Obstacle avoidance system of mower
By using left and right ultrasonic sensors on the lawn mower to send ultrasonic signals of different frequencies and comparing the received reflected signals, the problem of the existing technology being difficult to detect objects close at a certain angle is solved, and accurate judgment and effective avoidance of the object path is achieved.
Patent Information
- Application Number
- CN202410624443.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-08-28
- Filing Date
- 2024-05-20
- Publication Date
- 2025-02-28
AI Technical Summary
The existing lawn mower obstacle avoidance system is difficult to effectively detect objects such as walls or columns that are approaching at a certain angle, resulting in the inability to accurately determine whether the object is on the path of the lawn mower.
The left ultrasonic sensor and the right ultrasonic sensor installed on the lawn mower are used to transmit the ultrasonic signals at the first frequency and the second frequency respectively, and the position and path of the object intersect by comparing the received reflected signals.
The ability to detect objects close to a certain angle is improved, and it can accurately determine whether the object is on the path of the lawn mower, thereby effectively avoiding obstacles and ensuring the normal operation of the lawn mower.
Smart Images
Figure CN119536242A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an obstacle avoidance system for a lawn mower, such as a robotic lawn mower and other lawn mowers having a guidance system. Background Art
[0002] Lawn mower obstacle avoidance systems can include torque sensing, accelerometers, collision detection, or ultrasonic sensors. Ultrasonic sensors can detect obstacles without contacting the object or obstacle by transmitting energy in the form of ultrasonic waves and then receiving the waves reflected from the object or obstacle back to the sensor.
[0003] However, ultrasonic sensors may not detect certain objects or obstacles, such as walls or posts that are positioned at an angle relative to the lawn mower, because the sound energy may be deflected from the angled object in other directions and not return to the ultrasonic sensor on the lawn mower. Ultrasonic sensors also receive signals reflected from objects or obstacles that do not block the lawn mower.
[0004] There is a need for a lawn mower obstacle avoidance system that can improve detection of an object or obstacle that the lawn mower is approaching at an angle. There is a need for a lawn mower obstacle avoidance system that can determine whether an object or obstacle is in the path of the lawn mower. Summary of the invention
[0005] The lawn mower obstacle avoidance system includes a left ultrasonic sensor and a right ultrasonic sensor mounted on the lawn mower. The left ultrasonic sensor transmits an ultrasonic signal at a first frequency and the right ultrasonic sensor transmits an ultrasonic signal at a second frequency. Each ultrasonic sensor receives ultrasonic signals reflected back at the first frequency and the second frequency. If an object is detected, the vehicle controller commands the traction drive system of the lawn mower to slow the lawn mower and, if the object is within the passing area of the lawn mower, to stop and turn based on a comparison of the reflected ultrasonic signals received by the first ultrasonic sensor and the second ultrasonic sensor. The system detects objects or obstacles positioned at an angle relative to the lawn mower and determines whether they are in the path of the lawn mower. BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Figure 1 2 is a top view of an obstacle avoidance system for a lawn mower according to a first embodiment of the present invention.
[0007] Figure 2 is a side view of an obstacle avoidance system for a lawn mower according to a first embodiment of the present invention.
[0008] Figure 3 is a logic diagram of an obstacle avoidance system for a lawn mower according to a first embodiment of the present invention.
[0009] Figure 4 is a schematic diagram of an obstacle avoidance system for a lawn mower according to a first embodiment of the present invention, wherein an ultrasonic signal is deflected by an object O1 at a first approach angle.
[0010] Figure 5 is a schematic diagram of the obstacle avoidance system for a lawn mower according to the first embodiment of the present invention, wherein the ultrasonic signal is deflected by the object O1 at a second approach angle.
[0011] Figure 6 is a schematic diagram of an obstacle avoidance system for a lawn mower according to a first embodiment of the present invention, wherein an ultrasonic signal is deflected by an object O2 at a first approach angle.
