Patent Description:
In the related art, in a crane including a boom, when a suspended load is lifted from the ground, that is, when the suspended load is dynamically lifted off, a work radius is increased due to deflection of the boom, so that "load swing" in which the suspended load swings in a horizontal direction has been a problem (see <FIG>).

For the purpose of preventing load swing at the time of dynamic lift-off, for example, a vertical dynamic lift-off control device described in Patent Literature <NUM> is configured to detect the rotation speed of the engine by an engine rotation speed sensor and correct the hoisting operation of the boom to a value according to the engine rotation speed.

Patent Literature <NUM> discloses that in a case in which a hanging load is vertically hung and released with a crane having either a jib or a boom which can be raised or fallen. The disclosure of Patent Literature <NUM> can also be applied to a case in which the long hanging load <NUM> is raised from its fallen state to its vertical state so as to be hung-up and released. A control device has a control means for performing automatically the raising of the jib or boom and the winding-up or down of the winding-up rope in cooperation with each other in response to their initial states. In case that the initial angle of the jib or boom is large or small, it is controlled in such a way as a rate of variation of the hanging load DELTA T applied to the winding-up rope becomes constant and then it has means for positioning the extreme end of the jib or boom on the vertical line passing through a center of gravity of the hanging load. With such a control device as above, the hanging load is not oscillated and a smooth vertical releasing is carried out. An entire long hanging load is vertically hung up and released from the ground after its vertical releasing without displacing the position of the other end from its fallen state. This document discloses the preamble of claim <NUM>.

Patent Literature <NUM> discloses crane making it possible to obtain operability and vibration suppression effect corresponding to an operating state. A crane calculates the resonance frequency of the fluctuation of a suspended load determined from the hanging length of a main wire rope or a sub wire rope, generates a control signal for a swing hydraulic motor and an undulating hydraulic cylinder, which are actuators, in accordance with the operation of a turning operation tool, a hoisting operation tool and the like, and generates a filtering control signal for the actuators in which a frequency component in an arbitrary frequency range has been attenuated from the control signal at an arbitrary ratio in reference to the resonance frequency. When the swing hydraulic motor and the undulating hydraulic cylinder are controlled by the operation of the respective operation tool and when the swing hydraulic motor and the undulating hydraulic cylinder are controlled regardless of the operation of the respective operation tool, the frequency range of the frequency component to be attenuated and the attenuation ratio are switched to different settings.

Meanwhile, in the conventional dynamic lift-off control device including Patent Literature <NUM>, in order to keep the work radius constant, control is performed using a winch actuator and a derricking actuator in combination. Therefore, there is a problem that it takes time to perform the dynamic lift-off due to complicated control.

Therefore, an object of the present invention is to provide a dynamic lift-off control device capable of quickly dynamically lifting off the suspended load while suppressing the load swing, and a crane including the dynamic lift-off control device.

According to a first aspect the present disclosure provides a dynamic lift-off control device in accordance with independent claim <NUM>. According to a second aspect the present disclosure provides a crane in accordance with independent claim <NUM>. Further aspects are set forth in the dependent claims, the drawings, and the following description.

In an aspect of the dynamic lift-off control device not according to the present invention, the dynamic lift-off control device is mounted on a crane including a boom and a winch for winding a wire rope and that controls dynamic lift-off of a suspended load, wherein the dynamic lift-off control device includes a load detection unit that detects a load acting on the boom, and a control unit that controls a winding action of the winch and a hoisting action of the boom, and the control unit controls the hoisting of the boom by using a control signal, which is generated on the basis of the change over time in the value detected by the load detection unit and to which a filter for dampening a frequency component in a predetermined range is applied, to suppress swaying of the suspended load.

According to the present invention, it is possible to provide the dynamic lift-off control device capable of quickly dynamically lifting off the suspended load while suppressing the load swing, and the crane including the dynamic lift-off control device.

Hereinafter, an example of an embodiment according to the present invention will be described with reference to the drawings. However, the components described in the following embodiments are merely examples, and the technical scope of the present invention is limited by the claims.

