CN117837370A - Working machine with power assistance, mower and push-pull force estimation method - Google Patents

Abstract

The application discloses take helping hand work machine, lawn mower and thrust estimation method, the work machine includes: the host machine comprises a walking assembly and a driving motor for driving the walking assembly; a handle device connected to the host; wherein: the handle device includes: an operating member including a grip portion for a user to grip; the connecting rod is connected to the host; further comprises: motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor; an angle detection device configured to detect an inclination angle of a work surface of the working machine with respect to a horizontal plane; and a controller configured to estimate a thrust force exerted on the handle device based on the rotor position and/or the operating current and the tilt angle.

Description

Working machine with power assistance, mower and push-pull force estimation method

Technical Field

The present disclosure relates to a power assisted tool, for example, to a power assisted work machine, a mower, and a push-pull force estimation method.

Background

A lawnmower is typically a machine used by a user to cut lawns. In some relatively intelligent mowers, the user's thrust can be sensed by a pressure sensor, and the travel speed of the mower can be controlled in accordance with the thrust. However, the accuracy of the thrust detection can be affected by the sensing accuracy of the pressure sensor, the mounting position, the matching state of the pressure sensor and other components in the mower, and the like, so that the travelling control comfort of the mower is affected.

Other ways of directly measuring the thrust without a sensor avoid the need to add more other types of sensors to detect parameters such as acceleration or inclination angle relative to the horizontal plane in the current environment in which the mower is working, so as to indirectly obtain the thrust of the user.

Disclosure of Invention

In order to solve the defects in the prior art, the application provides a working machine capable of determining user thrust according to parameters of a motor.

In order to achieve the above object, the present application adopts the following technical scheme:

a power assisted work machine comprising: the host machine comprises a walking assembly and a driving motor for driving the walking assembly; a handle device connected to the host; wherein: the handle device comprises: an operating member including a grip portion for a user to grip; a connecting rod connected to the host; further comprises: motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor; the angle detection device is used for detecting the inclination angle of the working surface of the backward self-propelled working machine relative to the horizontal plane; a controller configured to estimate a thrust force exerted on the handle means as a function of the rotor position and/or the operating current and the tilt angle.

In one embodiment, the controller is configured to: and determining the rotating speed of the motor according to the rotor position.

In one embodiment, the controller is configured to: constructing a thrust observation model according to the current stress balance relation of the backward self-propelled working machine; and adopting the rotating speed and the working current as input parameters of the thrust observation model to determine the thrust.

In one embodiment, the force balance relationship includes at least the thrust force, the driving force of the driving motor, the resistance of the walk-behind self-propelled working machine in the current working environment, and the resultant force to which the walk-behind self-propelled working machine is subjected.

In one embodiment, the controller is configured to: constructing a relation model of the working current, the rotating speed and the resultant force according to the thrust observation model; determining the resultant force according to the operating current and the rotational speed; and determining the thrust according to the difference between the resultant force and the resistance.

A boosted mower comprising: the host machine comprises a walking assembly and a driving motor for driving the walking assembly; a handle device connected to the host; wherein: the handle device comprises: an operating member including a grip portion for a user to grip; a connecting rod connected to the host; further comprises: motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor; the angle detection device is used for detecting the inclination angle of the working surface of the backward self-propelled working machine relative to the horizontal plane; a controller configured to estimate a thrust force exerted on the handle means as a function of the rotor position and/or the operating current and the tilt angle.

In one embodiment, the controller is configured to: constructing a thrust observation model according to the current stress balance relation of the back-walking mower; and adopting the rotating speed and the working current as input parameters of the thrust observation model to determine the thrust.

In one embodiment, the force balance relationship includes at least the thrust force, the driving force of the driving motor, the resistance of the walk-behind mower in the current working environment, and the resultant force experienced by the walk-behind mower.

In one embodiment, the controller is configured to: constructing a relation model of the working current, the rotating speed and the resultant force according to the thrust observation model; determining the resultant force according to the operating current and the rotational speed; and determining the thrust according to the difference between the resultant force and the resistance.

