JPS62280200A - Load detector for unmanned forklift - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application Field] The present invention relates to an improvement of a load detection device for an unmanned forklift, and in particular to loading and unloading using the forks of an unmanned forklift. The present invention relates to a load detection device for an unmanned forklift that can non-contactly detect the load weight during unloading cargo handling using an inclination angle detection sensor and automatically control the cargo handling operation of a fork.

[Prior art]

The work system of an unmanned forklift, which performs cargo handling consisting of transporting, loading, and unloading, by running the unmanned forklift along a preset BM "L travel path at a factory site, etc. is well known, and this work system is well known. In some cases, an unmanned forklift includes a travel and cargo handling control device consisting of a microprocessor, a memory, an input/output interface, etc., various devices connected to this control device, such as a forward/reverse pick-up device that detects the taxiway, and a wheel axle. A drive device consisting of a travel drive motor and its travel control circuit coupled to the steering mechanism, a steering control device consisting of a steering motor and a steering control circuit coupled to the steering mechanism, and a braking device consisting of an electromagnetic brake and a brake control circuit that control braking of the wheels. It is equipped with a control device, a load-throwing device that operates the lifting and lowering of the forks of the forklift and tilting them back and forth, that is, a cargo-handling device consisting of hydraulic cylinders such as lifting cylinders and tilt cylinders, electromagnetic pulp for controlling them, and electromagnetic valve control circuits. In addition, in conventional unmanned forklifts, a detection actuator is installed at the base end of each fork on the loading surface in order to detect whether the load is correctly placed on the loading surface of the fork during cargo handling by the fork. Install the load detector so that it protrudes upward from the fork, and when the detection signals from both load detectors are obtained, the load is correctly placed on the fork, but if only one detection signal is detected, it is abnormal. A load sensing device is generally provided which is adapted to emit a signal.

In other words, the load condition is detected by direct contact between the cargo detector and the cargo.

[Problems to be solved]

However, the above-mentioned conventional load detection device for an unmanned forklift has various drawbacks because cargo handling is performed unmanned, for example, the detection activation part of the load detector cannot always be correctly operated during cargo handling operation even without adjustment by an operator. There is an inconvenience in that the mounting structure has a slight effect on the operating performance, and the structure in which the detection actuation part protrudes from the loading surface of the fork may cause the load to be drawn to the detection actuation part. There is also the problem that normal cargo handling operations cannot be carried out if the cargo is hung up.

Therefore, the present invention improves the load detection device of the conventional unmanned forklift, and non-contactly issues a signal corresponding to the weight of the load to control cargo handling, that is, to control the loading and unloading of the cargo using the fork. To provide a load detection device for an unmanned forklift that can be operated in the correct posture.

[Means of solution and action]

According to the present invention, there is provided a load detection device for controlling cargo handling by detecting a load during loading and unloading operations using the forks of an unmanned forklift that guides itself along a travel route, and is provided at the front of the vehicle body of the forklift. A tilt angle detection sensor is provided which is attached to the fork support body and emits a transmission output according to the amount of the forward and backward tilt angle of the acid fork, and by receiving a transmission output signal corresponding to the amount of the tilt angle, it is possible to detect the fork from the horizontal position. The tilt angle detection sensor is connected to a control device that can detect the amount of longitudinal tilt angle and control the operating amount of the tilt cylinder device connected to the fork support, so that the posture of the fork during cargo handling operations is always optimized for cargo handling. The present invention provides a load detection device for an unmanned forklift that maintains the posture, and since the inclination angle detection sensor attached to the fork support is installed at a non-contact operating position that is unrelated to the loading surface of the fork, the fork is horizontal in advance. If it is installed so that a zero output signal is generated when the fork is in the posture, when the fork tilts back and forth depending on the load placed on the fork during cargo handling operations, the output will correspond to the direction and angle of the tilt. A signal is sent out, and by connecting this output signal to the control device of the unmanned forklift, it is possible to control the tilt cylinder that adjusts the attitude of the fork, thereby constantly maintaining the fork in the optimum cargo handling attitude. Hereinafter, the present invention will be explained in more detail based on examples.

〔Example〕

Fig. 1 is a perspective view showing a schematic outline of an unmanned forklift equipped with a load detection device according to the present invention, and Fig. 2 shows the arrangement of the load detection device attached to the fork support of the unmanned forklift. FIG. 3 is a block diagram showing the configuration of the traveling and cargo handling control device provided on the unmanned forklift and various devices connected thereto, and FIG. 4 shows the output signal from the load detection device according to the present invention. Explanatory diagram showing the working process when unloading cargo based on
FIG. 6 is a flowchart explaining the action of the control device in the same process, FIG. 6 is an explanatory diagram showing the process when loading cargo, and FIG. 7 is a flowchart of the same process.

