Method for estimating the pushing force of a work machine with assistance, mower
By detecting motor parameters and accelerometers in a lawnmower, a thrust observation model was constructed, which solved the problem of low accuracy of pressure sensors and achieved accurate and low-cost thrust estimation and comfortable walking control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING CHERVON IND
- Filing Date
- 2022-09-29
- Publication Date
- 2026-07-24
AI Technical Summary
Existing methods for detecting thrust in lawnmowers rely on pressure sensors, which suffer from low accuracy and increase the complexity of detection by adding other sensors, affecting the accuracy and comfort of thrust estimation.
By detecting the rotor position and operating current of the drive motor, and combining this with accelerometer measurements of the tilt angle, a thrust observation model is constructed to estimate the user's thrust, eliminating the need for pressure sensors and other complex sensors.
It improves the accuracy and comfort of thrust estimation, reduces the types and costs of detection devices, and ensures smooth walking control and real-time response.
Smart Images
Figure CN117813995B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a gardening tool, such as a method for estimating the push-pull force of a assisted working machine or lawnmower. Background Technology
[0002] Lawn mowers are machines used by users to trim lawns. Some more intelligent lawn mowers use pressure sensors to detect the user's thrust and control the mower's speed accordingly. However, the accuracy of the pressure sensor, its installation location, and its interaction with other components in the lawn mower can all affect the accuracy of thrust detection, thus impacting the comfort of the lawn mower's movement control.
[0003] Other methods that don't directly measure thrust using sensors inevitably require additional sensors to detect parameters such as acceleration or the lawnmower's tilt angle relative to the horizontal plane in the current operating environment, in order to indirectly obtain the user's thrust. The tilt angle is typically detected using an attitude sensor, which consists of a gyroscope, accelerometer, and magnetometer. This sensor measures the machine's yaw, pitch, and roll angles to calculate the lawnmower's tilt angle relative to the ground. The large number of parameters required for measurement makes it difficult to guarantee the accuracy of angle detection, thus affecting the accuracy of thrust estimation. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this application provides a working machine that can obtain user thrust without the need for a pressure sensor.
[0005] To achieve the above objectives, this application adopts the following technical solution:
[0006] A power-assisted working machine includes: a main unit including a walking assembly and a drive motor for driving the walking assembly; and a handle device connected to the main unit; wherein: the handle device includes: an operating element including a grip for a user to hold; and further includes: a motor parameter detection device configured to detect operating parameters of the drive motor; an accelerometer configured to detect acceleration of the working machine in at least one direction in the current working environment; and a controller configured to determine the tilt angle of the working machine relative to a horizontal plane based on the acceleration, and to estimate the push-pull force applied to the handle device based on the operating parameters and the tilt angle.
[0007] In one embodiment, the operating parameters include the rotor position and / or operating current of the motor.
[0008] In one embodiment, the controller is configured to determine the rotational speed of the motor based on the rotor position.
[0009] In one embodiment, the operating parameters include the motor's rotational speed and operating current.
[0010] In one embodiment, the controller is configured to: construct a thrust observation model based on the current force balance relationship of the assisted working machine; and use the rotational speed and the operating current as input parameters of the thrust observation model to determine the thrust-pull force.
[0011] In one embodiment, the force balance relationship includes at least the push-pull force, the driving force of the drive motor, the resistance of the assisted working machine in the current working environment, and the resultant force on the assisted working machine.
[0012] In one embodiment, the controller is configured to: construct a relationship model between the operating current, the rotational speed, and the resultant force based on the thrust observation model; determine the resultant force based on the operating current and the rotational speed; and determine the push-pull force based on the difference between the resultant force and the resistance.