A thrust estimation method suitable for a mower comprises a host machine, wherein the host machine comprises a walking assembly and a driving motor for driving the walking assembly; a handle device connected to the host; wherein: the handle device comprises: an operating member including a grip portion for a user to grip; a connecting rod connected to the host; further comprises: motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor; an angle detection device configured to detect an inclination angle of a work surface of the walk-behind mower with respect to a horizontal plane; the estimation method comprises the following steps: constructing a thrust observation model according to the current stress balance relation of the back-walking mower; the rotor position and/or the working current are used as input parameters of the thrust observation model to determine the resultant force applied to the mower and calculate the push-pull force applied to the handle device according to the resultant force and the resistance applied to the mower.

The beneficial point of the application lies in: by constructing a thrust observation model and utilizing the rotor position or phase current of the motor detected by the mower walking control system in the process of controlling the driving motor to rotate, the thrust of a user can be estimated without adding other detection devices or elements. In addition, as the control technology of the mower walking control system is mature, the accuracy of parameters detected in the system can be ensured, and the accuracy of thrust estimation is also ensured.

Drawings

FIG. 1 is a perspective view of a work machine with assistance;

FIG. 2 is a logic control diagram of the boosted work machine of FIG. 1;

FIG. 3 is a force analysis schematic diagram of a power assisted work machine in an embodiment of the present application;

FIG. 4 is a schematic diagram of acceleration analysis of a boosted work machine in an embodiment of the present application;

FIG. 5 is a flow chart of a method of overall machine control of the boosted work machine of FIG. 1;

fig. 6 is a flowchart of a method of overall machine control of the boosted work machine of fig. 1.

Detailed Description

The present application is described in detail below with reference to the attached drawings and specific embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not limiting. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present application are shown in the drawings.

It will be appreciated that the boosted work machine may be a tool device such as a mower, snowplow, dolly, etc. In this application, a hand propelled mower operable by a user at the rear side of the mower will be described as an example.

Referring to the mower 100 shown in fig. 1, the mower mainly includes a handle device 11, a connecting rod 111, an operating member 112, an operating switch 112a, a main body 12, and a traveling assembly 121. Wherein host 12 includes a walking assembly 121, and a power mechanism (not shown). Optionally, the handle device 11 includes a connecting rod 111 and a handling member 112 for holding. Wherein the operation piece 112 includes a grip portion for a user to grip and an operation switch 112a; the connecting rod 111 has a hollow long rod structure, and the connecting rod 111 connects the operating member 112 and the host 12. The traveling assembly 121 is mounted to the main body 12, and the traveling assembly 121 can be rotated about a rotation axis so that the entire mower 100 can move on the ground. In the present embodiment, the traveling assembly 121 includes a traveling wheel 1211 of the mower 100 and a power mechanism that drives the traveling wheel 1211 to travel.

In this embodiment, the mower 100 has a self-propelled control function, and the power mechanism can drive the walking assembly 121 to rotate, so as to drive the mower 100 to move on the ground, so that a user does not need to manually push the mower 100 to move. The power mechanism may specifically be a driving motor 122, which can output a driving force for driving the traveling assembly 121 to rotate. In some embodiments, a power button 112b, a trigger 112c are also integrated into the handle device 11 of the mower 100. Illustratively, the power button 112b, trigger 112c, and operating switch 112a of the mower 100 are all integrated on the operator 112. In addition, the operation switch 112a is not limited to a physical switch or a signal switch, and any device that can control the on and off of the current in the circuit is applicable. In fact, the operation switch 112a is not limited to control of the current, and may be a mechanical means for controlling the on or off of the self-walking function.

