GB2279774A

GB2279774A - Construction vehicle diagnostic system

Info

Publication number: GB2279774A
Application number: GB9417608A
Authority: GB
Inventors: Jin Han Lee; Myeong-Hun Song; Sang-Tae Jeong; Goo-Tack Lee; Jin-Tae Kim; Chan-Hee Lee; Joo-Kyung Kim
Original assignee: Samsung Heavy Industries Co Ltd
Current assignee: Samsung Heavy Industries Co Ltd
Priority date: 1990-12-31
Filing date: 1994-09-02
Publication date: 1995-01-11
Also published as: GB2280047A; GB9417609D0; GB9417608D0

Abstract

In a remote diagnostic system for a construction vehicle eg an excavator, commands from an external input means are communicated 114, 115 to the CPU 1 of the vehicle and the response of the vehicles actuator systems are detected with the results being sent back 116, 114 to the external input means. The system allows the condition of the vehicles actuator systems to be determined without the need for the operator to be present in the vehicle. Also disclosed are a system for teaching the vehicle to perform repetitive operations automatically (figures 1 - 5) and a system to allow the operator to select the pattern of actuator manipulation functions he is familiar with. <IMAGE>

Description

SYSTEM FOR AUTOMATICALLY CONTROLLING OPERATION OF CONSTRUCTION VEHICLE BACKGROUND OF THE INVENTION Field of The Invention The present invention relates two a system for controlling operations of construction vehicles, and more particularly to an automatic system for controlling of operations of construction vehicles which is capable of programming a desired operation and automatically and repeatedly performing the programmed operation as requested, optionally selecting a manipulation pattern for control levers which is familiar to the operator irrespective of types of the vehicles and controlling the operations of the construction vehicles by means of an external instruction of an external computer.

Description of The Prior Art Conventionally, it is well known that the hydraulic construction vehicles, such as an excavator, a road roller, a scraper and the like, are useful industrial machines. The vehicles are generally provided with operational members which practically carry out desired operations, several actuators for actuating the operational members, a driving motor for supplying the driving power, a pair of hydraulic pumps for supplying compressed hydraulic fluid for the actuators upon receiving the driving power from the motor, proportional valves such as wobbling angle control valves for controlling wobbling angles of wobble plates of the hydraulic pumps, directional control valves for controlling fluid flow and flowing direction of the hydraulic fluid, control levers/pedals being manipul2ted by the operator in order to manually control-the actuators; an electronic controller for controlling the operations of. the actuators upon receiving manipulation signals from the control levers/pedals.

The actuators of the construction vehicles are controlled by virtue of operator, 5 manipulation for the control levers/pedals so that the actuators efficiently actuates the operational members in order to carry out several operations such as an excavating operation, a surface finishing operation, a loading operation and the like.

However, the construction vehicles have the following disadvantages, resulting in fatigue of the operator in order to deteriorate the operational effect of the excavator, and causing the actuators to be suddenly broken and a safety accident to occur during the operations.

First, the construction vehicles have to generally perform some repeated operations, such as the excavating operation, the surface finishing operation, the loading operation and the like. Thus, the operator of the vehicles has to repeatedly manipulate the control leversYpedals in order to perform a desired repeated operation whenever it is requested to be performed, thereby causing the operator to feel fatigue and tediousness due to the repeated manipulations for the control levers/pedals.

Second, as described above, the construction vehicles are provided with a plurality of control levers in forward space inside the control cab. Thus, the operator minutely manipulates the control levers in order to cause the controller to control the actators in accordance with the manipulation signals of the levers. However, the manipulation patterns for the control levers of the known construction vehicles are generally different from each other in accordance with a manufacturer thereof as described in FIGS. 6A to 26D which show, for example, four types of manipulation patterns for control levers of an excavator, a kind of a construction vehicle.In the drawings, the arrow marks denote a manipulation directions of the control levers, and the alphabet marks represent respective actuators and moving directions of the actuators, that is, DS/in and DS/out represent that a dipper stick moves toward and away from the frame of the excavator, respectively, BK/in and BK/out represent that a bucket turns in opposite directions in order to excavate the ground and pour the excavated earth, and BM/up and BM/down represent that a boom goes up and down.

However, an operator of the vehicles has conventionally operated a type of construction vesicle repeatedly so that he is familiar with the manipulation pattern of the construction vehicle, while he is not familiar with manipulation patterns of other types of construction vehicles except for the type of the vehicle in which he is skilled. In accordance, the known construction vehicles have a disadvantage in that there may be a possibility of. occurrence of confusion in manipulating the control levers when the operator has to operate other types of construction vehicle except for the skilled type, thereby causing a considerable inconvenience in manipulation for the control levers, and more parti=larly causing a safety accident to occur due to the confusion in the manipulation.

Third, the electronic controllers of the known construction vehicles conventionally control the actuators in accordance with the operator's manipulation for the control levers/pedals. Thus, the known construction vehicles have a disadvantage in that the actuators thereof need practically actuating by the operator's manipulation for- the control levers/pedals even in case of testing actuating states of the actuators, thereby causing considerable inconvenience in checking the troubled parts thereof.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a system for automatically controlling operations of construction vehicles in which the above-mentioned problems can be overcome, and a desired repeated operation, such as an excavating operation, a surface finishing operation, a loading operation and the like can be programmed in an electronic controller in order to be automatically and repeatedly performed by a simple selection for the programmed operation as it is requested to be performed, thereby causing repeated operations to be automatically performed without operator's manipulation for control levers/pedals.

It is another object of this invention to provide a system for automatically controlling operations of construction vehicles which is provided with several types of manipulation patterns for control levers,*thereby causing a manipulation pattern which is familiar to the operator to be optionally selected in order to manipulate the control levers under the selected pattern irrespective of the types of the construction vehicles.

It is still another object of this invention to provide a system for automatically controlling operations of construction vehicles in which an electronic controller is controlled by means of an external instruction,of an external computer in order to operate actuators without operator's practical manipulation for the control levers/pedals, thereby causing the checking for the actuating conditions of the actuators and the detection 'or troubled parts to be efficiently performed by means of the communicative control for the controller by the external computer.