[0013] A method for estimating the thrust of a lawnmower, the lawnmower including a main unit, including a walking component and a drive motor for driving the walking component; a handle device connected to the main unit; wherein: the handle device includes: an operating element including a grip for a user to hold; and further includes: a motor parameter detection device configured to detect the operating parameters of the drive motor; an accelerometer configured to detect the acceleration of the lawnmower in at least one direction in the current working environment; the estimation method includes: determining the tilt angle of the assisted lawnmower relative to a horizontal plane based on the acceleration; constructing a thrust observation model based on the current force balance relationship of the lawnmower; and using the rotational speed, the operating current, and the tilt angle as input parameters of the thrust observation model to determine the push-pull force applied to the handle device.
[0014] In one embodiment, the force balance relationship includes at least the thrust, the driving force of the drive motor, the resistance of the assisted working machine in the current working environment, and the resultant force on the assisted working machine.
[0015] In one embodiment, the method further includes: constructing a relationship model between the operating current, the rotational speed, and the resultant force based on the thrust observation model; determining the resultant force based on the operating current and the rotational speed; and determining the push-pull force based on the difference between the resultant force and the resistance.
[0016] The advantages of this application are: by constructing a thrust observation model and utilizing the rotor position or phase current of the motor detected by the lawnmower's walking control system during the control of the drive motor's rotation, the user's thrust can be calculated without adding any other detection devices or components. Furthermore, because the control technology of the lawnmower's walking control system is relatively mature, the accuracy of the parameters detected in the system can be guaranteed, thus ensuring the accuracy of the thrust estimation. Attached Figure Description
[0017] Figure 1 It is a 3D view of a machine tool with power assistance;
[0018] Figure 2 yes Figure 1 A logic control diagram of a machine tool with assisted operation;
[0019] Figure 3 This is a schematic diagram of the force analysis of the assisted working machine in the embodiments of this application;
[0020] Figure 4 This is a schematic diagram of the acceleration analysis of the machine with assistance in the embodiments of this application;
[0021] Figure 5 yes Figure 1 A flowchart illustrating the overall control method for a machine with assisted operation.
[0022] Figure 6 yes Figure 1 The flowchart shows the overall control method for a machine with assisted operation. Detailed Implementation
[0023] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present application and not the entire structure.
[0024] Understandably, assisted working machines can be tools and equipment such as lawnmowers, snowplows, and wheelbarrows. This application uses a push-type lawnmower, which can be operated from the rear, as an example.
[0025] Reference Figure 1The lawnmower 100 shown mainly includes a handle device 11, a connecting rod 111, an operating component 112, an operating switch 112a, a main unit 12, and a walking assembly 121. The main unit 12 includes the walking assembly 121 and a power mechanism (not shown). Optionally, the handle device 11 includes a connecting rod 111 and an operating component 112 for gripping. The operating component 112 includes a grip for the user and an operating switch 112a; the connecting rod 111 is a hollow long rod structure, connecting the operating component 112 and the main unit 12. The walking assembly 121 is mounted on the main unit 12 and can rotate around a rotation axis, allowing the entire lawnmower 100 to move on the ground. In this embodiment, the walking assembly 121 includes the lawnmower 100's wheels 1211 and a power mechanism that drives the wheels 1211.
[0026] In this embodiment, the lawnmower 100 has a self-propelled control function. The power mechanism can drive the walking component 121 to rotate, thereby moving the lawnmower 100 on the ground, so that the user does not need to manually push the lawnmower 100 to move. Specifically, the power mechanism can be a drive motor 122, which can output a driving force to drive the walking component 121 to rotate. In some embodiments, the handle device 11 of the lawnmower 100 also integrates a power button 112b and a trigger 112c. For example, the power button 112b, trigger 112c and operation switch 112a of the lawnmower 100 are all integrated on the operating component 112. In addition, the operation switch 112a is not limited to a physical switch or a signal switch; any device that can control the opening and closing of the current in the circuit is applicable. In fact, such operation switches 112a are not limited to controlling the current; they can also control the opening or closing of the self-propelled function by mechanical means.
