Lawn mower with safety feature and method relating thereto

Abstract

A lawnmower with safety features and a related method are disclosed. The lawnmower includes: a body; a cutting element coupled to the body; a motor configured to drive the cutting element; a sensor including an accelerometer configured to detect angular displacement of the lawnmower relative to a vertical axis and sway of the cutting element relative to a horizontal plane; and a processor configured to: compare the detected angular displacement with a tilt threshold; compare the detected sway with a sway threshold; and control the operating speed of the cutting element when the angular displacement exceeds the tilt threshold or when the sway exceeds the sway threshold.

Description

Technical Field

[0001] This invention relates to lawnmowers, and more particularly to lawnmowers having a processor configured to improve operational safety. Background Technology

[0002] Lawn mowers come in a wide variety of designs, including push mowers, ride-on mowers, automatic mowers, and combinations thereof. Typically, a lawn mower includes one or more cutting elements, such as one or more sharp blades, that trim the lawn to a desired height. Typically, the cutting elements rotate at high speeds to produce a clean cut.

[0003] Lawn mowers often tip over during use, especially when operated incorrectly or on steep surfaces. In such cases, the rotating cutting element can pose a direct danger to the operator.

[0004] Therefore, there is a need for a lawnmower with improved operational safety. Summary of the Invention

[0005] Aspects and advantages of the invention will be set forth in part in the description which follows, or may be obvious in the description, or may be learned by practice of the invention.

[0006] According to one aspect, this disclosure relates to a lawnmower comprising: a body; a cutting element coupled to the body; a motor configured to drive the cutting element; a sensor including an accelerometer configured to detect angular displacement of the lawnmower relative to a vertical axis and sway of the cutting element relative to a horizontal plane; and a processor. The processor is configured to compare the detected angular displacement with a tilt threshold; compare the detected sway with a sway threshold; and control the operating speed of the cutting element when the angular displacement exceeds the tilt threshold or when the sway exceeds the sway threshold.

[0007] According to another aspect, this disclosure relates to a lawnmower comprising: a sensor including an accelerometer configured to detect angular displacement of the lawnmower relative to a vertical axis and sway of at least a portion of the lawnmower, such as measured relative to a horizontal plane; and a processor configured to: compare the detected angular displacement with a tilt threshold; compare the detected sway with a sway threshold; and adjust the operational aspects of the lawnmower when the angular displacement exceeds the tilt threshold or when the sway exceeds the sway threshold.

[0008] According to yet another aspect, this disclosure relates to a method of operating a lawnmower. The method includes moving the lawnmower across a surface, wherein the cutting element of the lawnmower is rotating. The method further includes detecting angular displacement of the lawnmower relative to a vertical axis and sway of the cutting element relative to a horizontal plane using a MEM sensor. The method further includes processing the detected angular displacement and sway by: comparing the detected angular displacement with a tilt threshold; comparing the detected sway with a sway threshold; and controlling the operating speed of the cutting element when the angular displacement exceeds the tilt threshold or when the sway exceeds the sway threshold.

[0009] These and other features, aspects, and advantages of the invention will be better understood by referring to the following description and appended claims. The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. Attached Figure Description

[0010] The specification sets forth a complete and practicable disclosure of the invention with reference to the accompanying drawings, including the best mode for those skilled in the art.

[0011] Figure 1 Including a perspective view of a lawnmower according to an embodiment of this disclosure;

[0012] Figure 2 A schematic diagram of the logic device of a lawnmower according to embodiments of the present disclosure;

[0013] Figure 3 Including schematic diagrams of lawnmowers according to embodiments of this disclosure;

[0014] Figure 4 This includes fluctuations in angular displacement and sway detected by the logic device representing the lawnmower according to embodiments of this disclosure;

[0015] Figure 5 This includes methods of using a lawnmower according to embodiments of this disclosure. Detailed Implementation

[0016] Referring now to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Reference numerals are repeated throughout this specification and the drawings to denote the same or similar features or elements of the invention. Each example is intended to explain the invention and not to limit it. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to obtain another embodiment. Therefore, it is contemplated that the invention covers such modifications and variations within the scope of the appended claims and their equivalents.

