JPH04303397A - Sensor abnormality detecting device for high place working vehicle - Google Patents

Abstract

PURPOSE:To ensure a safety for a high place working vehicle by detecting an abnormality of a sensor relating to control of a boom of the high place working vehicle so as to control the boom on the safe side. CONSTITUTION:In a flow chart, after control signals for driving a lift solenoid valve and a telescopic solenoid valve are outputted at step ST16, at steps ST17 and ST18, it is judged that a boom rising angle sensor and a boom extension length sensor become abnormal if signals from the boom rising angle sensor and the boom extension length sensor do not vary exceeding predetermined values, and then the boom is controlled on the safe side at step ST4.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is an abnormality detection device for an aerial work vehicle that detects when an abnormality occurs in various sensors that detect the operating state of the boom when the boom of the aerial work vehicle is operated. Regarding.

0002

[Prior Art] Conventionally, when a boom is extended and contracted by operating a boom hoisting operation means and a boom extension and contraction operation means,
An example of an aerial work vehicle in which a loading platform attached to the tip of a boom is automatically controlled to fall within an allowable operating range is disclosed in Japanese Patent Laid-Open No. 62-211296.

[0003] Hereinafter, the above-mentioned conventional aerial work vehicle and its control will be specifically explained based on the drawings. In FIG. 2 showing the whole of the aerial work vehicle, 1 is a vehicle body, 2 is a swivel table installed on the vehicle body 1 so as to be horizontally rotatable, and is equipped with a hydraulic system equipped with a pinion 4 that meshes with a fixed large gear 3 on the vehicle body side. It is designed to be driven by a motor 5. 6 is operated by a lift cylinder 7 attached to the swivel base 2, and
It is a boom that is extendable and retractable by a telescope cylinder 8, and a work platform (loading platform) 9 is installed at its tip. An operation panel 10 is attached to the workbench 9, and the operation panel 10 is provided with a lift lever 11 for boom hoisting operation and a telescope lever 12 for boom extension/retraction operation, as shown in the electric control circuit of FIG. A swing lever 13 for operation, a drive lever 14 for running operation, etc. are provided. A potentiometer is attached to each of the lift lever 11, telescope lever 12, swing lever 13, and drive lever 14, and is configured to output a voltage signal corresponding to the operating angle of each lever.

On the other hand, a boom undulation angle sensor 15 is installed near the lift cylinder 7 and is comprised of a potentiometer that operates in response to the stroke of the lift cylinder 7 and outputs a voltage signal corresponding to the undulation angle of the boom 6. There is. Furthermore, a boom extension/contraction length sensor 16 is installed near the telescope cylinder 8 and is comprised of a potentiometer that operates in response to the stroke of the telescope cylinder 8 and outputs a voltage signal corresponding to the extension/contraction length of the boom 6. . In addition, switch SW1 is used for lift operation, telescope operation, and swing operation from the ground side.
, SW2 and SW3 are provided, and these switches are connected to the I/O port of the microcomputer CPU.

The aerial work vehicle also includes a lift solenoid valve 17 that supplies the required pressure oil to the lift cylinder 7.
and a telescope solenoid valve 18 for supplying required pressure oil to the telescope cylinder 8, and a swing solenoid valve 19 for supplying pressure oil from a hydraulic pump (not shown) to the hydraulic motor 5; A drive solenoid valve 20 is provided for supplying necessary pressure oil to a travel motor (not shown) for driving the work vehicle.

Voltage signals output from the potentiometers of the lift lever 11, telescope lever 12, swing lever 13, and drive lever 14, the boom elevation angle sensor 15, and the boom extension/contraction length sensor 1.
The voltage signals output from each of the six potentiometers are converted into digital signals by the AD converter 23 and then output to the microcomputer CPU.

[0007] The microcomputer CPU performs calculations and processes to be described later in accordance with a calculation control program stored in a storage element (not shown), and then outputs control signals for controlling each of the valves. The control signal outputted from the microcomputer CPU is transmitted to the lift solenoid valve 17,
The signal is input to a drive circuit 24 that supplies drive current to each of the telescope solenoid valve 18, the swing solenoid valve 19, and the drive solenoid valve 20.

