A non-uniform antenna segmentation method for modular wireless power transmission antenna array

Abstract

A wireless power delivery system for transmitting power to robots in a robotic working environment, comprising a power generation unit; a plurality of antenna segments which are deployed along a robot movement path within the working environment; a controller which comprises a scanning circuitry with an associated operational algorithm, for activating the antenna segments in a low-power scanning mode, sampling electrical parameters of the antenna segments and detecting the position of each of the robots relative to the antenna segments, based on the sampled electrical parameters; one or more power distribution units, for selectively activating one or more antenna segments upon detecting predetermined overlap between a robot and one or more segments, by delivering high power to the activated antenna segments, for wirelessly charging the robot from the power generation unit.

Description

[0001] 1

[0002] A NON-UNIFORM ANTENNA SEGMENTATION METHOD FOR MODULAR WIRELESS POWER TRANSMISSION ANTENNA ARRAY

[0003] Field of the Invention

[0004] The present invention relates to the field of wireless power transmission. More particularly, the present invention relates to a non-uniform segmentation method for modular wireless power transmission antenna array, designed to support wide area Wireless PowerTransmission (WPT) to mobile robotic systems that are in motion.

[0005] Background of the Invention

[0006] Mobile autonomous robots of rapidly increasing sophistication and capacity are assuming an expanding variety of services and activities in factories, warehouses, restaurants, hospitals, and airplanes. Normal charging is made either by plugging into a power socket to receive energy by wire or by assuming a particular pose to receive wirelessly transmitted energy. However, this type of charging entails striking their activity for the entire charging period.

[0007] In order to support their functions in the working environments in which they operate, it is required that these robots will not be required to stop for charging at designated power stations. However, providing a system that is operable to provide robots with energy they need while moving to carrying out their assigned tasks in their working environments is a complex challenge, due to several reasons.

[0008] The first reason is that Wireless Power Transmission (WPT) requires working with high power levels (at least hundreds of Watts), which induce very strong electromagnetic fields, which can overheat the transmitting antenna. Another reason is that high power levels cause strong radiation which may interrupt neighboring systems.

[0009] Different working environments require the deployment of charging antennas in various patterns and sizes, which may reach up to 10 meters long. However,2

[0010] activating such large antennas entails generating very strong electromagnetic fields. Since the robot is in motion and is about lm long, activating the entire length of a deployed antenna to charge the robot leads also to substantial energy waste.

[0011] It is therefore an object of the present invention to provide a non-uniform antenna segmentation method for modular wireless power transmission antenna array, designed to support wide area Wireless Power Transmission (WPT) to mobile robotic systems that are in motion

[0012] Other objects and advantages of the invention will become apparent as the description proceeds.

[0013] Summary of the Invention

[0014] A wireless power delivery system for transmitting power to robots in a robotic working environment, comprising:

[0015] a) a power generation unit;

[0016] b) a plurality of antenna segments being deployed along a robot movement path within the working environment;

[0017] c) a controller comprising:

[0018] c.l) a scanning circuitry with an associated operational algorithm, for activating the antenna segments in a low-power scanning mode, sampling electrical parameters of the antenna segments and detecting the position of each of the robots relative to the antenna segments, based on the sampled electrical parameters; and

[0019] c.2) one or more power distribution units, for selectively activating one or more antenna segments upon detecting predetermined overlap between a robot and one or more segments, by delivering high power to the activated antenna segments, for wirelessly charging the robot from the power generation unit.3

[0020] Each antenna segment may be associated with a switching module configured to selectively conduct or block alternating current for feeding the antenna segment.

[0021] The switching module may comprise a bidirectional, isolated, low-parasitic-capacitance switching architecture adapted to operate in a high electromagnetic field environment.

[0022] The system may further comprise an impedance matching network between the power distribution unit and each antenna segment. The matching network may comprise:

[0023] a) a first portion located within the power distribution unit and shared among multiple antenna segments; and

[0024] b) a second portion located within each antenna segment.

[0025] The first and second portions of the impedance matching network are electrically coupled via a transmission line.

[0026] In one aspect, there is no wireless communication / data transfer between the receiver of the robot and transmitter the powers activated antenna segments.

