Patent Publication Number: US-2023152819-A1

Title: Autonomous mobile robot with enhanced sensing and reporting of obstacles

Description:
TECHNICAL FIELD 
     The subject matter herein generally relates to robots, in particular to autonomous mobile robots. 
     BACKGROUND 
     Autonomous mobile robots brings a lot of benefits to homes and industry. An autonomous mobile robot system involves signal acquisition, signal processing, and signal transmission. Signal output by a sensor of the autonomous mobile robot may be weak, and often becomes distorted during a signal transmission process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG.  1    is a diagram of an embodiment of an autonomous mobile robot according to the present disclosure. 
         FIG.  2    is a diagram of an embodiment of an obstacle detection system of the autonomous mobile robot of  FIG.  1   . 
         FIG.  3    is a circuit diagram of an embodiment of an obstacle detection system of the autonomous mobile robot of  FIG.  1   . 
         FIG.  4    is a layout structure diagram of a proximity sensor of the autonomous mobile robot of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean “at least one”. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. 
       FIG.  1    illustrates a diagram of an obstacle detection system  100  in one embodiment of the present application. The obstacle detection system  100  can be operated in an autonomous mobile robot (AMR)  200 . The AMR  200  can detect obstacles and perform path planning based on the obstacle detection system  100 . 
     Referring to  FIG.  2   , the obstacle detection system  100  can comprises a processor  10 , a multiplexer  20 , and a plurality of proximity sensors  30 . Each proximity sensor  30  transmits first sensing signals to the processor  10  through the multiplexer  20 . The multiplexer  20  can be arranged on a first printed circuit board (PCB), and the plurality of proximity sensors  30  can be arranged on multiple second PCBs. 
     In this embodiment, by setting multiplexer  20  between the processor  10  and the proximity sensors  30 , the first sensing signals output by the proximity sensors  30  can be enhanced. The processor  10  can switch communication paths of the multiplexer  20  to achieve communication through one communication port of the processor  10  receiving the first sensing signals of multiple proximity sensors  30 , communication port resources of the processor  10  can be saved. 
     In one embodiment, the processor  10  may be a central processing unit (CPU), an application specific integrated circuit (ASIC), a microcontroller unit (MCU), a single chip, etc. The multiplexer  20  may be a two-to-one multiplexer switch, an eight-to-one multiplexer switch, a sixteen-to-one multiplexer switch, etc. The proximity sensors  30  may be infrared sensors or other sensors that can sense distance. 
     In one embodiment, the AMR  200  can further comprise a light detection and ranging (LDR) module  40 . The LDR module  40  is coupled to the processor  10  and transmits second sensing signals to the processor  10 . The processor  10  can perform path planning based on the first sensing signals and the second sensing signals. 
     In one embodiment, the AMR  200  can obtain environment information through the LDR module  40 , and build an environment map based on a simultaneous localization and mapping (SLAM) algorithm. The AMR  200  can perform autonomous navigation and path planning based on the environment map. For example, the environment information obtained by the LDR module  40  can be transmitted to the processor  10 , and the processor  10  can execute the SLAM algorithm to build the environment map. 
     In one embodiment, the proximity sensors  30  can assist the LDR module  40  to detect obstacles, discover low-angle areas and blind areas that cannot be detected by the LDR module  40 . An ability of the AMR  200  to detect local environment is enhanced and a safety is improved. 
     In one embodiment, the proximity sensors  30  can be arranged on an area with a radius greater than or equal to a preset value, and a center of the area is a laser emission point of the LDR module  40 . The preset value can be defined according to an actual size or a layout structure of the AMR  200 , for example, the preset value can be 10 cm. 
     Referring to  FIG.  3   , the number of proximity sensors  30  is eighteen as an example, and two multiplexers  20  are arranged between the processor  10  and the eighteen proximity sensors  30 . One multiplexer  20  is a two-to-one multiplexer switch, the other one multiplexer  20  is a sixteen-to-one multiplexer switch. The processor  10  can communicate with the two multiplexers  20  through two inter-integrated circuit (I2C) ports. Each of the two I2C ports can comprise three I2C communication pins, a serial data (SDA) pin, a serial clock (SCL) pin, and an interrupt (INT) pin. The multiplexer  20  can comprise an input terminal, an output terminal, and a control terminal. The input terminals of the multiplexer  20  are coupled to the proximity sensors  30 . The control terminal of the multiplexer  20  is coupled to an input/output (I/O) pin of the processor  10 , such as a general purpose input/output (GPIO) pin. The output terminal of the multiplexer  20  is coupled to the I2C communication pin of the processor  10 . The processor  10  can switch the communication path of the multiplexer  20  through the control terminal and the I/O pin. 