In the present embodiment, examples of the mobile crane include a rough terrain crane, an all-terrain crane, and a truck crane. Hereinafter, a rough terrain crane will be described as an example of the work vehicle according to the present embodiment, but the dynamic lift-off control device according to the present invention can also be applied to another mobile crane. Furthermore, the dynamic lift-off control device according to the present invention can also be applied to a crawler crane or a tower crane.

First, the configuration of the mobile crane will be described with reference to <FIG>. As illustrated in <FIG>, a rough terrain crane <NUM> of the present embodiment includes a vehicle body <NUM> serving as a main body portion of a vehicle having a traveling function, outriggers <NUM> provided at four corners of the vehicle body <NUM>, a turning table <NUM> attached to the vehicle body <NUM> so as to be horizontally turnable, and a boom <NUM> attached to the rear of the turning table <NUM>.

The outrigger <NUM> can be slidably extended/slidably stored outward in the width direction from the vehicle body <NUM> by expanding and contracting the slide cylinder, and can be jack-extended/jack-stored in the vertical direction from the vehicle body <NUM> by expanding and contracting the jack cylinder.

The turning table <NUM> includes a pinion gear to which power of the turning motor <NUM> is transmitted, and the pinion gear meshes with a circular gear provided on the vehicle body <NUM> to turn about a turning shaft. The turning table <NUM> includes an operator's seat <NUM> disposed on the right front side and a counterweight <NUM> disposed on the rear side.

Furthermore, a winch <NUM> for winding up and winding down a wire rope <NUM> is disposed behind the turning table <NUM>. The winch <NUM> rotates in two directions of a winding up direction (winding direction) and a winding down direction (unwinding direction) by rotating a winch motor <NUM> in the forward direction or the reverse direction.

The boom <NUM> is configured in a telescopic manner by a proximal end boom <NUM>, an intermediate boom (or booms) <NUM>, and a distal end boom <NUM>, and is expanded and contracted by a telescopic cylinder <NUM> disposed therein. A sheave is disposed on a most distal boom head <NUM> of the distal end boom <NUM>, and the wire rope <NUM> is hung on the sheave to suspend a hook <NUM>.

A proximal end portion of the proximal end boom <NUM> is rotatably attached to a support shaft installed on the turning table <NUM>. The proximal end boom <NUM> can be is derricked up and down about a support shaft as a rotation center. A derricking cylinder <NUM> is stretched between the turning table <NUM> and the lower face of the proximal end boom <NUM>. By extending and contracting the derricking cylinder <NUM>, the entire boom <NUM> is derricked.

Next, a configuration of a control system of a dynamic lift-off control device D of the present embodiment will be described with reference to a block diagram of <FIG>. The dynamic lift-off control device D is mainly configured by a controller <NUM> as a control unit. The controller <NUM> is a general-purpose microcomputer having an input port, an output port, an arithmetic device, and the like. The controller <NUM> receives an operation signal from operation levers <NUM> to <NUM> (a turning lever <NUM>, a derricking lever <NUM>, a telescopic lever <NUM>, a winch lever <NUM>) and controls the actuators <NUM> to <NUM> (a turning motor <NUM>, the derricking cylinder <NUM>, the telescopic cylinder <NUM>, the winch motor <NUM>) via a control valve not illustrated.

Furthermore, the controller <NUM> of the present embodiment is connected to a dynamic lift-off switch 20A for starting or stopping the dynamic lift-off control, a winch speed setting means 20B for setting the speed of the winch <NUM> in the dynamic lift-off control, a pressure measuring instrument <NUM> as a load detection unit for detecting a load acting on the boom <NUM>, a posture measuring means <NUM> for detecting posture information of the boom <NUM>, and a rotation speed measuring instrument <NUM> for measuring the rotation speed of the winch <NUM>. The posture measuring means <NUM> corresponds to an example of a posture detection unit.

The dynamic lift-off switch 20A is an input device for instructing to start or stop the dynamic lift-off control. For example, the dynamic lift-off switch 20A may be added to a safety device of the rough terrain crane <NUM>. Preferably, the dynamic lift-off switch 20A is disposed at the operator's seat <NUM>.