[0012] Figure 7 is a schematic diagram of the obstacle avoidance system for a lawn mower according to the first embodiment of the present invention, wherein the ultrasonic signal is deflected by the object O2 at a second approach angle.
[0013] Figure 8 is a schematic diagram of the obstacle avoidance system for a lawn mower according to the first embodiment of the present invention, wherein the ultrasonic signal is deflected by the object O2 at a third approach angle.
[0014] Fig. 9 is a schematic diagram of the obstacle avoidance system for a lawn mower according to the first embodiment of the present invention, wherein the ultrasonic signal is deflected by the object O2 at a fourth approach angle. DETAILED DESCRIPTION
[0015] like Figure 1 and Figure 2 As shown, the lawn mower obstacle avoidance system 101 may include a pair of ultrasonic sensors: a left ultrasonic sensor 102 and a right ultrasonic sensor 104. The left ultrasonic sensor may be mounted near the left front corner of a lawn mower such as the robotic lawn mower 100, and the right sensor may be mounted near the right front corner. Each ultrasonic sensor may transmit energy in the form of ultrasonic waves and may receive any waves reflected back to the sensor from an object or obstacle. Alternatively, the lawn mower obstacle avoidance system may include three or more ultrasonic sensors. The obstacle avoidance system may be mounted on a robotic lawn mower or other lawn mower with a guidance system, such as a fairway mower, a lawn tractor, or a zero-turn mower.
[0016] In one embodiment, the lawn mower obstacle avoidance system 101 may include two or more ultrasonic sensors, at least two of which transmit signals at different frequencies. For example, the left ultrasonic sensor 102 may transmit an ultrasonic signal L having a first frequency, and the right ultrasonic sensor 104 may transmit an ultrasonic signal R having a second frequency. The ultrasonic signals L and R may be reflected by an object or obstacle back to the same sensor. For example, an obstacle or object may reflect signal L back to the left sensor and reflect signal R back to the right sensor. The reflected signals may indicate the proximity of the obstacle or object to the lawn mower.
[0017] In one embodiment, the lawn mower obstacle avoidance system 101 may include two or more sensors that transmit ultrasonic signals that may be reflected to other sensors. Thus, each sensor may detect ultrasonic signals of two or more frequencies. For example, the signal R from the right sensor 104 may be used as the signal The reflected signal L from the left sensor 102 may be reflected to the right sensor as signal r. Each reflected signal may have a deflection angle. The deflection angle may depend on the angle at which the mower approaches the obstacle, the direction of the obstacle relative to the mower, and the shape of the obstacle. The reflected signal r may have a deflection angle a and the reflected signal r may have a deflection angle b. The reflected signal may also have a scattering angle that depends on the surface roughness of the obstacle.
[0018] In one embodiment, the lawn mower obstacle avoidance system 101 may include a controller 106 that commands the traction drive system to reduce the lawn mower speed below normal speed if one or both sensors 102, 104 receive an ultrasonic signal reflected from an object or obstacle within a maximum distance 110 and a minimum distance 111 from the sensors. Figure 1 and Figure 2 1, the area between them is shown as a deceleration area 112. If one or more ultrasonic signals are reflected back to one or both sensors from an object or obstacle in the deceleration area, the controller 106 can command the traction drive system to slow down the lawn mower. For example, the controller can command the wheel motors of the lawn mower's differential drive system to reduce the speed of the rear wheels 108.
[0019] In one embodiment, the lawn mower obstacle avoidance system 101 may include a controller 106 that can track ultrasonic signals reflected from an object or obstacle back to either sensor 102, 104. If either sensor receives a reflected signal from an object or obstacle in the deceleration zone 112, the controller can command the traction drive system to reduce the speed of the lawn mower. If neither sensor continues to receive a reflected signal from an object or obstacle detected in the deceleration zone, the controller can command the lawn mower to return to normal speed after the lawn mower passes the last detected position of the object. Alternatively, if neither sensor continues to receive a reflected signal at a stopping distance 116 from the object or obstacle, the controller can command the lawn mower to return to normal speed. If either sensor continues to receive a reflected signal from an object at the stopping distance 116, the controller can command the traction drive system to stop the lawn mower and steer to avoid the object or obstacle.