[0017] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and do not necessarily indicate the order or importance of the components. As used herein, approximate terms such as “approximately” or “about” include values ​​greater than or less than ten percent of the stated value. When used in the context of angles or directions, these terms include values ​​greater than or less than ten degrees of the stated angle or direction. For example, “approximately perpendicular” includes directions within ten degrees perpendicular in any direction (e.g., clockwise or counterclockwise).

[0018] Referring now to the accompanying drawings, this disclosure generally relates to a lawnmower with safety-enabled features. Figure 1 A perspective view of an exemplary lawnmower 100 (hereinafter interchangeably referred to as a "lawnmower") according to embodiments described herein is shown. The lawnmower 100 includes a body 102 with a handle 104 attached. The body 102 may define a cutting element 118 (…). Figure 3 The cutting area 106 of the cutting element 118 is configured to cut grass or other ground cover plants. The cutting element 118 may include, for example, a fixed blade, a rotatable blade, and / or a wire.

[0019] The main body 102 can accommodate the motor 120. Figure 2 The motor is configured to drive the cutting element 118. In one embodiment, the motor 120 may be powered by an engine, such as a gasoline engine. In another embodiment, the motor 120 may be powered by a battery 108 or via an external electrical outlet.

[0020] In the illustrated embodiment, lawnmower 100 is a push-type lawnmower. The lawnmower 100 is operated by a user who stands behind handle 104 and pushes the lawnmower 100 over the underlying surface. In another embodiment, lawnmower 100 may include a push-assisted lawnmower, which includes, for example, one or more powered wheels 110 that assist in moving the lawnmower 100 over the underlying surface. The one or more powered wheels 110 may be powered by the same motor 120 (as previously described) and / or by one or more separate motors. In other embodiments, lawnmower 100 may include a ride-on or semi-ride-on lawnmower. In yet another embodiment, lawnmower 100 may include an autonomous or semi-autonomous lawnmower, i.e., a lawnmower configured to operate without activating operator input.

[0021] The lawnmower 100 may include a trimming bag 112 configured to receive trimmings discharged from the cutting area 106. The bag 112 can be removed from the body 102 to allow an operator to empty the bag when it is full. A sensor 114 can detect the presence of the bag 112. When the bag 112 is removed from the lawnmower 100, the sensor 114 can generate a signal to notify the processing element (e.g., a processor described later) that the bag 112 has been removed.

[0022] Reference Figure 2 The lawnmower 100 may further include a logic device 116 having one or more electronic components and / or a processor. The logic device 116 may be a printed circuit board assembly (PCBA) including various components such as resistors, integrated circuits, capacitors, transformers, etc. The logic device 116 may be electrically connected to the motor 120 and the motor controller switch 122. The motor controller switch 122 may be positioned along the handle 104 of the lawnmower 100 to allow the operator to selectively control the operation of at least one aspect of the lawnmower 100, such as the operation of the cutting element 118. In an embodiment, the logic device 116 may be arranged in series with the motor 120 and the motor controller switch 122. During operation, the logic device 116 may control the operational aspects of the lawnmower 100 in response to user input at the motor controller switch 122.

[0023] Logic device 116 may include tilt detection sensor 124 configured to detect operational aspects of lawnmower 100. For example, tilt detection sensor 124 may monitor angular displacement of lawnmower 100 relative to its vertical axis. The vertical axis may correspond to the axis of gravitational acceleration. Tilt detection sensor 124 may further detect sway of cutting element 118 relative to a horizontal (e.g., XY) plane, as described in more detail later.