The winch speed setting means 20B is an input device that sets the speed of the winch <NUM> in the dynamic lift-off control. The winch speed setting means 20B may be of a type of selecting an appropriate speed from preset speeds, or of a type of inputting with a numeric keypad. Further, the winch speed setting means 20B may be configured to be added to the safety device of the rough terrain crane <NUM>, as in the dynamic lift-off switch 20A. The winch speed setting means 20B is preferably disposed at the operator's seat <NUM>. By adjusting the speed of the winch <NUM> by the winch speed setting means 20B, the time required for the dynamic lift-off control can be adjusted.

The pressure measuring instrument <NUM> as a load detection unit is a measuring instrument that measures a load acting on the boom <NUM>. The pressure measuring instrument <NUM> is, for example, a pressure gauge that measures the pressure acting on the derricking cylinder <NUM>. A pressure signal measured by the pressure measuring instrument <NUM> is transmitted to the controller <NUM>.

The rotation speed measuring instrument <NUM> is installed near the rotation axis of the winch (drum) <NUM> to measure the number of rotations (rotation speed) of the winch (drum) <NUM>. The number of rotations (rotation speed) measured by the rotation speed measuring instrument <NUM> is transmitted to the controller <NUM> and used for calculating the winch winding-up speed and the length of the wire rope.

The posture measuring means <NUM> is a measuring instrument that detects posture information of the boom <NUM>, and includes a derricking angle meter <NUM> that measures a derricking angle of the boom <NUM> and a derricking angular velocity meter <NUM> that measures a derricking angular velocity. Specifically, the derricking angle meter <NUM> is, for example, a potentiometer. The derricking angular velocity meter <NUM> is, for example, a stroke sensor attached to the derricking cylinder <NUM>. The derricking angle signal measured by the derricking angle meter <NUM> and the derricking angular velocity signal measured by the derricking angular velocity meter <NUM> are transmitted to the controller <NUM>.

The controller <NUM> is a control unit that controls operations of the boom <NUM> and the winch <NUM>. When the dynamic lift-off switch 20A is turned ON to wind up the winch <NUM> to dynamically lift off the suspended load, the controller <NUM> predicts the amount of change in the derricking angle of the boom <NUM> on the basis of the change over time in the load measured by the pressure measuring instrument <NUM> as the load detection unit, and hoists the boom <NUM> to compensate for the predicted amount of change.

More specifically, the controller <NUM> corresponds to an example of a control unit, and includes, as function units, a selection function unit 40a of a characteristic table or a transfer function and a dynamic lift-off determination function unit 40b that stops the dynamic lift-off control by determining whether the dynamic lift-off has actually been performed.

The characteristic table or transfer function selection function unit 40a receives the input of the initial value of the pressure from the pressure measuring instrument <NUM> as the load detection unit and the initial value of the derricking angle from the derricking angle meter <NUM> as the posture detection unit, and determines the characteristic table or transfer function to be applied. Here, as the transfer function, a relationship using the linear coefficient a can be applied as follows.

First, as shown in the load-derricking angle graph of <FIG>, it is found that the load and the derricking angle (distal end angle with respect to the ground) have a linear relationship when the boom distal end position is adjusted so as to be always directly above the suspended load so as not to cause the load swing. Assuming that the load Load<NUM> changes to Load<NUM> during the dynamic lift-off from time t<NUM> to time t<NUM>, the relationship between the derricking angle θ and the load Load, the relationship between the derricking angle θ<NUM> and the load Load<NUM>, and the relationship between the derricking angle θ<NUM> and the load Load<NUM> are expressed by the following equations.

The difference between the two equations is expressed by the following equation by a difference equation.

In order to control the derricking angle, it is necessary to give a derricking angular velocity represented by the following equation. <MAT> where, a is a constant (linear coefficient).

That is, in the derricking angle control, the change over time (differential) in the load is input.

The lifting off of the dynamic lift-off determination function unit 40b monitors time series data of the value of the load calculated from the pressure signal from the pressure measuring instrument <NUM> as the load detection unit, and determines the presence or absence of the dynamic lift-off. A method of the dynamic lift-off determination will be described later with reference to <FIG>.