[0027] Generally, to sense the user's thrust and thus control parameters such as the lawnmower's walking speed or output torque, a pressure sensor and a triggering component are typically included in the handle assembly 11. In one embodiment, the triggering component drives the pressure sensor to deform. Thus, when the user applies thrust to the grip 115, the triggering component applies force to the pressure sensor, causing it to deform and generate an electrical signal. In this embodiment, the lawnmower 100 may also include a signal processing device and a control unit. The electrical signal generated by the pressure sensor is sent to the signal processing device, which then sends the processed signal to the control unit to control the lawnmower 100's movement on the ground. However, the electrical signal output by the pressure sensor requires a long communication link to be transmitted to the host 12; furthermore, accurate sensing of the user's thrust requires high precision from the pressure sensor, and after prolonged use, the sensor's sensitivity to deformation may decrease. In summary, using a pressure sensor to sense the user's thrust suffers from performance instability or reduced accuracy, which affects the user's comfort in controlling the lawnmower 100.
[0028] Existing technologies include methods for estimating the thrust applied by a user's lawnmower 100 to the handlebar assembly 11 without the need for pressure sensors. For example, the thrust applied by the user to the handlebar can be obtained by comprehensively analyzing parameters such as the current and acceleration of the drive motor or the angle of inclination of the lawnmower's working plane relative to the horizontal plane. While these methods eliminate the need for pressure sensors, the addition of other detection devices due to the detection of parameters like acceleration or inclination inevitably increases the likelihood of thrust estimation being unaffected by the installation position of these detection devices.
[0029] In sensorless operating machines, in order to reduce the types of detection devices and ensure the accuracy of estimation results, the user's thrust can be estimated using parameters in the lawnmower's walking control system.
[0030] In this embodiment, as Figure 2 The control logic diagram shown illustrates that the control circuit of the main unit 12 of the lawnmower 100, in addition to the drive motor 122 and controller 123, also includes a motor parameter detection device 124 capable of acquiring relevant parameters during the lawnmower's movement, which can detect the rotor position of the drive motor 122 and / or the motor's operating current. An angle detection device 125 can detect the tilt angle of the lawnmower 100's current working surface relative to the horizontal plane. The control circuit also includes at least a power supply 13 and a drive circuit 126.
[0031] The power source 13 can be a battery pack or AC mains power. Specifically, the power supply voltage can be converted by a power conversion circuit to power the controller 123, the motor parameter detection device 124, and the angle detection device 125.
[0032] The drive circuit 126, connected between the controller 123 and the drive motor 122, has several semiconductor switching elements to switch the motor's energizing state. In one embodiment, the drive circuit 127 is electrically connected to each phase of the stator winding of the drive motor 122 to transmit power current to the stator windings to drive the brushless motor 122 to rotate. As one embodiment, such as... Figure 2 As shown, the drive circuit 126 includes multiple switching elements Q1, Q2, Q3, Q4, Q5, and Q6. The gate of each switching element is electrically connected to the controller 123 to receive a control signal from the controller 123. Each drain or source of the switching element is connected to the stator winding of the drive motor 122. The switching elements Q1-Q6 receive the control signal from the controller 123 and change their respective conduction states, thereby changing the current applied to the stator winding of the drive motor 122. In one embodiment, the switching elements Q1-Q6 in the drive circuit 126 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., FETs, BJTs, IGBTs, etc.), or any other type of solid-state switch, such as an IGBT or BJT.
[0033] In one embodiment, the motor parameter detection device 124 may be a Hall sensor capable of directly acquiring the rotor position of the drive motor 122. In another embodiment, the motor parameter detection device 124 may be a sampling resistor capable of detecting the phase current of the motor. In yet another embodiment, the motor parameter detection device 124 may also be a device that senses motor current through a magnetic field. In one embodiment, when estimating the thrust applied by the user to the handle device, the controller 123 may use either the rotor position or the phase current, or both parameters.
