustrated inFIG. 1including items18,20and22. Simultaneously the torque sensor is paired via Wi-Fi and/or Bluetooth wirelessly to the smartphone28through signal broadcast by the torque sensor antenna16.

As stated above, the user can set the threshold and/or range values for any of the above mentioned metrics to trigger an alert on the smartphone28.

Referring toFIG. 2, the torque sensor10is shown connected between a rotary power tool30and a bolt head driver32which, as shown, is in engagement with the head of a threaded fastener34being driven into a steel plate36. The tool30operates at a high rotational rate and the torque sensor10ensures that the fastener34is properly torqued in as an end result of the fastening operation.

Once again, the torque sensor10is equipped with a cable connector16which can be connected to any of the devices18,20and22, the connection to computer22through the USB port24.

Further, the torque sensor10is also equipped with an antenna26capable of wireless two-way communication with the smartphone28or tablet29as described above. The system shown inFIG. 2can achieve all of the functions described above with respect toFIG. 1.

TheFIG. 2system is used to measure the torque and rotational angle delivered by the power tool30to verify it torque and rotational angle as it fastens bolts34into the fixed plate36using the torque sensor10instrumented as describe above and as will be apparent to person skilled in the art with strain gages or other types of torque censoring elements. The torque sensor10is designed to send analog signals by way the cable connection to any of the computing devices including any of the hand-held displays and/or the computer via USB port. Simultaneously the torque sensor10is paired with the smartphone28or tablet29via Wi-Fi or Bluetooth through the antenna16.

The smartphone28displays the following in real time:1. Rotary torque sensor output in VDC;2. Instantaneous torque measured by the rotary torque sensor10in NM or any other unit of measurement selected by the user;3. Rotational speed in RPM or any other unit of measurement selected by the user;4. Rotational angle in degrees or any other unit of measurement selected by the user;5. Rotational angle in degrees or any other unit of measurement can be distributed for any of the bolts or screws in the system;6. Temperature inside the rotary torque sensor10in Fahrenheit or Celsius or any other unit of measurement selected by the user;7. Misalignment occurring during installation; and/or8. Misalignment or instability during operation as hereinafter described.

In addition, the user can set threshold values and/or range values using the smartphone28for any of the above mentioned metrics to trigger an alert on the smartphone28or tablet29. The user can also log any of the above mention metric in any spreadsheet available on the smartphone28or tablet29. In addition, the user is capable of sending commands to the rotary torque sensor10using the smartphone or tablet through Wi-Fi and/or Bluetooth. In this regard, the user is able to:1. Modify calibration data points and configurations of the torque sensor10wirelessly in order to use the same sensor at different capabilities with different power tools with different power capabilities;2. Modify the sampling rate of the rotary torque sensor10wirelessly for ease of data logging for long term testing;3. Enable or disable linearization features of the rotary torque sensor10wirelessly to improve the accuracy of measurements in load points; and4. Perform shunt calibration remotely.

Referring toFIG. 3, a computing device118usable for one-way or two-way communication with the torque sensor10disclosed herein is shown. The computing device118can be a smartphone or tablet28, a laptop computer22, or other computing device comprising a CPU120, a memory122, and a network interface126. The CPU120can be a conventional central processing unit and include single or multiple processors, each having single or multiple processing cores. Alternatively, the CPU120may include another type of device, or multiple devices, capable of manipulating or processing information now-existing or hereafter developed. The memory122can be RAM, DRAM, or any other suitable type of storage device. The memory122may include executable instructions and data for immediate access by the CPU120. Alternatively, the memory122may include another type of device, or multiple devices, capable of storing data for processing by the CPU120now-existing or hereafter developed. The CPU120may access and manipulate data in the memory122via a bus124. The network interface126may be any component configured to permit one- or two-way communication with the computing device118, for example, over wireless communication. The CPU120may access and utilize the network interface126for data communication via the bus124.

The computing device118can also include other components. For example, it can further include storage128and/or one or more input/output devices130. The storage128can include executable instructions along with other data. Examples of executable instructions may include, for example, an operating system and one or more application programs for loading in whole or part into the memory and to be executed by the CPU120. The storage128may comprise one or multiple devices and may utilize one or more types of storage, such as solid state or magnetic. An application program in the storage128can comprise executable instructions for receiving and processing data from torque sensor10and/or generating and transmitting requests or commands to the torque sensor10. The one or more input/output devices130can include devices for receiving input from a user of the computing device and outputting data to the user. Examples of input devices can include keyboards, mice, and other controls. Examples of output devices can include a display, which may be implemented in various ways, including by a LCD, CRT, LED, OLED, or the like. In an implementation, the display can be a touch screen display configured to receive touch-based input, for example, in manipulating data output to the display.