In one aspect2 the present invention provides a control system for automatically controlling operation of a construction vehicle comprising: an electronic controller; function select means for optionally selecting a teaching function for programming a desired operation ard a performance function for practically performing said programmed operation as requested; means for generating a start signal and a stop signal; means for selecting an operational moe for limiting a maximum fluid flow of hydraulic fluid which is to be outputted from hydraulic pumps in accordance with said selected operational mode; and means for displaying respective positions of actuators of the excavator thereon, whereby a desired operation being optionally programmed and simply selected as requested in order to be automatically performed without operator's manipulation.

In another aspect, the present invention provides a control system for automatically controlling operation of a construction vehicle comprising: means for selecting a desired manipulation pattern for control levers; and an electronic controller electrically connected to said means comprising; a central processing unit for controlling said system in accordance with said selected manipulation pattern selected by said means; analog/digital signal converters for converting analog signals of manipulation values of said control levers into digital signals; a decoder for controlling the signal conversion of said analog/digital signal converters in accordance with a control signal from said central processing unit; a RAM for storing data values from the analog/digital signal converters; and a ROM for storing a control program of the central processing unit, whereby an order for activating the analog/digital signal converters being changed in accordance with the manipulation pattern having been selected by the means for setting the manipulation pattern or an order for reading data values having been stored in said RAM being changed in accordance with the selected manipulation pattern, thereby manipulating the control levers in a desired manipulation pattern which is familiar to the operator.

In still another aspect, the present invention provides a control system for automatically controlling operation of a construction vehicle comprising: an electronic controller; external data input means being connected to said controller and transmitting control data to said controller in a data communication; a communication interface for interfacing said external data input means to the controller; a receiving buffer for receiving input data from the external data input means by way of said communication interface; and a transmitting buffer for transmitting output data from the controller to the external data input means, whereby the controller being capable of actuating actuators in accordance with an instruction data applied from the external data input means thereto, calculating positional values of said actuators on the basis of electric signal of positional displacements applied from positional sensors of the actuators thereto, calculating the positional displacements of the actuators on the basis of said electric signals in order tc obtain calculating results, then transmitting said calcul atl ng results of the positional displacements of the actuaors to She external data input means.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic circuit diagram showing a basic hydraulic circuit of an excavator, a kind of a construction vehicle, in accordance with the present invention; FIG. 2 is a schematic block diagram shewing a construction of a control system for automatically programming a repeated operation and performing the programmed operation as requested in accordance with this invention; FIG. 3 is a block diagram showing an inner construction of the electronic controller of FIG. 2; FIG. 4 is a flowchart showing a process for automatically programming a desired operation by the electronic controller of FIG. 2; FIG.5 is a flowchart showing a process for automatically performing the operation having been programmed by the process of FIG. 4; FIGS. 6A to 6D are schematic views showing several types of manipulation patterns for the control levers of FIG. 1; FIG. 7 is a schematic block diagram showing a construction of a control system for optionally selecting a manipulation pattern which is familiar to the operator and controlling the actuators under the selected pattern; FIG. 8 is a block diagram showing the inner construction of the electronic controller and the manipulation patterns for the control levers; FIG. 9A is a flowchart showing a process for automatically controlling the actuators under a selected manipulation pattern which is familiar to the operator;; FIG. 9B is , a flowchart showing a process for automatically activating analog/digital signal converters in accordance with the selected manipulation pattern in order to operate the actuators according to the selected pattern; FIG. 9C is a flowchart showing an another embodiment of a reading order for reading the data stored in the R-.'A; FIG. 10 is a schematic block diagram showing a construction of a communication circuit for communloatively controlling the actuators by means of an external computer in accordance with this invention; FIG. 11 is a flowchart showing a process for communicatively controlling the actuators by means of the circuit of FIG. 10; and FIGS. 12A to 12I each shows a format of each actuating data shown in the flowchart of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the embodiments, a hydraulic excavator will be described as a representative example of a hydraulic construction vehicle for illustrative purpose. However, it is of course understood to those skilled in the art will appreciate that a control system of the present invention can be used for another type of construction vehicle besides the excavator.

Referring first to FIG. 1 which is a schematic circuit diagram showing a basic hydraulic circuit of a hydraulic excavator, a kind of a construction vehicle, in accordance with the present invention, the basic hydraulic circuit of the excavator includes a driving engine M for generating a driving power for the driving elements of the excavator, a pair of main hydraulic pumps, that is, first and second hydraulic pumps 4a and 4b sequentially and straightly connected to a driving shaft of the engine M, each ccmprising a wobble plate pump. The second pump 4b is straightly connected to a subhydraulic pump or a third pump.4c having a relatively smaller capacity than those of the first and second main pumps 4a and 4b and outputting a pilot hydraulic flUid.

The first main pump 4a is, as shown in the drawing, straightly connected to a first group of directional control valves in order to be communicated therebetween, for example a first directional control valve a for controlling the actuating direction of a swing motor 6 adapted for swinging the upper frame provided with the control Cb with respect to the lower frame provided with a pair of crawler-type travelling members, a second directional control valve 5b for controlling the actuating direction of a dipper cylinder 7 for driving a dipper stick, and a third directional control valve 5c for controlling the actuating direction of a left travelling motor 8 for driving the ~weft side crawler-type travelling member of the excavator.

In the same manner, the second main pump 4b is straightly connected to a second group of directional control valves in order to provide a fluid communication therebetween, for example a fourth directional control valve 5d for controlling the actuating direction of a right travelling motor 9 for driving the right side crawler-type travelling member of the excavator, a fifth directional control valve Se for controlling the actuating direction of a bucket cylinder 10 for driving a bucket, a sixth directional control valve 5f for controlling the actuating direction of a boom cylinder 11 for driving a boom.In addition, the main pump 4b may be provided with a preparatory directional control valve (not shown) for controlling the actuating direction of an auxiliary actuator (not shown) which may be equipped in the excavator as required by the consumer.

Additionally, the hydraulic fluid outputted from the third hydraulic pump 4c having the relatively smaller capacity than those of the first and second main pumps 4a and 4b is used as a pilot hydraulic fluid for controlling the wobble plates 4'a and 4'b of the first and second main pumps 4a and 4b and the spools of the directional control valves 5a to 5f.

