WO2023126651A1

WO2023126651A1 - Simultaneous wireless information and power transfer system for rotating sensors

Info

Publication number: WO2023126651A1
Application number: PCT/IB2021/062421
Authority: WO
Inventors: João André MORAIS GOMES DOS SANTOS; Miguel CAMPOS NOGUEIRA; Adérito Daniel MENDES ABREU; José AUGUSTO AFONSO; José Alberto FERNANDES SALGADO; Ruben Emanuel FERNANDES FIGUEIREDO; João LUÍS AFONSO; Vítor Duarte FERNANDES MONTEIRO; José Gabriel OLIVEIRA PINTO; Manuel João SEPÚLVEDA MESQUITA DE FREITAS; João Miguel CLEMENTE DE SENA ESTEVES; Luiz Alberto LISBOA DA SILVA CARDOSO
Original assignee: Bosch Car Multimedia Portugal, S.A.; Universidade Do Minho
Priority date: 2021-12-28
Filing date: 2021-12-29
Publication date: 2023-07-06

Abstract

This invention discloses a Simultaneous Wireless Information and Power Transfer (SWIPT) system, integrated with a brushless DC motor, that is configured to wirelessly provide interface of information and power capabilities for a rotating/scanning sensor, such as a LiDAR. The herein disclosed Simultaneous Wireless Information and Power Transfer unit for rotating sensors comprises a static module connected to a static structure through a wired interface; a rotating module connected to a rotating sensor through a wired interface and positioned over the static module within a centrally aligned rotation axis; and a brushless motor that ensures the rotation of the rotating module over the static module; the unit may be configured to ensure wireless power transfer and wireless bidirectional information transfer between the static and rotating modules.

Description

DESCRIPTION "Simultaneous Wireless Information and Power Transfer system for rotating sensors"

Technical Field

The present appl ication describes a Simultaneous Wireless Information and Power Trans fer system for rotating sensor systems .

Background art

The autonomous driving industry is an emerging area that is becoming an attractive market . Scanning sensors , such as LiDARs ( Light Detection and Ranging) are important for an autonomous vehicle to achieve a fully autonomous system .

LiDAR sensors have been widely recogni zed as key components for advanced driver-assisted systems and autonomous driving, as they enable 3D mapping of the environment . The principle of operation of common LiDAR sensors is based on time-of- flight ( ToF) measurement between the emission of a laser light pulse and its arrival after reflecting on a distant obj ect . In order to increase the sensor Field-of-View ( FoV) , a rotating LiDAR sensor is a usual requirement . In order to achieve the highest FoV, it is often necessary to rotate the sensor' s optical system by 360 ° . In this configuration it is usually required to trans fer power from the vehicle to the sensor, to power it on, and data between the vehicle and the sensor, to collect information produced by the sensor subsystem and to control it .

Slip rings are a traditional industrial solution for transmitting both power and electric signals carrying information through a rotating axis. This solution employs galvanic connection between a rotating disk or cylinder and series of brushes that, by being in parallel connection, minimize the electrical noise in the transmission. This solution is in general very satisfactory to handle low speed rotation of joints.

By using slip rings, however, the contacts tend to have a shorter lifetime due to the friction of the metallic brushes or contacts, which is especially sensitive in the case of the angular speeds normally required for scanning sensors, such as LiDARs and RADARs for automated driving applications, where it can be used rotations in the order of 600 rpm or more. At high angular speeds, the situation is worsened when slip rings are considered for the high-speed data transfer of information.

Because of these limitations, some inventive effort has been observed in recent years (US 2016/0274221 Al, WO 2018/125709 Al, WO 2019/158301 Al) , using inductive wireless power transfer technology (IWPT) , in association with some wireless information transfer technique.

