Auxiliary steering system for lawn maintenance vehicle

Abstract

A lawn mower includes: a wheel; a motor operably coupled to drive the wheel; a user input configured to receive a steering control input from a user; and a controller configured to operate in a steering assist mode in which the controller: receives information from the user input, the information including a position of the user input; comparing the location of the user input with a gain pattern stored in a memory of the controller; determining a scale factor from the gain mode based on the comparison; generating a command instruction for controlling the speed of the motor based on the position of the user input and the determined scale factor; and transmitting the command instruction to the motor to affect the speed of the motor.

Description

Cross - Reference to Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 822,439, filed on January 3, 2024, the entire content of which is incorporated herein by reference. Technical Field

[0002] This disclosure generally relates to steerable turf maintenance vehicles, and more particularly to an auxiliary steering system for lawn mowers and other vehicles used for turf maintenance. Background Art

[0003] Turf maintenance is often performed by powered vehicles that travel on the ground and perform turf maintenance on or above the ground. For example, lawn mowers can include push mowers, riding mowers, and autonomous mowers, all of which travel on the underlying ground and cut the grass that emerges from the ground. Lawn mowers can be equipped with various attachments that allow for additional turf maintenance operations. For example, lawn mowers can be equipped with leaf collection systems, leaf blowing systems, edgers, spray and dispersion systems for spraying various substances on the lawn or nearby objects, etc.

[0004] The forces acting on a lawn mower can have undesirable effects. For example, when traversing a slope, a lawn mower will often tend to turn downhill due to the force of gravity acting on the lawn mower. Similarly, when traversing bumpy ground, one or more wheels of the lawn mower can be jostled and turned due to undulations in the ground. Both of these instances can cause the lawn mower to deviate from the desired path, such as input by a riding operator via one or more safety bars, joysticks, steering wheels, etc.

[0005] Accordingly, there is a need in the art for improved auxiliary steering systems. In particular, it would be advantageous to provide an auxiliary steering system that provides simple and efficient steering correction. Summary of the Invention

[0006] In accordance with this disclosure, various aspects and embodiments will be set forth in part in the following description.

[0007] According to one embodiment, a lawn mower is provided. The lawn mower includes: wheels; a motor operably coupled to drive the wheels; a user input configured to receive a steering control input from a user; and a controller configured to operate in a steering assist mode, in which the controller: receives information from the user input, the information including the position of the user input; compares the position of the user input with a gain pattern stored in the memory of the controller; determines a scale factor from the gain pattern based on the comparison; generates a command instruction for controlling the speed of the motor based on the position of the user input and the determined scale factor; and transmits the command instruction to the motor to affect the speed of the motor, wherein the gain pattern has a first scale factor associated with a first position of the user input and a second scale factor associated with a second position of the user input, and wherein the first scale factor is different from the second scale factor.

[0008] According to another embodiment, a steering assist system for a lawn mower is provided. The steering assist system includes: an inertial measurement unit (IMU); and a controller configured to operate in a steering assist mode, in which the controller: receives information from the user input, the information including the position of the user input; receives a measured angular velocity of the lawn mower from the IMU; calculates a deviation between the measured angular velocity and an expected angular velocity based on the position of the user input; compares the position of the user input with a gain pattern stored in the memory of the controller; determines a scale factor from the gain pattern based on the comparison; generates a command instruction for controlling the speed of the motor of the lawn mower based on the position of the user input, the determined scale factor, and the calculated deviation; and transmits the command instruction to the motor to affect the speed of the motor, wherein the gain pattern has a first scale factor associated with a first position of the user input and a second scale factor associated with a second position of the user input, and wherein the first scale factor is different from the second scale factor.

[0009] According to another embodiment, a non-transitory computer-readable medium storing instructions is provided, which when executed cause a method of adjusting the travel direction of a lawn mower using a steering assist system to be performed. The method includes: determining, by a controller of the lawn mower, an expected angular velocity of the lawn mower based on the position of a user input device configured to receive a steering input from a user; measuring, by an inertial measurement unit (IMU) of the lawn mower, an actual angular velocity of the lawn mower; calculating, by the controller, a deviation between the expected angular velocity and the actual angular velocity; comparing, by the controller, the position of the user input device with a gain pattern stored in a memory of the controller; determining, by the controller, a proportionality factor from the gain pattern based on the comparison, wherein the gain pattern has a first proportionality factor associated with a first position of the user input device and a second proportionality factor associated with a second position of the user input device, and wherein the first proportionality factor is different from the second proportionality factor; applying, by the controller, the determined proportionality factor to the calculated deviation; determining, by the controller, a command instruction based on the calculated deviation according to the applied determined proportionality factor; and transmitting the command instruction to a motor of the lawn mower to affect the speed of the motor.

[0010] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present technology and, together with the description, serve to explain the principles of the present technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following detailed description refers to the accompanying drawings in which:

[0012] Figure 1 is a perspective view of a lawn mower according to an embodiment of the present disclosure;

[0013] Figure 2 is a schematic diagram of a control system of a lawn mower according to an embodiment of the present disclosure;

[0014] Figure 3 is a graph including a gain pattern used by a control system of a lawn mower according to an embodiment of the present disclosure;

[0015] Figure 4 is a graph including a gain pattern used by a control system of a lawn mower according to an embodiment of the present disclosure;

[0016] Figure 5 is a graph including multiple gain patterns used by a control system of a lawn mower according to an embodiment of the present disclosure; and

[0017] Figure 6It is a schematic diagram of a gain pattern covering the ground where the lawn mower is located according to an embodiment of the present disclosure, as well as various paths and correction paths according to the implemented gain pattern. Detailed Description

[0018] Now, embodiments of the present invention will be described in detail. One or more examples of embodiments of the present invention are shown in the accompanying drawings. The term "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. In addition, each example is provided by way of explanation rather than limitation of the technology. In fact, it will be apparent to those skilled in the art that the technology can be modified and varied without departing from the scope or spirit of the claimed technology. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield yet another embodiment. Accordingly, it is intended that this disclosure cover such modifications and variations that fall within the scope of the appended claims and their equivalents. In the detailed description, numerical and alphabetical labels are used to refer to features in the drawings. The same or similar labels have been used in the drawings and the description to refer to the same or similar parts of the present disclosure.