In other words, a part of the pilot hydraulic fluid from the third pump 4c is supplied through a fluid passage to a pair of wobbling angle control members 19a and 19b, each adapted for controlling the wobbling angle of the wobble plate 4'a, 4'b of the main pump 4a, 4b, by way of a wobbling angle control valve 19 which comprises a proportional valve provided with a solenoid.The other part of the pilot hydraulic fluid from the third pump 4c is supplied through another fluid passage to respective spools of the directional control valves 5a to 5f by way of a pair of electronic proportional valve blocks Ba and 18b which are connected to the directional control vales 5a to 5f and an electronic.controller 1 through a line, and actuated under the control df the controller 1 in accordarce with operator's manipulation for the control levers/pedals 2 provided in the control cab.

Also, the control levers/pedals 2 comprises the s-me number of levers and pedals as those of the directicral control valves 5a to 5f, that is, the number of actuators 6 to 11. Also, the proportional pilot solenoid valve blocks Ba and 18b each includes therein the same number of proportional pilot valves (not shown) as those of a group of directional control valves 6 to 8 or 9 to 11 connected to the corresponding valve block 18a, 18b. Therefore, a control lever/pedal 2 for an actuator which is to be actuated is handled in order to proportionally drive a proportional pilot solenoid valve provided in the valve block 18a, 18b corresponding to the manipulated control lever/pedal 2.Thus, the pilot hydraulic fluid outputted from the third pump 4c is supplied to a directional control valve 5 corresponding to tne actuatorwhichis to be actuated. Therefore, the spool of the directional control valve 5 supplied with the pilot hydraulic fluid from the third pump 4c moves rightwards or leftwards in order to last actuate the operating members, such ds the bucket, the dipper stick, the boom or the like, in a desired direction.

As shown in FIG. 1, the hydraulic circuit is additionally provided with a plurality of sensors 12 to 17 for sensing positional displacement of the actuators 6 to 11 according to the actuation for the actuators. The sensors 12 to 17 are disposed closely near the actutors, respectively. Thus, the sensors 12 to 17 comprise the same number of sensors as that of the actuators. Also, the sensors 12 to 17 is electrically connected to the controller 1 so as to output a sensing signal representing the displacementrof the subject actuator to the controller 1.

On the other hand, a pair of amplifiers (not shown) each is electrically connected to the pilot proportional valve block 18a, 18b and the controller 1 so as to be disposed therebetween, while another amplifier (not shown) is electrically connected to the wobbling angle control valve 19 and the controller 1 so as to be disposed therebetween. The controller 1 is electrically connected to the positional displacement sensors 12 to 17.

The positional displacement sensors 12 to 17 may comprise several types of known sensors. For example, the sensor 12 of the swing motor 6 may comprise an absolute type encoder capable of sensing the absolute position of the upper frame with respect to the lower frame of the excavator, while the sensors 14 and 15 mounted to the travelling motors 8 and 9 each may comprise an incremental encoder.In the same manner, the sensors 13, 16 and 17 mounted to the cylinder actuators such as the dipper cylinder 7, the bucket cylinder 10 and the boom cylinder 11 each may comprise a sensor which comprises a variable resistance potentiometer and magnetic materials arranged on piston rods of the 9ylinder actuators 7, 10 and 11 so that the potentiometer counts the number of magnetic materials which are moving as the actuators moves, then outputs an electric signal resulting from the counting.

Therefore, electric current signals generated in accordance with the manipulation values of the control levers/pedals 2 are applied to the controller 1 in order to be calculated thereby, and amplified in the amplifiers each disposed between the controller 1 and the pilot valve blocks 18a and 18b, and then applied to the valve blocks 18a and 18b so as to control the fluid flow of the pilot hydraulic fluid outputted from the third hydraulic pump 4c to the spools of respective directional control valves 5a to 5f.Also, the sensors 12 to 17 each outputs a signal representing the positional displacement of each actuator sensed thereby to the controller 1 so that the controller 1 calculates the data values of the signals of positional displacements of the actuators 6 to 11, outputted from the sensors 12 to 17 thereto, on the basis of the load on the actuators and the required fluid flow of the hydraulic fluid for the actuators so as to adjustable control the first and second main pumps 4a and 4b, thereby allowing the first and second main pumps 4a and 4b to equally charge a load in case of occurrence of an overload on an actuator.

Turning next to FIG. 2 which is a schematic block diagram showing a construction of a control system for automatically programming a desired operation and repeatedly performing the programmed operation as requested in accordance with this invention, the system comprises a function select rotary switch 20 for selecting a function of the control system, said function comprises two types, that is, a teaching function for programming the desired operation and a performing function for performing the programmed operation, an actuating switch 21 for generating start and stop signals which are to be outputted to the controller 1, an operational mode select switch 22 for selecting an operational mode M and controlling a maximum fluid flow of hydraulic fluid which is to be outputted from the main pumps 4a and 4b in accordance with the selected operational mode M, a display monitor 23 for displaying the sensed positions of the actuators 6 to 11 and an input keyboard 24.

Conventionally, the operational mode M of the excavator comprises a plurality of operational modes. For example, the operational mode M of this invention comprises five types of modes, that is, H mode, Sn mode, Sm mode, SL mode and L mode.

FIG. 3 is a block diagram showing an inner construction of the electronic controller 1 of FIG. 2. As shown in the drawing, the controller 1 comprises a ROM 35, a RAM 36, an analog/digital sjgnal converters 32 (hereinafter, referred to simply as "the A/D signal converter") adapted to convert an analog signa.l from the controlJlevers/pedals 2 into a digital signal under the control of the CPU 31, an A/D signal converter and counter 34 adapted to convert analog signals from positional sensors 12 to 17 into digital signals, respectively, under thq control of the CPU 31, a pair of D/A signal converters 37 and 38 adapted to convert digital signals from the CPU 31 into analog signals under the control of the CPU 31, and a pair of amplifying parts 39.-and 40 adapted to amplify the analog signals from the D/A signal converters 37 and 38. In addition, the controller 1 is provided at the input part thereof with a pair of input interfaces each adapted to interface the CPU 31 to the switches 20, 21 and 22 and the input keyboard 24, while it is provided at the output part thereof with an output interface 42 for interfacing the CPU 31 to the display monitor 23, said output interface 42 connected to a monitor driving part 43 for driving the display monitor 23.