Document US2016274221A1 describes a rotating optical range finder including a stationary base, a rotating base, an optical sensor, a transmitting circuit, a receiving circuit, a first induction coil, and a second induction coil. The rotating base is disposed on the stationary base. The optical sensor is disposed in the rotating base. The transmitting circuit is disposed in the stationary base. The receiving circuit is disposed in the rotating base and electrically connected to the optical sensor. The first induction coil is disposed in the stationary base and electrically connected to the transmitting circuit . The second induction coil is disposed in the rotating base and electrically connected to the receiving circuit .

Document WO2018125709A1 describes an interface for trans ferring power and data between a non-rotating body and a rotating body may include a power trans fer device coupled to the non-rotating body, and a power receiver coupled to the rotating body and configured to receive electrical power from the power trans fer device . The interface may further include a first data transmitter coupled to the rotating body, and a first data receiver coupled to the non- rotating body and configured to receive data signals from the first data transmitter . The interface may also include a second data transmitter coupled to the non-rotating body, and a second data receiver coupled to the rotating body and configured to receive data signals from the second data transmitter . The wireless coupling between the power trans fer device and the power receiver may include an inductive coupling, and the first data transmitter and the first data receiver may each include an optical communication device .

Document W02019158301A1 describes a LiDAR system of the scanning type for optically detecting a field of view for a working device and/or a vehicle , wherein a stator, a rotor that can rotate about an axis of rotation relative to the stator, a transmitter optic, a receiver optic and a communications unit are designed for contactless data transmission between the stator and the rotor, at least one part of the transmitter optic and/or a part of the receiver optic are accommodated in the rotor, the communications unit has a first communications channel for contactless data transmission from the stator to the rotor and a second communications channel for contactless data transmission from the rotor to the stator, and the first and the second communication channels are designed to be of a di f ferent nature .

Summary

The present invention describes a Simultaneous Wireless Information and Power Trans fer unit for optical automotive rotating transducers and/or sensors comprising : a SWIPT-TX module connected to a static structure through a wired interface ; a SWIPT-RX module connected to a rotating sensor through a wired interface and positioned over the SWIPT-TX module within a centrally aligned rotation axis ; and a brushless motor mechanically connected between the SWIPT-TX module and the SWIPT-RX module .

In a proposed embodiment of present invention, the SWIPT-TX module , which is stationary, comprises an electrically compensated Transmitting Circular Flat Spiral Single or Multi-Layered Coil , and H-Bridge , a Stationary Optical Transceiver, and a Connection Control system .

Yet in another proposed embodiment of present invention, the SWIPT-RX module , which rotates with respect the SWIPT-TX module , comprises an electrical ly compensated Receiving Circular Flat Spiral Single or Multi-Layered Coil and Recti fier, a multiple voltage output DC-DC Converter, and a Rotating Optical Transceiver .

Yet in another proposed embodiment of present invention, the electrically compensated Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge is configured to safely ensure wireless power trans fer to the compensated Receiving Circular Flat Spiral Single or Multi-Layered Coil and Recti fier under nominal load, underload and open circuit through maximum current limitation .

Yet in another proposed embodiment of present invention, the Stationary Optical Transceiver is configured to ensure a wireless information trans fer to and from the Rotating Optical Transceiver through a bidirectional high speed optical link .

Yet in another proposed embodiment of present invention, the SWIPT-RX module comprises a hollow shaft surrounding the centrally aligned rotation axis .

Yet in another proposed embodiment of present invention, the hollow shaft is configured to ensure an interference- free optical path for the wireless information trans fer between the SWIPT-TX module and the SWIPT-RX module .

Yet in another proposed embodiment of present invention, an external portion of the hollow shaft surrounding the optical path comprises at least one of a cylindrical ferrite layer or a ferrite sheet or axial ferrite inserts , to increase the magnetic coupling and the electrical ef ficiency of the wireless power trans fer between the Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge and the Receiving Circular Flat Spiral Single or Multi-Layered Coil and Recti fier .

Yet in another proposed embodiment of present invention, the brushless motor, controlled by a motor driver connected to the Transmitting Circular Flat Spiral Single or Multi- Layered Coil and H-Bridge through a wired power connection, is configured to promote the rotation of the SWIPT-RX module over the SWIPT-TX module within the centrally aligned rotation axis , accordingly to a predefined required rotation pattern .

