Overspeed detection device

Abstract

The invention relates to a vehicle (1) comprising a chassis (10) and a wheel motor assembly (12) comprising a drive wheel (120) and a driving electric motor (122), the vehicle (1) comprising an overspeed detection device (2), the overspeed detection device (2) comprising a first sensor (20), the first sensor (20) being configured to measure a rotational speed, the overspeed detection device (2) comprising a speed reference device (22) for establishing a maximum rotational speed, the reference device (22) comprising an optical sensor (220) for determining a near environment, the maximum rotational speed being a function of the near environment, a predefined functional speed threshold and a direction of rotation, the overspeed detection device (2) comprising a comparator (24) between the rotational speed and the maximum rotational speed,the comparator (24) being configured to stop the rotation of the drive wheel (120) if the speed of is greater than the maximum rotational speed. Figure for the abbreviation: Fig. 1,

Description

Title of the invention: Overspeed detection device

[0001] The invention relates to the field of robots moving autonomously and, more specifically, autonomous mobile robots capable of transporting goods or loads over a predefined movement area.

[0002] Autonomous mobile robots enabling the movement of objects are specifically designed for autonomous and safe driving.

[0003] The safety system of such autonomous mobile robots includes means for detecting obstacles in a predefined movement area around the autonomous mobile robot and means for bringing the autonomous mobile robot to a safe stop before colliding with any obstacle detected in a defined movement area.

[0004] A known solution for detecting obstacles all around an autonomous mobile robot is to mount two opposing laser scanners at the corners of a typically rectangular mobile robot. Each scanner generally covers a 270° field of view, that is, from one side of the mobile robot to the other side for a corresponding corner. Thus, the two scanners can cover a protective zone around the autonomous mobile robot.

[0005] In a known manner, such a type of autonomous mobile robot can also include other types of sensors allowing, for example, the measurement of the speed of the autonomous mobile robot at any time.

[0006] It is then possible to detect, from the data of the scanners and / or sensors, a potential overspeed situation of the autonomous mobile robot, which is characterized by a situation in which the autonomous mobile robot moves at a speed that can be described as excessive, particularly in relation to its movement area and its immediate surroundings. This is especially the case when the autonomous mobile robot moves near obstacles; it must then adapt its speed and movement in relation to its immediate surroundings and these obstacles.

[0007] All these sensors and scanners are generally connected to a digital controller that analyzes the digital speed and obstacle presence data provided by the various sensors and / or scanners in order to control the drive wheels of the autonomous mobile robot. The digital controller thus adapts the speed and trajectories of the autonomous mobile robot in real time with respect to the robot's immediate environment and the immediate danger that obstacles identified by the sensors or scanners may represent.

[0008] However, the use of such a digital controller and such digital sensors This presents numerous drawbacks. Indeed, using a digital controller or encoder introduces complexity into the architecture of the autonomous mobile robot, primarily due to the use of digital means. Beyond the significant costs of such an architecture, its complexity can lead to long reaction times, which are incompatible with the robot's safety. Furthermore, in terms of safety related to using such digital means to control the movement and braking of the autonomous mobile robot, a digital controller also has the disadvantage of having to comply with safety standards. Obtaining certification to these standards can be difficult.

[0009] In order to avoid using the software-based architecture mentioned above, it may be possible to rely exclusively on a hardware architecture implementing hardwired logic and analog components to manage the speed of the mobile robot within its movement range. Indeed, implementing a hardware architecture has the advantage of meeting different, less stringent safety standards compared to a software-based architecture.

[0010] Thus, the invention aims to overcome all or part of the problems mentioned above by providing a device for detecting overspeed of the autonomous mobile robot that operates exclusively on a hardware-based logic and requires only the use of a simple sensor positioned in a drive wheel of the autonomous mobile robot or on a shaft driven by the wheel, and a lidar sensor to detect obstacles and the environment surrounding the autonomous mobile robot. This overspeed detection device, operating solely on a hardware-based architecture, has the advantage of being simpler than a software-based architecture, while fully complying with the safety standards applicable to this type of system.

