DE68913412T2 - Intuitive control lever for an implement. - Google Patents

Description

The invention relates generally to a control system for controlling an implement or tool on a work vehicle and, more particularly, to a control system that provides an intuitive control interface between the implement and the vehicle operator.

In the field of work vehicles, particularly those vehicles that perform digging or loading functions, such as excavators, backhoes and shovels, the work equipment is generally controlled with two or more operator controls in addition to other vehicle function controls. The manual control systems often include foot pedals as well as hand-operated levers. For example, a backhoe manufactured by J. I. Case Manufacturing Co. uses three levers and two pedals to control the shovel or digging implement or tool. A backhoe manufactured by Ford Motor Co. has four levers to control the same. There are serious disadvantages associated with these equipment control schemes. One is operator stress and fatigue as a result of having to manipulate or operate so many levers and pedals. A vehicle operator must have a relatively high level of experience in order to efficiently manipulate and coordinate the multitude of control levers and foot pedals. To become productive, an inexperienced operator will need a long training period to become familiar with the controls and their functions.

Some manufacturers recognize the disadvantages of having too many controls and have adopted a two-lever control scheme as Standard. Generally, two vertically mounted dual-axis levers share the duties of controlling the linkages (boom and arm) and the bucket or bucket of the implement. For example, hydraulic excavators currently manufactured by Caterpillar Inc. use one control lever for arm and swing control and another control lever for boom and bucket control. Similarly, Deere & Co. has a hydraulic excavator with one control lever for boom and swing control and another for arm and bucket control. In any case, the number of controls has been reduced to two, making machine operation much easier. However, these two lever control schemes are still not entirely desirable. The association of the implement links with the joysticks is completely free, and there is no correlation between the direction of movement of the implement links and that of the control levers. To cause the boom to raise, the arm to move toward the vehicle, and the bucket to rotate in, as in a typical grading operation, the operator on a Caterpillar hydraulic excavator manipulates the right-hand control handle diagonally rearward and to the left of the vehicle to rotate or rotate in the bucket and raise the boom, and the left-hand control handle rearward of the vehicle to move the arm.

The desirable correlation of device movement intuitively with the controls was only partially fulfilled in the known systems.

Such a system is described in US-A-4 059 196. The control system shown here comprises a manual control lever in the form of a miniature implement consisting of a miniature boom, arm and bucket. To dig, the operator manipulates all three elements of the miniature controller to go through the same movements as the excavator. The cascade control system (master-slave control system) addresses the problem of correlating the controls with the implement, but the three-element joystick is effectively a three-lever control system, which inherently has the same multiple control problems mentioned above. In addition, not only does the control system not provide a comfortable grip, but it is also strange to manipulate, position and coordinate all three elements to mimic the operating sequence of the boom, arm and bucket. The joystick is also not of a conventional design and thus requires special manufacturing.

Another known system is described in US-A-4 645 030. This describes a multi-function directional control unit containing various levers, switches and buttons, where each separate control element is associated with a working movement. Although the direction of the human control movements mostly coincide with those of the controlled equipment movements, the interface or interface established by this control unit is not intuitive, nor does it match natural expectations. Moreover, it is still necessary for the operator to become accustomed to the 1:1 layout of each control element with its corresponding function and the multiple controls make the operation of the machine slightly confusing and challenging. This system also has a special structure and requires special manufacturing.

DE-A-2 230 897 shows a control lever system which does not operate in a manner which enables the movement of the control lever to correspond to the movement of the device or tool (although it does show a control lever with a head part which is rotatable with respect to the main part of the control lever) and is therefore not intuitive to use, but provides a system from which the present invention is distinguished.

The present invention is directed to eliminating the above-mentioned problems.

It is a primary object of the present invention to provide a more intuitive control interface between the operator and the vehicle implement or tool, wherein the controls and the direction and speed of the implement movements they control have a logical correlation.

Other objectives are to provide a control system that is easily manipulated to reduce operator stress and fatigue, and a control system that uses controls of conventional shape and design that do not require special manufacturing.

According to the invention there is provided a control system for controlling a working device or tool on a vehicle, the working device comprising: a first link connected to the vehicle, a second link connected to the first link, and a working device connected to the second link, the first link, the second link and the working device being controllably and pivotably movable in a substantially vertical plane with respect to one another, and hydraulic actuating means for controlling the working device of the second link and the first link in response to control signals from the control system, the control system comprising: a joystick movable in first and second directions for generating electrical signals corresponding to the movement; and

control means for providing a plurality of implement control signals to the hydraulic actuating means in response to receipt of the electrical signals;

characterized in that:

the control means are arranged so that the vertical movement of the working device is controlled by movement of the control lever in the vertical direction and horizontal movement of the working device is controlled by movement of the control lever in the horizontal direction; and

the control lever is arranged essentially horizontally and can be rotated about its longitudinal axis.

The control means may be operated to coordinate the movements of the links and the working device to effect a resultant linear movement of the working device.

In one example, the movement of the first link is controlled by movement of the control lever in the substantially vertical direction and the movement of the second link is controlled by movement of the control lever in the substantially horizontal direction; and the control means are arranged so that the movement of the working device with respect to the second link is controlled by rotational movement of the control lever about its longitudinal axis.

The present invention significantly reduces the time required to train an inexperienced operator. In addition, the system is intuitive and does not have arbitrary control function design. The control levers can be of conventional design and manufacture.