Yet in another proposed embodiment of the present invention, the SWIPT-RX module comprises a magnetically encoded disk attached and central-aligned with the rotation axis , which is read by a magnetic header solidary with the stationary SWIPT-TX module , to accurately determine the current relative angular position of the SWIPT-RX module with respect to the SWIPT-TX module .

Yet in another proposed embodiment of present invention, the SWIPT-TX module ( 21 ) is configured to safely ensure variable wireless power trans fer ( 39 ) from zero to a nominal maximum power value of up to a few hundred Watts , and to ensure simultaneous bidirectional wireless information trans fer ( 32 ) at a nominal sustained maximum rate of up to a few GBits/ s , to the SWIPT-RX module ( 20 ) .

Yet in another proposed embodiment of present invention, the Simultaneous Wireless Information and Power Trans fer unit comprises a single cross-roller bearing configured to ensure a compact and stable mechanical connection between the SWIPT- TX module and the SWIPT-RX module , in order to improve robustness of the wireless power trans fer and wireless information trans fer , while providing lower vibration noise and enhancing precision of the relative angular position of the SWIPT-RX module with respect to the SWIPT-TX module . General Description

This invention discloses the use o f a Simultaneous Wireless Information and Power Trans fer ( SWIPT ) system, integrated with a brushless DC (BLDC ) motor, that is configured to wirelessly provide these required interface capabilities for a rotating/ scanning transducer or sensor, such as a LiDAR .

SWIPT is a technology that can supply power to LiDAR systems and similarly constituted modules (unidirectional energy trans fer from the stator to the rotor ) . It also provides bidirectional information interconnection between the rotor and the stator, which is connected to a control system running on board of the vehicle .

The herein disclosed solution will overcome some state-of- the-art issues , allowing to accommodate the installation of a scanning sensor of large FoV on a vehicle while reducing the total number of LiDAR sensors necessary for autonomous driving . Some additional benefits include the possibility of eliminating all galvanic contacts in the electric power transmission between two assemblies that are mechanically connected by a shaft , producing controlled rotation between these assemblies by the use of an electric motor that is controllable from the stationary assembly ( stator ) , and providing a sel f-contained subsystem that can be the basis for the construction of di f ferent scanning sensors of high pointing precision . Finally, the LiDAR sensor optics complexity ( ID optical system - Vertical ) will decrease , allowing it to be totally enclosed, including its power source and data connection subsystem, in a rotating assembly . Overcoming the above-mentioned problems will allow to obtain additional advantages that comprise hori zontal scanning with rotation, 360° FoV based on the use of a single sensor scanning all the environment around the car, suitable for urban environments, higher frame rate and independence of the power transfer system and the information transfer system.

Brief description of the drawings

For the better understanding of the present application, figures representing preferred embodiments are herein attached. However, they are not intended to limit the technique disclosed herein.

Fig. 1 - illustrates the electrical module architecture, showing the combination of a wireless power transfer (WPT) system with a high-speed bidirectional optical link, and having a LiDAR as an example of sensor subsystem that can be supported by the Simultaneous Wireless Information and Power Transfer (SWIPT) with an embedded Brushless DC (BLDC) motor. The reference numbers refer to:

10 - LiDAR Sensor Control & Data Acquisition system;

11 - DC-DC Converter;

12 - Rotating Optical Transceiver;

13 - Receiving Circular Flat Spiral Single or Multi- Layered Coil and Rectifier;

14 - Stationary Optical Transceiver;

15 - Transmitting Circular Flat Spiral Single or Multi- Layered Coil and H-Bridge;

16 - Connection Control system;

17 - Motor Driver / controller;

18 - BLDC Motor;

19 - Mechanical connection; 20 - SWIPT-RX module;

21 - SWIPT-TX module;

22 - SWIPT unit;

23 - Wireless interface ;

24 - Wired interface to vehicle;