Next, with reference to a block diagram of <FIG>, an input/output relationship between all elements including the dynamic lift-off control according to the present embodiment will be described in detail. First, a load change calculation unit <NUM> calculates a load change on the basis of time series data of a load measured by the pressure measuring instrument <NUM> as a load detection unit. The calculated load change is input to a target shaft speed calculation unit <NUM>. The input/output relationship in the target shaft speed calculation unit <NUM> will be described later with reference to <FIG>.

The target shaft speed calculation unit <NUM> calculates a target shaft speed on the basis of the initial value of the derricking angle, the set winch speed, and the input load change. Here, the target shaft speed is a target derricking angular velocity (and, although not required, the target winch speed). The calculated target shaft speed is input to a shaft speed controller <NUM>. The first half control up to this point is processing related to the dynamic lift-off control of the present embodiment.

Thereafter, the operation amount is input to a control target <NUM> via the shaft speed controller <NUM> and a shaft speed operation amount conversion processing unit <NUM>. The latter half control of is a process related to normal control, and is feedback-controlled on the basis of the measured derricking angular velocity.

Next, an input/output relationship between elements in the target shaft speed calculation unit <NUM> of the dynamic lift-off control in particular will be described with reference to a block diagram of <FIG>. First, an initial value of the derricking angle is input to a characteristic table/transfer function selection function unit <NUM> (40a). In the selection function unit <NUM>, the most appropriate constant (linear coefficient) a is selected using the characteristic table (LookupTable) or the transfer function (equation).

Then, numerical differentiation (differentiation with respect to time) of the load change is performed in a numerical differentiation unit <NUM>, and the target derricking angular velocity is calculated by multiplying the result of the numerical differentiation by the constant a. That is, the target derricking angular velocity is calculated by executing the calculation of (equation <NUM>) described above. As described above, the control of the target derricking angular velocity is feedforward-controlled using the characteristic table (or the transfer function).

Next, an operation of applying a band removal filter that dampens a predetermined band when generating the derricking angular velocity control signal on the basis of the target derricking angular velocity (the derricking angular velocity target value) will be described with reference to the block diagram of <FIG>. First, a first control signal generation unit <NUM> instructs a crane <NUM> (winch motor <NUM>) to be controlled to maintain the speed of the winch <NUM> at a constant rotational speed γd by the start command. The winch speed control is feedback-controlled on the basis of the measured rope length. On the other hand, the measured rope length is used for the dynamic lift-off determination to trigger activation of a filter application unit <NUM>.

Thereafter, a second control signal generation unit <NUM> instructs a PID control unit <NUM> on the target derricking angular velocity on the basis of the target derricking angle θd and the measured derricking angular velocity. The PID control unit <NUM> generates a derricking angular velocity control signal by PID control. That is, the derricking angular velocity control signal is generated on the basis of the difference between the measured derricking angular velocity and the target derricking angular velocity. This derricking angular velocity control is feedback-controlled on the basis of the measured load and the measured derricking angular velocity (see <FIG> and <FIG>). On the other hand, the measured load (pressure value) is used for the dynamic lift-off determination to trigger activation of the filter application unit <NUM>.

Then, the controller <NUM> determines the presence or absence of the dynamic lift-off on the basis of the time series data of the measured rope length or the time series data of the measured load (pressure value). When the controller <NUM> determines that the dynamic lift-off has been completed, the filter application unit <NUM> applies a band removal filter that dampens a predetermined band to the derricking angular velocity control signal. When the controller <NUM> determines that the dynamic lift-off is not completed, the filter application unit <NUM> does not apply the band removal filter to the derricking angular velocity control signal. Note that the filter application unit <NUM> may always apply the band removal filter to the derricking angular velocity control signal regardless of whether the dynamic lift-off is completed.

Then, a band removal filter (band stop filter) is applied when the derricking angular velocity control signal is generated. The band removal filter has a frequency characteristic in which most frequencies are passed as it is, but only frequency components in a predetermined range are dampened to a very low level. The band removal filter preferably includes a notch filter having a narrow stop band. In the following embodiment, a specific example in which the notch filter is applied will be described, but this is an example, and other band removal filters can also be used.