[0024] The tilt detection sensor 124 may be a portion of the previously described PCBA, for example, soldered thereto, or part of a separately operating element in electronic communication with one or more processors of the logic device 116. In an embodiment, the tilt detection sensor 124 includes a microelectromechanical (MEMS) sensor. A MEM sensor may include one or more integrated circuits, accelerometers, capacitors, resistors, etc. In another embodiment, the tilt detection sensor 124 may include a piezoresistive and / or piezoelectric accelerometer. In an embodiment, the MEM sensor may have a diameter of less than 1 cm. 2 For example, less than 0.75cm 2 For example, less than 0.5cm 2 For example, less than 0.25cm 2 For example, less than 0.1cm 2 The size of the area.

[0025] Reference Figure 3 The tilt detection sensor 124 can be configured to detect the angular displacement α of the lawnmower 100 or a portion thereof (e.g., body 102) relative to the vertical axis 126. For example, as the lawnmower 100 moves along a surface, the changing tilt angle of the surface may cause the lawnmower 100 to tilt. When the lawnmower 100 tilts, the tilt detection sensor 124 can detect the angular displacement of the lawnmower 100 relative to the vertical axis 126.

[0026] In this embodiment, the tilt detection sensor 124 can detect angular displacement caused by the sensing force applied by gravity. When the lawnmower 100 is perfectly horizontal, such that the angular displacement α of the lawnmower 100 is 0°, the tilt detection sensor 124 can detect a gravitational acceleration of approximately 9.8 m / s². 2 More specifically, when horizontal, the detected gravitational acceleration is typically around 9.76 m / s². 2 With 9.83m / s 2 Within a certain range, depending on the geographical location. When the lawnmower 100 begins to tilt, the gravitational acceleration detected by the tilt detection sensor 124 can decrease. For example, when the lawnmower 100 tilts (e.g., measured relative to the vertical axis 126) by an angular displacement of approximately 45°, the detected gravitational acceleration can be approximately 6.93 m / s². 2 For example, it is approximately 0.707 times the gravitational acceleration when the lawnmower 100 is in an upright orientation.

[0027] Refer again Figure 2The logic device 116 may further include a processor 128 configured to analyze detected angular displacement of the lawnmower 100. The processor 128 may be part of, for example, soldered to, the previously described PCBA, or part of a separately operating element in electronic communication with the tilt detection sensor 124. The processor 128 may include one or more processing elements, including one or more logic elements 130 and a memory storage device 132. The memory storage device 132 may be programmable to receive a tilt threshold indicating the maximum specified operating angular displacement of the lawnmower 100 under safe operating conditions. The tilt threshold may indicate a preferred angular displacement at which any additional angular displacement may be considered dangerous. For example, in an embodiment, the tilt threshold may be approximately 45° (e.g., measured relative to the vertical axis 126). In a more specific embodiment, the tilt threshold may include an error tolerance, for example, an angular tolerance of ±15° for the tilt threshold. Including an error tolerance may be particularly suitable for low-resolution tilt detection sensors 124 and allows for manufacturing variances and tolerances regarding the mounting position and angle of the tilt detection sensor 124 in the factory.

[0028] The processor 128 can determine the angular displacement of the lawnmower 100 based on the force sensed by the tilt detection sensor 124. For example, the processor 128 can use trigonometric functions to determine the angular displacement of the lawnmower 100 in response to the force sensed by the tilt detection sensor 124.

[0029] Processor 128 can be configured to compare angular displacement detected by tilt detection sensor 124 with a tilt threshold. When the detected angular displacement exceeds the tilt threshold, processor 128 can generate a signal controlling operational aspects of lawnmower 100, such as the operating speed of cutting element 118. In a particular embodiment, processor 128 can reduce the speed of cutting element 118 when the tilt threshold is exceeded. In a more particular embodiment, processor 128 can terminate the rotation of cutting element 118 when the detected angular displacement exceeds the tilt threshold.