FIG. 4 shows a control flowchart regarding the boom of a conventional aerial work vehicle. The microcomputer CPU is initialized in step ST1 of the flowchart shown in FIG.
2, the microcomputer CPU takes in the output signals from the boom elevation angle sensor 15 and the boom extension/contraction length sensor 16. Then, in step ST3, the signals output from each of the above sensors fall within a preset range, that is, a predetermined resistance value A as shown in FIG.
It is determined whether the value of the signal based on the value between 1 and A2 is indicated. If the signal from the sensor has a value outside the above range, it is determined that something abnormal has occurred, and step S
Except for outputting a drive signal that causes the telescope cylinder 8 to contract to the telescope solenoid valve 18 as shown at T4, output of other drive signals is stopped. On the other hand, if the signals output from each of the above sensors are within the set range, step ST5 is performed based on each signal.
As shown in the figure, there is a loading platform (work platform) 9 at the tip of the boom 6.
Calculate and detect the position of. In step ST6, signals corresponding to the inclination angles of the lift lever 11 and the telescope lever 12 are input, and in step ST7, the valve drive amounts for the lift solenoid valve 17 and the telescope solenoid valve 18 are calculated based on the output characteristics shown in FIG.
Both solenoid valves 17, 1 based on the drive amount of both valves.
8, a drive signal is output to supply pressure oil to the lift cylinder 7 and telescope cylinder 8, and the boom is operated. In addition, FIG. 5 shows the nonlinear output characteristics of the valve drive signal with respect to the operation signal output from each operation lever when each operation lever is tilted forward (+) or forward (-) from the neutral state. It is something that

[0009] The microcomputer CPU performs step S
At T8, the boom tip position based on the boom attitude, that is, the loading platform position is set in advance at the regulation line LN shown in FIG.
Determine whether it will go outside of 2. As a result of the determination, if it is determined that the boom tip position is not outside the regulation line LN2, the process proceeds to step ST12, whereas if it is determined that the boom tip position is outside the regulation line LN2, the process proceeds to step ST9.

[0010] In step ST9, the lift lever 11
It is determined whether or not the boom 6 is being operated in the direction of lowering it. If it is determined that the boom 6 is being operated in the lowering direction, the process proceeds to step ST10, and if not, the process proceeds to step ST11. In step ST10, the telescope cylinder 8 is regulated in the contraction direction according to the following equation, for example.

[0011]

##EQU1## However, in the above equation, I represents the telescope valve drive amount, Kp represents the proportional gain, KD represents the differential gain, and E represents the deviation from the regulation line LN2.

[0012] Based on the above formula, the amount of drive that will cause the telescope cylinder 8 to retract smoothly to the regulation line LN2 is calculated according to the deviation from the regulation line LN2, that is, the amount by which the boom 6 exceeds the regulation line LN2. .

On the other hand, in step ST11, when the lift lever 11 is not operated in the direction of lowering the boom 6, that is, when the telescope cylinder 8 is extended and crosses the regulation line LN2, the extension of the telescope cylinder 8 is stopped. Calculate change to drive amount. Step ST16
Then, a control signal based on the drive amount calculated in step ST10 or step ST11 is output to the drive circuit 24, and a drive current is applied from the drive circuit 24 to the telescope solenoid valve 18 to control the telescope cylinder 8. , the tip of the boom 6 is controlled so as not to exceed the regulation line LN2.

On the other hand, if it is determined in step ST8 that the position of the loading platform 9 is within the safe working range, then in step ST12, the moving speed of the loading platform 9 is set to the regulated speed for safely moving the loading platform 9. Determine whether it is within the control range. As a result of the judgment, if there is no need to regulate the moving speed of the loading platform 9, the process proceeds to step ST16, while if it is within the speed control range, step ST1
3, a regulation command value for reducing the moving speed of the loading platform 9 to a safe speed is calculated.