25 - Wired interface to LiDAR;

26 - Wired power connection to vehicle: VGND, VBAT;

27 - Wired communication connection to vehicle: CAN BUS;

28 - Wired TCP/IP communication connection to vehicle: data bus;

29 - Wired TCP/IP communications;

30 - Wired power supply: LGND, L3V3, L5V, L12V;

31 - Unregulated VDC;

32 - Bidirectional high speed optical link / wireless information transfer (WIT) ;

33 - Wired power connection;

34 - Enable channel;

35 - Wired power connection;

36 - PWM-0 channel;

37 - PWM-1 channel;

38 - Wired power connection;

39 - Wireless power transfer (WPT) .

Fig. 2 - depicts a vertical cut view of the developed system, wherein the reference numbers refer to:

12 - Rotating Optical Transceiver / LiFi Transceiver;

13 - Receiving Circular Flat Spiral Single or Multi- Layered Coil and Rectifier / RX Coil;

14 - Stationary Optical Transceiver / LiFi Transceiver;

15 - Transmitting Circular Flat Spiral Single or Multi- Layered Coil and H-Bridge / TX Coil;

18 - BLDC Motor; 20 - SWIPT-RX module / rotor main chassis;

21 - SWIPT-TX module / stator main chassis;

39 - Wireless power transfer (WPT) ;

40 - Axial ferrite insert;

41 - Single cross-roller bearing;

42 - Centrally aligned rotation axis;

43 - Hollow shaft optical path.

Description of Embodiments

With reference to the figures, some embodiments are now described in more detail. However, they are not intended to limit the scope of the present application.

A particular embodiment of the Simultaneous Wireless Information and Power Transfer (22) system disclosed herein is intended for the use in rotating sensor systems, particularly in LiDAR sensors (10) .

In the proposed SWIPT (22) , comprised of a SWIPT-RX module (20) and a SWIPT-TX module (21) , the wireless power transfer (WPT) (39) and wireless information transfer (WIT) (32) functionalities are mechanically integrated into one single unit with virtually no electromagnetic mutual interdependence or interference. The exception is the capacity of turning on and off the WPT (39) by issuing special messages (commands) to the SWIPT system, that are decodified by a Connection Control (16) Block, as shown in Figure 1.

The SWIPT-TX module (21) of the SWIPT system (22) comprises a Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge (15) and a Stationary Optical Transceiver (14) , which are controlled through a Connection Control (16) . The SWIPT-TX module (21) is connected to the vehicle through a wired interface (24) . This wired interface (24) comprises power connections (26) and communication connections (27, 28) .

The SWIPT-RX module (20) of the SWIPT system (22) comprises a Receiving Circular Flat Spiral Single or Multi-Layered Coil and Rectifier (13) , a Rotating Optical Transceiver (12) and a DC-DC Converter (11) , being both the Rotating Optical Transceiver (12) and the DC-DC Converter (11) connected to the LiDAR Sensor Control & Data Acquisition system (10) through a wired interface (25) . This wired interface (25) comprises a wired power supply (30) and wired TCP/IP communications (29) . The Receiving Circular Flat Spiral Single or Multi-Layered Coil and Rectifier (13) is connected to the DC-DC Converter (11) , which in turn is connected to the Rotating Optical Transceiver (12) to provide a wired power connection (33) .

The Transmitting Circular Flat Spiral Single or Multi- Layered Coil and H-Bridge (15) of the SWIPT-TX module (21) is also connected to the Motor Driver (17) , through a wired power connection (38) , which controls the BLDC Motor (18) that is mechanically connected (19) to the LiDAR Sensor Control & Data Acquisition system (10) . The Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H- Bridge (15) is connected to the Stationary Optical Transceiver (14) and also to the Connection Control (16) through a wired power connection (35) . The Connection Control (16) controls the operational behavior of both the

Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge (15) through two PWM (Pulse-Width

Modulation) channels (36, 37) , and the Stationary Optical

Transceiver (14) through an enable channel (34) . The Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge (15) is configured to ensure the wireless power transfer (39) to the Receiving Circular Flat Spiral Single or Multi-Layered Coil and Rectifier (13) , and the Stationary Optical Transceiver (14) is configured to ensure the wireless information transfer (32) to the Rotating Optical Transceiver (12) through a bidirectional high speed optical link.