Here, characteristics of the notch filter are illustrated in an explanatory diagram of <FIG>. As illustrated in <FIG>, when the notch filter is applied, the amplitude is greatly dampened before and after the center frequency. When the notch filter is applied, a phase delay characteristic is obtained at the lower frequency than the center frequency, and a phase advance characteristic is obtained at the higher frequency. The natural frequency of the boom <NUM> varies depending on the state of the boom <NUM>. The state of the boom <NUM> is, for example, a length of the boom <NUM> and/or a telescopic pattern of the boom <NUM>. That is, when the telescopic pattern of the boom <NUM> is different even when the length of the boom <NUM> is the same, the natural frequency of the boom <NUM> is different. Here, in the mobile crane, it is preferable to calculate and measure the natural frequency for each length and/or for each telescopic pattern of the boom <NUM> in advance and store the natural frequency. That is, the storage unit of the mobile crane preferably stores the natural frequency in association with the length and/or the telescopic pattern of the boom <NUM>. It is preferable that the natural frequency of the work vehicle is actually measured for each vehicle when the work vehicle is shipped from the factory.

Next, the overall flow of the dynamic lift-off control of the present embodiment will be described with reference to the flowchart of <FIG>.

First, the operator presses the dynamic lift-off switch 20A to start the dynamic lift-off control (START). At this time, the target speed of the winch <NUM> is set via the winch speed setting means 20B before or after the start of the dynamic lift-off control in advance. Then, the controller <NUM> starts winch control at the target speed (step S1). This target speed is, for example, a constant speed.

Next, at the same time as the winch <NUM> is wound up, measurement of a suspended load (detection of a derricking cylinder pressure) is started by the pressure measuring instrument <NUM> as a load detection unit, and a load value (pressure value) is input to the controller <NUM> (step S2).

Next, the selection function unit 40a receives the input of the initial value of the load value (pressure value) and the initial value of the derricking angle from the derricking angle meter <NUM> as the posture detection unit, and determines the characteristic table or the transfer function to be applied (step S3). Next, the controller <NUM> calculates the derricking angular velocity on the basis of the applied characteristic table or transfer function and the load change (step S3). That is, the derricking angular velocity control is performed by the feedforward control.

Next, a time-series change in the rope length is detected for use in the subsequent dynamic lift-off determination (step S4). Specifically, the controller <NUM> receives a measurement result of the rotation speed measured by the rotation speed measuring instrument <NUM> and the posture (derricking angle, derricking angular velocity, boom length) measured by the posture measuring means <NUM> to calculate the rope length, and the time-series change is monitored.

Then, the controller <NUM> determines the presence or absence of the dynamic lift-off on the basis of the time series data of the measured load and/or rope length (step S5). The determination method will be described later. As a result of the determination, when the dynamic lift-off has not been performed (NO in step S5), the process returns to step S3 to repeat the feedforward control based on the load (steps S3 to S5).

As a result of the determination, when the dynamic lift-off is completed (YES in step S5), the notch filter is activated when the gentle stop control is performed (step S6). That is, the controller <NUM> applies the notch filter (band removal filter) when generating the derricking angular velocity control signal on the basis of the derricking angular velocity target value in the gentle stop of the derricking action after the dynamic lift-off. At this time, a notch filter according to the length of the boom <NUM> is selected as the notch filter to be applied. Note that the timing at which the notch filter is applied can be applied only for a predetermined time or for a time for which a prescribed number of times of vibration is measured from the time at which it was determined that the dynamic lift-off has been performed. The generated derricking angular velocity control signal is used in the next step S7.

Next, the dynamic lift-off control is gently stopped using the derricking angular velocity control signal after the notch filter is applied (step S7). That is, the hoisting action of the boom <NUM> by the derricking cylinder <NUM> is stopped while gradually reducing the speed (step S7). The gentle stop can be realized, for example, by linearly decreasing the angular velocity. Here, in the present embodiment, when the hoisting drive is stopped while reducing the speed (that is, when the derricking angular velocity is gently stopped), the vibration is suppressed by moving the boom <NUM> so as to avoid the natural frequency of the boom <NUM>.