Looking now toFIGS. 4 and 5, they are shown respectively, in block diagram the analog cable connection system and the wireless connections system, in this case by way of the Bluetooth data packet52to the smartphone28or tablet29. In addition, as shown inFIG. 5, the smartphone/tablet,28,29can be connected to a mobile app54, which in turn, is capable of transmitting data to and from any of the elements shown in the right hand column of boxes56,58,60,62,63,64,65,66, and67with torque value56at the top and adjustment of data at endpoint configurations67at the bottom as described above.

Also present is the ability to log data to cloud storage, the ability to set threshold or range values to trigger an alert and a box indicating the capability of monitoring metrics.

Referring now toFIG. 6, a flow chart entitled “Torque Sensor Communicating with Flowchart” is shown. The upper left box80, shows the user supplying power to the stationary cover of the torque sensor10. Elliptical step82, indicates the wireless power transmission from the stationary cover of the torque sensor10to the rotating shaft of the sensor through transformer coil shown in each ofFIGS. 8, 9 and 10.

Below that is step84showing the power being consumed on the rotating shaft by a microcontroller and by one or more accelerometers in strain gages with are the torque sensing elements in order to produce output signals as desired by the user.

The next step86in the flowchart is the use of the induced signals on the rotating shaft being transmitted to the stationary cover printed circuit board through the rf module.

As shown in step88the received signal on the stationary cover of the torque sensor10is processed by a microcontroller to be broadcast in analog form as well as wirelessly via Wi-Fi and/or Bluetooth modules to perform any of the steps90,92and94as indicated by the legends in those blocks.

FIG. 7illustrates the steps involved in the user communicating to the torque sensor by inputting commands from the smartphone/tablet28,29keyboard to the electronics in the torque sensor10. Step96shows the user sending commands to the torque sensor wirelessly by way of Bluetooth or a Wi-Fi connection31. Step98shows the reception of the commands from the user whereas step100shows the commands being processed by a microcontroller in the stationary cover of the torque sensor10.

Step102shows the process commands being transmitted from the stationary cover PCB to the rotating shaft by rf transmission module in PCB and step104shows the received commands on the rotating shaft being processed by the microcontroller on the rotating in order to implement to required modifications or configurations or adjustments commanded by the user.

Referring now toFIG. 8, the shaft106of the torque sensor10is shown along with the printed circuit board108including a microcontroller on the housing cover110of the sensor10. Reference numeral112indicates the mounting slots for the two PCBs106aand106bcontaining the accelerometers112aand112b(seeFIGS. 15 and 16) which are mounted on the rotating shaft106and reference character114indicates the transformer coil which is used to transmit power using inductive coupling from the housing cover110to the electronics on the rotating shaft. An accelerometer is mounted on each PCB on the shaft106. The measuring axis of each accelerometer is perpendicular to the shaft axis at “no torque.” For instance, in the TRS300 the spacing between the shaft axis and the accelerometer is 0.741″. At “no Torque,” both accelerometers are oriented in parallel since the PCBs are mounted in parallel slots as described above. Torque being applied, the shaft gets twisted so that the PCBs and the accelerometers are no longer parallel. Therefore, at the higher torque values one sees greater differences in the measurements of the accelerometers with respect to one another.

Referring toFIG. 9, the reference numeral116shows the printed circuit board (PCB) mounted on the shaft106whereas reference numeral114again identifies the two-part coil which is used to make inductive coupling to furnish power from the stationary housing to the electronics on the rotating shaft.

FIG. 10shows the sensor10in greater detail to include a housing, the rotatable shaft106, and the cover110which, on the inside surface thereof carries the printed circuit board (PCB)108shown inFIG. 8. The cable coupling16and Wi-Fi/Bluetooth antenna26are also shown.

FIG. 11shows the mounting of an encoder PCB300mounted on the inside of the housing sensor10. Encoder310acts as an angle sensor and can be either optical or magnetic encoder for measurement of rotational angle and speed of the rotating shaft. For instance, Avtron item #ADKXL2202-900-41/38 (see attached spec sheet) could be used where the magnetic ring is mounted on the rotating shaft & the Encoder PCB is mounted on the stationary housing. When the shaft rotates, the magnetic ring spins with the shaft and the encoder PCB picks up the number of revolutions per second and feeds the microprocessor on the stationary housing accordingly.

FIG. 12shows the PCB108mounted on the inside of the cover110.

FIG. 13shows in detail how the PCB108is mounted to the cover110.

FIG. 14shows in detail the interior of the sensor housing with cover removed; the two coil windings, i.e., primary and secondary are114aand114b, respectively.

FIG. 15shows the two PCBs before they are mounted on the shaft and interconnected by flex cable201, as shown inFIG. 8.

FIG. 16shows the two accelerometer PCBs106aand106bmounted on the shaft in the slots shown inFIG. 8.

FIG. 17shows the circuit diagram for the accelerometers106aand106bin the shaft-mounted PCBs116. It is a commercially available product.