Considering the disclosed Figure 2 as a possible customized embodiment of the proposed solution, the proposed SWIPT system (22) is composed of two perfectly centrally aligned main chassis, the rotor chassis (20) , which is related to the SWIPT-RX module (20) , and a stator chassis (21) , which is related to the SWIPT-TX module (21) , separated by one precision bearing (40) . The rotating behaviour is ensured by a BDLC motor (18) which is configured and adapted to the SWIPT system (22) . The Light Fidelity (Li-Fi) transceivers, i.e., the Rotating Optical Transceiver (12) and the Stationary Optical Transceiver (14) are fixed to a central portion of the SWIPT-TX module (21) and into a central portion of the SWIPT-RX module (20) , respectively, which are perfectly aligned with the rotation axis of the SWIPT-RX module (20) , for correct bidirectional data communications (32) between the referred modules (20, 21) , allowing to achieve Gigabit transfer data rates. Since the data transfer light system between the two modules (20, 21) requires an interference-free path to send information, the SWIPT-RX module (20) main chassis incorporates a hollow shaft (43) for the mentioned optical path, which will ensure the bidirectional high speed optical link (32) . These transceivers (12, 14) use a nonpolarized optical beam. Therefore, the communication is rotating invariant. The shaft (43) is also responsible for supporting the sensor payload allocated on the rotating module (20) . In the surrounding external portion of the shaft (40) , a cylindrical ferrite sheet (40) is installed to increase the receiving coils (13, 15) mutual inductance and reduce losses on the mechanical shaft (43) . On the back of each coil (13, 15) , a ferrite plate is also placed for the same intent with a hole, leaving a gap between the ferrite and the shaft.

Regarding the wireless power transfer (39) system, it is important to assure that the LiDAR sensor (10) works with a continuous and reliable power supply. A control system (16) must be implemented to prevent overcurrent outputs and to ensure a suitable output power for the system necessities.

Considering the wireless information transfer (32) system, it is necessary to guarantee that all the information is transferred without any errors or disconnections. It needs to provide enough data rate to enable the transfer of all the data generated by the control system (16) with the minimum latency possible.

The invention herein disclosed constitutes, however, an improved solution for the implementation of rotating sensors over these previously proposed solutions, due to the unique reunion of generic auto-contained and versatile solutions for simultaneous power and information transfer capability that are sensor independent. The use of flat spiral coils on both the SWIPT-TX module (21) and the SWIPT-RX module (20) for wireless power transfer (39) , in both of which the flat ferrite core (13, 15) is transfixed at center by bidirectional modulated laser beams (32) that transfer information, data and commands, between the SWIPT-TX module (21) attached to the vehicle and the SWIPT-RX module (20) attached to the sensor (10) , for instance, a light ranging device or subsystem, is also an innovation with regard to present known state-of-the-art. The complete signal separation between power transfer through induction (39) and information transfer through modulated light beams (32) connection subsystems, where the power supply for each of the two transceiver modules (12, 14) of wireless information transfer subsystem is locally provided either by the WPT transmitter or the WPT receiver circuits .

The present invention also comprises the full integration of a brushless electric motor (18) and its controller (17) as part of the electro-mechanical configuration, and the mechanical assembly with a single cross-roller bearing (41) as the sole principal mechanical connection (19) between the stationary (21) and the rotating parts (20) , which greatly improve robustness while keeping low vibration and high pointing precision of the sensor being rotated.

The present invention also optionally comprises the integration of a high precision internal or external angular encoder .