[0034] Angle detection device 125 is used to detect the angle of inclination of the plane on which the lawnmower 100 travels relative to the horizontal plane, such as... Figure 3 The angle θ is shown. In one embodiment, the angle detection device 125 can be an attitude sensor. The attitude sensor can consist of a gyroscope, an accelerometer, and a magnetometer, and can measure three attitude angles of the lawnmower 100 in the body coordinate system and the ground coordinate system, namely yaw, pitch, and roll. Then the controller 123 can determine the tilt angle θ based on the above three attitude angles.
[0035] To better understand the principle by which controller 123 estimates the user's thrust, we can perform a force analysis at any point on the lawnmower 100. For example... Figure 3 As shown, the thrust applied by a person's hand to the lawnmower is The driving force of the motor generated by the drive motor 122 is The frictional resistance experienced by the wheels of the lawnmower 100 is The component of gravity that hinders the forward movement of the lawnmower 100 is The net force acting on the lawnmower 100 in the forward direction is Therefore, all forces acting on the lawnmower 100 at any given time satisfy the following force balance relationship: Among them, the rolling friction resistance of the wheel Components of gravity , working together Where a is the forward acceleration of lawnmower 100 relative to the ground. The weight of the lawnmower. The coefficient of friction. The components of frictional resistance and gravity can be combined to form the resistance of the lawnmower in its current working environment. In summary, the force balance relationship of the lawnmower is as follows:
[0036]
[0037] In this embodiment, sliding friction and changes in the rolling friction coefficient are not considered. Furthermore, as mowing progresses, the weight of the lawnmower's grass collection device increases, and the weight M of the lawnmower also increases. In this embodiment, the average weight of the lawnmower at different times can be taken as the weight M and substituted into the aforementioned force balance relationship. The controller 123 can construct a thrust observation module based on the aforementioned force balance relationship and input the parameters detected by the motor parameter detection device 124 as input parameters into the aforementioned thrust observation model to determine the user's thrust. Different model building strategies can be used to construct thrust observation models, and this embodiment does not impose any restrictions on this.
[0038] In one embodiment, the controller 123 can determine the rotational speed of the drive motor 122 based on the motor rotor position, or based on the phase current. The controller 123 can then input the motor rotational speed and operating current as input parameters into the thrust observation model to calculate the magnitude of the thrust.
[0039] In one embodiment, the controller 123 can construct a relationship model between the motor's operating current (phase current), rotational speed, and the resultant force acting on the lawnmower based on the aforementioned thrust observation model. Then, it determines the resultant force based on the operating current and rotational speed, and further determines the thrust based on the difference between the resultant force and the resistance. When constructing the thrust observation model, the relationship between motor rotational speed and acceleration, and the relationship between rolling friction and motor speed, can be used to construct observation models for the resultant force, motor speed, and phase current. In one embodiment, the relationship model between the phase current, rotational speed, and the resultant force acting on the lawnmower determined based on the thrust observation model is as follows: ,in, Motor speed, This is the operating current of the motor. This coefficient is determined by the lawnmower system parameters and environmental parameters. Controller 123 can determine the resultant force on the lawnmower based on the motor speed and operating current. Alternatively, the rotational speed can be determined based on the operating current, and then the resultant force can be determined in conjunction with the operating current. Therefore, the thrust can be determined. .
[0040] The lawnmower's travel control system needs to detect the motor's rotor position or phase current during the control of the drive motor's rotation. By constructing a thrust observation model, it uses the rotor position and phase current to calculate the user's thrust without adding any other detection devices or components. Furthermore, because the control technology of the lawnmower's travel control system is relatively mature, the accuracy of the parameters detected in the system can be guaranteed, thus ensuring the accuracy of the thrust estimation.
[0041] In constructing a thrust observation model and calculating the user's thrust using rotor position and phase current, an attitude sensor is typically used to detect the tilt angle θ. The attitude sensor itself comprises three instruments: a gyroscope, an accelerometer, and a magnetometer. The tilt angle θ is calculated by detecting these three angles. The use of multiple instruments and the detection of numerous parameters make the tilt angle calculation process complex.