FIG. 18is an overall system block diagram. The system as shown provides for DC power to be provided to the sensor10; this power is converted by the housing-mounted PCB to AC for inductive coupling via coil114a,114bto the shaft-mounted PCBs, i.e., the outer half of the coil is stationary and acts as the “primary” while the inner half rotates with the shaft106and is the receiver or “secondary” coil. The AC power from the inner coil is converted back to DC for application to a Wheatstone bridge circuit106aincluding the variable-resistance strain gages on the shaft flexure area. Torque and misalignment data are conveyed by rf coupling from the shaft-mounted PCB circuits116aand116bto the housing-mounted PCB circuits108from which this data can be sent via cable to any of the devices18,20,22,24, and26shown inFIG. 1, and by Wi-Fi and/or Bluetooth to smartphone28and/or tablet29. Commands as described above can be generated by the user via smartphone28or tablet29and sent wirelessly to the housing mounted PCB and thereafter used to make the adjustments described above.

As stated above,FIG. 17shows a circuit diagram for the accelerometers106which are mounted in slots on the shaft112to detect shaft misalignment during installation and/or misalignment and/or instability during high speed rotation. The accelerometer is a high performance wide bandwidth accelerometer identified as model number ADXL001 available from Analog Devices, Inc. A full product specification is available on the Analog Devices website.

The microcontrollers on the printer circuit boards108and116are PIC18F47J53 microcontrollers built in the torque sensor10as CPU, the specification sheets are available http://www.one.microchip.com/downloads/en/DeviceDoc/39964B.pdf. The rf module is nRF2401rf built into the torque sensor10to facilitate the communication between the rotating shaft and the stationary housing. The specification sheet is available at https://www.nordicsemi.com/eng/Products2.4 GHz-RF/nRF2401A.

A suitable Wi-Fi module is the CC3100 SimpleLink™ built into the torque sensor10to facilitate the Wi-Fi communication. A suitable Bluetooth module is the nRF8001 Bluetooth module and is built into the torque sensor10to facilitate the Bluetooth communication. The high efficiency coil is manufactured using 3F3 material to supply power to the electronic modules. In an implementation, the torque sensor10can use a computing device118to facilitate one- or two-way communications with a user device28, such as a smartphone or tablet, a laptop computer22, or the like, wherein the computing device118used by the torque sensor10can receive data from and transmit data to the torque sensor10via a network or software interface. For example, where wireless communication is implemented via Wi-Fi, the computing device118used by the torque sensor10can connect to a desired Wi-Fi network usable for communicating data. Where wireless communication is implemented via Bluetooth, the computing device118used by the torque sensor10can include a device identifier usable for pairing with the selected other computing device118over the Bluetooth protocol. In an implementation, a dedicated network interface component can be coupled to the torque sensor10so as to obviate the use of the facilitating computing device118.

Overall operation is as follows: DC power is supplied by the user to the housing-mounted electronics. DC is converted to AC by the housing electronics and inductively coupled via coils114a,114b, to the shaft-mounted electronics. The shaft electronics convert part of the AC power back to DC for application to the Wheatstone bridge circuit including the strain gages in the center part of the shaft8and to the accelerometers for misalignment sensing. All bridge circuit signals (torque) and accelerometer signals (misalignment) are rf coupled to the housing-mounted PCB where outputs are provided to both cable outlet16and wireless antenna26. The user can (a) read output data on Wi-Fi or Bluetooth devices28,29and (b) wirelessly send commands back to the system to change units/limits/set points and other metrics as desired.

FIG. 19, as indicated above, shows a Wheatstone bridge circuit for the torque sensor static gages, here connected in parallel with a shunt320. Periodic verification of strain gauges performance is required, of course, to assure the accuracy and/or linearity of the Torque sensor. Decreasing the resistance of a bridge arm by shunting with a larger resistor offers a simple, potentially accurate means of simulating the action of a strain gage. This method, known as shunt calibration is widely used in the industry for periodic verification of torque sensors performance. When the user send the commands for the “Shunt Calibration”; the microprocessor on the stationary housing sends a command to the microprocessor on the shaft via rf link. Then the microprocessor on the shaft triggers the switch ADG702L (See attached spec sheet), so the 70.1 ohms shunt resistor kicks in to the -Excitation and -Signal leg of the Wheatstone bridge (See attached FIG.). Therefore, the resistance of the mentioned leg is decreased as if a mechanical load is being applied to the bridge. Consequently, the induced signal will be processed by the A/D on the shaft and then microprocessor on the shaft. Afterwards, the induced signal gets transmitted to the microprocessor on the stationary housing via rf link. The microprocessor on the stationary housing broadcasts the induced signal via Bluetooth/Wi-Fi/Analog output. The user could compare the output with the reference output provided by FUTEK conducted in the controlled lab & during calibration to see how well the torque sensor performs. The user may send the “shunt calibration” command through the Mobile App.