In operation, upon selecting the T (Teaching) function by turning the function select rotary switch 20 toward the "T" mark thereof in order to teach a desired operation, that is, in order to teach that a desired operation is to be programmed, the controller 1 of the control system of FIG. 2 programs the desired operation by performing the process described in a flowchart of - FIG. 4.As shown in the flowchart, the controller 1 receives at a step 51 a selected operational -mode M which hasi been selected by operator's manipulation for the operational mode select switch 22 in order to control the main pumps 4a and 4b to output a maximum fluid flow of the hydraulic fluid in correspondence with the selected operational mode M, then sets a teaching operational speed of the excavator corresponding to the selected operation. Thereafter, at a step 52 it is determined whether the actuating switch 21 has been turned onf- If the switch 21 has not been turned on, the controller 1 repeatedly performs the step 52 until the switch 21 is turned on.However, if the switch 21 has been turned on, the controller 1 proceeds to a next inquiry step 53 wherein it is determined whether the memory capacity MCRM of the RAM 36 of the controller 1 has been full. If the memory capacity has been full, the controller 1 outputs an alarm signal to an alarm device (not shown) in order to alarm the operator to the condition that the memory capacity of the RAM 36 has been pull, and resets the data, then ends the process.

However, if the memory capacity of the RAM 36 is not full, the controller 1 performs a next inquiry step 54 wherein it is determined whether the present time cycle is a sampling cycle in which an information for the positional displacements of the actuators 6 to 11 is sampled by the controller 1, said information being supplied from the sensors 12 to 17 of the actuators 6 to 11 thereto. If the present time cycle is the sampling cycle, at a step 55 the controller 1 receives electric current signals of the positional values Si of the actuators 6 to 11 outputted from the sensors 12 to 17 by way of the A/D signal converter.and counter 34 thereof, then stores the digital signal data into the RAM 36. But, if the time cycle is not the sampling cycle, the step 54 is repeatedly performed until the time cycle is the sampling cycle.

The controller 1 determines, thereafter, at a step 56 whether the actuating switch 21 has been turned off. If the actuating switch 21 has been continuously turned on, that is, if 'the operational teaching by the controller 1 needs continuing, the controller 1 returns to the step 53 in order to continuously performing the process for receiving the positional values Si of the actuators 6 to 11 and storing the positional data of the values Si -nto the RAM 36 thereof. On the contrary, if the actuating switch 21 is turned off, that is, if the process has to end, at a step 57 the controller 1 sets a name of the processed operation, that is, the operation desired to be programmed, so as to allow the another late performance for the programmed operation to be easily carried out by virtue of facilitation in selection thereof caused by the specified name.

On the other hand, if the operation having been programmed through the teaching process of FIG. 4 needs to be automatically and repeatedly performed, the operator turns the function select switch 20 to the "P' (Performing) position for the performing function, then resets the positional values Si of the actuators 6 to 11 in order to locate the actuators 6 to 11 at respective original positions.

Thereafter, the controller 1 performs a process for automatic and repeated performance of the desired operation, as described in a flowchart of FIG. 5.

As described in the flowchart, the controller 1 first receives at a step 61 respective present positional values Si of the actuators 6 to 11 from the sensors 12 to 17. Here, conventional types of sensors can be used as the sensors 12 to 17 as described above.

That is, for accomplishing the sensors 13, 16 and 17 for sensing the positional displacements of the cylinder actuators, such as the dipper stick cylinder 7, the bucket cylinder 10 and the boom cylinder 11, the piston roods of the actuators 7, 10 and 11 are generally provided with a plurality of magnetic materials which are lengthwisely arranged thereon with a certain space therebetween. Thus, each of the sensors 13, 16 and 17 comprising the potentiometer electrically counts the number of the magnetic materials of the piston rod as the actuator 6, 10, 11 moves in opposite directions under the control of the controller 1; then outputs an electric signal of the number of magnetic materials counted thereby to the controller 1, said number of the magnetic materials capable of representing the positional displacement of the cylinder actuators 7, 10 and 11. Upon receiving the electric signals from the sensors 13, 16 and 17, the controller 1 filters the signals and counts the magnitude of the signals by means of the A/D signal converter and counter 34 thereof, thereby last obtaining an information for the positional displacement of each cylinder actuator 7, 10, 11.

On the other hand, the absolute-type encoder as the sensor 12 for the swing motor 6 is capable of sensing -a swinging angle of the upper frame of the excavator with respect to the lower frame of the excavator, then outputs an electric signal of the sensed swinging angle to the controller 1. The incremental encoders as the sensors 14 and 15 for the travelling motors 8 and 9 each is capable of sensing a rotating position and a travelling speed of th3 motor 8, 9, then outputs an electric signal of the sensed position and the travelling speed of the motor 8, 9 to the controller 1.

Turning again to the flowchart of FIG. 5, at a step 62 the controller 1 then receives first teaching data stored in the RAM 36, and at a step 63 outputs a display signal to the display monitor 23 in order to cause a present bucket position SBKi and an initial bucket position -::'o to be displayed thereon. Thereafter, it is determined at a step 64 whether the present position SBKi satisfies the initial position SBKos that is, whether the present position of the bucket cylinder 10 is within an efficient positional range thereof.If the present position SBKi does not satisfy the initial position S6Ko, the controller 1 performs a step 87 wherein it outputs an al.arm signal to an alarm device (not shown) in order to alarm the operator to the condition that the present position of the bucket cylinder 10 is not within an efficient positional range. Thereafter, the process returns -to the step 61 in order to make the positions of the actuators 6 to 11 be within the efficient positional range thereof.

However, at the step 64 if it is determined that the position of the bucket cylinder 10 is within the effective positional range, the controller 1 determines at a next inquiry step 65 whether the actuating switch 21 has been turned on. If the switch 21 has been turned on, at a step 66 the first teaching data is set as object positional data of object positions Sio of the actuators 6 to 11; then the controller 1 receives a selected operational mode M of the excavator at a step 67 and calculates an actuating speed Vi of each actuator corresponding to the operational mode M by using the object positional data.Thereafter, the controller 1 outputs at a step 69 electric control signals representing the actuating speed Vi of the actuators to the proportional valves 18 and 19 by way of the D/A signal converters 37 and 38 and the signal amplifying parts 39 and 40. Thus, the wobbling angle control proportional valve 19 controls the wobbling angles of the wobble plates 4'a and 4'b of the pumps 4a and 4b in order to control the output fluid flow of the fluid outputted from the pumps 4a and 4b. At this time, the valve 19 is supplied with the pilot fluid outputted from the third pump 4c, as described above, so that the valve 19 is capable of controlling the wobbling angles of the wobble plates 4'a and 4'b of the main pumps 4a and 4b by virtue of the pilot fluid from the third pump 4c upon receiving the control signals from the controller 1.