[0011] To this end, the invention relates to a vehicle configured to move in a movement zone, the vehicle comprising a chassis and a wheel motor assembly comprising at least one drive wheel and an electric motor driving the drive wheel in rotation, the vehicle comprising a device for detecting overspeed of the drive wheel, the overspeed detection device comprising a first overspeed sensor, the first overspeed sensor being configured to measure a rotational speed of the drive wheel,

[0012] the overspeed detection device comprising a speed reference device configured to establish a maximum rotational speed of the drive wheel, the speed reference device comprising an optical sensor configured to determine an environment near the drive wheel, the optical sensor being disposed against the chassis, the maximum rotational speed being at least a function of the near environment, a predefined functional speed threshold and a direction of rotation of the drive wheel,

[0013] the overspeed detection device comprising a speed comparator between the rotational speed of the drive wheel and the maximum rotational speed of the drive wheel, the speed comparator being configured to stop the rotation of the drive wheel if the rotational speed of the drive wheel is greater than the maximum rotational speed of the drive wheel.

[0014] According to one aspect of the invention, the first overspeed sensor comprises a fixed element positioned in the drive wheel and at least one movable element positioned along a radial end of the movable wheel relative to the axis of rotation.

[0015] According to one aspect of the invention, the first overspeed sensor includes a signal converter configured to convert a flip frequency of the first overspeed sensor into an analog voltage.

[0016] According to one aspect of the invention, the first overspeed sensor includes a filter disposed between the signal converter and the speed comparator.

[0017] According to one aspect of the invention, the optical sensor is a lidar sensor.

[0018] According to one aspect of the invention, the lidar sensor is configured to generate a In the first mapping of the immediate environment, the lidar sensor includes a second programming input configured to program a vehicle attention zone within the movement area.

[0019] According to one aspect of the invention, the overspeed detection device comprises a second overspeed sensor and disposed at a predefined angle relative to the first overspeed sensor, the second overspeed sensor being configured to measure a rotational speed of the drive wheel.

[0020] According to one aspect of the invention, the first overspeed sensor and the second overspeed sensor are hall effect sensors or rotary sensors or optical sensors.

[0021] According to one aspect of the invention, the overspeed detection device comprises a third overspeed sensor and disposed at a predefined angle relative to the first overspeed sensor and relative to the second overspeed sensor, the third overspeed sensor being configured to measure a rotational speed of the drive wheel.

[0022] According to one aspect of the invention, the overspeed detection device comprises a generalized malfunction detector for the first overspeed sensor, the second overspeed sensor, and the third overspeed sensor, the generalized malfunction detector being configured to detect a simultaneous malfunction of the first overspeed sensor and the second overspeed sensor, or of the second overspeed sensor and the third overspeed sensor, or of the first overspeed sensor and the third overspeed sensor, or of the first overspeed sensor, second overspeed sensor and third overspeed sensor.

[0023] According to one aspect of the invention, the electric motor is incorporated into the drive wheel.

[0024] The invention will be better understood and other advantages will become apparent upon reading the detailed description of an embodiment given by way of example, a description illustrated by the accompanying drawing in which:

[0025] [Fig-1] [Fig.1] represents a schematic view of an autonomous vehicle including a vehicle overspeed detection device according to the invention;

[0026] [Fig.2] [Fig.2] represents a schematic view of the autonomous vehicle according to a second configuration mode;

[0027] [Fig.3] [Fig.3] represents a schematic view of the autonomous vehicle of [Fig.1] comprising two overspeed sensors;

[0028] [Fig.4] [Fig.4] represents a schematic view of the autonomous vehicle comprising a generalized malfunction detector according to the invention;

[0029] [Fig.5] [Fig.5] represents a schematic view of the autonomous vehicle including a preferred configuration of the overspeed detection device according to the invention.

[0030] For the sake of clarity, the same elements will bear the same references in the different figures.

[0031] Figure 1 shows a schematic view of a vehicle 1 configured to move within a movement area. Vehicle 1 can be interpreted as any land vehicle capable of moving by means of wheels. According to a preferred aspect of the invention, vehicle 1 can be a robot capable of moving autonomously.