[0030] In an embodiment, processor 128 is configured to wait for a period of time after a detected angular displacement exceeds a tilt threshold before inducing an adjustment of the operational aspect of lawnmower 100, such as terminating the rotation of cutting element 118. This time period can be programmed into and stored in memory storage device 132, and can include a duration of at least 1 second, such as at least 2 seconds, at least 3 seconds, at least 4 seconds, or at least 5 seconds. Delaying the adjustment of the operational aspect, such as terminating the rotation of cutting element 118, can prevent undesirable shutdown of lawnmower 100 due to brief angular displacements typically unrelated to lawnmower tipping. For example, when rapidly changing the direction of the lawnmower, the operator can tilt the lawnmower 100 backward by using the handle. That is, when suddenly changing the direction of the lawnmower, the operator typically presses down the handle, causing the lawnmower to pivot on the rear wheel and allowing for easier change of direction. In such cases, shutting down the lawnmower 100 due to angular displacement exceeding the tilt threshold is less desirable. Therefore, the duration of the delay can be selected to reduce undesirable shutdowns. In some cases, processor 128 can be configured to learn about operational aspects (e.g., the pivot angle used by the operator to change position) and update values ​​(e.g., delay time), thus preventing unintended shutdown.

[0031] In this embodiment, processor 128 may be configured to filter noise from the detected angular displacement α. The noise may be associated with swaying on a horizontal plane. Swaying may be caused by one or more unbalanced blades of the cutting element 118, motor swaying, etc. Specifically, swaying may be caused by eccentric, unbalanced rotation of the cutting element 118. The swaying of the cutting element 118 can be detected by tilt detection sensor 124, taking the form of an angular displacement α of the lawnmower 100 relative to the vertical axis 126.

[0032] Reference Figure 4 The tilt detection sensor can detect the absolute angular displacement of the lawnmower 100, as shown by line 404. Absolute angular displacement can include tilting and swaying. The processor 128 can use an algorithm to determine and filter out swaying caused by swaying. The filtered swaying is generally represented by a sine wave 400, which is caused by the rotational momentum and swaying of the cutting element 118 circulating around its 360° axis at approximately uniform time intervals.

[0033] The approximately sine wave 400 can define a crest 402 and a trough 404 relative to the vertical axis 126. The crest 402 can generally relate to an angular displacement in a first direction, and the trough 404 can generally relate to an angular displacement in a second direction opposite to the first direction. The crest 402 can define a first amplitude α1, and the trough 404 can define a second amplitude α2. In an embodiment, the first amplitude and the second amplitude can be approximately equal to each other. The approximately sine wave 400 can be further defined as a time interval between balanced, i.e., non-angularly displaced orientations. A first time interval T1 can be defined when the approximately sine wave 400 is in a crest phase, and a second time interval T2 can be defined when the approximately sine wave 400 is in a trough phase. In an embodiment, the first time interval and the second time interval can be approximately equal to each other.

[0034] Processor 128 may be configured to filter out noise associated with swaying (e.g., manifested as a generally sinusoidal wave 400) from the detected angular displacement for the purpose of determining the angular displacement α of lawnmower 100, and to isolate swaying for determining the swaying of cutting element 118. For example, processor 128 may include logic configured to detect or infer the sinusoidal wave 400 and reduce swaying including that calculated from the angular displacement.

[0035] Subtracting the sine wave 400 from the detected absolute angular displacement of the lawnmower 100 (shown by line 404) is a simplified way to determine the actual angular displacement of the lawnmower 100 independently of the sway. The actual angular displacement is shown by line 406. In the exemplary embodiment shown, it is clear that the angular displacement of the lawnmower 100 increases independently of the sway over time. In the embodiment, the processor 128 can use the actual angular displacement of the lawnmower 100 when compared with a tilt threshold.

[0036] In an embodiment, processor 128 may be configured to further monitor sway detected in angular displacement (e.g., a generalized sine wave 400) and generate a signal when the amplitude of the generalized sine wave 400 exceeds a predetermined safety level. This may occur, for example, when one or more blades of cutting element 118 break; when something becomes stuck within cutting element 118; or when cutting element 118 deforms, resulting in an eccentric, oblique load condition. The resulting sway detected by tilt detection sensor 124 can terminate the rotation of cutting element 118 to prevent damage to lawnmower 100 or injury to the operator.