[0020] In one embodiment, the lawn mower obstacle avoidance system 101 can determine whether a detected object or obstacle is in a passage 114 window that would block the path of the lawn mower. The passage window can depend on the location of the sensors 102, 104 on the lawn mower 100, and can include a minimum height above ground level, a maximum height above the lawn mower, and a width of the lawn mower. The system can determine whether a detected object or obstacle is in the passage window at a minimum distance 110 from the deceleration zone 112, or when the lawn mower reaches a stopping distance 116 from the object or obstacle. If the object or obstacle reflects an ultrasonic signal back to either sensor at the stopping distance, the object or obstacle is within the passage window. If the object or obstacle does not reflect an ultrasonic signal back to either sensor at the stopping distance, the object or obstacle is outside the passage window.
[0021] In one embodiment, the lawn mower obstacle avoidance system 101 may include a pair of ultrasonic sensors 102, 104 that detect only objects or obstacles above the cutting height 120 above the ground plane 118, and do not detect grass or other objects below the cutting height. The ultrasonic sensors 102, 104 may be mounted on the lawn mower top surface 126, which may be tilted so that the ultrasonic signals L, R have a trajectory above the cutting height 120 through the deceleration zone 112. Alternatively, the controller 106 may ignore any signals reflected from objects or obstacles below the cutting height 120.
[0022] In one embodiment, the lawn mower obstacle avoidance system 101 can stop and turn the lawn mower for objects or obstacles in the passage window, and move the lawn mower past objects outside the passage window. Each sensor can transmit an ultrasonic signal in a trajectory based in part on the surface of the lawn mower body on which the sensor is mounted. For example, the trajectory can be generally conical. The left ultrasonic sensor 102 can be positioned between the left side surface 122 and the right side surface 124, which can define the left and right sides of the trajectory from the sensor, and the right ultrasonic sensor 104 can be positioned between the left side surface 128 and the right side surface 130 that define the side of its trajectory.
[0023] In one embodiment, the lawn mower obstacle avoidance system 101 may include a controller 106 that can decelerate the traction drive system if the ultrasonic signal is reflected back to any sensor in the deceleration zone 112. When the lawn mower reaches a stopping distance 116 of an object or obstacle, if the object is within the passage window, the controller can command the traction drive system to stop the lawn mower because it reflects the signal back to any sensor. At the stopping distance 116, if the object is not within the passage window, the controller can command the traction drive system to continue at a reduced speed because the object does not reflect the signal back to any sensor until the controller determines that it has passed the last detected position of the object or obstacle.
[0024] In one embodiment, the lawn mower obstacle avoidance system 101 may include a controller 106 that commands the traction drive system to turn the lawn mower in a clockwise or counterclockwise direction after stopping to avoid an object or obstacle. The controller may determine which direction to turn to by comparing the ultrasonic signal reflected to each of the pair of sensors. For example, the controller may compare the amplitude of the reflected ultrasonic signal with the left sensor and the right sensor, and the minimum amplitude is the minimum distance to the object or obstacle. The sensor that does not receive the reflected signal may not be included in the comparison. The controller may then command the traction drive system of the lawn mower to turn the lawn mower in a clockwise or counterclockwise direction until no object or obstacle is detected.