[0032] The vehicle 1 comprises a chassis 10 and a wheel motor assembly 12. The chassis 10 is connected to the wheel motor assembly 12, which includes a drive wheel 120 and an electric motor 122. In this embodiment, the wheel motor assembly 12 comprises the electric motor 122 directly integrated into the drive wheel 120, which is capable of propelling the vehicle 1. The main advantages of such a wheel motor assembly 12 are its compact size and the fact that it does not require a transmission between the electric motor 122 and the drive wheel 120. The drive wheel 120 is then driven in rotation directly by the electric motor 120 about an axis of rotation AL

[0033] Alternatively, the electric motor 122 is on a shaft driven by the drive wheel 120. Separating the electric motor 122 from the drive wheel 120 has the advantage of allowing the electric motor 122 to drive several drive wheels via the drive shaft.

[0034] The vehicle 1 also includes an overspeed detection device 2 of the drive wheel 120. The overspeed detection device 2 is configured to detect when the vehicle 1 is exceeding its speed within its travel range. To this end, the overspeed detection device 2 includes a first overspeed sensor 20 located at the drive wheel 120. More specifically, the first overspeed sensor 20 comprises a fixed element 20' positioned within the drive wheel 120, or near its axis of rotation A1, and one or more movable elements 20" positioned along a radial end of the movable wheel 120 relative to the axis of rotation A1. The fixed element 20' is positioned so as to be stationary within the drive wheel 120 and provides a reference measurement for the rotation of the drive wheel 120. Alternatively, the movable element 20" is randomly fixed against the drive wheel 120.

[0035] More specifically, when the moving element 20' undergoes a complete rotation relative to the fixed element 20', resulting in a complete rotation of the drive wheel 120 about itself, the overspeed sensor 20 detects this complete rotation by switching from an incomplete state to a complete state. The incomplete state of the overspeed sensor 20 therefore indicates an incomplete rotation of the drive wheel 120 and the moving element 20', while the complete state indicates a complete rotation, i.e., 360°, of the drive wheel 120 and the moving element 20'. Following a switch to the full state, the first overspeed sensor 20 switches back to the incomplete state until it detects a new full rotation of the drive wheel 120. The first overspeed sensor 20 is then configured to measure a rotational speed of the drive wheel 120.The fixed element 20' of the first overspeed sensor 20 is positioned relative to a defined reference frame, for example, near the end of the drive wheel 120 at a known angle. Therefore, the overspeed sensor 20 can measure the angle of rotation of the drive wheel 120 during its rotation, or the angle of rotation of the moving element 20" relative to the fixed element 20' of the overspeed sensor 20. Alternatively, the reference frame can be any point, such as the point of contact between the drive wheel 120 and the interface on which the drive wheel 120 moves.

[0036] The fixed element 20' and the moving element(s) 20" are preferably arranged so as to be close to each other in order to improve the detection of the first overspeed sensor. And, according to an ideal embodiment, the moving element(s) 20" are arranged as close as possible to the fixed element 20' without the fixed element 20' being in contact with the moving element(s) 20". By way of example, the fixed element 20' is less than 15 millimeters from the moving element(s).

[0037] Therefore, it is also possible to know precisely the number of complete rotations that the drive wheel 120 has made and, knowing the duration during As the drive wheel 120 is in motion, the overspeed sensor 20 can also measure the rotational speed of the drive wheel 120 in real time. The overspeed sensor 20 therefore acts as an angular position sensor of the moving element 20' relative to the fixed element 20' and relative to the defined reference frame, and as a rotational speed sensor by measuring the frequency of the overspeed sensor 20 switching from its incomplete to its complete state.

[0038] The overspeed detection device 2 also includes a speed reference device 22 configured to establish a maximum rotational speed for the drive wheel 120. The speed reference device 22 ensures the function of preventing the rotation of the drive wheel 120 and allows the material and functional limits of the drive wheel 120 to be defined when it is in motion. To this end, the speed reference device 22 includes a lidar sensor 220 configured to determine the environment near the drive wheel 120. The lidar sensor 220 is fixed to the chassis 10 so as to be able to emit a light wave continuously in a predefined direction.Advantageously, the lidar sensor 220 emits a light wave in the direction of movement of vehicle 1 so as to enable the lidar sensor 220 to detect sufficiently quickly any obstacle in front of vehicle 1 that could cause an accident.