[0019] As used herein, the terms "first", "second", and "third" can be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" include plural referents. Unless otherwise specified herein, the terms "coupled", "fixed", "attached to", etc. refer to both direct coupling, fixing, or attaching, and indirect coupling, fixing, or attaching through one or more intermediate components or features. As used herein, the term "comprises", "comprising", "includes", "including", or any other variation thereof is intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a series of features is not necessarily limited to those features, but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless there is a clear contrary indication, "or" means an inclusive "or" rather than an exclusive "or". For example, any of the following cases satisfies the condition A or B: A is true (or exists) while B is false (or does not exist), A is false (or does not exist) while B is true (or exists), and both A and B are true (or exist).

[0020] Approximate terms such as "about", "substantially", "generally", or "essentially" include values within ten percent (10%) greater than or less than the stated value. When used in the context of an angle or direction, such terms include angles or directions within ten degrees (10°) greater than or less than the stated angle or direction. For example, "substantially vertical" includes directions within ten degrees (10°) in any direction (e.g., clockwise or counterclockwise) of vertical.

[0021] Lawn mowers and other lawn maintenance tools (such as tractors, powered carts, skid steer loaders, etc.) can receive user input indicating a desired direction of travel and convert the received user input into a control signal for controlling a motor to achieve the desired direction of travel. For example, a lawn mower can include a left safety bar and a right safety bar. When a user (e.g., a rider) adjusts the safety bars relative to each other, the control system of the lawn mower can adjust the control signal to the motor to cause the lawn mower to turn.

[0022] A lawn mower can include a motion tracking element that detects and / or records information associated with the movement of the lawn mower, such as an inertial measurement unit (IMU). For example, the IMU can detect various forces applied to the lawn mower, including, for example, direction of movement, moving force, moving magnetic orientation, acceleration, and gyroscopic motion.

[0023] Generally, the lawn mowers, lawn maintenance tools, systems, and methods described herein can provide assisted steering control to achieve a smooth driving experience while also allowing precise manual steering control, particularly for quick and sharp turns. In an embodiment, a lawn mower can include a control system having a processor and a memory storing instructions that, when executed by the processor, cause the lawn mower to implement assisted steering control in which the rate of active steering adjustment (i.e., the amount of adjustment actively implemented by the control system to affect the steering output of the lawn mower) is affected. The rate of active steering adjustment can vary based on one or more parameters, such as the amount of steering input received from the user at a user input of the lawn mower, the speed of the lawn mower on the underlying ground, the motor speed (e.g., as measured in revolutions per minute (RPM)), etc.

[0024] In some embodiments, when the lawn mower (and more particularly, the control system of the lawn mower) is expected to travel in a straight line, for example in response to receiving a user input that minimally adjusts the direction of the lawn mower relative to a straight path, but the direction information received from, for example, an IMU indicates that the lawn mower is traveling on a non - straight path, the amount of active steering adjustment implemented by the control system may be relatively high. Conversely, when the lawn mower is expected to turn, for example in response to receiving a user input indicating a quick or sharp turn, the amount of active steering adjustment implemented by the control system may be relatively low. In this way, when the control system of the lawn mower is expected to travel in a straight or relatively straight path, the control system can reduce the bouncing and swaying of the lawn mower while also allowing the lawn mower to quickly and precisely respond to user inputs indicating relatively sharp turns.

[0025] The control system can include a look - up table or other instructions that include information associated with one or more gain modes. Each gain mode can correspond to a different handling feel of the lawn mower. For example, implementing a first example gain mode can result in relatively unaffected steering control (i.e., steering control similar to a one - to - one steering control mode where the lawn mower moves relative to the user input at a one - to - one ratio), while implementing a second example gain mode can result in a relatively large amount of corrective steering control. Implementing the second example gain mode can thus cause the control system of the lawn mower to provide a greater degree of corrective action.

[0026] In some embodiments, the lawn mower can operate using only a single gain mode. In other embodiments, the lawn mower can have a selector that allows a user (e.g., a rider) to switch between multiple different gain modes. In some instances, the lawn mower can remain in the selected operating state (i.e., maintain the selected gain mode) until the user switches to a different gain mode among the multiple gain modes. In other instances, the lawn mower can default to a preferred operating state (i.e., a specific gain mode) when a trigger event occurs. For example, the trigger event can include starting the lawn mower from a closed state or setting the lawn mower to a closed state. When the trigger event occurs, the lawn mower can assume the preferred operating state. In some instances, when the lawn mower is in use (e.g., when the lawn mower is actively moving), the user can adjust the operating state (i.e., the selected gain mode). In other instances, the user can adjust the operating state of the lawn mower only when the lawn mower is in a certain state, such as when the lawn mower is not actively moving.

[0027] When a lawn mower traverses the ground, several forces can act on the lawn mower simultaneously, all of which tend to cause the lawn mower to deviate from the desired path, as expected based on feedback received from a user input device. For example, when traversing a slope (such as a hill) in a direction perpendicular to the slope, gravity tends to cause the lawn mower to turn downhill. As a result, the operator typically must turn the lawn mower uphill to maintain a straight path across the slope. Similarly, when traversing rough or uneven terrain, the wheels of the lawn mower may be affected by the ground (e.g., turned), causing the lawn mower to turn. For example, if the lawn mower traverses a depression in the ground such that one or more wheels effectively traverse a slope perpendicular to the depression, the lawn mower may tend to turn in a direction relative to the expected direction of travel. Conversely, if the lawn mower traverses a ridge on the ground at an angle between 15° and 75°, the lawn mower may tend to turn in a direction relative to the expected direction of travel. The foregoing forces are merely examples of the types of forces that can act on the lawn mower. In some instances, the lawn mower may encounter multiple different forces simultaneously, which tend to cause the lawn mower to deviate from the desired path.