[0015] In step ST14, the operation speed (moving speed) is determined based on the operation signal output from each lever.
If it is determined that the actual movement speed of each lever is smaller than the regulation command value, the process directly proceeds to step ST16, while if it is determined that it is larger than the regulation command value, in step ST15, the actual moving speed of each lever is corrected and the safe The lever movement speed is calculated, and in step 16, a control signal for driving the telescope solenoid valve 18 is output to the drive circuit 24 based on the movement speed.

[0016]

[Problems to be Solved by the Invention] In the boom control of the above-mentioned conventional aerial work vehicle, the signals output from the respective potentiometers provided in the boom heave angle sensor 15 and the boom extension/contraction length sensor 16 have a predetermined output. If the range is rising, it is determined that something abnormal has occurred, and a drive signal is output to the telescope solenoid valve 18 to cause the telescope cylinder 8 to contract.
The output of other drive signals is stopped.

However, if the potentiometer becomes stuck and its output signal does not change within the predetermined output range, the boom luffing angle sensor 15 having the potentiometer that is stuck etc. Alternatively, there is a problem that an abnormality in the boom extension/contraction length sensor 16 cannot be detected.

Therefore, in the present invention, a sensor abnormality is determined when the signal output from the boom hoisting angle sensor or the boom extension/contraction length sensor does not change even though the boom hoisting operation means or the boom extension/contraction operation means is being operated. The technical problem to be solved is to safely control the boom.

[0019]

[Means for Solving the Problems] Therefore, the technical means for solving the above problems in the present invention is to provide a swivel platform that is rotatably installed on the vehicle body, which is raised and lowered by the hydraulic drive of a lift cylinder, and a telescope cylinder. A boom that is extended and retracted by hydraulic drive, an operating means for operating the boom to raise and lower and extend and contract, a boom lifting angle sensor that detects the lifting angle of the boom and outputs a signal corresponding to the lifting angle, and a boom lifting angle sensor that detects the lifting angle of the boom and outputs a signal corresponding to the lifting angle. A boom telescoping length sensor detects the telescoping length and outputs a signal corresponding to the telescoping length, and inputs an operation signal corresponding to the operation amount of the boom hoisting operation means and the boom telescoping operation means, and connects the lift cylinder and the telescope. A drive control circuit that outputs a drive signal to each valve that drives the cylinder to operate the boom to raise/lower and extend/retract, and an abnormality detection means to detect an abnormality in the boom lifting/lowering angle sensor and the boom extension/retraction length sensor. In the vehicle sensor abnormality detection device, when there is no change in the signal from the boom hoisting angle sensor or the boom extension/contraction length sensor while the operation signal is being output from the boom hoisting operation means or the boom extension/contraction operation means. The abnormality detection means is configured to stop outputting drive signals other than the drive signal for driving the boom to retract.

[0020]

[Operation] According to the above-described sensor abnormality detection device for a high-altitude work vehicle, the abnormality detection means is configured to detect the boom hoisting angle sensor or the boom in a state where an operation signal is output from the boom hoisting operation means or the boom extension/contraction operation means. When there is no change in the signal from the telescopic length sensor, it is determined that the sensor is abnormal and the output of drive signals other than the drive signal that drives the boom to retract is controlled to be stopped, thereby controlling the boom to the safe side.

[0021]

[Embodiment] Next, an embodiment of the present invention will be described. In addition, in this embodiment, FIG.
3 is an electric control circuit block diagram, FIG. 5 is an output characteristic diagram of a valve drive signal based on the operation signal of the operating lever, and FIG. 6 is a boom raising angle sensor 1.
Since the characteristic diagrams showing the output signal ranges of the boom telescopic length sensor 5 and the boom extension/contraction length sensor 16 are used as common drawings, explanations regarding the respective drawings will not be given.

FIG. 1 is a flowchart of boom control according to the present invention. The flowchart shown in FIG. 1 shows that when the signals output from the potentiometers provided in the boom elevation angle sensor 15 and the boom extension/contraction length sensor 16 are within a predetermined output range, electrical or mechanical It is determined that an abnormality has occurred, and a drive signal is output to the telescope solenoid valve 18 to cause the telescope cylinder 8 to contract. At the same time, each of the potentiometers becomes stuck, and within the above output range, the output signal This shows that even if the current does not change, this is detected as an abnormality and the boom 6 is controlled to be driven to the safe side.