[0037] In this embodiment, the tilt detection sensor 124 is configured to detect the cutting element 118 relative to the horizontal plane. Figure 3 The swing (represented by line 134). As previously shown relative to... Figure 4The swing can be described as an approximate sine wave of 40°. The resulting swing can be compared by processor 128 with a swing threshold. The swing threshold can correspond to a predetermined swing safety threshold. When the swing exceeds the swing threshold, processor 128 can generate signals controlling aspects of the lawnmower 100's operation, such as the operating speed of the cutting element 118. In a particular embodiment, when the swing threshold is exceeded, processor 128 can reduce the speed of the cutting element 118. In a more particular embodiment, when the swing exceeds the swing threshold, processor 128 can terminate the rotation of the cutting element 118.

[0038] The swing threshold can be different from the tilt threshold. For example, the amplitude of the wave that is allowed to swing can be smaller than the amplitude set for the tilt threshold.

[0039] In one embodiment, similar to a tilt threshold, the processor 128 is configured to wait for a period of time after the sway exceeds the sway threshold before inducing an adjustment in the operation of the lawnmower 100, such as terminating the rotation of the cutting element 118. This period of time can be programmed into and stored in the memory storage device 132, and can include a duration of at least 1 second, such as at least 2 seconds, at least 3 seconds, at least 4 seconds, or at least 5 seconds.

[0040] In an embodiment, processor 128 may be configured to prevent lawnmower 100 from starting when sensor 124 detects an angular displacement greater than a preset value, such as a tilt threshold, or another determined value (e.g., a different tilt threshold from the tilt threshold). In this respect, lawnmower 100 can be stored in a vertical orientation without the risk of accidentally rotating cutting element 118. Processor 128 may be configured to delay starting cutting element 118 until lawnmower 100 remains horizontal for a period of time, such as at least 1 second, at least 2 seconds, at least 3 seconds, at least 4 seconds, or at least 5 seconds. This delay may be programmed into and stored in memory storage device 132.

[0041] As previously described, the lawnmower 100 may include a sensor 114 configured to detect the removal of a bag 112. In an embodiment, the sensor 114 may communicate the status of the bag 112 to a processor 128, which may abort operation of the cutting element 118 when the removal of the bag is detected.

[0042] In an embodiment, the lawnmower 100 may further include a temperature sensor configured to monitor the temperature of at least one component of the lawnmower 100, such as the PCBA. The temperature sensor may be configured to detect the temperature of at least one component and send a signal to logic device 116 to indicate the detected temperature. In an embodiment, processor 128 may use information from the temperature sensor to influence the operation of the lawnmower 100. For example, when the detected temperature exceeds a temperature threshold, processor 128 may shut down the lawnmower 100 or change its operating state. The temperature threshold may be stored in memory storage device 132.

[0043] In an embodiment, the lawnmower 100 may further include a safety switch (e.g., a safety shut-off switch 136) configured to provide a safety function, such as turning off the lawnmower 100 when the sensor 124 senses that the processor 128 determines that a tilt threshold has been exceeded. By way of example, the safety shut-off switch 136 may be arranged to communicate electrically with the battery and motor controller switch 122.

[0044] Figure 5 A method 500 using a lawnmower is illustrated. Method 500 includes a step 502 of moving the lawnmower across a surface, wherein the cutting element of the lawnmower is rotating. In one embodiment, step 502 can be performed by pushing the lawnmower. In other embodiments, step 502 can be performed by at least partially motorized wheels of the lawnmower. Method 500 further includes a step 504 of detecting angular displacement of the lawnmower relative to a vertical axis and oscillation of the cutting element relative to a horizontal plane using microelectromechanical sensors. Method 500 further includes a step 506 of processing the detected angular displacement and oscillation.

[0045] Method 500 may further include step 508 of comparing the detected angular displacement of step 506 with a tilt threshold. In step 510, when the angular displacement exceeds the tilt threshold, the processor may then control the operating speed of the cutting element. The method may also include step 512 of comparing the detected sway with a sway threshold. In step 514, when the sway exceeds the sway threshold, the processor may then control the operating speed of the cutting element.