[0027] The power distribution box may be configured to activate antenna segments by: a) limiting the transmitted power by controlling all antenna segments to be at low-power transmission mode, where there is no robot nearby;

[0028] b) activating a scanning mode, in which each antenna segment is turned on at the low-power transmission mode and sampled serially;

[0029] c) reading the voltage and current values Vant, lantof the sampled antenna segment;

[0030] d) comparing the sampled values to predetermined thresholds ThVant, Th|ant, respectively;4

[0031] e) if both Vant,>ThVant and lant>Thiant, determining that the robot is at least partially above a sampled antenna segment;

[0032] f) activating the sampled antenna segment by switching it to a high-power transmission mode, otherwise, determining that the robot is not above the sampled antenna segment and controlling the sampled antenna segment to remain in low-power transmission mode.

[0033] Whenever during movement the robot partially overlaps two adjacent antenna segments, the antenna segment may be activated with larger overlap.

[0034] The robot impedance Zrobot may be:

[0035] >

[0036]

[0037] At least one portion of the impedance matching network may be implemented as an LC resonant network.

[0038] Portions of the antenna segments may be deployed symmetrically relative to the power distribution unit, to reduce tuning variation between segments.

[0039] Electronic components associated with switching and control of multiple antenna segments may be centralized within the power distribution unit, and each antenna segment comprises passive resonant elements.

[0040] The antenna segmentation may be non-uniform.5

[0041] The switching module may comprise a validation circuit configured to prevent unintended activation caused by electromagnetic interference.

[0042] The controller may be configured to control a plurality of antenna segments using a single power distribution unit.

[0043] A method for wireless power delivery to a mobile robot moving along a predefined path in a robotic working environment, the method comprising:

[0044] a) segmenting a wireless power transmission antenna deployed along the path into a plurality of antenna segments having non-uniform electrical and / or physical characteristics;

[0045] b) operating the antenna segments in a low-power scanning mode; c) sequentially sampling electrical parameters of each antenna segment while the robot is in motion;

[0046] d) detecting the presence and relative position of the robot with respect to at least one antenna segment, based on a variation in the sampled electrical parameters caused by wireless coupling with the robot; and

[0047] e) selectively transitioning at least one detected antenna segment from the low-power scanning mode to a high-power transmission mode, to wirelessly deliver power to the robot while the robot continues moving.

[0048] The antenna segments may differ in at least one of the following parameters: segment length;

[0049] resonant characteristics;

[0050] impedance;

[0051] power handling capability;

[0052] spatial deployment density.6

[0053] The non-uniform segmentation may be determined based on at least one of the following parameters:

[0054] expected robot speed;

[0055] dwell time;

[0056] stopping locations;

[0057] power demand profile;

[0058] environmental constraints along the path.

[0059] Two or more adjacent antenna segments may be dynamically grouped into a logical transmission segment, based on detected robot position or power demand.

[0060] The presence of a robot may be determined by detecting a change, fluctuation, or deviation from a baseline in at least one of antenna voltage, antenna current, phase, impedance, or reflected load.

[0061] The robot position may be detected without wireless communication or data exchange between the robot and the antenna system.

[0062] Whenever a robot partially overlaps more than one antenna segment, the antenna segment or logical group having a greater effective overlap or coupling with the robot may be selectively activated.

[0063] Transition of an antenna segment from low-power mode to high-power mode may be performed within a time interval sufficient to maintain continuous power delivery to the moving robot.

[0064] Brief Description of the Drawings

[0065] The above and other characteristics and advantages of the invention will be better understood through the following illustrative and non-limitative detailed description7

[0066] of preferred embodiments thereof, with reference to the appended drawings, wherein:

[0067] Fig. la (prior art) illustrates the activation of a long antenna for charging;

[0068] Fig. lb (prior art) illustrates the activation of a segmented antenna for charging a moving robot;

[0069] Fig. lc illustrates the activation of a segmented antenna for charging a moving robot using a single control box, according to an embodiment of the invention; Fig. Id is a flowchart of the process of activating an antenna segment, according to an embodiment of the invention ;