[0039] Advantageously, the speed reference device 22 can include several lidar sensors 220 oriented in different directions so as to be able to perform a more complete mapping of the environment near the vehicle 1.

[0040] Indeed, the immediate environment of vehicle 1 is defined as the area near vehicle 1 subjected to the light waves of the lidar sensor 220. The immediate environment is therefore an area close to and accessible to vehicle 1 included in the area of ​​movement of the vehicle and mapped by the lidar sensor 220.

[0041] The immediate environment can also be interpreted as the critical zone of vehicle 1 in which vehicle 1 may encounter an obstacle during its movement, an obstacle identifiable by the lidar sensor 220. The concept of proximity can also be interpreted as a distance between an object identified by the lidar sensor 220 and vehicle 1 that is small enough to risk a collision. The immediate environment depends, in particular, on the rotational speed of the drive wheel 120.

[0042] Therefore, in order to prevent any unwanted collision between the vehicle 1 and a potential obstacle, the speed reference device 22 makes it possible to establish a maximum rotation speed of the drive wheel 120 in order to limit the speed of movement of the vehicle when the environment near the vehicle 1 identified by the lidar sensor 220 presents obstacles likely to induce collisions.

[0043] The maximum rotational speed of the drive wheel 120 is then a calculated speed by the speed reference device 22 as a function of the immediate environment, a predefined functional speed threshold and a direction of wheel rotation. More specifically, the functional speed threshold defines the maximum speed at which vehicle 1 can functionally move and perform the function for which vehicle 1 was defined.

[0044] By way of illustrative example, when the lidar sensor 220 detects a potential obstacle in the immediate environment that could cause a collision with the vehicle, the speed reference device 22 establishes a lower maximum rotational speed of the drive wheel 120. The reference device can also establish a lower maximum rotational speed of the drive wheel 120 when the vehicle 1 is loaded and the operating speed threshold is lower.

[0045] The maximum rotational speed is an indicative speed. Indeed, the maximum rotational speed should be interpreted as the speed at which the drive wheel 120 must move in order to comply with the information related to its immediate environment and its operation. The maximum rotational speed of the drive wheel is therefore a speed reference that fluctuates in real time according to the parameters mentioned above.

[0046] The overspeed detection device 2 also includes a speed comparator 24 configured to compare the rotational speed of the drive wheel 120 and the maximum rotational speed of the drive wheel 120 established by the speed reference device 22. The speed comparator 24 is also configured to stop the rotation of the drive wheel 120 if the rotational speed of the drive wheel 120 is greater than the maximum rotational speed of the drive wheel 120 established by the speed reference device 22.

[0047] Thus, when the rotational speed of the drive wheel 120 exceeds the maximum rotational speed established by the speed reference device 22, the vehicle 1 is moving too fast relative to its immediate surroundings, and there is a significant risk of a collision between an obstacle, whether identified by the lidar sensor 220 or not, and the vehicle 1. The speed comparator 24 then acts on the electric motor 122 to brake the electric motor 122 and the drive wheel 120. Advantageously, the speed comparator 24 can also act on the electric motor 122 to stop the drive wheel 120. The speed comparator 24 thus acts as a safety measure against a potential overspeed situation of the drive wheel 120 and the vehicle 1 by stopping the rotation of the drive wheel 120.