On the other hand, upon receiving the control signals from the controller 1, the proportional valves 18a and 18b controls the pilot fluid supplied from the third pump 4c thereto in order to control movements of the spools of the directional control valves 5a to 5f. Thus, the fluid flow and the flowing direction of the hydraulic fluid outputted from the pumps 4a and 4b to the directional valves 5a to 5f are efficiently controlled by virtue of the movements of the spools thereof, thereby causing the actuation for the actuators 6 to 11 to be controlled as desired.

The controller 1 again receives at a step 70 electric signals representing respective present positions Si of the actuators 6 to 11 from the positional sensors 12 to 17, then determines at an inquiry step 71 whether the performing function, that is, the selection of the "P" position of the function select switch 20 has been continued. If the performing function has been continued, the controller 1 determines at a step 72 whether respective actuators 6 to 11 normally operate, while if the present function of the control system is not the performing function, the process simply ends.In determining whether respective actuators 6 to 11 normally operate at the step 72, the controller 1 compares the present positions Si of the actuators 6 toX11 with the object positions Sio thereof in order to determine whether the one satisfies the other, that is, the one is within the range of the other. If the present positions Si of the actuators 6 to 11 are within the range of the object positions Sio, the controller 1 determines at a next inquiry step 73 whether the actuators 6 to 11 are to be manually controlled by means of the operator's manipulation for the control levers/pedals 2.

However, if the present posit.ions Si of the actuators 6 to 11 are not within the range of the object positions Sio, the controller 1 outputs at a step 86 an alarm signal to the alarm device in order to alarm the operator to the state that the present positions Si of the actuators 6 to 11 are not within the range of the object positions Sio, then ends the control process.

If it is determined that the actuators 6 to 11 are to be manually controlled by means of the operator's manipulation, the controller 1 performs steps 80 to 83 in order to actuate the actuators 6 to 11 in accordance with the electric signals representing manipulation values Oi outputted from the control levers/pedals 2 thereto.

Upon accomplishing the desired operation by the actuators 5 11 by means of the operator's manipulation for the control levers/pedals 2, the controller 1 outputs at a step 83 display signals representing the present positions Si of the actuators 6 to 11 and the object positions Sio thereof to the display monitor 23 in order to display them thereon.

Thereafter, the controller 24 determines at a step 83 whether the bucket cylinder is positioned within the effective range. At this time, the controller 1 compares the present bucket position SeKi with the object bucket position SBKo in order to determine whether the one is within the range of the other. If the present position SaKj is not within the object position SBKo' the steps 83 and 84 are repeatedly processed by the controller 1 until the present position 58Ki is within tn object position SEKo.However, if the present position SBKi is within the object position SBKo, at a step 85 the controller sets the object position Sio, then proceeds to a step A wherein it is determined whether the positional values of tir object positions Sio of the actuators 6 to 11 are larder than that of the present positions Si..

On the other hand, at the step 73 if it is determined that the actuators 6 to 11 are not to be manually controlled but to be automatically controlled, the controller . simply proceeds to the step 74. If the positional value of t.- object positions Sio of the actuators 6 to 11 are larder th--n those of the present positions Si, the process returrs to the stetp 70 in order to add an additional value to each p:itiona.

value of the present position Si until the positional value cf the present position Si is equal to or larger than that of the object position. However, If it is determined that the positional values of the object positions Sio of the actuators 6 to 11 are larger than those of the present positions Si, the controller 1 proceeds to a step 75 wherein it is determined whether the data is the last data. If the data is not the last data, the controller 1 receives at a step 76 next data (+1 data), then at a step 77 sets the next data as the object positional value. Thereafter, the process proceeds to the step 67 in order to perform an inner loop for actuating the actuators 6 to 11.However, if the data is the last data, the controller 1 receives at a step 78 the first data of the teaching operation, then at a step 79 sets the first data as the object positional value, thereafter, returns to the step 67 in order to perform the inner loop.

Therefore, according to the control system of this invention, a desired operation can.be optionally programmed in the controller 1 and automatically and repeatedly performed as requested without the operator's manipulation for the control levers/pedals 2.

In addition, the present invention can provides a control system for selecting a manipulation pattern for the control levers 2, which is familiar to the operator, irrespective of the types of excavators and automatically controlling the actuators under the selected manipulation pattern. The control system of this invention is provided with four types of manipulation patterns sho'wn in FIGS0 6A to 6D, said patterns being identical with those of known patterns, Thus, according to the system of this invention, a manipulation pattern of an excavator which is familiar to the operator can be optionally selected as desired, thereby facilitating the manipulation for the levers 2 without confusion irrespective of the difference of the patterns of the excavators.

The control system for selecting a manipulation pattern and controlling the actuators under the selected pattern will be described in detail in conjunction with the drawings.

FIG. 7 is a schematic block diagram showing a construction of the control system, and FIG. 8 is a block diagram showing the inner construction of the electronic controller 1 and the control levers 2.

As described in FIG. 7, the control system comprises the electronic controller 1, a pattern input panel 44 for setting a desired manipulation pattern for the control levers 2, an alarm device 46 and a display monitor 45. As described in FIG. 8, the controller 1 comprises the CPU 31 for controlling the system in accordance with a manipulation pattern for the levers 2 selected by the pattern input panel 44, a plurality of A/D signal converters 32a to 32d for converting the analog signals of the manipulation values ei of the control levers 2 into the digital signals, a decoder 47 for controlling the signal conversion by the A/D signal converters 32a to 32d in accordance with a control signal from the controller 1, the ROM 35 for storing control programs and the RAM 36 for storing input data applied from the A/D signal converters 32 thereto.

Here, the CPU 31 can change the order of signal conversions, each performed by each A/D signal converters 32a to 32d, in accordance with the selected manipulation pattern for the control levers 2 by changing the order for activating the converters 32a to 32d, or can change the order of reading the data stored in the RAM 36.