[0025] like Figure 3As shown, the lawn mower obstacle avoidance system may include a controller on a lawn mower (e.g., a robot lawn mower) that can execute the logic steps set in the software. When mowing begins in box 200, the system may be activated. In box 201, an object is encountered, and if the object is between the maximum distance and the minimum distance, the ultrasonic signal is reflected to any sensor. In box 202, the controller may command the lawn mower traction drive system to slow the lawn mower to a reduced speed. In box 203, the lawn mower reaches the stopping distance of the object or obstacle and determines whether the object is in the channel window. If the object or obstacle is still reflecting the ultrasonic signal to any sensor, the object or obstacle is in the channel window. If it is in the channel window, the controller may command the traction drive system to stop the lawn mower in box 206. In box 207, the controller may compare the reflected signals to determine which sensor receives the signal with the minimum distance value or the closest to the object or obstacle. If there is no reflected signal, it is not included in the comparison. If the left sensor receives the reflected signal with the lowest value, then in box 208, the controller can command the traction drive system to turn the mower in a clockwise (or right) direction until the object is cleared. If the right sensor has the lowest value, then in box 209, the controller can command the traction drive system to turn the mower in a counterclockwise (or left) direction until the object is cleared. The controller can then command the traction drive system to resume mowing at normal speed in box 205. In box 203, if neither sensor receives an ultrasonic signal reflected from an object in the channel window, the controller can move the mower past the last position where the object reflected the signal and then return the mower to normal speed. Alternatively, the controller can wait to command the traction drive system to accelerate the mower back to normal speed until the mower passes the position of the object from which the sensor last received a reflected signal.
[0026] like Figure 4 and Figure 5 As shown, the lawn mower obstacle avoidance system may be used on a robotic lawn mower approaching an object or obstacle O1 having a large divergence angle (eg, a generally spherical or cylindrical object). Figure 4 and Figure 5 1 and 2 show different approach angles of the lawn mower to an object. The left ultrasonic sensor 102 and the right ultrasonic sensor 104 can transmit signals L and R to the obstacle O1, which reflects the signals back to both sensors. The left sensor 102 can transmit a signal L to the obstacle O1, which reflects the signal L back to the left sensor 102 and reflects the signal r to the right sensor 104 at a deflection angle a. The right sensor 104 can transmit a signal R to the obstacle O1, which reflects the signal R back to the right sensor 104 and reflects the signal R at a deflection angle b. The ultrasonic wave is reflected to the left sensor 102. The controller can compare the reflected ultrasonic wave signals to determine which sensor receives the reflected signal with the lowest value. Figure 4 In this case, L is less than or equal to R or r, and is less than or equal to r or R, so the controller can command the traction drive system to turn the lawn mower in a clockwise (or right) direction to avoid obstacle O1. Figure 5 R is less than or equal to L or and / or r is less than or equal to Or L, so the controller can command the traction drive system to turn the lawn mower in a counterclockwise (or left) direction to avoid obstacle O1.
[0027] like Figure 6-9 As shown, the lawn mower obstacle avoidance system can be used on a robotic lawn mower approaching an obstacle O2, which can be a flat obstacle such as a wall. The lawn mower approach angle and the obstacle position are Figure 6-9 The left ultrasonic sensor 102 and the right ultrasonic sensor 104 can transmit signals L, R, which are reflected back to one of the sensors by the obstacle O2 at a deflection angle that depends on the angle of the object and the approach angle of the lawn mower. In each example, the obstacle O2 reflects the ultrasonic signal back to the other sensor. Figure 6 and Figure 7 In the example, sensor 104 emits a signal R, and obstacle O2 transmits the signal is reflected back to the left sensor 102. The sensor 102 transmits a signal L which does not reach the obstacle O2 or has a deflection angle away from any sensor. Figure 8 and Fig. 9 In Figure 1, the left sensor 102 transmits a signal L, and the obstacle O2 reflects a signal r back to the right sensor 104. The sensor 104 transmits a signal R, which does not reach the obstacle O2 or has a deflection angle away from either sensor. The controller compares the reflected signals to determine which sensor has a signal with a lower value or a reflection of a closer object, and uses the comparison to command the traction drive system which direction to turn. For example, in Figure 6 and Figure 7 In , the left sensor 102 receives a signal with a lower value (it is the only reflected signal), so the controller can command the traction drive system to turn the robotic mower in a clockwise (or right) direction to avoid obstacle O2. Figure 8 and Fig. 9 In the example, the right sensor receives a signal with a lower value (it is the only signal reflected), so the controller can command the traction drive system to turn the robotic mower in a counterclockwise (or left) direction to avoid obstacle O2.