[0070] Figs. 2a-2b are schematic diagrams of a circuit for detecting fluctuations in the voltage of the antenna segment, according to an embodiment of the invention; Figs. 3a-3c are a schematic diagram of an equivalent circuit for reflecting the robot using capacitive coupling, according to an embodiment of the invention; Fig. 4 illustrates impedance matching between the power distribution box 14 and each antenna segment;

[0071] Fig. 5 illustrates the deployment of portions of the matching networks, according to an embodiment of the invention;

[0072] Fig. 6 illustrates a symmetric deployment of portions of the matching networks, according to an embodiment of the invention;

[0073] Fig. 7 illustrates the deployment of portions of the matching networks with centralized electronics, according to another embodiment of the invention; and Fig. 8 illustrates the implementation of the activation switch, according to an embodiment of the invention.

[0074] Detailed Description of the Present Invention

[0075] The present invention provides non-uniform antenna segmentation method for modular wireless power transmission antenna array, designed to support wide area Wireless Power Transmission (WPT) to mobile robotic systems that are in motion along a predetermined robot movement path within a working environment. Antenna segmentation is typically non-uniform.8

[0076] Fig. la (prior art) illustrates the activation of a long antenna for charging. In this case, the entire antenna 10 is activated, while the robot 11 moves over from left to right. This approach causes a safety problem of very strong radiation to the environment, which is not focused on the charged robot. Another problem caused using this approach is that about 75% of the radiated energy remains unused, due to the fact that the robots overlaps only 25% of the entire length while moving above the activated antenna.

[0077] Fig. lb (prior art) illustrates the activation of a segmented antenna for charging a moving robot. In this case, the antenna consists of shorter segments 12a-12c, where each segment is controlled by a hardware-implemented power distribution box 13a-13c, respectively. However, even though this solution improves safety and reduces energy waste, it still requires the deployment of several power distribution boxes, which reduces the flexibility while deploying the segments and associated power distribution boxes. Another drawback is the high cost of using a separate power distribution box for each segment.

[0078] Fig. lc illustrates the activation of a segmented antenna for charging a moving robot using a single power distribution box, according to an embodiment of the invention. In this case, the antenna consists of shorter segments 12a-12c, where all segments are controlled by a controller, via a single hardware-implemented power distribution box / unit 14. The controller comprises a scanning circuitry with an associated operational algorithm for activating antenna segments in a low-power scanning mode. The scanning circuitry samples electrical parameters of the antenna segments and detects the position of each of the robots relative to the antenna segments, based on the sampled electrical parameters.

[0079] The controller is configured to control a plurality of antenna segments using a single power distribution unit.9

[0080] One or more power distribution units 14 are used for selectively activating one or more antenna segments upon detecting predetermined overlap between a robot and one or more antenna segments, by delivering high power to the activated antenna segments, to wirelessly charge the robot from a power generation unit.

[0081] Each antenna segment is associated with a switching module configured to selectively conduct or block alternating current for feeding the antenna segment. The switching module comprises a bidirectional, isolated, low-parasitic-capacitance switching architecture, which is adapted to operate in a high electromagnetic field environment. The switching module comprises a validation circuit, which is configured to prevent unintended activation caused by electromagnetic interference.

[0082] Power distribution box / unit 14 comprises sensing capabilities to identify the location of the robot in real-time and activate only the relevant required segment. In this example, power distribution box 14 identifies that the robot 11 is above segment 12c and activates only that segment, while disabling segments 12a-12b. This solution improves safety and reduces energy waste, while keeping flexibility in the deployment reducing the cost of the required control hardware.

[0083] Fig. Id is a flowchart of the process of activating an antenna segment, according to an embodiment of the invention. At the first step 101, power distribution box 14 limits the transmitted power (several watts) by controlling all antenna segments to be at low-power transmission mode where there is no robot nearby. At the next step 102, power distribution box 14 activates a scanning mode, in which each antenna segment 12j is turned on (at the low-power transmission mode) and sampled serially, every period of TsampieSec. At the next step 103, power distribution box 14 reads the voltage and current values Vant, lant of the sampled antenna segment 12j. At the next step 104, power distribution box 14 compares the sampled values to predetermined thresholds ThVant, Th|ant, respectively. If both Vant,>ThVantand lant>Th|ant, at the next10