[0048] In order to more easily measure the rotation of the drive wheel 120 and the rotational speed of the drive wheel 120, the first overspeed sensor 20 may include a signal converter 200, as shown in [Fig. 2], configured to convert a flip frequency of the first overspeed sensor 20 into a binary signal or an analog signal. As a preferred example, the signal converter 200 is configured to convert the switching frequency of the first overspeed sensor 20 into an analog voltage. As mentioned previously, when the moving element 20” undergoes a complete rotation relative to the fixed element 20', resulting in a complete rotation of the drive wheel 120, the overspeed sensor 20 detects this complete rotation by switching from an incomplete state to a complete state. Following the switch to the complete state, the first overspeed sensor 20 switches back to the incomplete state until it detects another complete rotation of the drive wheel 120. To facilitate the detection of this switch indicating a complete rotation of the drive wheel 120, it can therefore be considered to convert this switch into an analog signal.The conversion according to the analog signal thus makes it possible to highlight a frequency of occurrence of the flip of the overspeed sensor 20 and therefore a measurement of the rotational speed of the drive wheel 120. As an indicative example, the signal converter 200 can generate an electrical signal between 0 volt and 5 volts in order to measure the rotational speed of the drive wheel 120.

[0049] Alternatively, the overspeed sensor 20 can also be configured to measure a rotation angle between the moving element 20” and the fixed element 20'. Indeed, when the rotational speed of the drive wheel 120 is low, the switching frequency of the overspeed sensor 20 is also low, making it difficult to measure this rotational speed. Knowing this rotational angle then allows the rotational speed of the drive wheel 120 to be measured without detecting a complete rotation of the drive wheel 120. The signal converter 200 can also allow this rotational angle to be measured via a square wave signal, for example, or any other periodic signal with a frequency proportional to the rotational speed of the electric motor 120.

[0050] In other words, the first overspeed sensor 20 allows a complete rotation or rotation angle of the drive wheel 120 to be measured and the rotation speed of the drive wheel 120 via the switching frequency of the first overspeed sensor 20 between the incomplete and complete state.

[0051] The lidar sensor 220 is thus configured to identify or digitally represent the environment near the vehicle 1 by means of a first map 222. The lidar sensor 220 makes it possible, by this first map 222, to scan the environment near and to know where the objects are in its field of vision and at what distance from the vehicle 1.

[0052] It may also be envisaged to program, in the lidar sensor 220 via a second programming input 224, an attention zone for vehicle 1 in the first map 222. Programming this attention zone allows a user to define, within the movement area of ​​vehicle 1, zones in in which vehicle 1 must not move or must move at restricted speeds. These attention zones can thus be interpreted as critical zones where a collision is highly likely.

[0053] It is thus possible to obtain a first more precise mapping combining the scan of the lidar sensor 220 and the programming of the attention zones by means of the second programming input 224 of the lidar sensor 220. The programming of the attention zone(s) can also be done before a movement of the vehicle 1 or during the movement of the vehicle 1 in its movement zone.

[0054] It may also be envisaged to replace the lidar 220 sensor with another optical or proximity sensor such as a sonar, a ToF sensor or even a camera.

[0055] Thus, from the first map 222, completed or not by the second programming input 224, the speed reference device 22 establishes the maximum rotational speed of the drive wheel 120. As stated previously, the speed reference device can also take into consideration other input parameters such as the material limits of the vehicle 1.

[0056] Advantageously, the overspeed detection device 2 may include a second overspeed sensor 26, as shown in [Fig. 3], fixed to the drive wheel 120 and disposed at a predefined angle relative to the first overspeed sensor 20. Similar to the first overspeed sensor 20, the second overspeed sensor 26 includes a fixed element 26' of the second overspeed sensor positioned near the axis of rotation Al of the drive wheel 120 and a movable element 26" of the second overspeed sensor 26 positioned at a radial end of the movable wheel 120 relative to the axis of rotation Al, the movable element 26" being disposed at a predefined angle relative to the movable element 20" of the first overspeed sensor 20. The second overspeed sensor 26 is configured to measure a rotational speed of the wheel.In other words, the second overspeed sensor 26 allows for the measurement of a complete rotation or a rotation angle of the drive wheel 120 and the rotational speed of the drive wheel 120 via a switching frequency of the second overspeed sensor 26 between the incomplete and complete state.

[0057] The use of a second overspeed sensor 26 thus has the advantage of obtaining data related to the rotation of the drive wheel 120, providing redundancy with respect to the data measured by the first overspeed sensor 20. The second overspeed sensor 26 also has the advantage of allowing the wheel's rotational speed to be measured without requiring a complete rotation of the drive wheel 120.