In operation, upon receiving electric signals representing the manipulation values ei for the control levers 2, the controller 1 of the control system controls ne proportional control valves 18 and 19 in accordance with te manipulation pattern selected by the pattern select panel -t, thereby controlling the directional control valves a to 5f and the wobbling angle cohtrol members 19a and lOb. The controller 1 outputs a display signal to a pattern display monitor 45 in order to display the selected manipulation pattern, said monitor 45 electrically connecting to the controller 1 as described in FIG. 7.

In FIG. 8, the A/D signal converters 32a to Z2d correspond to respective manipulation patterns of a type to "d" type of a manipulation pattern table 49, said types a to "d" of the manipulation patterns of the table 49 correspond,ng to the types of the manipulation patterns.showing in FIGS. 6A to 6D, respectively. In the drawling, the reference numeral 58 denotes an input interface for interfacing the pattern input panel 44 to the CPU 31.

In operation, upon receiving a manipulation pattern having been selected by the pattern input panel 44 and received by way of the input interface 48, the CPU 31 controls the signal converters 32a to 32d by means of the decoder 47 in order to receive manipulation values #i of the control levers 2, then stores the data values #i in the RAM 3q. Thereafter, the CPU 31 orderly reads the data values ei stored in the RAM 36 in order to perform a program stored in the ROM 35 on the basis of the data values ei, thereby controlling the actuators 6 to 11 under the selected pattern.At this time, the CPU 31 may convert decode values of the decoder 47 in accordance with the selected manipulation pattern in order to change the order for activating the A/D signal converters 32a to 32d, stores the data values ei in the RAM 26 orderly and reads the data values ei of the RAM 36 orderly in order to operate the actuators 6 to 11 according to the values ei, or may orderly activate the converters 32a to 32d without change of the order1 stores the data values ei in the RAM 36, then changes the reading order of the data values ei of the RAM 36 according to the selected pattern. The two types of changing the order in accordance with the selected pattern have the same operational effect with each other.

Thus, if the operator selects a manipulation pattern for the control levers 2 which is familiar to him, then manipulates the control levers 2 according to the selected pattern, the CPU 31 changes the order for receiving the manipulation values ei of the levers 2 according to the selected pattern so that a data value el for an actuator can be stored in a certain area 2, 93 or the like of the RAM 36. Thereafter, the CPU 31 orderly reads the data stored in each area of the RAM 35, thereby accomplishing an automatic control for the actuators 6 to 11 in accordance with a predetermined reading order. Thus, the system allows the operator to manipulate the control levers 2 in a man pulaticn pattern which is familiar to him irrespective of te difference of the types of the excavators.

Turning to FIG. 9A which is a flowchart showing a process for automatically selecting.a type-of manipulation pattern for the control levers 2 which 'is familiar to the'operator and controlling the actuators 6 to 11 according to the selected pattern, the controlter 1 performs steps 90 and 91 in order to determine whether the engine M has been started by means of a start switch (not shown), then at a step 92 receives an electric signal of a reference select key value ep from the pattern input panel 44 by way of the input inter-ace 48, thereby being informed of the selected pattern. Thereafter, at a step 93 upon receiving a display signal from the controller 1, the monitor 45 displays the selected manipulation pattern.

The controller 1 then determines at a step 94 whether a changing switch (not shown) of the panel 44 has been turned on. If the switch of the panel 44 has been turned on, the controller 1 performs a step 95 in order to receive an electric signal of present select key value eXP of the panel 44, then determines at an inquiry step 96 whether the present select key vaTue e s p is equal to the reference key value eP.

If the select key value B'p is not equal to the reference key value ep, the controller 1 determines at a next inquiry step 97 whether the control levers 2 are positioned at respective neutra' positions. At this time, if it is determined that the control levers 2 are not positioned at respective neutral positions, at a step 98 the controller 1 outputs an alarm signal to the alarm device 46 in order to alarm the operator to the present positional state of the control levers 2, then returns to the step 97.

On the other hand, if the changing switch of the panel 44 is turned off, or if the select key value 8'p is equal to the reference key value ep or if the control levers 2 are positioned at neutral positions, the controller 1 simply proceeds to a step 99 wherein it outputs display signal to the monitor 45 in order to display the selected manipulation pattern on the monitor 45.

Thereafter, at a step 100 the controller 1 receives electric signals of manipulation values ei of the control levers 2 in a predetermined receiving order corresponding to the selected manipulation pattern as described in a flowchart showing a sub-routine of FIG. 9B. Thus, the controller 1 controls the actuators 6 to ii according to the selected manipulation pattern. In the flowchart of FIG. 9B, respective processes for activating the A/D signal converters 32a to 32d according to respective patterns A to D corresponding to the patterns of FIGS. 6A to 6D are similar to each other except for difference of order of activating the converters 32a to 32d, so that it will be described only for the process en case of the D pattern, for example.

If the operator selects the D pattern1 through the steps 94 to 97 of the flowchart of FIG. 9A it will be determined that the D pattern has been selected, the CPU 31 of the controller 1 controls the decode values of the decoder 47 through steps 106 to 109, and orderly activates the A/D signal converters 32a to 32d in a predetermined order of 32c - > 32d > 32a - > 32b. In other words, the CPU 31 activates the third converter 32c at the step 106, the fourth converter 32d at the step 107, the first converter 32a at the step 108 and the second converter 32b at the step 103. Accordingly, the analog signals of manipulation values 8i are orderly converted into the digital signals. That is, the signal corresponding to the bucket cylinder 10 is first converted, the signal corresponding to the boom cylinder 11 is second converted, the signal corresponding to the swing motor 6 is third converted, then the signal corresponding to the dipper stick 7 is last converted.

Thereafter, the controller 1 orderly stores the data values of the manipulation values ei in respective areas of the RAM 36, the first to fourth areas 1 to 4, then orderly reads the data values of the RAM 36 in a predetermined reading order of 1 - > 2 - > 3 - > 4 in order to actuate the actuators 6 to 11 in accordance with the D pattern.

On the other hand, in the process for actuating the actuators 6 to 11 in accordance with an optionally selected manipulation pattern for the control levers 2 may be changed into another type, as described above. That is, the CPU 31 may not change the activating order for activating the A/D signal converters 32a to 32din response to the selected manipulation patterns but orderly activate the converters 32a to 32d in a.sequent order, that is, from the first converter 32a to the fourth converter 32d, in order to orderly receive the manipulation values ei for the swing motor 6, the dipper stick cylinder 7, the bucket cylinder 10 and the boom cylinder 11, then orderly stores the data values of the manipulation values ei in respective areas 1 to 4 of the RAM 36.