First, referring to FIGS. 1 and 2, the unmanned forklift truck has a vehicle body 10, and wheels 12 for running and steering are provided at the front and rear of the vehicle body 10. On the vehicle body 10, a control device 14 for controlling driving and cargo handling, which is the center of control in unmanned driving, is provided.
A driver's seat is also provided on the vehicle body 10 so that a worker can board and drive the vehicle. A steering wheel 16 of a steering mechanism is provided in front of the driver's seat in the same manner as in a normal forklift.

A mast 18 of an elevating mechanism is attached to the front of the vehicle body 10, and an elevating bracket/elevating bracket that ascends and descends along this mast 18.
A pair of left and right forks 22a and 22b are detachably attached to the seat 20 as required. And left and right 1
Detection sensors 22 a and 22 b for forward detection are generally attached to the tips of the pair of forks 22 a and 22 b. The lifting bracket 20 is attached to the vehicle body 10 so that it can move up and down in the vertical direction, and is generally mounted on the mast 1.
It moves up and down via a pair of chains 18a in response to the operation of a lifting cylinder provided on the side of the 8, and is equipped with a lifting height sensor to sense the upper and lower lifting limits and perform correct lifting and lowering operations. It has become. Further, the mast 18 itself can be tilted back and forth along the longitudinal axis of the vehicle body 10 in accordance with the operation of a tilt cylinder 28 together with a lifting bracket 20 and forks 22a and 22b. and,
On one side of the lifting bracket 20, that is, the fork 22
An inclination angle detection sensor 24 is mounted at a position apart from the load mounting surfaces a and 22b. The structure and mounting state of this inclination angle detection sensor 24 are shown in detail in FIG. Although not shown in the figure, the unmanned forklift is further equipped with a forward pick-up device and a reverse pick-up device, which are configured to extend along the travel path and send a weak current through them, and whose detection signals are controlled. A conventional control action is applied to the device 14 to drive the vehicle along the path. Note that the fork 22a.

A side shift cylinder is also provided for moving the side shift cylinder 22b left and right on the front of the vehicle body, and although not shown in the figure, an output signal from a detector that detects the amount of operation of the side shift cylinder is applied to the control device 14. As in the conventional case, the amount of lateral movement of the quarks 22a and 22b is controlled by the control device 14 based on the signal.

Now, as shown in FIG. 2, the inclination angle sensor 24 for detecting the inclination angle of the forks 22a, 22b according to the present invention is mounted on a column member 20a forming the side surface of the lifting bracket 20 using an appropriate mounting port 34. That is, the sensor box 32 is attached to the column member 20a by the mounting bolts 34.
The tilt angle sensor 24 is appropriately held within the sensor box 32 using a bracket or the like.

The tilt angle sensor 24 may be a commercially available sensor that outputs the tilt angle as a linear electrical output, that is, sends out voltage signals proportional to the tilt angle in a thousand directions centered on the zero tilt angle state. A tilt sensor using a Hall element can be optimally used. Since the tilt angle sensor 24 is attached to the lifting bracket 20 in this way, the tilt cylinder 2 shown in FIG.
8 is activated and the lifting bracket 20 together with the mast 18 tilts in the longitudinal direction of the vehicle body 10, an output signal corresponding to the tilt angle is sent out.

Of course, it goes without saying that this inclination angle amount is also the inclination angle of the forks 22a and 22b.

Therefore, when the unmanned forklift performs cargo handling consisting of unloading and loading at the loading platform position, the forks 22a, 2
When the fork tilts together with the lifting bracket 20 in response to the ups and downs in the front part of the vehicle body 10 due to the load decrease when unloading from 2b and the load increase when loading the load,
The inclination is detected and an output signal proportional to the inclination angle is generated. The output signal is then sent to a control device 14 for driving and handling the unmanned forklift, as will be described later.