[0058] Indeed, vehicle 1 generally moves at relatively low speeds, less than three kilometers per hour. Therefore, the time required to obtain a Obtaining the first quantifiable measurement of the rotational speed of the drive wheel 120 can generally require a relatively long delay. However, during this measurement period, the environment surrounding the vehicle 1 can easily change, and an obstacle in the immediate vicinity may appear in front of the vehicle, transforming a normal operating condition of the vehicle 1 into a potentially dangerous collision situation. Using a second overspeed sensor 26 at a predefined angle relative to the first overspeed sensor 20 thus limits the time required to measure the rotation of the drive wheel 120 and its rotational speed, since this measurement is obtained when the angle between the first overspeed sensor 20 and the second overspeed sensor 26 is complete.

[0059] In order to allow the most accurate possible measurement of the rotational speed of the drive wheel 120, the overspeed detection device 2 may include a third overspeed sensor 28 also fixed to the drive wheel 120 and arranged at a predefined angle with respect to the first overspeed sensor 20 and with respect to the second overspeed sensor 26.Similar to the first overspeed sensor 20 and the second overspeed sensor 26, the third overspeed sensor 28 comprises a fixed element 28' of the third overspeed sensor 28 positioned near the axis of rotation Al of the drive wheel 120 and a moving element 28" of the third overspeed sensor 28 positioned along a radial end of the moving wheel 120 relative to the axis of rotation Al, the moving element 28" of the third overspeed sensor 28 being arranged at a predefined angle relative to the moving element 20'' of the first overspeed sensor 20 and relative to the moving element 26" of the second overspeed sensor 26. The third overspeed sensor is also configured to measure a rotational speed of the drive wheel 120.In other words, the third overspeed sensor 28 allows measurement of a complete rotation or a rotation angle of the drive wheel 120 and the rotational speed of the drive wheel 120 via a switching frequency of the third overspeed sensor 28 between the incomplete and complete state.

[0060] The use of three overspeed sensors 20, 26 and 28 thus has the advantage of allowing a uniform angular distribution in the drive wheel 120 without cluttering the motor-wheel assembly 12. In addition, if one of the overspeed sensors among the first overspeed sensor 20, the second overspeed sensor 26 or the third overspeed sensor 28 does not function correctly, the overspeed detection device 2 is not affected in its measurement of the rotational speed of the drive wheel 120. The multiplication of overspeed sensors also makes it possible to meet a redundancy requirement in terms of safety.

[0061] According to a preferred embodiment, it may be envisaged that the first overspeed sensor 20, the second overspeed sensor 26 and the third overspeed sensor 28 share a single fixed element, namely, for example, the fixed element 20' of the first overspeed sensor 20, and each comprises a predetermined number of moving elements, so that the overspeed detection device 2 comprises a predetermined sum of moving elements distributed uniformly over the drive wheel 120. As an illustrative example, each overspeed sensor may comprise ten moving elements, so that the overspeed detection device 2 comprises thirty moving elements distributed uniformly over the drive wheel 120.

[0062] In an ideal variant, a single overspeed sensor, for example the first overspeed sensor 20, may be the only overspeed sensor included in the overspeed detection device 2 and the first overspeed sensor may comprise thirty moving elements distributed over the drive wheel 120 as shown in [Fig.5].

[0063] Therefore, the signal converter 200, which must process slow signals, is thus able to transcribe, into an analog signal, a predefined number, namely, in our example, thirty, of toggles between the complete state and the incomplete state during a complete rotation of the drive wheel. Indeed, the first overspeed sensor 20 changes state between the incomplete state and the complete state every twelve degrees.

[0064] Increasing the number of moving elements 20'', and therefore the number of times the first overspeed sensor 20 switches between the incomplete and complete states, has the advantage of improving the response of the overspeed detection device, as previously stated. Indeed, since the drive wheel rotates at a relatively low speed and no reduction gear is installed between the electric motor 122 and the drive wheel 120, the switches between the complete and incomplete states of the first overspeed sensor occur, thanks to the use of thirty moving elements, at a frequency of 7.8 Hz at, for example, one kilometer per hour, and therefore with a period of 128 milliseconds. However, the overspeed detection device needs a fast reaction time, i.e., less than 300 milliseconds, which is advantageously achieved when the first overspeed sensor 20 comprises thirty moving elements 20''.