Generally, in order to sense the thrust of a user and further control related parameters in the traveling process such as the traveling speed or the output torque of the mower. A pressure sensor and a triggering assembly for triggering the pressure sensor are typically provided within the handle means 11. In one embodiment, the trigger assembly is capable of driving the pressure sensor to deform. Thus, when a user applies a pushing force to grip 115, the trigger assembly applies a force to the pressure sensor, which deforms and generates an electrical signal. In this embodiment, the mower 100 may further include a signal processing device and a control unit, the electrical signal generated by the pressure sensor is transmitted to the signal processing device, and the signal processing device transmits the processed signal to the control unit to control the mower 100 to walk on the ground. However, when the electrical signal output by the pressure sensor needs to be transmitted to the host 12 through a long communication link; in addition, in order to accurately sense the thrust of the user, the accuracy requirement on the pressure sensor is high, and after the pressure sensor is used for a long time, the problem of reduced sensitivity to deformation sensing possibly occurs. In summary, the manner of sensing the thrust of the user by the pressure sensor has the problem of unstable performance or reduced accuracy, which affects the comfort of the user in controlling the operation of the mower 100.

There are some methods in the prior art for estimating the thrust exerted by the user mower 100 on the handle device 11 without the need for a pressure sensor. For example, by detecting parameters such as current and acceleration of the drive motor or inclination angle of the mower working plane relative to the horizontal plane, the thrust exerted on the handle by the user is obtained after comprehensive analysis. Although a pressure sensor is not needed, other detection devices are inevitably added due to the detection of parameters such as acceleration or inclination, so that the thrust estimation cannot be guaranteed to be not influenced by the installation position of the detection devices.

In the working machine without the pressure sensor, in order to reduce the variety of the detection device and ensure the accuracy of the estimation result, the thrust of the user can be estimated by using the parameters in the mower travel control system.

In this embodiment, as shown in the control logic diagram of fig. 2, the control circuit of the host 12 of the mower 100 includes a motor parameter detecting device 124 capable of acquiring relevant parameters during the walking of the mower in addition to a driving motor 122 and a controller 123, and is capable of detecting the rotor position of the driving motor 122 and/or the phase current of the working motor of the motor. The angle detection device 125 is capable of detecting the inclination angle of the current work surface of the mower 100 with respect to the horizontal plane. The control circuit further comprises at least a power supply 13 and a drive circuit 126.

The power source 13 may be a battery pack or ac mains. Specifically, the power supply voltage may be converted by the power conversion circuit, and then the controller 123, the motor parameter detecting device 124, and the angle detecting device 125 are powered on.

The driving circuit 126, which can be connected between the controller 123 and the driving motor 122, has a plurality of semiconductor switching elements to switch the energized state of the motor. In one embodiment, the drive circuit 127 is electrically connected to each phase of the stator windings of the drive motor 122 for delivering power current to the stator windings to drive the brushless motor 122 to rotate. As one example, as shown in fig. 2, the driving circuit 126 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, Q6. Each gate terminal of the switching element is electrically connected to the controller 123, and is configured to receive a control signal from the controller 123. Each drain or source of the switching element is connected to a stator winding of the drive motor 122. The switching elements Q1-Q6 receive control signals from the controller 123 to change the respective conductive states, thereby changing the current applied by the power supply to the stator windings of the drive motor 122. In one embodiment, switching elements Q1-Q6 in 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, BJT, etc.

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 one embodiment, the motor parameter sensing device 124 may be a sampling resistor capable of sensing the phase current of the motor. In one embodiment, the motor parameter sensing device 124 may also be a device that senses motor current through a magnetic field. In one embodiment, the controller 123 may use one or both of the rotor position and phase current parameters in estimating the thrust exerted by the user on the handle assembly.

An angle detection device 125 for detecting an inclination angle of a plane on which the mower 100 travels with respect to a horizontal plane, such as an angle θ shown in fig. 3. In one embodiment, the angle detection device 125 may be an attitude sensor. The attitude sensor may be composed of a gyroscope, an accelerometer, and a geomagnetic meter, and is capable of measuring three attitude angles of the mower 100 in relation to the body coordinate system and the ground coordinate system, namely, a Yaw angle Yaw, a Pitch angle Pitch, and a Roll angle Roll, respectively. The controller 123 can then determine the tilt angle θ based on the three attitude angles.