[0028] The control system can at least partially counteract the effects of the forces by applying corrective steering to the lawn mower to offset the effects of the forces on the direction of travel of the lawn mower. As described above, the relative amount (degree) of reaction applied by the control system to adjust the trajectory of the lawn mower can vary according to one or more parameters, such as the amount of steering input received from the user at the user input device. In the case where the amount of steering input received at the user input device is nominal (e.g., less than 2% of the possible (maximum) user input), the control system can apply the maximum amount of reaction to offset the effects of the forces. In the case where the amount of input received at the user input device is relatively large (e.g., greater than 10% of the possible (maximum) user input), the control system can apply a reduced amount of reaction to offset the effects of the forces. In this regard, although the forces act on the lawn mower, the lawn mower can follow a straight or substantially straight path while also allowing the user to quickly adjust the orientation of the lawn mower by providing steering input at the user input device without generating a reaction force that tends to prevent the adjustment.

[0029] Now referring to the accompanying drawings, Figure 1FIG. 0 shows a lawn mower 100 according to an exemplary embodiment. The depicted lawn mower 100 is a riding lawn mower, however, in other instances, the lawn mower 100 can be a push lawn mower, an autonomous lawn mower, or other types of powered lawn maintenance tools, such as tractors, powered carts, skid steer loaders, etc. The lawn mower 100 generally includes a frame 102 and a walking element for transporting the frame 102 over the underlying ground. In an embodiment, the walking element includes a plurality of wheels 104 that support the frame 102. The wheels 104 can include at least one powered (drive) wheel 104A. The wheels 104 can include at least one passive wheel 104B, such as a caster wheel. In an embodiment, the at least one powered wheel 104A includes a plurality of powered wheels 104A, such as a left powered wheel and a right powered wheel. Each of the powered wheels 104A is driven by a motor (not shown). In some embodiments, the motor can directly drive the powered wheel 104A. In other embodiments, a gearbox or other intermediate torque transmission element can be disposed between the motor and the powered wheel 104A. Steering of the lawn mower 100 can be performed by adjusting the speed of the motor associated with each powered wheel 104A. For example, the lawn mower 100 can turn left in response to the right powered wheel 104A being driven faster than the left powered wheel 104A. Conversely, the lawn mower 100 can turn right in response to the left powered wheel 104A being driven faster than the right powered wheel 104A. In some instances, the passive wheels 104B do not have independent steering control and rotate freely about a rotational axis 106. In other instances, the passive wheels 104B can be steered, for example, by a motor that drives the passive wheels 104B about the rotational axis 106.

[0030] The lawn mower 100 can further include a cutting deck 108 supported by the frame 102. The cutting deck 108 can house one or more cutting implements (not shown), such as blades, that are rotatably driven by a motor (not shown). The cutting deck 108 can include a discharge chute 110 for guiding debris from the cutting deck 108 during operation of the cutting implements. The cutting deck 108 can be coupled to the frame 102 by a suspension 112 that allows the cutting deck 108 to move relative to the frame 102.

[0031] The seat 114 is coupled to the frame 102 and provides a seating area for a user while the user operates the lawn mower 100. The seat 114 is located near one or more user inputs that allow the user to control the operation of the lawn mower 100. The depicted user inputs include a left safety bar 116 and a right safety bar 118. The left safety bar 116 and the right safety bar 118 are each rotatable about a pivot axis to allow the user to input steering commands to the lawn mower 100. The user can push and pull on the left safety bar 116 and the right safety bar 118, causing the safety bars 116 and 118 to displace about the pivot axis. The further forward the left safety bar 116 and the right safety bar 118 are pushed, the faster the lawn mower 100 travels. By pushing the right safety bar 118 further forward than the left safety bar 116, i.e., creating a relative displacement between the left safety bar 116 and the right safety bar 118, the control system of the lawn mower 100 can determine that the user wants the lawn mower 100 to turn in one direction (e.g., left). By pushing the left safety bar 116 further than the right safety bar 118, the control system can determine that the user wants the lawn mower 100 to turn in the opposite direction (e.g., right). The relative difference in the displacement between the left safety bar 116 and the right safety bar 118 can provide an input regarding how fast the user wants the lawn mower 100 to turn. When the user wants to turn quickly, the relative displacement between the left safety bar 116 and the right safety bar 118 is relatively large (i.e., one of the safety bars 116 or 118 is displaced significantly further than the other safety bar 116 or 118). When the user wants to turn relatively slowly, the relative displacement between the left safety bar 116 and the right safety bar 118 is smaller. In other embodiments, the (one or more) user inputs can include an accelerator, a steering wheel, a joystick, another steering implement, or any combination thereof.

[0032] Figure 2 A schematic illustration of a control system 120 is shown that is configured to control the travel of the lawn mower 100 based on inputs received at the left safety bar 116 and the right safety bar 118. Although the following description is made with respect to the left safety bar 116 and the right safety bar 118, it should be understood that the systems, techniques, and methods described herein can be implemented with other types of user inputs (including, for example, joysticks, steering wheels, etc.).

[0033] The control system 120 generally includes a first sensor 122 that detects the position of the left safety bar 116 and a second sensor 124 that detects the position of the right safety bar 118. By way of non-limiting example, the first sensor 122 and the second sensor 124 may each include a rotary encoder (e.g., an absolute encoder or a relative encoder) that senses the relative displacement of the left safety bar 116 or the right safety bar 118. The first sensor 122 and the second sensor 124 may each generate a signal indicative of the relative position of the left safety bar 116 and the right safety bar 118, respectively, and transmit the signal to the controller 125. In an embodiment that includes a single user input (or more particularly, a single steering input, such as a steering wheel), the first sensor 122 and the second sensor 124 may be replaced by a single sensor that detects the position of the single user input.