[0042] In one embodiment, to obtain the tilt angle θ simply, quickly, and accurately, this application analyzes the acceleration of the lawnmower on the working plane. For example... Figure 4 As shown, the acceleration in the forward direction of the lawnmower 100 Equal to the forward acceleration of the lawnmower The component of gravitational acceleration in the direction of the lawnmower's movement The sum of Among them, the forward acceleration of the lawnmower ,in, For wheel speed, Let ω be the radius of the wheel and ω be the angular velocity of the wheel. For the angular velocity of the drive motor, For speed ratio, The motor speed is specified. Controller 123 can determine the motor speed based on the rotor position and / or phase current of the drive motor. Thus, the lawnmower's forward acceleration It can be confirmed.
[0043] Since the accelerometer's axis is parallel to the lawnmower's forward direction, it can be used to measure the lawnmower's acceleration in that direction. Under different walking surfaces, such as flat ground, downhill, and uphill environments. and The relationship can be represented as:
[0044]
[0045] As shown above, it is only necessary to determine the acceleration in the forward direction of the lawnmower. The tilt angle θ can then be calculated. In this embodiment, an accelerometer can be used to measure the acceleration of the lawnmower in the forward direction. Therefore, the tilt angle can be determined. .
[0046] In one embodiment, the tilt angle Also, acceleration in the direction perpendicular to the direction of the lawnmower's movement. Related. In this embodiment, under different walking surfaces, such as flat ground, downhill, and uphill environments. and The relationship can be represented as:
[0047]
[0048] As can be seen from the above, under different running surfaces, and The relationships are different. And... With tilt angle The relationship is fixed. Therefore, it can be utilized With tilt angle Relationship calculation and utilize and Different relationships determine different walking surfaces The calculation method is as follows:
[0049]
[0050] In this embodiment, an accelerometer can be used to measure the acceleration of the lawnmower in the forward direction. and acceleration in the direction perpendicular to the direction of the lawnmower's movement. Determine the tilt angle .
[0051] In this embodiment, there is no need to install high-cost and demanding detection devices such as accelerometers and attitude sensors. The user's thrust can be accurately estimated simply by using accelerometers and commonly used detection parameters in the walking control system, namely rotor position and / or phase current. This reduces costs while ensuring the accuracy of thrust estimation.
[0052] The control from torque to speed requires time integration, resulting in a lag in speed response and causing a pulling or jerking sensation in autonomous driving control, leading to lower comfort. However, the embodiment of this application, after estimating the user's thrust, can change the motor's driving force, i.e., change the motor's output torque, based on the aforementioned force balance relationship. Therefore, the driving force can change in real time in response to changes in thrust, making the autonomous driving control process smoother and more comfortable for the user.
[0053] In this embodiment, the process by which the controller 123 changes the motor output torque in response to the user's thrust can be applied to FOC control, BLDC control, or a combination of both.
[0054] refer to Figure 5 The walking control method for a rear-walking lawnmower includes the following steps:
[0055] S101 detects the rotor position and / or operating current of the drive motor.
[0056] In one embodiment, the motor speed can be determined based on the motor's rotor position and / or operating current.
[0057] S102, construct a thrust observation model based on the current force balance relationship of the lawnmower.
[0058] S103 uses rotational speed and operating current as input parameters for the thrust observation model to determine the thrust.
[0059] Understandably, by inputting rotational speed and operating current as input parameters into the thrust observation model, the resultant force can be obtained. Furthermore, the relationship between the resultant force, thrust, and drag can be used to calculate the resultant force. Determine thrust The value of .
[0060] S104 changes the motor's output torque based on the balance between thrust and force.
[0061] refer to Figure 6 The walking control method for a rear-walking lawnmower includes the following steps:
[0062] S201, detects the rotor position and / or operating current of the drive motor.
[0063] In one embodiment, the motor speed can be determined based on the motor's rotor position and / or operating current.
[0064] S202, Detect the acceleration of the lawnmower in at least one direction in the current working environment.
[0065] S203 determines the tilt angle of the lawnmower relative to the horizontal plane based on acceleration.