[0084] step 105, power distribution box 14 determines that the robot 11 is above the sampled antenna segment 12j (such that the receiving antenna of the robot 11 starts overlapping the sampled antenna segment 12j and starts consuming more power, which typically causes Vantto increase or to have fluctuations above the minimal voltage threshold) and activates it by switching it to a high-power transmission mode (on the order of hundreds of watts), so as to provide full charging power to the robot 11, where the charging process is initiated within approximately 10 mS. Otherwise, at step 106, power distribution box 14 determines that the robot 11 is not above the sampled antenna segment 12j and controls it to remain in low-power transmission mode, for the next sampling time. During movement, the robot 11 will be charged from the antenna segment 12j with overlap of 35% or more between antennas. If during movement the robot 11 partially overlaps two adjacent antenna segments 12j; 12j+i, the power distribution box 14 will activate the antenna segment with larger overlap. In any case, only one antenna segment 12j or 12i+iwill be activated. This process is effective since it does not require any communication or data transfer with the robot.

[0085] Figs. 2a-2b are schematic diagrams of a circuit for detecting fluctuations in the voltage of the antenna segment, according to an embodiment of the invention. The wireless coupling between the robot 11 and the sampled antenna segment is reflected back to the power transmitting side using an inductive WPT model, shown in Fig. 2a or a capacitive WPT model, shown in Fig. 2b. In the inductive model of Fig.

[0086] 2a, the wireless medium is represented by a T configuration of inductors LMI, LM2 and LM. In the capacitive model of Fig. 2b, the wireless medium is represented by a PI configuration CP, Csand CM.

[0087] Figs. 3a-3c are simplified schematic diagrams of equivalent circuits illustrating how the robot's impedance, Zrobot, is reflected through the capacitive coupling, according to an embodiment of the invention. This allows calculating the robot's power consumption based on the output current, lout, and the reflected impedance.In Fig. 3a, the load model consists of the robot represented by a load resistance Rrobot, connected via a serial inductor Lsand a parallel capacitor Csand a serial capacitor CMwhich represents the wireless medium. The impedance is given by:

[0088]

[0089] After transformation, the load model consists of a parallel connection of a resistor RTxand a capacitor CTx, as shown in Fig. 3b. After further transformation, the load model consists of a robot impedance Zrobot, which is given by:

[0090] &

[0091]

[0092] >

[0093] as shown in Fig. 3c.

[0094] Fig. 3d illustrates the waveforms of the transmitter voltage Vp, the transmitter current Ip and the voltage Vant of the antenna segment.

[0095] Fig. 4 illustrates impedance matching between the power distribution box 14 and each antenna segment 12j. The impedance matching network is divided into two portions: one portion 201 which resides inside power distribution box 14, and is common (shared among) to all antenna segment 12j and a mating (second) portion 202, which resides in each antenna segment 12; and is almost identical to all antenna segments. The communication between the two portions is implemented by a transmission line 203. Since the distance between each antenna segment 12; and the power distribution box 14 is different, an individual fine tuning of the mating portion 202 of the matching network is required.12

[0096] The antenna segments can differ in segment length, resonant characteristics, impedance, power handling capability or spatial deployment density.

[0097] The first and second portions of the impedance matching network are electrically coupled via a transmission line and may be implemented as an LC resonant network. There is no need for wireless communication / data transfer between the receiver of the robot and transmitter the powers activated antenna segments.

[0098] Portions of the antenna segments can be deployed symmetrically relative to the power distribution unit, to reduce tuning variation between segments.

[0099] Fig. 5 illustrates the deployment of portions of the matching networks, according to an embodiment of the invention. In this example, the two portions 201 and 202 are implemented as LC matching networks. Each antenna segment 12j also comprises a switch 203, for switching between active and inactive modes.

[0100] Fig. 6 illustrates a symmetric deployment of portions of the matching networks, according to an embodiment of the invention. In this example, the power distribution box 14 is located in the middle, such as the lengths of all transmission lines 203a-203d are equal. In this deployment, no individual fine tuning of the mating portion 202 of the matching network is required. However, such symmetric deployment is not always available.