[0034] The controller 125 may include one or more processors 126. The (one or more) processors 126 may be any suitable processing device (e.g., control circuitry, processor core, microprocessor, application specific integrated circuit, field programmable gate array, controller, microcontroller, etc.) and may be one processor or multiple processors operably connected. The (one or more) processors 126 may be coupled to a memory 128. The memory 128 may include one or more non-transitory computer-readable storage media, such as RAM, ROM, EEPROM, EPROM, one or more memory devices, flash memory devices, etc., and combinations thereof. The memory 128 may store information accessible by the (one or more) processors 126. For example, the memory 128 (e.g., one or more non-transitory computer-readable storage media, memory devices) may include computer-readable instructions 130 executable by the (one or more) processors 126. The instructions 130 may be software, firmware, or both written in any suitable programming language, or may be implemented in firmware or hardware. Additionally or alternatively, the instructions 130 may be executed in logically and / or virtually separate threads on the (one or more) processors 126. For example, the memory 128 may store instructions 130 that, when executed by the (one or more) processors 126, cause the (one or more) processors 126 to perform operations such as any of the operations and functions described herein.

[0035] The controller 125 can communicate with one or more motor controllers, such as a first motor controller 132 that communicates with the first motor 134 and a second motor controller 136 that communicates with the second motor 138. The first motor 134 can be associated with the first drive wheel 104A of the lawn mower 100, and the second motor 138 can be associated with the second drive wheel 104A of the lawn mower 100. The first motor 134 and the second motor 138 can receive power from a power source of the lawn mower 100, such as an on-board battery (e.g., a rechargeable battery). The motor controllers 132 and 136 can modulate signals, such as current or voltage, supplied to the motors 134 and 138 in response to information received at the controller 125 from the first sensor 122 and the second sensor 124, for example, using proportional-integral-derivative (PID) control logic. By modulating the signals to the motors 134 and 138, the motor controllers 132 and 136 can control the direction of the lawn mower 100 and the speed at which the lawn mower 100 turns. It should be understood that the control system 120 can be other arrangements and configurations without departing from the scope of the present disclosure. For example, in some embodiments, one or both of the motor controllers 132 or 136 can be integrated into the controller 125. In other embodiments, the controller 125 can include separate controllers, each associated with a different one of the motor controllers 132 and 136. In some instances, the motor controllers 132 and 136 can have a hierarchical arrangement relative to each other, such that, for example, the first motor controller 132 is disposed upstream of the second motor controller 136 and provides instructions to the second motor controller 136.

[0036] In an embodiment, the control system 120 further includes a motion tracking element, such as an inertial measurement unit (IMU) 131. The IMU 131 can detect and / or record various forces applied to the lawn mower 100, including, for example, direction of movement, moving force, moving magnetic orientation, acceleration, and gyroscopic motion. In an embodiment, the IMU 131 can include a gyroscope arrangement that detects gyroscopic motion of the lawn mower 100 along three axes (e.g., the X-axis, the Y-axis, and the Z-axis). The IMU 131 can include an accelerometer that detects the rate of acceleration or deceleration along three axes (e.g., the X-axis, the Y-axis, and the Z-axis). In some embodiments, the IMU 131 can be part of the controller 125. For example, the IMU 131 can be integrated with a printed circuit board (PCB) of the controller 125. In some instances, the IMU 131 can include more than one IMU to improve accuracy and eliminate errors over time.

[0037] The IMU 131 can be communicatively coupled to the controller 125. The controller 125 can receive data from the IMU 131 and process the data when generating commands for operating the lawn mower 100. In an embodiment, the controller 125 can implement a modification to the commands for operating the lawn mower 100 in response to the processed data from the IMU 131.

[0038] In some instances, the IMU 131 can be calibrated prior to use. As a non-limiting example, calibration can be performed by moving the IMU 131 in a preset motion pattern, such as an “8-shaped” pattern. The IMU 131 can detect and record acceleration and gyroscopic motion while being exposed to this motion pattern to complete the calibration. As another example, the IMU 131 can be calibrated during startup of the lawn mower 100, as it is generally assumed that the lawn mower is stationary and on relatively level ground during startup. In some instances, calibration can occur once, such as when the lawn mower 100 is used for the first time. In other instances, calibration can occur repeatedly, such as during successive startup procedures. For example, when the lawn mower 100 starts up, the IMU 131 can automatically initiate calibration when power is received.

[0039] The control system 120 can control the movement of the lawn mower 100 on the underlying ground in response to user input (e.g., received at the left safety bar 116 and the right safety bar 118). For example, information associated with the positions of the left safety bar 116 and the right safety bar 118 detected by the first sensor 122 and the second sensor 124 can be transmitted to the controller 125, which can generate command instructions for the motor controllers 132 and 136 to operate the motors 134 and 138 accordingly. The motors 134 and 138 can drive the drive wheels 104A to implement a desired movement pattern (e.g., steering).

[0040] In some implementations, the control system 120 can adjust between different control schemes. For example, the lawn mower 100 can include a selector (e.g., a digital selector, a mechanical selector, an electrical selector, or any combination thereof) that allows the user to switch between different control schemes. In an embodiment, each control scheme can operate by employing a different gain protocol. As described below, different gain protocols can result in different performance characteristics of the lawn mower 100 as experienced by the user (e.g., the rider). For example, a first gain protocol can result in a one-to-one steering control of the lawn mower 100, while a second gain protocol can result in a variable steering control of the lawn mower 100.

