Patent Application
20240097310
The present disclosure relates to wireless sensor technology that can be used with a spacecraft while in space.
A sensor is a device that transforms a measured quantity into a readable format, typically into an electrical signal. There are commercially available sensors for many different measurement purposes. According to their connectivity, sensors can be divided into wired and wireless sensors. Wired sensors are connected via wiring harnesses or cable assemblies to a reader device. Wireless sensors can be read without a physical connection to the sensor, and are often realized by equipping the sensor with a radio transceiver. The transmitted radio signal is interpreted by a receiver which converts the wireless signal into a desired output. Wireless operation can be beneficial in many applications where a wired connection is difficult, for example, due to harsh operating conditions (like temperature and pressure) in space, rotating parts, cost and/or complexity of wiring. However, wireless sensors also have some drawbacks such as limited lifetime due to battery and limited read-out distance due to attenuation and interference.
Based on the power source and communication principle, wireless sensors can be divided into two categories: active sensors and passive sensors. Active wireless sensors usually have both a radio transceiver and an on-board battery that is used to power the transceiver. Active wireless sensors, having their own power sources, can use powerful transmitters and sensitive receivers. However, the battery on board limits the lifetime and also increases the size and weight. Due to the more complex circuit, the price of an active sensor can be much higher than that of a passive sensor.
Unlike active sensors, passive sensors do not require an on-board battery. Therefore they can be less complex, smaller, less expensive, and their lifetime is not limited by the power supply. However, passive sensor have limited transmission range and limited length of sensor readings.
One category of passive wireless sensors comprises radio frequency identification (RFID) tags. RFID is an technology that uses radio waves to communicate between tags/sensors and a reader. For example,
RFID has been shown to be suitable for sensing by equipping a RFID tag with an external (or internal) sensor and logic to read the sensor. For purposes of this document, a RFID tag that includes or is otherwise physically connected to a sensor is referred to as a RFID sensor. While RFID sensors have been deployed for many uses, RFID sensors (like other passive sensors) have limited transmission range and limited length of sensor readings.
It is proposed to use passive RFID sensors for space applications. For example, RFID sensors can be mounted on or near spacecrafts (e.g., satellites, rockets, shuttles, etc.) to measure various properties relevant to the spacecrafts. In such use cases, the RFID reader can be mounted on the spacecraft body (e.g., near and connected to spacecraft control electronics) and the RFID sensor can be mounted at or near the component to be monitored. However, due to the size of many spacecraft, the distance between the RFID reader and the RFID sensor will be too far for reliable wireless data transmission due to the limited transmission range of passive RFID tags that rely on the small amounts of harvested power from the interrogation signal. Furthermore, the small amounts of harvested power from the interrogation signal will limit the sample length of any such sensor.
For example, it may be desired to monitor temperature of a solar array connected to a spacecraft at a distal point of the solar array. However, as described above, the small amounts of harvested power from the interrogation signal may not be enough to allow for reliable transmission of the temperature data back to the RFID reader and will limit the sample length of the temperature sensor (e.g., limit number of samples and resolution of temperature readings).
To overcome the above-described issues, it is proposed to provide a RFID sensor with additional power in order to increase the range of data transmission and increase the length of sensor readings by having the RFID sensor harvest and use power from two radio frequency (“RF”) signals, including the RFID interrogation signal received from the RFID reader and an additional RF signal from surrounding RF energy which is at a different frequency (and, possibly, higher power) than the RF interrogation signal.
One example embodiment of a proposed RFID sensor comprises a sensor, a control circuit connected to the sensor such that the control circuit is configured to obtain sensor data from the sensor, a first antenna configured to receive a first RF signal at a first frequency range for RFID, a first voltage circuit connected to the first antenna and the control circuit such that the first voltage circuit is configured to output a first voltage signal to provide power to the control circuit based on the first RF signal, a second antenna configured to receive a second RF signal at a second frequency range that is non-overlapping with the first frequency range, a second voltage circuit connected to the second antenna and the control circuit such that the second voltage circuit is configured to output a second voltage signal to provide power to the control circuit based on the second RF signal, and a RFID transmission circuit connected to the control circuit. The transmission circuit is configured to wirelessly transmit sensor information based on the sensor data via the first antenna in response to the first RF signal. More details are provided below.
The example system of
In an example, bus 202 houses and carries the payload 204, such as the components for operation as a communication satellite. The bus 202 includes a number of different functional sub-systems or modules, some examples of which are shown. Each of the functional sub-systems typically include electrical systems, as well as mechanical components (e.g., servos, actuators) controlled by the electrical systems. These include a command and data handling module or sub-system (C&DH) 210, attitude control system 212, mission communication system 214, power subsystem 216, gimbal control electronics 218, a propulsion system 220 (e.g., thrusters), propellant 222 to fuel some embodiments of propulsion system 220, and thermal control subsystem 224, all of which are connected by an internal communication network 240, which can be an electrical bus (a “flight harness”) or other means for electronic, optical or RF communication when spacecraft 100 is in operation. Also represented are an antenna 243, that is one of one or more antennas used by the mission communication systems 214 for exchanging communications (via RF signals) for operating of the spacecraft with ground terminals, and a payload antenna 217, that is one of one or more antennas used by the payload 204 for exchanging communications (via RF signals) with ground terminals, such as the antennas used by a communication satellite embodiment. The spacecraft also includes one or more RFID readers 225 connected to internal communication network 240 for interrogating RFID sensors positioned at various locations on or near spacecraft 100. Other equipment can also be included.