[0066] S204, construct a thrust observation model based on the current force balance relationship of the lawnmower.
[0067] S205 uses rotational speed and operating current as input parameters for the thrust observation model to determine the resultant force.
[0068] S206, calculate the thrust based on the relationship between the resultant force, thrust, and drag, and the value of the inclination angle.
[0069] Understandably, by inputting rotational speed and operating current as input parameters into the thrust observation model, the resultant force can be obtained. Furthermore, the relationship between the resultant force, thrust, and drag can be used to calculate the resultant force. Determine thrust The value of .
[0070] S207 changes the motor's output torque based on the balance between thrust and force.
[0071] Note that the above are merely preferred embodiments and the technical principles employed in this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application, the scope of which is determined by the scope of the appended claims.
Claims
1. A machine tool with assisted operation, comprising: The main unit includes a walking component and a drive motor that drives the walking component; A handle device is connected to the main unit; in: The handle device includes: The operating element includes a grip for the user to hold; Also includes: A motor parameter detection device is configured to detect the operating parameters of the drive motor. An accelerometer is configured to detect the acceleration of the machine in at least one direction in the current working environment; The controller is configured to determine the tilt angle of the working machine relative to the horizontal plane based on the acceleration, and to estimate the push-pull force applied to the handle device based on the working parameters and the tilt angle; to construct a thrust observation model based on the current force balance relationship of the assisted working machine, and to use the working parameters and the tilt angle as input parameters of the thrust observation model to determine the push-pull force; wherein, the user does not need to manually push the working machine to move.
2. The assisted working machine according to claim 1, characterized in that, The operating parameters include the rotor position and / or operating current of the motor.
3. The assisted working machine according to claim 2, characterized in that, The controller is configured to determine the speed of the motor based on the rotor position.
4. The assisted working machine according to claim 1, characterized in that, The operating parameters include the motor's rotational speed and operating current.
5. The assisted working machine according to any one of claims 3 or 4, characterized in that, The controller is configured to use the rotational speed and the operating current as input parameters of the thrust observation model to determine the thrust-pull force.
6. The assisted working machine according to claim 5, characterized in that, The force balance relationship includes at least the push-pull force, the driving force of the drive motor, the resistance of the assisted working machine in the current working environment, and the resultant force on the assisted working machine.
7. The assisted working machine according to claim 6, characterized in that, The controller is configured to: construct a relationship model between the operating current, the rotational speed, and the resultant force based on the thrust observation model; determine the resultant force based on the operating current and the rotational speed; and determine the push-pull force based on the difference between the resultant force and the resistance.
8. A method for estimating the push-pull force of a lawnmower, the lawnmower comprising a main unit, a walking assembly, and a drive motor for driving the walking assembly; Handle device, connected to the main unit; wherein: The handle device includes: an operating element, including a grip for a user to hold; and further includes: a motor parameter detection device configured to detect the operating parameters of the drive motor; and an accelerometer configured to detect the acceleration of the lawnmower in at least one direction in the current working environment; wherein the user does not need to manually push the lawnmower to move; the estimation method includes: The tilt angle of the lawnmower relative to the horizontal plane is determined based on the acceleration. A thrust observation model is constructed based on the current force balance relationship of the lawnmower. The operating parameters include the motor's rotational speed and operating current. The rotational speed, operating current, and tilt angle are used as input parameters for the thrust observation model to determine the push-pull force applied to the handle device.
9. The method for estimating push-pull force according to claim 8, characterized in that, The force balance relationship includes at least the thrust, the driving force of the drive motor, the resistance of the lawnmower in the current working environment, and the resultant force on the lawnmower.
10. The method for estimating push-pull force according to claim 9, characterized in that, The method further includes: constructing a relationship model between the operating current, the rotational speed, and the resultant force based on the thrust observation model; determining the resultant force based on the operating current and the rotational speed; and determining the push-pull force based on the difference between the resultant force and the resistance.