[0041] In an embodiment, the control system 120 may implement steering of the lawn mower 100 using a one-to-one (1:1) steering control mode. When operating in the one-to-one steering control mode, the movement of the lawn mower 100, and more particularly the steering performance of the lawn mower 100, is proportional to the (multiple) inputs received at the user input members (e.g., the left safety bar 116 and the right safety bar 118). For example, when implementing one-to-one steering control, a 50% displacement of the left safety bar 116 produces approximately half the effect compared to a 100% displacement of the left safety bar 116. Similarly, a 10% displacement of the right safety bar 118 produces approximately one-tenth (1 / 10 th ) of the effect compared to a 100% displacement of the right safety bar 118. Thus, the steering performance is scaled on a one-to-one basis.

[0042] In other embodiments, the control system 120 may control the lawn mower 100 to operate using a variable steering control mode. Variable steering control may refer to a situation where the control system 120 implements control logic to variably control the movement of the lawn mower 100 in response to the (multiple) inputs received at the user input members (e.g., the left safety bar 116 and the right safety bar 118), rather than on a one-to-one basis. To implement variable steering control, the control system 120 may implement a gain mode to adjust the control instructions provided from the controller 125 to the motor controllers 132 and 136 based on the detected information received at the first sensor 122 and the second sensor 124.

[0043] The relative gain amount implemented by the control system 120 at any given time may be determined in response to the inputs received at the (multiple) user input members (e.g., the first safety bar 116 and the second safety bar 118) and the corresponding scale factor α provided by the gain mode based on the received inputs. Tables 1 and 2 provide example gain modes depicted graphically in Figure 3 and Figure 4 respectively. Input steering amount (%) Scaling factor (α) 1 2 2 2 13.5 1.25 25 0.5 50 0.5 Table 1 - First gain mode Input steering amount (%) Scaling factor (α) 1 2 2 2 13.5 0.8 25 0.5 50 0.5 Table 2 - Second gain mode

[0044] The gain patterns in Table 1 and Table 2 provide example scale factors α for adjusting the steering of the lawn mower 100 according to the example embodiments based on the amount of steering input received at the user input members (e.g., the left safety bar 116 and the right safety bar 118). The input amounts shown in Table 1 and Table 2 are measured as a percentage of the maximum possible steering ability of the lawn mower 100. For example, if the lawn mower 100 is capable of steering at a maximum rate of 90° per second, a 50% input causes the lawn mower 100 to steer at a rate of 45° per second. Similarly, if the lawn mower 100 is capable of performing a 180° turn in 2 seconds, a 50% input causes the lawn mower 100 to turn 180° in 4 seconds. It should be understood that in some embodiments, the maximum steering rate or steering ability of the lawn mower may be determined at least in part by the relative speed of the lawn mower. For example, the lawn mower may be capable of steering at a first steering rate (i.e., a first angular velocity) when the lawn mower is traveling at a first speed and at a second rate (i.e., a second angular velocity) when the lawn mower is traveling at a second speed, where the first steering rate and the second steering rate are different from each other. The scale factor α may be implemented considering the steering rate at the traveling speed. Thus, a certain steering input may be implemented differently when the lawn mower is traveling at the first speed compared to when the lawn mower is traveling at the second speed.

[0045] Figure 3 A graph showing the first gain pattern shown in Table 1 is presented, where the Y-axis corresponds to the value of the scale factor α and the X-axis corresponds to the amount of steering input (steering input) received at the user input member, i.e., the percentage of the total steering ability of the lawn mower 100. It should be understood that the amount of steering input shown on the X-axis is an absolute value and applies to steering in both the left and right directions. Referring to Table 1 and Figure 3 , when the steering input is between straight-ahead heading (i.e., 0% steering) and 2% steering input, the first gain pattern maintains a constant scale factor α of 2. Between 2% steering input and 25% steering input, the scale factor α linearly decreases from 2 to 0.5. Any steering input above 25% (e.g., 30%, 40%, 50%, etc.) results in a scale factor α of 0.5.

[0046] Figure 4 A graph showing the second gain pattern shown in Table 2 is presented, where the Y-axis corresponds to the scale factor α and the X-axis is the steering input, i.e., the percentage of the total steering ability of the lawn mower 100. It should be understood that the amount of steering input shown on the X-axis is an absolute value and applies to steering in both the left and right directions. Referring to Table 2 and Figure 4, when the steering input is between the straight-ahead heading (i.e., 0% steering) and a 2% steering input, the second variable gain protocol maintains a constant scale factor α of 2. Between a 2% steering input and a 25% steering input, the scale factor α exponentially decreases from 2 to 0.5. Any steering input above 25% (e.g., 30%, 40%, 50%, etc.) results in a scale factor α of 0.5.

[0047] It can be other types of gain patterns. For example, as Figure 5 shown, the gain pattern can include: a fixed scale factor α, as shown by line 140, where the scale factor α remains constant throughout the range of the steering input; an increasing gain, as shown by line 142, where the scale factor α increases as the steering input increases; and a decreasing gain, as shown by line 144, where the scale factor α decreases as the steering input decreases. In some instances, the gain pattern can include a single linear slope, such as shown by each of lines 140, 142, and 144. In other instances, the gain pattern can include linear segments (piecewise), such as Figure 3 shown in the gain pattern depicted, where the first segment 146 occurs between 0% and 2% of the steering input, the second segment 148 occurs between 2% and 25% of the steering input, and the third segment 150 occurs at steering inputs above 25%. In other instances, the gain pattern can include an arcuate (curved) segment, such as Figure 4 shown in the gain pattern of, where the segment 152 has an arcuate curve extending between 2% and 25% of the steering input. It should be noted that while Figure 3 , Figure 4 and Figure 5 the graphs depicted in use the steering input along the X-axis, in other instances, the X-axis can correspond to the speed of the mower measured on the ground below, the motor speed (e.g., measured in revolutions per minute (RPM)), or any other suitable parameter.