The command and data handling module 210 includes any processing unit or units for handling data and commands including command control functions for spacecraft 100, such as for attitude control functionality and orbit control functionality. The attitude control systems 212 can include devices including torque rods, wheel drive electronics, and control momentum gyro control electronics, for example, that are used to monitor and control the attitude of the space craft. Mission communication systems 214 includes wireless communication and processing equipment for receiving telemetry data/commands, other commands from the ground control terminal 130 to the spacecraft and ranging to operate the spacecraft. Processing capability within the command and data handling module 210 is used to control and operate spacecraft 10. An operator on the ground can control spacecraft 100 by sending commands via ground control terminal 130 to mission communication systems 214 to be executed by processors within command and data handling module 210. In one embodiment, command and data handling module 210 and mission communication system 214 are in communication with payload 204. In some example implementations, bus 202 includes one or more antennas as indicated at 243 connected to mission communication system 214 for wirelessly communicating between ground control terminal 30 and mission communication system 214. Power subsystems 216 can include one or more solar arrays (panels) and charge storage (e.g., one or more batteries) used to provide power to spacecraft 100. Propulsion system 220 (e.g., thrusters) is used for changing the position or orientation of spacecraft 100 while in space to move into orbit, to change orbit or to move to a different location in space. The gimbal control electronics 218 can be used to move and align the antennas, solar panels, and other external extensions of the spacecraft 100.
In one embodiment, payload 204 is for a communication satellite and includes an antenna system (represented by payload antenna 217) that provides a set of one or more beams (e.g., spot beams) comprising a beam pattern used to receive wireless signals from ground stations and/or other spacecraft, and to send wireless signals to ground stations and/or other spacecraft. In some implementations, mission communication system 214 acts as an interface that uses the antennas of payload 204 to wirelessly communicate with ground control terminal 30. In other embodiments, the payload could alternately or additionally include an optical payload, such as one or more telescopes or imaging systems along with their control systems, which can also include RF communications to provide uplink/downlink capabilities.
RFID sensors 610, 612, and 614 can convert the received one or more RF pulses (the interrogation signal) in the 900 MHz band to power for use by the RFID sensors 610, 612, and 614. However, because one or more of RFID sensors 610, 612, and 614 are mounted further from RFID reader 225 than typical RFID tags, RFID sensors 610, 612, and 614 will need additional power to obtain sensor measurements and transmit the information back to RFID reader 225. To meet this need for additional power, the RFID sensors are configured to harvest a parallel form of power for the sensor electronics by capturing surrounding RF energy which is at a different frequency (e.g., C band, S band, X band) than RFID operations (e.g., 900 MHz). When in space, satellites (and other spacecraft), for example, tend to be in noisy environments (from an RF perspective) because the satellites (and other spacecraft), generate/emit a lot of RF energy due to their communicating via RF with ground terminals and other spacecraft. Additionally, environments in space can have a lot of stray RF energy from other sources.
In response to first RF signal 640, one or more of RFID sensors 610, 612, and 614 will obtain sensor readings and transmit information based on those sensor readings back to RFID reader 225 using power harvested from first RF signal 640, second RF signal 642 or both. For example,
RFID sensor 700 includes at least two antennas: antenna 702 configured to receive first RF signal 640 at 900 MHz and antenna 704 configured to receive second RF signal 642 at a frequency range of 4-8 GHz. No particular type of antenna is required as any suitable antenna known in the art will suffice. It may be possible to use one antenna to receive both signals in conjunction with filters or other electronics. In one embodiment, RFID sensor 700 as well as antennas 702 and 704 are all mounted on the spacecraft (e.g., on a solar array) for receiving RF signals in space.
The output of antenna 702 is provided to Analog RF Interface circuit 714 and Analog RF Interface circuit 716, which include amplifiers, filters and other suitable electronics. The output of Analog RF Interface circuit 716 is provided to voltage regulator circuit 724 which harvests power from the signal received at antenna 716. The output of voltage regulator circuit 724 is a first voltage signal that is provided to control circuit 732 to power the control circuit 732 and sensor(s) 734 based on the first RF signal received at antenna 716. The output of Analog RF Interface circuit 714 is provided to demodulator circuit 722 which demodulates the first RF signal received at antenna 716 to recover the data carried by the signal (e.g., interrogation request, sensor ID, etc.). The recovered data is provided to control circuit 732. In response to the first RF signal, control circuit 732 sends information for one or more sensor readings to modulator circuit 720 which creates an output signal that is sent to Analog RF Interface circuit 712 and then to antenna 702 for wireless transmission as response signal 644 back to RFID reader 225.