This invention is focused on describing an efficient SWIFT system (22) with high power transfer and high data rate capabilities. All the system is invariant to rotation and was built alongside the brushless motor (18) to deliver a fully integrated and compact product that can be used as a base subsystem for the implementation of scanning (rotating) sensors, including a high-performance LiDAR (10) for realtime automotive applications.

Claims

1. Simultaneous Wireless Information and Power Transfer unit (22) for optical automotive rotating transducers or/and sensors comprising: a SWIPT-TX module (21) connected to a static structure through a wired interface (24) ; a SWIPT-RX module (20) connected to a rotating sensor (10) through a wired interface (25) and positioned over the SWIPT-TX module (21) within a centrally aligned rotation axis (42) ; and a brushless motor (18) mechanically connected between the SWIPT-TX module (21) and the SWIPT-RX module (20) .

2. Simultaneous Wireless Information and Power Transfer unit (22) according to the previous claim, wherein the SWIPT-TX module (21) comprises an electrically compensated Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge (15) , a Stationary Optical Transceiver (14) and a Connection Control system (16) .

3. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the Rotating SWIPT-RX module (20) comprises a DC-DC Converter (11) , an electrically compensated Receiving Circular Flat Spiral Single or Multi-Layered Coil and Rectifier (13) and a Rotating Optical Transceiver (12) .

4. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the electrically compensated Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge (15) is configured to safely ensure wireless power transfer (39) to the compensated Receiving Circular Flat Spiral Single or Multi- Layered Coil and Rectifier (13) under nominal load, underload and open circuit through maximum current limitation.

5. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the Stationary Optical Transceiver (14) is configured to ensure a wireless information transfer (32) to and from the Rotating Optical Transceiver (12) through a bidirectional high-speed optical link.

6. Simultaneous Wireless Information and Power Transfer unit

(22) according to any of the previous claims, wherein the SWIPT-RX module (20) comprises a hollow shaft (43) surrounding the centrally aligned rotation axis (42) .

7. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the hollow shaft (43) is configured to ensure an interference- free optical path for the wireless information transfer (32) between the SWIPT-TX module (21) and the SWIPT-RX module

(20) .

8. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein an external portion of the hollow shaft (43) surrounding the optical path comprises at least one of a cylindrical ferrite layer or a ferrite sheet or axial ferrite inserts (40) , to increase the magnetic coupling and the electrical efficiency of the wireless power transfer (39) between the Transmitting Circular Flat Spiral Single or Multi-Layered Coil and Ji- Bridge (15) and the Receiving Circular Flat Spiral Single or Multi-Layered Coil and Rectifier (13) . 18

9. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the brushless motor (18) , controlled by a motor driver (17) connected to the Transmitting Circular Flat Spiral Single or Multi-Layered Coil and H-Bridge (15) through a wired power connection (38) , is configured to promote the rotation of the SWIPT-RX module (20) over the SWIPT-TX module (21) within the centrally aligned rotation axis (42) , accordingly to a predefined required rotation pattern.

10. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the SWIPT-RX module (20) comprises a magnetically encoded disk attached and central-aligned with the rotation axis (42) , which is read by a magnetic header solidary with the stationary SWIPT-TX module (21) , to accurately determine the relative angular position of the SWIPT-RX module (20) with respect to the SWIPT-TX module (21) .

11. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, wherein the SWIPT-TX module (21) is configured to safely ensure variable wireless power transfer (39) from zero to a nominal maximum power value of up to a few hundred Watts, and to ensure simultaneous bidirectional wireless information transfer (32) at a nominal sustained maximum rate of up to a few GBits/s, to the SWIPT-RX module (20) .

12. Simultaneous Wireless Information and Power Transfer unit (22) according to any of the previous claims, comprising a single cross-roller bearing (41) configured to ensure a compact and stable mechanical connection (19) between the 19

SWIPT-TX module (21) and the SWIPT-RX module (20) , in order to improve robustness of the wireless power transfer (39) and wireless information transfer (32) , while providing lower vibration noise and enhancing precision of the relative angular position of the SWIPT-RX module (20) with respect to the SWIPT-TX module (21) .