[0046] The lawnmower described herein according to one or more embodiments may offer enhanced operational safety. Specifically, the lawnmower can be configured to slow down or stop the rotation of the cutting element when tilting is detected, thereby exposing the cutting element and potentially causing injury to the operator or other nearby persons.

[0047] This written description discloses the invention using examples, including optimal modes, and also enables those skilled in the art to practice the invention, including making and using any apparatus or system and performing any of the included methods. The scope of patentability of the invention is defined by the claims, but may include other examples that would occur to those skilled in the art. Such other examples are contemplated within the scope of the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A lawnmower, comprising: ontology; A cutting element, which is connected to the body; A motor configured to drive the cutting element; The sensor includes an accelerometer configured to detect the angular displacement of the lawnmower relative to its vertical axis and the sway of the cutting element relative to a horizontal plane. as well as The processor is configured as follows: The detected angular displacement is compared with the tilt threshold; The detected sway is compared with a sway threshold; and When the angular displacement exceeds the tilt threshold or when the oscillation exceeds the oscillation threshold, the operating speed of the cutting element is controlled. The processor is further configured to filter noise from the detected angular displacement, which is associated with the swaying.

2. The lawnmower as described in claim 1, wherein, The processor is further configured to terminate the rotation of the cutting element when the angular displacement exceeds the tilt threshold or the sway exceeds the sway threshold.

3. The lawnmower as described in claim 2, wherein, The processor is configured to wait for a period of time after the detected angular displacement exceeds the tilt threshold, and then terminate the rotation of the cutting element.

4. The lawnmower as described in claim 3, wherein, In order for the processor to terminate the rotation of the cutting element, the detected angular displacement must remain above the tilt threshold for the entire duration, wherein the duration is at least 2 seconds.

5. The lawnmower as described in claim 1, wherein, The tilt threshold is 45° ± 15° relative to the vertical axis.

6. The lawnmower as described in claim 1, wherein, The sensor includes a microelectromechanical (MEMS) sensor, which is arranged on the platform of the lawnmower body.

7. The lawnmower as described in claim 1, wherein, The processor is further configured to prevent the rotation of the cutting element from starting when the lawnmower stops and exceeds the tilt threshold.

8. The lawnmower as claimed in claim 1, wherein, The processor is further configured to control the operating speed of the cutting element when the bag sensor detects that the trimming bag of the lawnmower has been removed.

9. The lawnmower as claimed in claim 1, wherein, The processor is further configured to control the operating speed of the cutting element when a temperature sensor detects that the temperature of at least one component of the lawnmower exceeds a temperature threshold.

10. The lawnmower as claimed in claim 1, wherein, The processor is arranged in series between the motor and the motor controller switch, which is configured to be activated by the operator.

11. The lawnmower as claimed in claim 1, wherein, The processor is configured to terminate the rotation of the cutting element after a duration exceeding a detected threshold of at least 2 seconds.

12. A method of operating a lawnmower, the method comprising: The lawnmower is moved across the surface, wherein the cutting element of the lawnmower is rotating; The angular displacement of the lawnmower relative to the vertical axis and the sway of the cutting element relative to the horizontal plane are detected using microelectromechanical (MEM) sensors. The detected angular displacement and sway are processed through the following methods: The detected angular displacement is compared with the tilt threshold; The detected sway is compared with a sway threshold; as well as The operating speed of the cutting element is controlled when the angular displacement exceeds the tilt threshold or when the sway exceeds the sway threshold. And the noise filtered from the detected angular displacement, which is associated with the swaying.

13. The method of claim 12, wherein, Controlling the operating speed of the cutting element includes terminating the rotation of the cutting element after the detected angular displacement exceeds the tilt threshold or the detected sway exceeds the sway threshold for a period of time.

14. The method of claim 12, further comprising: The operating speed of the cutting element is controlled when the bag sensor detects that the trimming bag of the lawnmower has been removed; as well as The operating speed of the cutting element is controlled when the temperature sensor detects that the temperature of at least one component of the lawnmower exceeds a temperature threshold.

Images