[0048] Compared to the expected one-to-one steering characteristic, the controller 125 uses the scale factor α to adjust the actual steering performance of the mower 100. Equation (1) shows an example method for implementing the scale factor α to adjust steering according to the stored gain pattern: ωcorrected = ωexpected + (α)(ωexpected - ωmeasured) (1)

[0049] where, ω 预期 is a measure of the angular velocity of the mower 100 expected to be detected by the IMU 131 based on user inputs (e.g., at the left safety bar 116 and the right safety bar 118), ω 测量 is the actual measured angular velocity of the mower 100 as detected by the IMU 131, α is the scale factor, and ω 校正is the corrected angular velocity which, when implemented, interprets the discrepancy between the measured angular velocity and the expected angular velocity of the lawn mower 100 based on the scale factor α.

[0050] The expected angular velocity (ω 预期 ) can be determined based on the feedback provided at the user input member. For example, in the case where the left safety bar 116 and the right safety bar 118 are positioned equally relative to each other (i.e., there is no relative displacement between the left safety bar 116 and the right safety bar 118), the controller 125 can determine that the expected angular velocity of the lawn mower 100 relative to the current heading should be equal to 0.0 radians per second (rad / s) (i.e., the lawn mower 100 is not turning). In the case where the IMU 131 measures an actual measured velocity different from the expected angular velocity of 0.0 rad / s (indicating that the lawn mower has experienced an angular displacement relative to the current heading), the controller 125 can adjust the control signals provided to the first motor controller 132 and the second motor controller 136 according to equation (1) and the active gain mode. Using the active gain mode may require querying a look-up table or other instructions including information associated with one or more gain modes to determine the appropriate scale factor α. Since the expected angular velocity of the lawn mower is nominal (0.0 rad / s), the scale factor may be relatively large. The adjusted control signals can cause the first motor controller 132 and the second motor controller 136 to control the motors 134 and 138 such that the lawn mower 100 maintains its current heading at an actual measured angular velocity of 0.0 rad / s. Effectively, the adjusted signals can cause the lawn mower 100 to turn in a manner that corrects for the unexpected deviation detected by the IMU 131.

[0051] By another example, in the case where the left safety bar 116 and the right safety bar 118 are displaced relative to each other such that the steering input is 50% of the steering ability of the lawn mower 100, the controller 125 can determine the expected angular velocity of the lawn mower 100, such as 0.75 rad / s. In the case where the IMU 131 measures an actual measured velocity different from the expected angular velocity of 0.75 rad / s (indicating that the angular displacement experienced by the lawn mower is different from the desired one), the controller 125 can adjust the control signals provided to the first motor controller 132 and the second motor controller 136 according to equation (1) and the active gain mode. Using the active gain mode may require querying a look-up table or other instructions including information associated with one or more gain modes to determine the appropriate scale factor α. Since the expected angular velocity of the lawn mower is relatively large (0.75 rad / s), the scale factor may be relatively small. Different from the first example where the expected angular velocity is 0.0 rad / s, here the expected angular velocity is 0.75 rad / s and the scale factor α is relatively small, and the adjusted signal may not cause the lawn mower 100 to significantly correct for the unexpected deviation detected by the IMU 131.

[0052] By applying a scale factor α to the steering control, the control system 120 can provide several improved behavioral characteristics that enhance the operating precision of the mower 100. Refer to Figure 6 , the mower 100 is depicted as being located on the underlying ground G, where an exemplary gain pattern is overlaid on the ground G to partition relative scale factors based on the current position of the mower 100 and potential steering parameters that can be received at user input members (e.g., left safety bar 116 and right safety bar 118). The depicted gain pattern is taken from Figure 3 and Table 1. When the mower 100 receives a user input indicating a steering input between 0% and 2% (i.e., steering within the first range 154), the mower 100 applies a first scale factor α corresponding to the scale factor depicted by segment 146 in Figure 3 and described as equal to 2.0 in Table 1. When the mower 100 receives a steering input between 2% and 25% (i.e., steering within the second range 156), the mower 100 applies a second scale factor α that is different from the first scale factor α. In an embodiment, the second scale factor α can correspond to the scale factor depicted by segment 148 in Figure 3 and described as between 0.5 and 2.0 in Table 1. When the mower 100 receives a steering input greater than 25% (i.e., steering within the third range 158), the mower 100 applies a third scale factor α that is different from the first and second scale factors α. In an embodiment, the third scale factor α can correspond to the scale factor α depicted by segment 150 in Figure 3 and described as equal to 0.5 in Table 1. Since the scale factor α corresponds to the amount of steering control implemented by the control system 120 (where a larger scale factor α results in greater control of steering by the steering assist system), it should be understood that when the user provides a steering input with a high scale factor α, such as when the user keeps the mower 100 within the first range 154, the correction input is higher than when the user provides a steering input while the mower 100 is steering within the second range 156 or the third range 158. In this regard, the mower 100 can provide a higher steering correction factor when the steering input is relatively minimal and a lower steering correction factor when the steering input is relatively large. Thus, the mower 100 can maintain its heading in a straight line regardless of bumpy and undulating terrain, sloping ground, and minor accidental steering control inputs. However, when the control system 120 recognizes that the user desires to change the direction of travel, the degree of correction control performed by the control system 120 is reduced, thereby allowing the user to change direction without having to overcome significant resistance generated by the assisted steering system.

[0053] Figure 6Shows three exemplary paths A, B, and C that a lawn mower 100 may follow in a one-to-one steering control implementation in response to three different steering inputs received at a user input member. Exemplary path A is within a first range 154, exemplary path B is within a second range 156, and exemplary path C is within a third range 158. Also depicted is the corrected path A C , B C , and C C to show the corrected paths that will be taken by the lawn mower 100 in response to the implementation of the assisted steering control function described herein. As depicted, the difference between A and A C is greater than the difference between B and B C (greater than the difference between C and C C ). This difference occurs because the control system 120 provides maximum correction control within the first range 154, reduced correction control within the second range 156, and further reduced correction control within the third range 158. Accordingly, the lawn mower 100 can provide a corrective steering override based on steering inputs received from the user at the left safety bar 116 and the right safety bar 118.