The output of antenna 704 is provided to Analog RF Interface circuit 718, which include amplifiers, filters and other suitable electronics. The output of Analog RF Interface circuit 718 is provided to voltage regulator circuit 726 which harvests power from the signal received at antenna 704. The output of voltage regulator circuit 726 is a second voltage signal that is provided to control circuit 732 to power the control circuit 732 and sensor(s) 734 based on the second RF signal received at antenna 716. In one embodiment, the first voltage signal from voltage regulator circuit 724 and the second voltage signal from voltage regulator circuit 726 are connected together such that control circuit 732 receives the highest voltage of the first voltage signal and the second voltage signal. In another embodiment, the first voltage signal from voltage regulator circuit 724 and the second voltage signal from voltage regulator circuit 726 are connected to a voltage combining circuit (not depicted in
Sensor(s) 734 can be one or more sensors that sense temperature, strain, stress, vibration, switch position, presence (or no presence) of a component, or other properties.
Control circuit 732 is a circuit that controls RFID sensor 700 including obtaining sensor data from sensor(s) 734 and communicating with RFID reader 225. For example, control circuit 732 can include analog circuits, digital circuits, and one or more microprocessors/controllers. As discussed above, control circuit 732 and sensor(s) 734 are powered from the voltage harvested from the signal received at antennas 702 and 704. In one embodiment, the amount of power from the second voltage signal is significantly greater than the amount of power from the first voltage signal; therefore, (in one embodiment) the RFID sensor responds to the interrogation signal using power from the second voltage signal (e.g., sense the sensor data and wirelessly transmit the sensor information using power from the second voltage signal). In one embodiment, the RFID sensor 700 does not include and is not connected to a battery.
A RFID sensor has been disclosed that has a larger range of communication and the ability to take longer samples since there is more power available to the RFID sensor.
One embodiment includes a sensor system, comprising: a sensor; a control circuit connected to the sensor, the control circuit is configured to obtain sensor data from the sensor; a first antenna configured to receive a first radio frequency (“RF”) signal at a first frequency range for Radio Frequency Identification (“RFID”); a first voltage circuit connected to the first antenna and the control circuit, the first voltage circuit is configured to output a first voltage signal to provide power to the control circuit based on the first RF signal; a second antenna configured to receive a second RF signal at a second frequency range that is non-overlapping with the first frequency range; a second voltage circuit connected to the second antenna and the control circuit, the second voltage circuit is configured to output a second voltage signal to provide power to the control circuit based on the second RF signal; and a RFID transmission circuit connected to the control circuit, the transmission circuit is configured to wirelessly transmit sensor information based on the sensor data via the first antenna in response to the first RF signal.
In one example implementation, the first RF signal is an RFID interrogation signal received from a RFID reader mounted on a spacecraft, the first antenna and the second antenna are mounted on the spacecraft (e.g., on a solar array or antenna reflector of the spacecraft), the first antenna is configured to receive the first RF signal in space, the second antenna is configured to receive the second RF signal in space, and the transmission circuit is configured to wirelessly transmit the sensor information to the RFID reader in space.
One embodiment includes a method of operating a sensor system, comprising: harvesting power from a first radio frequency (“RF”) signal that is at a first frequency range and is received from a Radio Frequency Identification (“RFID”) reader; harvesting power from a second RF signal that is at a second frequency range, the second frequency range is non-overlapping with the first frequency range; obtaining sensor data using a sensor; and using harvested power to transmit sensor information to the RFID reader based on the sensor data.
One embodiment includes a sensor system, comprising: a spacecraft; a Radio Frequency Identification (“RFID”) reader mounted on the spacecraft; and a RFID sensor configured to wirelessly communicate with the RFID reader in space. The RFID sensor is configured to harvest power from a first radio frequency (“RF”) signal at a first frequency range received from the RFID reader and from a second RF signal at a second frequency range that is different than the first frequency range.
For purposes of this document, it should be noted that the dimensions of the various features depicted in the figures may not necessarily be drawn to scale.
For purposes of this document, reference in the specification to “an embodiment,” “one embodiment,” “some embodiments,” or “another embodiment” may be used to describe different embodiments or the same embodiment.
For purposes of this document, a connection may be a direct connection or an indirect connection (e.g., via one or more other parts). In some cases, when an element is referred to as being connected or coupled to another element, the element may be directly connected to the other element or indirectly connected to the other element via intervening elements. When an element is referred to as being directly connected to another element, then there are no intervening elements between the element and the other element. Two devices are “in communication” if they are directly or indirectly connected so that they can communicate electronic signals between them.
For purposes of this document, the term “based on” may be read as “based at least in part on.”
For purposes of this document, without additional context, use of numerical terms such as a “first” object, a “second” object, and a “third” object may not imply an ordering of objects, but may instead be used for identification purposes to identify different objects.
For purposes of this document, the term “set” of objects may refer to a “set” of one or more of the objects.
The foregoing detailed description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the subject matter claimed herein to the precise form(s) disclosed. Many modifications and variations are possible in light of the above teachings. The described embodiments were chosen in order to best explain the principles of the disclosed technology and its practical application to thereby enable others skilled in the art to best utilize the technology in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the present technology be defined by the claims appended hereto.