     Referring to  FIG.  3   , if one multiplexer  20  is the sixteen-to-one multiplexer switch, the processor  10  can switch the communication path of the one multiplexer  20  through four I/O pins (for example, four I/O pins can be address bus pins add 0 , addl, add 2 , and add 3  of the processor  10 ). If the other multiplexer  20  is the two-to-one multiplexer switch, the processor  10  can switch the communication path of the other one multiplexer  20  through one I/O pin (address bus pin add 4  of the processor  10 ). 
     In one embodiment, in the AMR  200 , by setting the multiplexer  20  to couple with the proximity sensors  30 , the proximity sensors  30  share a section of I2C communication line, and thus a length of the total I2C communication line is reduced. A parasitic capacitance of the I2C communication line and likelihood of signal distortion are reduced, and a problem of signal slowdown is avoided by using the multiplexer  20 . 
     In one embodiment, the shorter the communication line between the proximity sensors  30  and the multiplexer  20 , the lower the likelihood of signal distortion. 
     In one embodiment, the proximity sensors  30  are arranged at corner areas of the AMR  200 , to compensate for the low-angle areas and the blind areas that cannot be detected by the LDR module  40 . The multiplexer  20  and the processor  10  may be arranged in a motherboard of the AMR  200 . The eighteen proximity sensors  30  are arranged on multiple sub-circuit boards, and the first sensing signals of the eighteen proximity sensors  30  are transmitted to the multiplexer  20  through multiple signal lines. The higher the conductivity of the signal lines, the larger the parasitic capacitance, and the slower the signal climbing speed. Ultra-low dielectric coefficient wires are used to transmit the first sensing signals, to reduce the parasitic capacitance. 
       FIG.  4    illustrates a layout structure diagram of an embodiment of the proximity sensor  30  of the present application. 
     In one embodiment, the proximity sensor  30  is the infrared sensor. The proximity sensor  30  can be arranged on the second PCB  101 . The proximity sensor  30  can comprise an infrared transmitter  301  and an infrared receiver  302 . Infrared light of the infrared transmitter  301  can be transmitted through a transparency lens  102 . A spacer  103  can be arranged between the infrared transmitter  301  and the infrared receiver  302 . The spacer  103  can be configured to block light reflected by the transparency lens  102  and stop it entering into the infrared receiver  302 , so light reflected by the translucent lens  102  can be reduced. 
     In one embodiment, the translucent lens  102  can also provide a basic protection of the proximity sensor  30 , to protect the proximity sensor  30  from collision, splashing water, static electricity, etc. The translucent lens  102  may comprise a lens body, a first anti-reflection (AR) coating disposed on one surface of the lens body, and a second AR coating and an anti-fingerprint (AF) coating disposed on the other surface of the lens body. Surface reflectance of the translucent lens  10  is reduced and a vertical light transmittance can be increased by the inner AR coating and the outer AR coating (first and second AR coatings). The translucent lens  102  can be made of polycarbonate (PC) and polymethyl methacrylate (PMMA) composite material, which improves the light transmittance and coating strength of the translucent lens  102 , reducing ageing caused by light source irradiation, and lower reflected noise. 
     In one embodiment, a material of the spacer  103  is rubber. 
     In one embodiment, in order to calibrate an obstacle detection accuracy of the proximity sensor  30 , a first sensing noise of the proximity sensor  30  is measured when there is no obstacle on a black floor, and sensing signals of an obstacle on the black floor are detected, then the sensing signal of the obstacle on the black floor can be calibrated based on the first sensing noise. A second sensing noise of the proximity sensor  30  is measured when there is no obstacle on a white floor, and sensing signals of an obstacle on the white floor is detected, then the sensing signal of the obstacle on the white floor can be calibrated based on the second sensing noise. An activation ratio of the proximity sensor  30  can be calculated through return values of sensor existing or not existing in respect of obstacles. The calculated activation ratio of each proximity sensor  30  in the worst case can be recorded into the AMR  200 , and the sensing accuracy of the proximity sensor  30  can be improved. In an actual operating environment, the floor may be different colors or slightly different colors, return values of each proximity sensor  30  may be checked for consistency. Each proximity sensor  30  can interact with a SLAM system of the AMR  200 , to record floor noise of areas when the AMR  200  performs map building and/or positioning during there are/no obstacles around the AMR  200 , to improve the sensing accuracy of the proximity sensors  30 . 
     The exemplary embodiments shown and described above are only examples. Many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, including in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the exemplary embodiments described above may be modified within the scope of the claims.