Thereafter, the CPU 31 reads the data values of the RAM 36 in a predetermined reading order corresponding to the selected manipulation pattern, for example, in the reading order of 3 - > 4 - > 1 - > 2 in case of selecting the D pattern, as described in FIG. 9C. As described above, the process of FIG.

9C provides the same operational. effect as that of the process of FIG. 9B.

In addition, the control system of this invention provides a communicative control system for the controller 1 by means of an external computer in order to control the actuators 6 to 11 as follows.

As described in FIG. 10 which is a schematic block diagram showing a construction of the communicative control system in accordance with this invention, the control system comprises an electronic controller 1 connected to the external computer. The controller 1 comprises a CPU 31, a communication interface 114 for interfacing the external computer to the 9PU 31, a receiving buffer 115 for receiving communication input data applied from the computer to the CPU 31, a transmitting buffer 116 for outputting communication output data applied from the CPU 31 to the computer, the A/D signal converters 32 for converting analog signals of manipulation values el of the control levers/pedals 2 into the digital signals.Here, the CPU 31 controls the actuators 6 to 11 in accordance with the communication data applied from the external computer thereto.

In FIG. 10, the reference numerals 1t9a and 119b denote a pair of switches for switching the electric circuit of the system of FIG. 10 under the control of the CPU 31, the numeral 117 denotes a LCD key (liquid crystal diode key) and the numeral 118 denotes an "OR" circuit.

Hereinafter, the description for the control for the actuators 6 to 11 by means of the controller 1 and the calculation for respective values, for example, the manipulation values ei of the control levers/pedals 2, the positional values Si of the actuators 6 to 11 and the like, can be referred to the previous description. Thus, the following description will be described only for the process for processing the data communication between the external computer and the controller 1 in conjunction with FIGS. 11 and 12.

As shown in FIG.- 11 which is a flowchart showing the process for the data communication, the controller 1 first determines at a step 120 whether there is a STX signal (Start of Text signal) in input signals having been applied from the external computer thereto by way of the receiving buffer 115.

Here, the input data for starting the data communication which is applied from the external computer to the controller 1 has a format shown in FIG. 12A. In FIG. 12A, the alphabets SYNC denotes a synchronizing signal, the STX denotes the start of text signal representing start of the data transmission, the ID denotes an identification signal, the ETX denotes an end of text signal representing end of data transmission and the FCS denotes a frame check sequence signal for discriminating the input data signals of the controller 1 as an information unit and checking said input signals.

In addition, the controller 1 is connected to the external computer by using the RS 422-type connection, the transmitting and 8 the receiving lines for the data communication are accomplished by the BSC type, and the dat.s is transmitted at a transmission speed of 400 KBPS.

On the other hand, the data transmission and the data reception are accomplished by a Full-duplex system in order to efficiently use the transmission speed, so that a Go-Back-4 ARQ (automatic repeat request) pattern is used, for example.

Turning again to FIG. 12A, the ID signal may be several types of signals different from each other as follows: That is, an ID signal of OdH: a proportional signal, an ID signal of 01H: a switch manipulation signal, an ID signal of 10H: a feedback request signal (a proportion signal), and an ID signal of 11H: a feedback request signal (an operations mode signal).

Here, the data (DATA) has two types of formats as shown in FIG. 12B in case of the ID signal of OOR-and in FIG. 12C in case of the ID signal of 01H, respectively. In FIG. 128, the "Travel L" means a left-side travelling of the excavator by means of the left-side crawler-type travelling member, while the "Travel R" means a right-side travelling of the excavator by means of the right-side crawler-type travelling member. In FIG. 12C, data corresponding to the switch value of 11H means switch on", while data of OOH means "switch off".

Additionally, in case of unnecessariness of proportion value, all- of the necessary proportion values are set as "1".

Turning again to FIG. 11, through steps 120 and 121 if it is determined that the STX signal has not been received for a predetermined time since the SYNC signal was received, the controller 1 outputs at a step 122 an error signal in order to display the error state of.the communicative control of the computer, then ends the process. However, at the step 120 if it is determined that the STX signal. has been received, at a step 123 the controller 1 receives the data from the external computer by way of the receiving buffer 115, then determines at a step 124 whether the ETXJsignal has been received.If the controller 1 has received no ETy signal it returns to the step 123 in order to again receive the data from the computer until the ETX signal will be received. But, if the controller 1 has received the ETX signal, it determines at steps 125 and 126 whether an error has generated in the data communication.

If there is no error in the data communication, the controller 1 outputs at a step 127 an ACK signal (an acknowledged signal) to the external computer by way of the transmitting buffer 116. However, if there is an error in the data communication, the controller 1 outputs at a step 128 a NAC signal (a notacknowledged signal) to the external computer by way of the transmitting buffer 116, then returns to the step 120.

Upon accomplishing the performance for the step 127, the controller 1 performs a next step 129 wherein it is determined whether a feedback request signal has to be transmitted from the controller 1 to the computer. At this time, the feedback request signal is outputted from the controller 1 to the computer in order to request to receive checking results for the actuators 6 to 11 in accordance with the data from the external computer. If the feedback request signal needs to be transmitted, the operator selects the actuator which is subjected to the feedback, then'transmits the feedback request signal at a time. The feedback request signal has the format shown in FIG. 12D.In FIG; 12D, the positional sensors comprises the swing sensor 12, the dipper stick sensor 13, the travelling motor sensors 14 and 15, the bucket cylinder sensor 16, the boom cylinder sensor 17 and a car frame inclination angle sensor (not shown) for sensing the inclination angled of the car frame of the excavator with respect to the ground. nI addition, the format of the feedback request signal generally comprises a 24 bit format, however, it is desired to select 8 bits for a transmission taking account of the transmission speed. At this time, if each positional sensor has been set in order to correspond to a key of the external computer, checking -results for an actuator which is requested to feedback will be obtained by simply pressing the corresponding key of the computer.For example, if an actuator is set at the % key of the external computer, the checking results for the actuator according to the data from the external computer can feedback upon simply pressing the % key of the computer.

Turning again to FIG. 11, at a step 129 if it is determined that the feedback has to be requested, at å step 130 the controller 1 transmits the data value for the actuator, which has been selected by the computer in order to be checked, to the external computer. The transmission data has several types of fbrmats shown in FIGS. 12E to 12I.