Here, the natural frequency of the boom <NUM> varies depending on the boom length, but in the present embodiment, the natural frequency can be expressed by a function on the basis of the measurement data, so that it is possible to be adapted to an any boom length and/or a telescopic pattern. Furthermore, in the present embodiment, the rotational speed of the winch <NUM> and the derricking angle of the derricking cylinder <NUM> are controlled, and one feature is that the winch <NUM> is operated at a constant speed and only the derricking angle is required to be gently stopped as a control target.

Finally, the rotational driving of the winch <NUM> by the winch motor is stopped while reducing the speed (step S8). In this way, the dynamic lift-off control is ended (END).

Next, a method of the dynamic lift-off determination of the present embodiment will be described with reference to the graph of <FIG>. In the present embodiment, the controller <NUM> monitors time series data of the measured load while winding up the winch <NUM> in the dynamic lift-off control, and determines that the dynamic lift-off has been performed by capturing the first maximum value of the time series data.

More specifically, as shown in <FIG>, in general, the time series data of the load data overshoots at the next moment after the dynamic lift-off has been performed, undershoots further, and then transitions to continue to vibrate. Therefore, it is possible to determine that the dynamic lift-off has been performed by capturing the time of the first peak of vibration, that is, the first maximum value. However, actually, it is conceivable that at the time when it is determined that the dynamic lift-off is performed, that is, at the time when the first maximum value is recorded, the slight overshoot due to the inertial force occurs.

The load data illustrated in <FIG> is a measurement value of the pressure measuring instrument <NUM> or a value (hereinafter, it is simply referred to as a "measurement value of the pressure measuring instrument <NUM>") calculated on the basis of the measurement value of the pressure measuring instrument <NUM>. That is, the measurement value of the pressure measuring instrument <NUM> changes (vibrates) so as to repeat vertical movement after the dynamic lift-off has been performed. Such a change (vibration) in the measurement value of the pressure measuring instrument <NUM> is affected by the natural frequency of the boom <NUM>. Therefore, the natural frequency of the boom <NUM> can be calculated on the basis of the change (vibration) in the measurement value of the pressure measuring instrument <NUM>. The natural frequency thus calculated may be applied to the above-described band removal filter (notch filter) as the center frequency.

In addition to the above method, the controller <NUM> of the present embodiment can be configured to determine the dynamic lift-off on the basis of a change over time in the measured load and a change over time in the measured rope length when dynamically lifting off the suspended load by winding up the winch <NUM> in the dynamic lift-off control.

Specifically, when dynamically lifting off the suspended load by winding up the winch <NUM>, the controller <NUM> as the control unit determines that the dynamic lift-off has been performed when a rope length is shorter than a threshold value set from an initial rope length with a rope length at the time when the measured load starts changing as the initial rope length.

Alternatively, when dynamically lifting off the suspended load by winding up the winch <NUM>, the controller <NUM> as the control unit determines that the dynamic lift-off has been performed when the winding speed, which is the change over time in the rope length, is faster than a threshold value set from an initial winding speed with the change over time in the rope length at the time when the measured load starts to change as the initial winding speed.

Next, effects obtained by the dynamic lift-off control device D of the present embodiment will be listed and described.

That is, in the dynamic lift-off control device D of the present embodiment, focusing on the linear relationship between the load and the derricking angle-compensation amount, it is possible to quickly dynamically lift off the suspended load by performing the feedforward control on the basis of the change over time in the load value without performing the complicated feedback control as in the related art.

In the dynamic lift-off control device D of the present embodiment, the vibration is suppressed by moving the boom <NUM> so as to avoid the natural frequency of the boom <NUM> using the function of the natural frequency according to the boom length in particular, when it is determined that the dynamic lift-off has been performed and the derricking angular velocity is gently stopped. Specifically, for example, the vibration is suppressed while the boom <NUM> is gently stopped by an operation of temporarily increasing and then decreasing the hoisting speed of the boom.