[0065] It may also be considered to add a filter 240 in the first overspeed sensor 20 at the output of the signal converter 200. The filter 240 is arranged between the signal converter 200 and the speed comparator 24. The filter at the output of the signal converter 200 must be sized to be able to produce a voltage smooth enough for the speed comparator 24 to perform a comparison while impacting as little as possible the time related to the provision of the speed measurement of the drive wheel 120 and the comparison between the measurement of the rotational speed of the drive wheel 120 and the maximum permissible rotational speed of the drive wheel 120.

[0066] According to a preferred configuration, the 240 filter is a third-order filter.

[0067] By way of example, filter 240 can be a first-order RC low-pass filter, consisting of a resistor and a capacitor, cascaded with an active Sallen-Key filter. Alternatively, the Sallen-Key filter can be replaced by two first-order RC low-pass filters or by a second-order LC passive filter, consisting of an inductor and a capacitor, for example.

[0068] The overspeed detection device 2 may also include a generalized malfunction detector 29 of the first overspeed sensor 20, the second overspeed sensor 26 and the third overspeed sensor 28, as shown in [Fig.4], intended to detect a simultaneous malfunction of the first overspeed sensor 20 and the second overspeed sensor 26 or of the second overspeed sensor 26 and the third overspeed sensor 28 or of the first overspeed sensor 20 and the third overspeed sensor 28 or even of the first overspeed sensor 20, the second overspeed sensor 26 and the third overspeed sensor 28.

[0069] Thus, when the generalized malfunction detector 29 detects that two overspeed sensors are not functioning correctly, then the generalized malfunction detector informs the user of a degraded operation of the overspeed detection device 2. And when the generalized malfunction detector 29 detects that the three overspeed sensors 20, 26 and 28 are not functioning correctly, then the generalized malfunction detector informs the user of a malfunction of the overspeed detection device 2.

[0070]

[0071] Furthermore, the first overspeed sensor 20, the second overspeed sensor 26 and / or the third overspeed sensor 28 can be Hall effect sensors. These sensors have a simple architecture and are very easily incorporated into the wheel motor assembly 12.

[0072] By way of illustrative example, since each overspeed sensor outputs a binary signal, the generalized malfunction detector 29 can simultaneously detect the state of each overspeed sensor, including the first overspeed sensor 20, the second overspeed sensor 26, and the third overspeed sensor 28. When the first overspeed sensor 20, the second overspeed sensor 26, and the third overspeed sensor 28 simultaneously display the same state, the generalized malfunction detector informs the user of a malfunction in the overspeed detection device 2. The generalized malfunction detector 29 thus prevents a common-cause failure that leads to the loss of the entire overspeed monitoring function of the vehicle 1. More specifically, according to a configuration with Three Hall effect overspeed sensors 20, 26, and 28 are used. The signals from the first, second, and third Hall effect overspeed sensors are phase-shifted to determine the approximate angular position of the electric motor 122. Each Hall effect overspeed sensor (the first, second, and third) can output a binary signal, resulting in eight possible combinations. However, only six signal combinations are possible for a desired arrangement of the first, second, and third Hall effect overspeed sensors. Therefore, the generalized fault detector 29 determines whether one of the two "impossible" combinations is obtained, indicating a fault in one of the overspeed sensors: the first overspeed sensor 20, the second overspeed sensor 26, or the third overspeed sensor 28.

[0073] Alternatively, the first overspeed sensor 20, the second overspeed sensor 26 and / or the third overspeed sensor 28 can be rotary sensors or optical sensors.

[0074] Advantageously, the invention operates for an electric motor 10 commonly referred to in the Anglo-Saxon literature as an "in-wheel" motor, that is, a motor directly connected to a drive wheel itself driven by the electric motor 122. However, it can easily be envisioned by those skilled in the art to add an intermediate component to, for example, modify the force and / or torque generated by the electric motor, such as a gearbox. A vehicle 1 comprising this type of motor-wheel assembly 12 and overspeed detection device 2 can be an autonomous vehicle, such as a robot or an autonomous delivery robot, or a remotely controlled vehicle, such as a controlled delivery robot.