Boom control will be explained below according to the flowchart shown in FIG. Step S of the flowchart in Figure 1
At T1, the microcomputer CPU is initialized, and at step ST2, the microcomputer CPU takes in output signals from the boom elevation angle sensor 15 and the boom extension/contraction length sensor 16. Then, in step ST3, it is determined whether the signals output from each of the above-mentioned sensors indicate values within a preset range. If the signal from the sensor has a value outside the above range, it is determined that something abnormal has occurred, and step ST
4, except for outputting a drive signal to the telescope solenoid valve 18 to cause the telescope cylinder 8 to contract, the output of other drive signals is stopped.

On the other hand, if the signals output from each of the above sensors are within the set range, the position of the loading platform (work platform) 9 at the tip of the boom 6 is determined based on the respective signals as shown in step ST5. Detect calculation. Step ST6
, lift lever 11 and telescope lever 12
In step ST7, the lift solenoid valve 17 is input based on the output characteristics shown in FIG.
and calculates the valve drive amount for the telescope solenoid valve 18, outputs a drive signal to both the solenoid valves 17 and 18 based on the drive amount of both valves, supplies pressure oil to the lift cylinder 7 and the telescope cylinder 8, and operates the boom. Activate.

[0025] The microcomputer CPU performs step S
At T8, the boom tip position based on the boom attitude, that is, the loading platform position is set in advance at the regulation line, that is, Fig. 2
It is determined whether or not it goes outside of the regulation line LN2 shown in . As a result of the determination, if it is determined that the boom tip position is not outside the regulation line LN2, the process proceeds to step ST12, whereas if it is determined that the boom tip position is outside the regulation line LN2, the process proceeds to step ST9.

[0026] In step ST9, the lift lever 11
It is determined whether the boom 6 is being operated in the direction of lowering the boom 6, and if it is determined that the boom 6 is being operated in the lowering direction, the process proceeds to step ST10, and if not, the process proceeds to step ST11. In step ST10, the above formula is

[Number 1
] The telescope cylinder 8 is regulated in the direction of contraction. That is, based on the above formula, the regulation line LN
According to the deviation from 2, that is, the amount by which the boom 6 exceeds the regulation line LN2, a driving amount is calculated so that the telescope cylinder 8 is smoothly retracted to the regulation line LN2.

On the other hand, in step ST11, when the lift lever 11 is not operated in the direction of lowering the boom 6, that is, when the telescope cylinder 8 is extended to cross the regulation line LN2, the extension of the telescope cylinder 8 is stopped. Calculate change to drive amount. Step ST16
Then, a control signal based on the drive amount calculated in step ST10 or step ST11 is output to the drive circuit 24, and a drive current is applied from the drive circuit 24 to the telescope solenoid valve 18 to control the telescope cylinder 8. , to prevent the boom 6 from exceeding the regulation line LN2.

On the other hand, if it is determined in step ST8 that the position of the loading platform 9 is within the safe working range, in step ST12, the moving speed of the loading platform 9 is set to the regulated speed for safely moving the loading platform 9. Determine whether it is within the control range. As a result of the judgment, if there is no need to regulate the moving speed of the loading platform 9, the process proceeds to step ST16, while if it is within the speed control range, step ST1
3, a regulation command value for reducing the moving speed of the loading platform 9 to a safe speed is calculated.

In step ST14, if it is determined that the operation speed (traveling speed) based on the operation signal output from each lever is smaller than the regulation command value, the process directly proceeds to step ST16, while if the operation speed is greater than the regulation command value. If it is determined that, in step ST15, a safe lever movement speed is calculated by correcting the actual movement speed of each lever, and in step ST16, both the solenoid valves 17 and 18 are driven based on the movement speed. A control signal for this purpose is output to the drive circuit 24.