To facilitate an understanding of the principle by which the controller 123 estimates the thrust of the user, we can perform a stress analysis at any point on the mower 100. As shown in FIG. 3, the pushing force exerted by a human hand on the mower is as followsThe driving force of the motor generated by driving motor 122 is +.>The frictional resistance to be applied to the traveling wheels of the mower 100 is +.>The weight component that constitutes an obstacle to the forward movement of mower 100 is +>The resultant force applied to the mower 100 in the advancing direction is +.>. Thus, all forces experienced by mower 100 at any instant satisfy the following force balance relationship: />. Wherein the rolling friction resistance of the wheelComponent of gravity->Resultant force->Where a is the acceleration of mower 100 in the forward direction, +.>For the weight of the mower->Coefficient of friction. The components of frictional resistance and gravity may be collectively referred to as the resistance of the mower in the current operating environment. The force balance relationship of the heald mower is as follows:

in the present embodiment, neither the sliding friction nor the change in the rolling friction coefficient is considered. In addition, as the mower advances, the weight of the mower-related device increases, so does the weight M of the mower, and in this embodiment, the average of the weight of the mower at different times may be taken as the weight M and substituted into the force balance relationship. The controller 123 may construct a thrust observation module according to the force balance relationship, and input the parameters detected by the motor parameter detecting means 124 as input parameters into the thrust observation model, thereby determining the user thrust. Different model construction strategies may be employed to construct the thrust vectoring model, which is not limited in this embodiment.

In one embodiment, the controller 123 may determine the rotational speed of the drive motor 122 based on the motor rotor position or the motor rotational speed based on the phase current. Further, the controller 123 may input the motor rotation speed and the operating current as input parameters into the thrust observation model to calculate the magnitude of the thrust.

In one embodiment, the controller 123 may rootAnd constructing a relation model of working current of the motor, namely phase current, rotating speed and resultant force born by the mower according to the thrust observation model, further determining resultant force according to the working current and the rotating speed, and determining thrust according to the difference value of the resultant force and the resistance. When the thrust observation model is constructed, the observation model of resultant force, motor speed and phase current can be constructed by utilizing the relation between the motor rotation speed and acceleration and the relation between the rolling friction force and the motor speed. In one embodiment, the relationship model of the phase current, the rotating speed and the resultant force applied by the mower determined according to the thrust observation model is thatWherein->For the motor speed>For the operating current of the motor, ">Is a coefficient determined by mower system parameters and environmental parameters. The controller 123 can determine the resultant force +_ applied to the mower based on the rotational speed and the operating current of the motor>Or the rotational speed can be determined according to the working current and then the resultant force can be determined by combining the working current>. Furthermore, the thrust +.>。

In the mower walking control system, in the process of controlling the driving motor to rotate, the rotor position or phase current of the motor needs to be detected, and the thrust of a user can be estimated by constructing a thrust observation model and utilizing the rotor position and the phase current, so that the thrust of the user can be estimated without adding other detection devices or elements. In addition, as the control technology of the mower walking control system is mature, the accuracy of parameters detected in the system can be ensured, and the accuracy of thrust estimation is also ensured.

In the process of constructing a thrust observation model and estimating the thrust of a user by using the rotor position and the phase current, an attitude sensor is generally used to detect the tilt angle θ. The attitude sensor comprises three instruments including a gyroscope, an accelerometer and a geomagnetic meter, and the inclination angle theta is calculated by detecting three angles. The adopted instruments are more, the detected parameters are more, and the inclination angle calculation process is complex.