[0101] Fig. 7 illustrates the deployment of portions of the matching networks with centralized electronics, according to another embodiment of the invention. In this example, all the electronic components (such as switch 203, for switching between active and inactive modes) of all antenna segments 12a-12d are integrated into the power distribution box 14. In this example, only the matching network portion 20213

[0102] remains within each antenna segment. This implementation prevents the exposure of the electronic components to strong electromagnetic fields when an antenna segment is activated. This configuration reduces the overall parasitic capacitances, and thereby, the overall losses.

[0103] Electronic components associated with switching and control of multiple antenna segments are centralized within the power distribution unit, and each antenna segment comprises passive resonant elements.

[0104] Fig. 8 illustrates the implementation of an activation switch, according to an embodiment of the invention. The activation switch comprises an isolated driver 61 fed by an isolated power supply 62. Upon receiving a command signal to activated an antenna segment via the input Control In, isolated driver 61 outputs a high signal which controls two high-power transistors QI and Q2 (which can be FETs, for example) to conduct and thereby, connect between terminals 2A that is connected to the transmitter electronics box and 2B (that is connected to the antenna), so as to feed the antenna segment with high power that is transmitted to the receiving antenna of the robot that is located above the antenna segment. A feedback signal is taken from sampling resistors Ri and R2which are serially connected between the output of isolated driver 61 and the common connection between QI and Q2. Sampling resistors Ri and R2attenuate the high voltages over QI or Q2 down to logic signal levels. The sampled signal passes a limiting circuit 64 and enters a logic gate 63, which executes a logic function between the sampled signal and the command signal. Switching will be enabled only after a validation step that detects whether or not there is a match between the two signals, in order to prevent false activation due to the strong electromagnetic fields induced at the high power environment.

[0105] The present invention also provides a method for wireless power delivery to a mobile robot moving along a predefined path in a robotic working environment. Accordingly, a wireless power transmission antenna is segmented and deployed14

[0106] along the path into a plurality of antenna segments having non-uniform electrical and / or physical characteristics. The antenna segments are operated in a low-power scanning mode and electrical parameters of each antenna segment are sequentially samples while the robot is in motion. The presence and relative position of the robot with respect to at least one antenna segment are detected, based on a variation in the sampled electrical parameters caused by wireless coupling with the robot; detected antenna segments are selectively transitioned from the low-power scanning mode to a high-power transmission mode, to wirelessly deliver power to the robot while the robot continues moving.

[0107] Non-uniform segmentation is determined, based on expected robot speed, dwell time, stopping locations, power demand profile and environmental constraints along the movement path. Two or more adjacent antenna segments are dynamically grouped into a logical transmission segment based on detected robot position or power demand.

[0108] The presence of a robot is determined by detecting a change, fluctuation, or deviation from a baseline in at least one of antenna voltage, antenna current, phase, impedance, or reflected load. The the robot position is detected without wireless communication or data exchange between the robot and the antenna system.

[0109] The transition of an antenna segment from low-power mode to high-power mode is performed within a time interval sufficient to maintain continuous power delivery to the moving robot.

[0110] The above examples and description have of course been provided only for the purpose of illustrations, and are not intended to limit the invention in any way. As will be appreciated by the skilled person, the invention can be carried out in a great variety of ways, employing more than one technique from those described above, all without exceeding the scope of the invention.

Claims

15CLAIMS1. A wireless power delivery system for transmitting power to robots in a robotic working environment, comprising:a) a power generation unit;b) a plurality of antenna segments being deployed along a robot movement path within said working environment;c) a controller comprising:c.l) a scanning circuitry with an associated operational algorithm, for activating said antenna segments in a low-power scanning mode, sampling electrical parameters of said antenna segments and detecting the position of each of said robots relative to said antenna segments, based on the sampled electrical parameters; andc.2) one or more power distribution units, for selectively activating one or more antenna segments upon detecting predetermined overlap between a robot and one or more segments, by delivering high power to the activated antenna segments, for wirelessly charging said robot from said power generation unit.

2. The system according to claim 1, in which each antenna segment is associated with a switching module configured to selectively conduct or block alternating current for feeding said antenna segment.