In step ST17, the microcomputer CPU takes in the output signals of the boom heave angle sensor 15 and the boom extension/contraction length sensor 16. Step S
At T18, after the control signal for driving both the solenoid valves 17 and 18 is output in step ST16, while the control signal is being output for a time dt, the boom hoisting angle sensor 15 and the boom extension/contraction length are It is determined whether the signal from the sensor 16 has changed in dB ohms, ie, there has been a change in the signal commensurate with the dB ohm change in the respective sensor potentiometer.

As a result of the determination, if it is determined that a change in the signal has occurred, it is assumed that the boom heave angle sensor 15 and the boom extension/contraction length sensor 16 are operating normally, and the process returns to step ST2. If it is determined that no change in the signal has occurred, it is assumed that an abnormality has occurred in the potentiometer of the boom elevation angle sensor 15 or the boom extension/contraction length sensor 16, and the process proceeds to step ST4, where the telescope solenoid valve 18 is The output of signals other than the drive signal for driving the scope cylinder 8 to contract is stopped.

Therefore, with the boom control described above, it is possible to detect an abnormality in the boom lifting angle sensor 15 or the boom extension/contraction length sensor 16 during operation of the lift lever 11 and the telescope lever 12, and when the abnormality is detected,
The boom 6 is driven to the safe side.

[0033]

As described above, according to the present invention, there is provided a boom hoisting angle sensor that detects the hoisting angle of the boom of an aerial work vehicle and outputs a boom hoisting angle corresponding signal, and a boom hoisting angle sensor that outputs a signal corresponding to the boom hoisting angle. If the signal from each boom extension/retraction length sensor that detects the extension/retraction length of the boom and outputs a signal corresponding to the extension/retraction length does not change even though the boom hoisting operation means or the boom extension/retraction operation means is being operated, there is a sensor malfunction. Since the boom can be driven to the safe side based on this judgment, it has the effect of further increasing the safety of the aerial work vehicle.

[Brief explanation of the drawing]

FIG. 1 is a boom control flowchart diagram according to an embodiment of the present invention.

FIG. 2 is an external view of the aerial work vehicle.

FIG. 3 is a block diagram of the electric control circuit of the aerial work vehicle.

FIG. 4 is a boom control flowchart of a conventional aerial work vehicle.

FIG. 5 is an output characteristic diagram of a valve drive signal with respect to an operation signal of an operation lever.

FIG. 6 is a characteristic diagram showing resistance value change ranges of potentiometers of a boom lifting angle sensor and a boom extension/contraction length sensor.

[Explanation of symbols]

1 Vehicle body 6 Boom 7 Lift cylinder 8 Telescope cylinder 9 Workbench 11 Lift lever 12 Telescope lever 15 Boom heave angle sensor 16 Boom telescopic length sensor 17 Lift solenoid valve 18 Telescope solenoid valve 23 AD converter 24 Drive circuit CPU Microcomputer

Claims (1)

[Claims] Claim 1: A boom that is raised and lowered by the hydraulic drive of a lift cylinder and extended and contracted by the hydraulic drive of a telescope cylinder on a swivel base that is rotatably installed on the vehicle body, and a boom that can be operated for raising and lowering and extending and contracting the boom respectively. a boom luffing angle sensor that detects the luffing angle of the boom and outputs a signal corresponding to the luffing angle;
A boom extension/contraction length sensor detects the extension/contraction length of the boom and outputs a signal corresponding to the extension/contraction length, and an operation signal corresponding to the operation amount of each of the boom hoisting operation means and the boom extension/contraction operation means is input, and the lift cylinder and The height control circuit includes a drive control circuit that outputs a drive signal to each valve that drives the telescope cylinder to operate the boom to raise/lower and extend/retract, and an abnormality detection means for detecting an abnormality in the boom lifting/lowering angle sensor and the boom extension/retraction length sensor. A sensor abnormality detection device for a work vehicle, wherein the abnormality detection means detects the boom hoisting angle sensor or the boom extension and contraction in a state where the operation signal is output from the boom hoisting operation means or the boom extension and contraction operation means. A sensor abnormality detection device for an aerial work vehicle configured to stop outputting drive signals other than the drive signal for driving the boom to retract when there is no change in the signal from the long sensor.