(<NUM>) Preferably, controller <NUM> calculates a dampening predetermined band on the basis of the natural frequency of boom <NUM> according to the length of boom <NUM>. With such a configuration, by dampening the band around the actual natural frequency of the boom <NUM>, it is possible to efficiently suppress the vibration and quickly end the dynamic lift-off control.

(<NUM>) Further, the controller <NUM> applies the band removal filter only for a predetermined time after determining that the dynamic lift-off has been performed. With such a configuration, it is possible to prevent the phase of the derricking angular velocity from being delayed in a scene other than the dynamic lift-off.

(<NUM>) In addition, it is preferable that the posture measuring means <NUM> that detects posture information of the boom <NUM> is further included, and the controller <NUM> selects a corresponding characteristic table or transfer function on the basis of the initial value of the measured posture of the boom <NUM> and the initial value of the measured load, and obtains the amount of change in the derricking angle of the boom <NUM> from the change over time in the measured load using the characteristic table or the transfer function.

With this configuration, at the start of the dynamic lift-off control, the winch <NUM> is wound up at a constant speed, and the amount of control of the hoisting angle is calculated from the characteristic table (or the transfer function) in accordance with the load change to perform the feedforward control, so that the dynamic lift-off can be promptly performed without the load swing. In addition, since the number of parameters to be adjusted is reduced, adjustment at the time of shipment can be quickly and easily performed.

(<NUM>) Furthermore, it is preferable that the controller <NUM> is configured to wind up the winch <NUM> at a constant speed when dynamically lifting off the suspended load by winding up the winch <NUM>. With this configuration, the influence of the disturbance such as the inertial force is suppressed, and the response (measured load value) is stabilized, so that the dynamic lift-off determination can be easily made.

(<NUM>) Preferably, the controller <NUM> is configured to adjust the time required for the dynamic lift-off by adjusting the speed of the winch <NUM> when dynamically lifting off the suspended load by winding up the winch <NUM>. With this configuration, it is possible to work safely and efficiently by selecting an appropriate speed of the winch <NUM> according to the weight of the suspended load and the environmental conditions.

(<NUM>) Furthermore, the controller <NUM> of the present embodiment is configured to monitor time series data of the measured load and determine that the dynamic lift-off has been performed by capturing the first maximum value of the time series data when dynamically lifting off the suspended load by winding up the winch <NUM>. By performing the control only on the basis of the load in this manner, it is possible to easily and quickly determine the dynamic lift-off.

(<NUM>) In addition, the rough terrain crane <NUM>, which is the mobile crane of the present embodiment, is provided with the above-described dynamic lift-off control device D, so that the rough terrain crane <NUM> is capable of quickly dynamically lifting off the suspended load while suppressing the load swing.

Although the embodiment of the present invention is described in detail with reference to the drawings, the specific configuration is not limited to the embodiment, and a design change that does not depart from the gist of the present invention is included in the present invention.

For example, although not specifically described in the embodiment, the dynamic lift-off control device D of the present invention can be applied to both the case of performing the dynamic lift-off using the main winch as the winch <NUM> and the case of performing the dynamic lift-off using the sub winch.

Claim 1:
A dynamic lift-off control device (D) that is mountable on a crane (<NUM>) including a boom (<NUM>) and a winch (<NUM>) for winding a wire rope (<NUM>) and that is configured to control dynamic lift-off of a suspended load, the dynamic lift-off control device (D) comprising:
a load detection unit (<NUM>) that is configured to detect a load acting on the boom (<NUM>); and
a control unit (<NUM>) that is configured to control a winding action of the winch (<NUM>) and a hoisting action of the boom (<NUM>), whereby
the control unit (<NUM>) is configured to control hoisting of the boom (<NUM>) by using a control signal which is generated on a basis of a change over time in a value detected by the load detection unit (<NUM>) characterised in that a filter (<NUM>) for dampening a frequency component in a predetermined range is applied to the control signal, to suppress swaying of the suspended load, wherein
the control unit (<NUM>) is configured to
calculate an amount of change in a derricking angle of the boom (<NUM>) on a basis of a change over time in the load,
calculate a target derricking angular velocity according to the calculated amount of change, and
generate the control signal on a basis of the target derricking angular velocity.