FIG. 12E shows response data which corresponds to the sensors 12 to 17 and a proportion signal and is periodically transmitted, while FIG. 12F6 shows response data which correspsnds to switches and an operational mode and is transmitted when the external computer generates a key stroke.

On the ether hand, FIG. 12G shows constructions of the ACK data signal format and ID data signal format of FIGS. 12E and 12F. In FIG. 12G, ID data signal of "0000" shows sensor data signal, while ID data signal of "1111" shows switch mode data signal. In addition, ACK signal of "0000" represents that the ACK signal has been received, while ACK signal of "1111' represents that the ACK signal is not received. On the other hand, FIGS. 12H and 12I show constructions of the data 1 of FIG. 12E and the data 2 of FIG. 12F, respectively.

Turning again to the flowchart of FIG. 11, upon transmitting the response data at the step 130, the controller 1 determines at a step 131 whether the ACK signal has been received. If the ACK signal-has been received,.the controller 1 returns to the step 120, while it determines at a step ;32 whether the NAK signal has been received if it is determined at the step 131 that the ACK signal has not been received. If the NAK signal has been received1 the controller 1 performs a step 133 wherein it is determined whether the transmission of the response data has to be retried. At this time, the times of retry of the response data transmission has been previously set. If the transmission of'the response data has to be retried, the controller 1 returns to the step 130.However, at the step.132 if it is determined that the NAK signal has not been received or at the step 133 if it is determined that predetermined retry of the response data transmission has been already accomplished, the controller 1 outputs at a step 134 an error signal, then ends the process.

The external computer can comprise a conventional type of computer.

As described above, the present invention provides a control system for excavators in which several advantages are provided as follows: First, a desired operation can be optionally programmed by the controller in order to be selected to be performed as requested, thereby simply, automatically and repeatedly performing the desired operation without operator's manipulation for the control levers/pedals. Thus, the system of the present in-ention provides advantage in that it facilitates the operation of the excavator, and even unskilled operator can efficiently operate the excavator.

Second, the system of this invention allows the operator to optionally select the manipulation pattern for the control levers, thereby causing the operator to select a manipulation pattern which is familiar to him irrespective of the types of the excavators. Thus, the systemof this invention provides advantage in that it provides convenience in manipulation for the control levers without occurrence of any confusion and efficiently prevents a safety accident due to the confusion in manipulation.

Third, the system of this invention can control the actuators by data communication between the actuators and an external computer which is connected to the controlAer. Thus, the system provides advantage in that an operational condition of each actuator can be easily check without operator's manipulation for the control levers/pedals.

Although the preferred embodiments of the present invention have been disclosed for illustrative purpose, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1 A control system for automatically controlling operation of a construction vehicle comprising: an electronic controller; external data input means being connected to said controller and transmitting control data to said controller in a data communication; a communication interface for interfacing said external data input means to the controller; a receiving buffer for receiving input data from the external data input means by way of said communication interface; and a transmitting buffer for transmitting output data from the controller to the external data input means, whereby the controller being capable of actuating actuators in accordance with an instruction data applied from the external data input means thereto, calculating positional values of said actuators on the basis of electric signals of positional displacements applied from positional sensors of the actuators thereto, calculating the positional displacements of the actuators on the basis of said electric signals in order to obtain calculating results, then transmitting said calculating results of the positional displacements of the actuators to the external data input means.

2 A control method for automatically controlling operation of a construction vehicle by using a control system of claim 1, said method comprising the steps of: determining whether a start signal representing start of data transmission, then receiving data from the external data input means; determining whether an error occurs in said data communication in order to transmit an acknowledged signal or a not-acknowledged signal to the external data input means; determining whether a feedback for requesting a checking result of an actuator is requested in order to transmit a feedback request signal to the means; and determining whether predetermined retry for the feedback have been accomplished.

3 A control system for automatically controlling operation of a construction vehicle comprising: an electronic controller; function select means for optionally selecting a teaching function for programming a desired operation and a performance function for practically performing said programmed operation as requested; means for generating a start signal and a stop signal; means for selecting an operational mode for limiting a maximum fluid flow of hydraulic fluid which is to be outputted from hydraulic pumps in accordance with said selected operational mode; and means for displaying respective positions of actuators of the excavator thereon, whereby a desired operation being optionally programmed and simply selected as requested in order to be automatically performed without operator's manipulation.

4 A control system for automatically controlling operation of a construction vehicle comprising: means for selecting a desired manipulation pattern for control levers; and an electronic controller electrically connected to said means comprising; a central processing unit for controlling said system in accordance with said selected manipulation pattern selected by said means; analog/digital signal converters for converting analog signals of manipulation values of said control levers into digital signals; a decoder for controlling the signal conversion of said analog/digital signal converters in accordance with a control signal from said central processing unit; a RAM for storing data values from the analog/ digital signal converters; and a ROM for storing a control program of the central processing unit; whereby an order for activating the analog/ digital signal converters being changed in accordance with the manipulation pattern having been selected by the means for setting the manipulation pattern or an order for reading data values having been stored in said RAM being changed in accordance with the selected manipulation pattern, thereby manipulating the control levers in a desired manipulation pattern which is familiar to the operator.

5 A control method for automatically controlling operation of a construction vehicle by using a control system of claim 4, said method comprising the steps of: determining whether a start switch has been turned on, then displaying a selected manipulation pattern on a display monitor upon receiving reference key values from means for selecting the desired manipulation pattern for control levels; determining whether a changing switch of the means has been turned on, then upon receiving key values from said means, determining whether said key values are equal to said reference key values; upon determining whether control levers are positioned at neutral positions, displaying the selected manipulation pattern on a display monitor; and actuating actuators in accordance with the selected manipulation pattern, then returning to the step wherein said switch of the means has been turned on, whereby said construction vehicle being manipulated in a manipulation pattern for the control levers which is familiar to the operator.

6 A control method as claimed in claim 5, wherein said step for actuating said actuators in accordance with the selected manipulation pattern comprises the steps of; determining which manipulation pattern has been selected; and orderly activating analog/digital signal converters in a predetermined activating order in accordance with the selected manipulation pattern.

7 A control system as hereinbefore described with reference to the accompanying drawings.