In one embodiment, the present application analyzes acceleration of the mower in the work plane for simple, quick and accurate acquisition of the tilt angle θ. As shown in fig. 4, acceleration in the advancing direction of the mower 100Equal to the forward acceleration of the mower>And the component of the gravitational acceleration in the advancing direction of the mower +.>The sum, i.e.)>. Wherein, the forward acceleration of the mower is +.>Wherein->For the wheel speed +.>For the wheel radius, ω is the wheel angular velocity, +.>For driving the motor angular velocity +.>For speed ratio->Is the motor speed. The controller 123 can determine the rotational speed of the motor based on the rotor position and/or the phase current of the drive motor>Whereby the forward acceleration of the mower is +.>It can be determined.

Since the axis direction of the accelerometer is parallel to the advancing direction of the mower, the accelerometer can be used for measuring the acceleration of the advancing direction of the mower. Under different walking surfaces, such as level ground, downhill and uphill conditions +.>And->The relationship of (2) can be expressed as:

from the above, only the acceleration in the advancing direction of the mower needs to be determinedThe tilt angle θ can be calculated. In this embodiment, an accelerometer may be used to measure the acceleration +.>. Thereby the inclination angle can be determined。

In one embodiment, the tilt angleAcceleration in the direction also perpendicular to the advancing direction of the mower>And (5) correlation. In this embodiment +.>And->The relationship of (2) can be expressed as:

from the above, under different walking surfaces,and->Is different. But->And dip angle->Is fixed in relation toThus can utilize +.>And dip angle->Relation calculation of +.>And use +.>And->The relation of (a) is different to determine +.>The calculation mode of (2) is as follows:

in this embodiment, an accelerometer may be used to measure acceleration in the forward direction of the mowerAnd acceleration in a direction perpendicular to the advancing direction of the mower +.>Determining the tilt angle->。

In this embodiment, the user thrust can be accurately estimated by only using the accelerometer and the detection parameters commonly used in the walking control system, namely, the rotor position and/or the phase current, without setting the high-cost and high-requirement detection devices such as the acceleration sensor and the gesture sensor. The accuracy of thrust estimation is ensured while the cost is reduced.

The torque to speed control also needs to integrate the elapsed time, so that the speed response has hysteresis, drag or blockage is brought to the self-walking control, and the comfort is low. In the embodiment of the application, after the user thrust is estimated, the driving force of the motor may be changed, that is, the output torque of the motor may be changed, based on the force balance relationship. Therefore, the driving force can be changed in real time in response to the change of the driving force, so that the self-propelled control process is smoother and smoother, and the user comfort is higher.

In the present embodiment, the process of changing the motor output torque by the controller 123 in response to the user thrust may be applied to the FOC control or the BLDC control or the control manner of the combination of both.

Referring to fig. 5, the walk control method of the walk-behind mower includes the steps of:

s101, detecting the rotor position and/or the working current of the driving motor.

In one embodiment, the rotational speed of the motor may be determined based on the rotor position and/or operating current of the motor.

S102, constructing a thrust observation model according to the current stress balance relation of the mower.

S103, taking the rotating speed and the working current as input parameters of a thrust observation model to determine thrust.

It can be understood that the rotational speed and the working current are used as input parameters to be input into the thrust observation model to obtain resultant force, and further the resultant force, the thrust and the resistance can be relatedDetermining thrust->Is a value of (2).

S104, changing the output torque of the motor according to the thrust and stress balance relation.

Referring to fig. 6, the walk control method of the walk-behind mower includes the steps of:

s201, detecting a rotor position and/or an operating current of the drive motor.

In one embodiment, the rotational speed of the motor may be determined based on the rotor position and/or operating current of the motor.

S202, detecting acceleration of the mower in at least one direction in the current working environment.

S203, determining the inclination angle of the mower relative to the horizontal plane according to the acceleration.

S204, constructing a thrust observation model according to the current stress balance relation of the mower.

S205, taking the rotating speed and the working current as input parameters of a thrust observation model to determine resultant force.

S206, calculating the thrust according to the relation among the resultant force, the thrust and the resistance and the inclination angle.