[0075] The invention thus has the advantage of allowing the detection of overspeed by the autonomous mobile vehicle during its movement in its movement zone according to its immediate environment by the coupled use of a sensor positioned directly in the drive wheel and a lidar type sensor allowing the vehicle 1 to be stopped when the situation seems critical.

Claims

Demands

1. A vehicle (1) configured to move within a travel zone, the vehicle comprising a chassis (10) and a wheel motor assembly (12) comprising at least one drive wheel (120) and an electric motor (122) rotating the drive wheel (120), the vehicle (1) comprising an overspeed detection device (2) for the drive wheel (120), the overspeed detection device (2) comprising a first overspeed sensor (20), the first overspeed sensor (20) being configured to measure a rotational speed of the drive wheel (120), the overspeed detection device (2) comprising a speed reference device (22) configured to establish a maximum rotational speed of the drive wheel (120), the speed reference device (22) comprising an optical sensor (220) configured to determine an environment near the drive wheel (120), the optical sensor (220) being disposed against the chassis (10),the maximum rotational speed being at least a function of the immediate environment, a predefined functional speed threshold and a direction of rotation of the drive wheel (120), the overspeed detection device (2) comprising a speed comparator (24) between the rotational speed of the drive wheel (120) and the maximum rotational speed of the drive wheel (120), the speed comparator (24) being configured to stop the rotation of the drive wheel (120) if the rotational speed of the drive wheel (120) is greater than the maximum rotational speed of the drive wheel (120), the first overspeed sensor (20) comprising a fixed element (20') positioned in the drive wheel (120) and at least one movable element (20”) positioned along a radial end of the movable wheel (120) with respect to an axis of rotation (A1) of the movable wheel (120).

2. Vehicle (1) according to claim 1, wherein the first overspeed sensor (20) includes a signal converter (200) configured to convert a flip frequency of the first overspeed sensor (20) into an analog voltage.

3. Vehicle (1) according to claim 2, wherein the first overspeed sensor (20) includes a filter (240) disposed between the signal converter (200) and the speed comparator (24).

4. Vehicle according to any one of claims 1 to 3, wherein the optical sensor (220) is a lidar sensor.

5. Vehicle (1) according to claim 4, lidar sensor (220) being configured to generate a first map (222) of the near environment, lidar sensor (220) comprising a second programming input (224) configured to program an attention zone of the vehicle (1) in the travel zone.

6. Vehicle (1) according to any one of claims 1 to 5, wherein the overspeed detection device (2) comprises a second overspeed sensor (26) and disposed at a predefined angle relative to the first overspeed sensor (20), the second overspeed sensor (26) being configured to measure a rotational speed of the drive wheel (120).

7. Vehicle (1) according to claim 6, wherein the first overspeed sensor (20) and the second overspeed sensor (26) are hall effect sensors or rotary sensors or optical sensors.

8. Vehicle (1) according to any one of the preceding claims, wherein the overspeed detection device (2) comprises a third overspeed sensor (28) and disposed at a predefined angle relative to the first overspeed sensor (20) and relative to the second overspeed sensor (26), the third overspeed sensor (28) being configured to measure a rotational speed of the drive wheel (120).

9. Vehicle (1) according to any one of the preceding claims, wherein the overspeed detection device (2) comprises a generalized malfunction detector (29) of the first overspeed sensor (20), the second overspeed sensor (26) and the third overspeed sensor (28), the generalized malfunction detector (29) being configured to detect a simultaneous malfunction of the first overspeed sensor (20) and the second overspeed sensor (26) or of the second overspeed sensor (26) and the third overspeed sensor (28) or of the first overspeed sensor (20) and the third overspeed sensor (28) or of the first overspeed sensor (20), the second overspeed sensor (26) and the third overspeed sensor (28).

10. Vehicle (1) according to any one of the preceding claims, wherein the electric motor (122) is incorporated in the drive wheel (120).

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