[0028] Having described the preferred embodiment, it will be apparent that various modifications may be made without departing from the scope of the invention as defined in the appended claims.
Claims
1. A lawn mower obstacle avoidance system, comprising: A left ultrasonic sensor and a right ultrasonic sensor mounted on the lawn mower; the left ultrasonic sensor sends an ultrasonic signal at a first frequency, and the right ultrasonic sensor sends an ultrasonic signal at a second frequency; each ultrasonic sensor receives ultrasonic signals reflected at the first frequency and the second frequency; and A vehicle controller commands a traction drive system of the lawn mower to avoid an obstacle based on a comparison of reflected ultrasonic signals received by the first ultrasonic sensor and the second ultrasonic sensor.
2. The lawn mower obstacle avoidance system according to claim 1, wherein: The vehicle controller commands the traction drive system to decelerate the lawn mower when at least one of the first and second ultrasonic sensors receives a reflected ultrasonic signal from an obstacle in a deceleration zone between a maximum distance and a minimum distance from the lawn mower.
3. The lawn mower obstacle avoidance system according to claim 2, wherein: The first ultrasonic sensor and the second ultrasonic sensor transmit ultrasonic signals each having a trajectory above a cutting height of the lawn mower in the deceleration area.
4. The lawn mower obstacle avoidance system according to claim 1, wherein: The vehicle controller compares the reflected ultrasonic signal to each sensor to command the traction drive system to steer the lawn mower in a clockwise or counterclockwise direction.
5. A lawn mower obstacle avoidance system, comprising: a pair of sensors mounted on the robotic lawn mower, each sensor emitting an ultrasonic signal in a track in front of the robotic lawn mower; and a controller programmed to command a traction drive system to stop and steer the robotic mower if either of the pair of sensors receives a reflected ultrasonic signal from an object at a stopping distance in front of the robotic mower and if the object is also within a passage window based on a cutting height, width, and height of the robotic mower.
6. The lawn mower obstacle avoidance system according to claim 5, wherein: The controller is programmed to command the traction drive system to decelerate the mower before stopping the mower if either of the pair of sensors receives an ultrasonic signal reflected from an object in front of the channel window in a deceleration zone between a maximum distance and a minimum distance from the pair of sensors.
7. The lawn mower obstacle avoidance system according to claim 5, wherein: The controller is programmed to command the traction drive system to turn the lawn mower in a clockwise or counterclockwise direction depending on the proximity of the object relative to the lawn mower.
8. The lawn mower obstacle avoidance system according to claim 5, wherein: Each sensor of the pair of sensors is capable of receiving a reflected ultrasonic signal emitted by the other sensor.
9. A lawn mower obstacle avoidance method, comprising the following steps: transmitting a plurality of ultrasonic signals from a plurality of ultrasonic sensors mounted to the lawn mower; decelerating the lawn mower from a normal speed to a reduced speed if at least one of the plurality of ultrasonic sensors receives a signal reflected from an object in a deceleration zone in front of the lawn mower; stopping the lawn mower and turning the lawn mower when at least one of the plurality of ultrasonic sensors receives a reflected signal at a stopping distance closer than the deceleration area; and The lawn mower is accelerated from the reduced speed to the normal speed in the event that none of the plurality of ultrasonic sensors continues to receive reflected signals from an object in the deceleration zone.
10. The lawn mower obstacle avoidance method according to claim 9, wherein: The steps of stopping and turning the lawn mower further include comparing reflected signals of a plurality of ultrasonic sensors to determine which has a minimum value.
11. The lawn mower obstacle avoidance method according to claim 9, wherein: The deceleration zone has a maximum distance and a minimum distance in front of the lawn mower.
12. The lawn mower obstacle avoidance method of claim 9, further comprising emitting ultrasonic signals at different frequencies from a plurality of ultrasonic sensors.