[0054] Although Figure 6 shows three different ranges 154, 156, and 158 with discrete crossover conditions where each range transitions to the next, it should be understood that in other embodiments, ranges 154, 156, and 158 may be combined together with a more gradual transition. For example, Figure 5 the gain pattern depicted by line 144 in Figure 3 results in a single range with a proportionality factor that linearly (constantly) decreases according to the amount of steering input received at the left safety bar 116 and the right left safety bar 118. This is substantially similar to the range depicted by segment 148 in Figure 3 , however, unlike segment 148 in

[0055] which is bounded by segments 146 and 150 with different proportionality factors, the gain pattern depicted by line 144 extends continuously from 0% steering input towards 100% steering input. In some instances, the gain pattern including a linearly (constantly) decreasing proportionality factor α may terminate with a segment having a constant proportionality factor α for the final range of steering input. For example, it may not be desirable for steering approaching 100% to have a proportionality factor α correction of 0 (zero). Thus, even the gain pattern depicted by line 144 may terminate with a proportionality factor α (e.g., 0.15).

[0056] Embodiment 1. A lawn mower, comprising: wheels; a motor operatively coupled to drive the wheels; a user input configured to receive a steering control input from a user; and a controller configured to operate in a steering assist mode, in which the controller: receives information from the user input, the information including the position of the user input; compares the position of the user input with a gain pattern stored in the memory of the controller; determines a scale factor from the gain pattern based on the comparison; generates a command instruction for controlling the speed of the motor based on the position of the user input and the determined scale factor; and transmits the command instruction to the motor to affect the speed of the motor, wherein the gain pattern has a first scale factor associated with a first position of the user input and a second scale factor associated with a second position of the user input, and wherein the first scale factor is different from the second scale factor.

[0057] Embodiment 2. The lawn mower according to any one or more of the embodiments, wherein the first position of the user input corresponds to a first steering input, wherein the second position of the user input corresponds to a second steering input, wherein the second steering input is greater than the first steering input, and wherein the scale factor at the second position of the user input is less than the scale factor at the first position of the user input.

[0058] Embodiment 3. The lawn mower according to any one or more of the embodiments, wherein the gain pattern includes a plurality of scale factors, each scale factor being associated with a different position of the user input.

[0059] Embodiment 4. The lawn mower according to any one or more of the embodiments, wherein generating a command instruction for controlling the speed of the motor includes: determining an expected angular velocity of the lawn mower based on the position of the user input; measuring the actual angular velocity of the lawn mower; calculating a deviation between the expected angular velocity and the actual angular velocity; applying the determined scale factor to the calculated deviation; and determining the command instruction based on the calculated deviation according to the applied determined scale factor.

[0060] Embodiment 5. The lawn mower according to any one or more of the embodiments, wherein measuring the actual angular velocity of the lawn mower is performed by an inertial measurement unit (IMU) disposed on the lawn mower and coupled to the controller.

[0061] Embodiment 6. The lawn mower according to any one or more of the embodiments, wherein the gain pattern can be selected from a plurality of different gain patterns stored in the memory of the controller.

[0062] Embodiment 7. The lawn mower according to any one or more of the embodiments, wherein the user input includes a safety bar, a steering wheel, a joystick, an accelerator, or any combination thereof.

[0063] Example 8. A lawn mower as described in any one or more of the embodiments, wherein the lawn mower further includes a motor controller that is arranged to be electrically connected between the controller and the motor, and wherein transmitting a command instruction to the motor includes: transmitting the command instruction from the controller to the motor controller and transmitting a command signal from the motor controller to the motor to affect the speed of the motor.

[0064] Example 9. A steering assist system for a lawn mower, the steering assist system including: an inertial measurement unit (IMU); and a controller configured to operate in a steering assist mode in which the controller: receives information from a user input member, the information including the position of the user input member; receives a measured angular velocity of the lawn mower from the IMU; calculates a deviation between the measured angular velocity and an expected angular velocity based on the position of the user input member; compares the position of the user input member with a gain mode stored in the memory of the controller; determines a scale factor from the gain mode based on the comparison; generates a command instruction for controlling the speed of the motor of the lawn mower based on the position of the user input member, the determined scale factor, and the calculated deviation; and transmits the command instruction to the motor to affect the speed of the motor, wherein the gain mode has a first scale factor associated with a first position of the user input member and a second scale factor associated with a second position of the user input member, and wherein the first scale factor is different from the second scale factor.

[0065] Example 10. A steering assist system as described in any one or more of the embodiments, wherein transmitting a command instruction to the motor includes: transmitting the command instruction from the controller to the motor controller and transmitting a command signal from the motor controller to the motor to affect the speed of the motor.

[0066] Example 11. A steering assist system as described in any one or more of the embodiments, wherein the first position of the user input member corresponds to a first steering input, wherein the second position of the user input member corresponds to a second steering input, wherein the second steering input is greater than the first steering input, and wherein the scale factor at the second position of the user input member is less than the scale factor at the first position of the user input member.

[0067] Example 12. A lawn mower as described in any one or more of the embodiments, wherein the gain mode includes a plurality of scale factors, each scale factor being associated with a different position of the user input member.

[0068] Example 13. A lawn mower as described in any one or more of the embodiments, wherein the gain mode can be selected from a plurality of different gain modes stored in the memory of the controller.

[0069] Example 14. A lawn mower as described in any one or more of the examples, wherein the user input member includes a left safety bar and a right safety bar, wherein the position of the left safety bar is detected by a first sensor, wherein the position of the right safety bar is detected by a second sensor, and wherein the first sensor and the second sensor communicate with a controller.