Here, referring to FIG. 3, the unmanned forklift is equipped with the traveling and cargo handling control device 14 as described above, and this control device 14 itself is the same as the one provided in the conventional unmanned forklift. The travel control device 14 is configured with a processor 40, a memory means 42, and an input/output interface 44, and is connected to a travel control circuit 46 and a steering control circuit 48 via a bus line as shown in the figure.
, a brake control circuit 50, and a cargo handling control circuit 52 are connected, as well as a forward pickup device 54, a reverse pickup device 56, the above-mentioned 1st inclination angle sensor 24, and a fork 2.
Connected to the input/output interface 44 are a front detection sensor 26 located at the tips of the lift brackets 2a and 22b that detects an obstacle in front, and a lift height sensor 30 that detects the upper and lower limits of vertical movement of the lifting bracket 20. The travel control circuit 46 is a circuit that controls the travel drive motor 58 that drives the wheels. The brake control circuit 50 responds to signals from the control device 14! The magnetic brake 62 is activated to brake and stop the movement of the unmanned forklift. The steering control circuit 48 is connected to a steering motor 64 that operates a steering mechanism 66 for steering, and controls the operation of the steering motor 64. Further, the cargo handling control circuit 52 controls the operation of an electromagnetic pulp 68 provided for controlling the operation of the cargo dumping means 70 described above.

If an unmanned forklift is equipped with the traveling and cargo handling control system configured as described above, reliable cargo handling control by the load detection device of the present invention can be efficiently and smoothly carried out in addition to the traveling and cargo handling control of conventional unmanned forklifts. It is possible. Next, the operation of the load detection device according to the present invention will be explained with reference to FIGS. 4 to 7.

Now, FIG. 4 shows the unloading process (a), (b), and
(c) is an explanatory diagram schematically showing process (a), in which the unmanned forklift lifts the lifting bracket 2o and the forks 22a, 22b once at a certain position away from the loading platform 60, and moves the workpiece W via the workpiece pallet 61. The workpiece W is pulled up to a higher position than the loading platform 60 to be unloaded, moves forward toward the loading platform 6o, and is about to unload the workpiece W onto the loading platform 60. That is, at this time, the inclination angles of the forks 22a and 22b are such that the workpiece W is being lowered onto the loading platform 60 while maintaining a constant angle θ that maintains the attitude of the workpiece W substantially horizontally.

Next, as shown in process (b), the workpiece W is placed on the pallet 61.
When the workpiece begins to be placed on the loading platform 60, the load applied from the workpiece W to the fork is reduced, so that the tire deformation (collapse) on the wheels 12 of the unmanned forklift is recovered, and as a result, the lifting bracket 20 and the fork tilt backward ( θ〉
0), and the inclination angle sensor 24 sends out the inclination angle to the control device 214 as, for example, a positive sending signal. When the forks 22a and 22b are released from supporting the work pallet 61, the forks become unloaded, so the elevating bracket 20 and the forks maintain their backward tilted postures. That is, the inclination angle sensor 24 sends out a constant sending signal ``m times. When this state is detected by the control device 14, the workpiece W is placed on the loading platform 6o together with the pallet 61, and the pallet and the fork are separated. The inclination angle detection process described so far and the judgment process of the control device 14 based on it are shown in the flow up to judgment step 'IJ' in FIG. 5.In this judgment step '14, Fork 22a, 22
When it is determined that the inclination angle of b has become constant in the backward tilted state (θ>Q), at that point the wJ control device 14 controls the cargo handling means 70 via the cargo handling control device 52 (see Fig. 3). The descent of the lifting bracket 20 and the fork is stopped, and the tilt cylinder 28 is actuated to tilt the lifting bracket 20 and the fork forward until the inclination angle θ of the fork reaches a horizontal state where θ=0. Then, the process shown in Figure 4 (
If the horizontal state is ensured as shown in c), the fork and work pallet 61 will be parallel to each other. Therefore, at that point, the control device 14 stops the forward tilting operation by the tilt cylinder 28, and switches the driving drive motor 5 of the unmanned forklift.
8 (see FIG. 3) to move backward away from the loading platform 60, the unloading process can be completed. The above-mentioned process is illustrated in the latter half of the flowchart of FIG. 5, including decision step "2J."

Next, Figures 6 and 7 show an unmanned forklift with a loading platform 60.
This explains the process of loading a load in which the load is lifted by the forks 22a and 22b. That is, the unmanned forklift lifts its forks 22a and 22b onto the loading platform 6.
0 (using the front detection sensor 26), and insert the fork below the work pallet 1-61. At this point, the lifting bracket 20 and the fork are held so that their inclination angle θ is a constant horizontal angle. In other words, the signal sent from the tilt angle sensor 24 continues to send a constant value. Next, as shown in step (b), when the lifting bracket 20 starts lifting and lowering to place the workpiece W on the fork, the forks 22a and 22b engage with the pallet 61, and the weight of the workpiece W unloads the load. It comes to hang on the vehicle body 10 of the forklift. As a result, the entire unmanned forklift tilts forward (θ<O) due to deformation of the tires of the wheels 12, so the tilt angle sensor 24
will now emit a transmission signal corresponding to the forward tilt angle.