3. The system according to claim 2, in which the switching module comprises a bidirectional, isolated, low-parasitic-capacitance switching architecture adapted to operate in a high electromagnetic field environment.

4. The system according to claim 1, further comprising an impedance matching network between the power distribution unit and each antenna segment, said matching network comprising:16a) a first portion located within said power distribution unit and shared among multiple antenna segments; andb) a second portion located within each antenna segment.

5. The system according to claim 4, in which the first and second portions of the impedance matching network are electrically coupled via a transmission line.

6. The system according to claim 2, in which there is no wireless communication / data transfer between the receiver of the robot and transmitter the powers activated antenna segments.

7. The system according to claim 1, in which the power distribution box is configured to activate antenna segments by:a) limiting the transmitted power by controlling all antenna segments to be at low-power transmission mode, where there is no robot nearby; b) activating a scanning mode, in which each antenna segment is turned on at the low-power transmission mode and sampled serially;c) reading the voltage and current values Vant, lant of the sampled antenna segment;d) comparing the sampled values to predetermined thresholds ThVant, Th|ant, respectively;e) if both Vant,>ThVant and lant>Th|ant, determining that the robot is at least partially above a sampled antenna segment;f) activating said sampled antenna segment by switching it to a high-power transmission mode, otherwise, determining that the robot is not above the sampled antenna segment and controlling said sampled antenna segment to remain in low-power transmission mode.

178. The system according to claim 1, in which whenever during movement the robot partially overlaps two adjacent antenna segments, activating the antenna segment with larger overlap.

9. The system according to claim 1, in which the robot impedance Zrobot is given by:>10. The system according to claim 4, in which at least one portion of the impedance matching network is implemented as an LC resonant network.

11. The system according to claim 13, in which portions of the antenna segments are deployed symmetrically relative to the power distribution unit, to reduce tuning variation between segments.

12. The system according to claim 1, in which electronic components associated with switching and control of multiple antenna segments are centralized within the power distribution unit, and each antenna segment comprises passive resonant elements.

13. The system according to claim 1, in which the antenna segmentation is non-uniform.1814. The system according to claim 2, in which the switching module comprises a validation circuit configured to prevent unintended activation caused by electromagnetic interference.

15. The system according to claim 1, in which the controller is configured to control a plurality of antenna segments using a single power distribution unit.

16. A method for wireless power delivery to a mobile robot moving along a predefined path in a robotic working environment, the method comprising: a) segmenting a wireless power transmission antenna deployed along said path into a plurality of antenna segments having non-uniform electrical and / or physical characteristics;b) operating said antenna segments in a low-power scanning mode; c) sequentially sampling electrical parameters of each antenna segment while the robot is in motion;d) detecting the presence and relative position of the robot with respect to at least one antenna segment, based on a variation in said sampled electrical parameters caused by wireless coupling with the robot; ande) selectively transitioning at least one detected antenna segment from the low-power scanning mode to a high-power transmission mode, to wirelessly deliver power to the robot while the robot continues moving.

17. The method according to claim 1, wherein the antenna segments differ in at least one of the following parameters:segment length;resonant characteristics;impedance;power handling capability;spatial deployment density.1918. The method according to claim 16, wherein the non-uniform segmentation is determined based on at least one of the following parameters:expected robot speed;dwell time;stopping locations;power demand profile;environmental constraints along the path.

19. The method according to claim 16, further comprising dynamically grouping two or more adjacent antenna segments into a logical transmission segment based on detected robot position or power demand.

20. The method according to claim 16, wherein the presence of a robot is determined by detecting a change, fluctuation, or deviation from a baseline in at least one of antenna voltage, antenna current, phase, impedance, or reflected load.

21. The method according to claim 16, wherein detecting the robot position is performed without wireless communication or data exchange between the robot and the antenna system.

22. The method according to claim 16, wherein whenever a robot partially overlaps more than one antenna segment, selectively activating the antenna segment or logical group having a greater effective overlap or coupling with the robot.

23. The method according to claim 16, wherein transition of an antenna segment from low-power mode to high-power mode is performed within a time interval sufficient to maintain continuous power delivery to the moving robot.

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