[0070] Example 15. A non-transitory computer-readable medium storing instructions that, when executed, cause a method for adjusting the travel direction of a lawn mower using a steering assist system to be performed. The method includes: determining, by a controller of the lawn mower, an expected angular velocity of the lawn mower based on the position of a user input member configured to receive a steering input from a user; measuring, by an inertial measurement unit (IMU) of the lawn mower, an actual angular velocity of the lawn mower; calculating, by the controller, a deviation between the expected angular velocity and the actual angular velocity; comparing, by the controller, the position of the user input member with a gain mode stored in a memory of the controller; determining, by the controller, a proportionality factor from the gain mode based on the comparison, wherein the gain mode has a first proportionality factor associated with a first position of the user input member and a second proportionality factor associated with a second position of the user input member, and wherein the first proportionality factor is different from the second proportionality factor; applying, by the controller, the determined proportionality factor to the calculated deviation; determining, by the controller, a command instruction based on the calculated deviation according to the applied determined proportionality factor; and transmitting the command instruction to a motor of the lawn mower to affect the speed of the motor.

[0071] Example 16. A non-transitory computer-readable medium as described in any one or more of the examples, wherein transmitting the command instruction to the motor includes: transmitting the command instruction from the controller to a motor controller and transmitting a command signal from the motor controller to the motor to affect the speed of the motor.

[0072] Example 17. A non-transitory computer-readable medium as described in any one or more of the examples, wherein the first position of the user input member corresponds to a first steering input, wherein the second position of the user input member corresponds to a second steering input, wherein the second steering input is greater than the first steering input, and wherein the proportionality factor at the second position of the user input member is less than the proportionality factor at the first position of the user input member.

[0073] Example 18. A non-transitory computer-readable medium as described in any one or more of the examples, wherein the gain mode includes a plurality of proportionality factors, each proportionality factor being associated with a different position of the user input member.

[0074] Example 19. A non-transitory computer-readable medium as described in any one or more of the examples, further comprising selecting, by a user, a gain mode from a plurality of gain modes stored in a memory.

[0075] Example 20. The non-transitory computer-readable medium as described in any one or more of the examples further includes enabling a steering assist system by a user.

[0076] The patentable scope of the present invention is defined by the claims and may include other examples conceivable to those skilled in the art. If these other examples include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not have a substantial difference from the literal language of the claims, then these other examples are intended to be included within the scope of the claims.

Claims

1. A lawn mower, comprising: Wheels; A motor operably coupled to drive the wheels; A user input configured to receive steering control input from a user; And A controller configured to operate in a steering assist mode, in which the controller: Receives information from the user input, the information including the position of the user input; Compares the position of the user input with a gain pattern stored in a memory of the controller; Determines a scale factor from the gain pattern based on the comparison; Generates a command instruction for controlling the speed of the motor based on the position of the user input and the determined scale factor; And Transmits the command instruction to the motor to affect the speed of the motor, Wherein the gain pattern has a first scale factor associated with a first position of the user input and a second scale factor associated with a second position of the user input, and wherein the first scale factor is different from the second scale factor.

2. The lawn mower according to claim 1, wherein, The first position of the user input corresponds to a first steering input, wherein the second position of the user input corresponds to a second steering input, wherein the second steering input is greater than the first steering input, and wherein the scale factor at the second position of the user input is less than the scale factor at the first position of the user input.

3. The lawn mower according to claim 1, wherein, The gain pattern includes a plurality of scale factors, each scale factor associated with a different position of the user input.

4. The lawn mower according to claim 1, wherein, Generating a command instruction for controlling the speed of the motor includes: Determining an expected angular velocity of the lawn mower based on the position of the user input; Measuring an actual angular velocity of the lawn mower; Calculating a deviation between the expected angular velocity and the actual angular velocity; Applying the determined scale factor to the calculated deviation; and Determining the command instruction based on the calculated deviation according to the applied determined scale factor.

5. The lawn mower according to claim 4, wherein, Measuring the actual angular velocity of the lawn mower is performed by an inertial measurement unit (IMU) disposed on the lawn mower and coupled to the controller.

6. The lawn mower according to claim 1, wherein, The gain pattern can be selected from a plurality of different gain patterns stored in a memory of the controller.

7. The lawn mower according to claim 1, wherein, The user input includes a safety bar, a steering wheel, a joystick, an accelerator, or any combination thereof.

8. The lawn mower according to claim 1, wherein, The lawn mower further includes a motor controller disposed to be electrically connected between the controller and the motor, and wherein transmitting the command instruction to the motor includes: Transmitting the command instruction from the controller to the motor controller, and Transmitting a command signal from the motor controller to the motor to affect the speed of the motor.

9. The lawn mower according to claim 1, wherein, Transmitting the command instruction to the motor includes transmitting the command instruction to the motor controller, and wherein the command instruction includes a command signal for affecting the speed of the motor.

10. A steering assist system for a lawn mower, the steering assist system comprising: An inertial measurement unit (IMU); And A controller configured to operate in a steering assist mode, in which the controller: Receives information from a user input, the information including the position of the user input; Receives the measured angular velocity of the lawn mower from the IMU; Calculates a deviation between the measured angular velocity and the expected angular velocity based on the position of the user input; Compares the position of the user input with a gain mode stored in the memory of the controller; Determines a proportionality factor from the gain mode based on the comparison; Generates a command instruction for controlling the speed of the motor of the lawn mower based on the position of the user input, the determined proportionality factor, and the calculated deviation; And Transmits the command instruction to the motor to affect the speed of the motor, Wherein the gain mode has a first proportionality factor associated with a first position of the user input and a second proportionality factor associated with a second position of the user input, and wherein the first proportionality factor is different from the second proportionality factor.

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