When the workpiece W eventually leaves the loading platform 60, the value of the signal sent from the inclination angle sensor 24 becomes constant. During this process, the control device 14 makes a constant determination of the inclination angle as shown in determination step "1" in FIG. When it is determined that the inclination angle θ has become constant, the workpiece W is placed on the pallet 61.
At the same time, it is determined that the vehicle has left the loading platform 60. Next, as shown in step (c) of FIG. 6, when a constant sending signal from the inclination angle sensor 24 indicating that the workpiece W has left the loading platform 60 is obtained, the lifting bracket 20 and the forks 22a, 22
The lifting and lowering operation of b is stopped via the cargo handling control circuit 52 (FIG. 3), and then the tilting cylinder 28 is operated to tilt backward until the inclination angle θ becomes zero. As a result, the work W placed on the fork and the loading platform 60 are in a parallel state.

At this point, the control device 14 executes the judgment process shown in judgment step '2J in the flowchart in FIG. 7 to obtain a horizontal state in which the above-mentioned inclination angle θ becomes zero. When this tilt angle θ=0 is obtained, the control device 14 stops the backward tilting operation by the tilt cylinder 28 via the cargo handling control circuit 52. At this point, the work W is completely lifted from the loading platform 60, so when the unmanned forklift is moved backward from the loading platform 60, the loading operation can be completed smoothly without any hindrance. In the above process, it can be determined by monitoring the output value of the filler angle sensor 24 that the workpiece W has left the loading platform 60 as shown in judgment step 1 in FIG. This means that the rearward tilting operation by the tilt cylinder 28 can be started, and therefore the loading process can be completed in the shortest possible time.

〔Effect of the invention〕

As is clear from the above description, the present invention includes an inclination angle sensor that non-contactly detects the load during cargo handling by an unmanned forklift, and the load from the inclination angle sensor is controlled by the traveling and cargo handling control device. Since cargo handling control is performed by determining the output signal value corresponding to the load detection sensor, first, the load detection sensor itself does not come into contact with the load, so there is no risk of damage and durability is guaranteed. Furthermore, unlike the load detection sensor in a conventional unmanned forklift, it is possible to avoid the risk of the load being caught in the detection actuator during the cargo handling process.

In addition, the load can be reliably detected during loading, and the moment the load leaves the loading platform can be detected, so the fork can be moved 2&tilt immediately after the load leaves to return it to a horizontal state. This eliminates wasteful lifting and lowering operations and shortens cargo handling time.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a schematic outline of an unmanned forklift equipped with a load detection device according to the present invention, and Fig. 2 shows the arrangement of the load detection device attached to the fork support of the unmanned forklift. FIG. 3 is a block diagram showing the configuration of the traveling and cargo handling control device provided on the unmanned forklift and various devices connected thereto, and FIG. 4 shows the output signal from the load detection device according to the present invention. Explanatory diagram showing the working process when unloading cargo based on
The figure is a flowchart explaining the action of the control device in the same action process, FIG. 6 is an explanatory view showing the action process when loading a load, and FIG. 7 is a flowchart of the same action process. DESCRIPTION OF SYMBOLS 10... Vehicle body, 12... Wheels, 14... Traveling and cargo handling control device, 18... Mast, 20... Lifting bracket, 22a
, 22b...-Fork, 24... Tilt angle sensor, 28... Tilt cylinder, 46... Travel control wholesale circuit, 52... Cargo handling control circuit.

Claims (1)

[Scope of Claims] 1. In a load detection device that detects the load and controls cargo handling during loading and unloading operations using the forks of an unmanned forklift that guides itself along a travel route, The horizontal position of the fork is determined by providing a tilt angle detection sensor that is attached to the provided fork support and emits a transmission output according to the amount of the longitudinal tilt angle of the fork, and receives a transmission output signal corresponding to the amount of the tilt angle. The tilt angle detection sensor is connected to a control device capable of detecting the amount of longitudinal tilt angle from the fork support and controlling the operating amount of the tilt cylinder device coupled to the fork support, so that the posture of the fork is always maintained during cargo handling operations. A load detection device for unmanned forklifts that maintains the optimal posture for cargo handling. 2. The load detection device for an unmanned forklift according to claim 1, wherein the inclination angle detection sensor is fixed to the fork support at a lateral position away from the loading surface of the fork. 3. The front detection device for an unmanned forklift according to claim 1 or 2, wherein the fork support is constituted by a bracket means that can be raised and lowered at the front of the vehicle body.