It can be understood that the rotational speed and the working current are used as input parameters to be input into the thrust observation model to obtain resultant force, and further the resultant force, the thrust and the resistance can be relatedDetermining thrust->Is a value of (2).

S207, changing the output torque of the motor according to the thrust and stress balance relation.

Note that the above is only a preferred embodiment of the present application and the technical principle applied. Those skilled in the art will appreciate that the present application is not limited to the particular embodiments described herein, but is capable of numerous obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the present application. Therefore, while the present application has been described in connection with the above embodiments, the present application is not limited to the above embodiments, but may include many other equivalent embodiments without departing from the spirit of the present application, the scope of which is defined by the scope of the appended claims.

Claims (10)

1. A power assisted work machine comprising:

the host machine comprises a walking assembly and a driving motor for driving the walking assembly;

a handle device connected to the host;

wherein:

the handle device comprises:

an operating member including a grip portion for a user to grip;

further comprises:

motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor;

an angle detection device configured to detect an inclination angle of a working surface of the power-assisted working machine with respect to a horizontal plane;

a controller configured to estimate a push-pull force exerted on the handle arrangement based on the rotor position and/or the operating current and the tilt angle.

2. The power assisted working machine of claim 1 wherein the controller is configured to: and determining the rotating speed of the motor according to the rotor position.

3. The power assisted working machine of claim 2 wherein the controller is configured to: constructing a thrust observation model according to the current stress balance relation of the working machine with the power assistance; and adopting the rotating speed and the working current as input parameters of the thrust observation model to determine the push-pull force.

4. A power assisted working machine according to claim 3 wherein the force balance relationship includes at least the thrust force, the driving force of the driving motor, the resistance of the power assisted working machine in the current working environment and the resultant force experienced by the power assisted working machine.

5. The power assisted working machine of claim 4 wherein the controller is configured to: constructing a relation model of the working current, the rotating speed and the resultant force according to the thrust observation model; determining the resultant force according to the operating current and the rotational speed; the push-pull force is determined from the difference between the resultant force and the resistance force.

6. A boosted mower comprising:

the host machine comprises a walking assembly and a driving motor for driving the walking assembly;

a handle device connected to the host;

wherein:

the handle device comprises:

an operating member including a grip portion for a user to grip;

further comprises:

motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor;

an angle detection device configured to detect an inclination angle of a working surface of the power-assisted working machine with respect to a horizontal plane;

a controller configured to estimate a push-pull force exerted on the handle arrangement based on the rotor position and/or the operating current and the tilt angle.

7. The assisted mower of claim 6, wherein the controller is configured to: constructing a thrust observation model according to the current stress balance relation of the back-walking mower; and adopting the rotating speed and the working current as input parameters of the thrust observation model to determine the push-pull force.

8. The assisted mower of claim 7 wherein said force balance relationship comprises at least said thrust force, a driving force of said driving motor, a resistance of said walk-behind mower in a current operating environment, and a resultant force experienced by said walk-behind mower.

9. The assisted mower of claim 8, wherein the controller is configured to: constructing a relation model of the working current, the rotating speed and the resultant force according to the thrust observation model; determining the resultant force according to the operating current and the rotational speed; the push-pull force is determined from the difference between the resultant force and the resistance force.

10. The utility model provides a force application estimation method suitable for a mower, wherein the mower comprises a host machine, a walking assembly and a driving motor for driving the walking assembly; a handle device connected to the host; wherein: the handle device comprises: an operating member including a grip portion for a user to grip; further comprises: motor parameter detection means arranged to detect a rotor position and/or an operating current of the drive motor; an angle detection device configured to detect an inclination angle of a work surface of the walk-behind mower with respect to a horizontal plane; the estimation method comprises the following steps:

constructing a thrust observation model according to the current stress balance relation of the back-walking mower;

the rotor position and/or the working current are used as input parameters of the thrust observation model to determine the resultant force applied to the mower and calculate the push-pull force applied to the handle device according to the resultant force and the resistance applied to the mower.