For a better understanding of the two examples of the control systems according to the present invention, reference is now made to the drawing, in which:

Fig. 1 is a diagrammatic view of the intuitive joystick control system and implement;

Fig. 2 is an isometric view of the intuitive joystick control system mounted relative to the operator seat;

Fig. 3 is a side view of the vehicle performing a shovel leveling movement, with the device movement being shown in dashed lines;

Fig. 4 is a block diagram of the coordinated control implementation.

In Fig. 1, a diagrammatic view of an embodiment of the intuitive joystick control system 10 is shown. Vehicles suitable for application of the present control system are excavator-type earthmoving or forestry or tractor machines, such as excavators, backhoes, shovel excavators, wheel loaders, track loaders, and rail or roller vehicles (vehicles not shown). The controlled implement 11 typically consists of linkages such as a boom 12 and arm 13 and a working device such as a shovel or bucket 14. However, the device configuration may vary from machine to machine and the configuration may include a working device other than a shovel or bucket, such as a grapple bucket or grab. In certain machines, such as the excavator, the operator's cab is rotatable along a vehicle center axis together with the implement; in others, such as a backhoe, the operator's cabin is stationary and the working device can be swivelled to another location, namely at the Pivot point at the base of the boom. This difference is not significant and the implementation of the intuitive joystick control system in the two cases is essentially identical.

The implement 11 of the vehicle is generally operated in a vertical plane 49 and is pivotable with the operator's cab to a plurality of second planes different from the first plane by rotating the vehicle platform or by pivoting the boom pivot base. The boom 12 is operated by two hydraulic cylinders 15, 16 which enable the raising and lowering of the implement 11. The arm 13 is pulled toward and away from the vehicle by a hydraulic cylinder 17. Another hydraulic cylinder 18 "opens" and "closes" the bucket or shovel. The hydraulic flow to the implement cylinders is regulated by hydraulic control valves 21, 22, 20, and 19, respectively.

The operator interface for controlling the implement consists of two control levers, one mounted horizontally and the other vertically for easy access, on the right and left sides of the operator's seat. The control levers are inductive control levers of conventional design, such as one manufactured by CTI Electronics of Bridgeport, CT, USA, but other types may be used. The horizontally mounted control lever 23 has three degrees of movement, all of which lie in a plane 50 that is substantially parallel to the implement plane 49: toward the front and rear of the vehicle (shown by arrow 25), vertically up and down (shown by arrow 26), and rotationally (shown by arrow 27) along its longitudinal center axis 52. The vertically mounted control lever 24 is movable to the left and right sides of the vehicle (shown by arrow 28). The horizontally mounted control lever 23 generates a signal for each corresponding degree of movement, each signal representing the control lever displacement direction and speed from the neutral position. Similarly, the vertically mounted control lever 24 generates a signal for the left-right displacement direction and speed for the implement side swing control. The electrical signals are received by a controller 30 which is responsive to supply a plurality of implement control signals to the hydraulic control valves 19, 20, 21, 22.

In Fig. 2, an isometric view of the operator seating area and manual controls is shown. The operator, when seated in the seat 31, can rest his or her arms on the armrests 32 where the control levers 23, 24 can be easily reached.

According to one embodiment of the present invention, the joysticks control the implement links independently of one another. In this embodiment, each axis of movement of the horizontally mounted joystick corresponds to a specific link on the implement. This is similar to current conventions of excavator-type machine controls. The operator must thus compensate for the geometry of the implement, with each link following an arc at each corresponding pivot point when actuated. For example, to keep the bucket level during certain digging operations, the operator must compensate for the arc of raising and lowering the boom while controlling the arm movement and bucket rotation or retraction. Nevertheless, this embodiment is still more intuitive than conventional designs.

In another and preferred embodiment, the control of the linkage movements is coordinated simultaneously. In Fig. 3, a vehicle 34 is shown performing a bucket leveling movement. When pulling the bucket, level toward the vehicle, all three links must be controlled simultaneously and in a coordinated manner. In the first dashed outline 35, the arm is extended and the bucket or scoop is in a closed position. When the device is pulled to the position shown in the second dashed outline 36, the boom is raised, the arm is closer to the vehicle, and the bucket is in a more open position. In the final position shown by the solid outline 37, the boom is lowered, the arm is retracted, and the bucket is open. In a vehicle with conventional controls, where each link is controlled independently, all link movements must be explicitly controlled and manipulated by the operator. Since the primary concern of the vehicle operator is bucket placement, the second embodiment of the invention allows precise operator displacement and directional control of the bucket regardless of the geometry of the implement. Therefore, to perform a planar bucket movement, such as in soil finishing, the operator only has to move the horizontally mounted control lever 23 toward the front or rear of the vehicle.

A block diagram of the coordinated control implementation is shown in Fig. 4. The electrical signals generated by the joysticks are shown as joystick speed request inputs to the block diagram. These speed request or command signals are specified in Cartesian coordinates corresponding to joystick movement. The speed requests are transformed at 60 into a different coordinate system based on the configuration and position of the links. The velocity transformation also receives link position data from sensors such as link angle resolvers and cylinder position sensors known in the art. Reference is made to Robot Manipulators: Mathematics, Programming and Control by Richard P. Paul, MIT Press, 1981. The cylinder velocity (or joint angular velocity) requests from this translation process are scaled in block 62 by a factor obtained in the proportional flow control block 61. Proportional hydraulic flow control is described in US-A-4,712,376. The basic concept of proportional flow control involves calculating the amount of hydraulic flow available for equipment actuation under the current operating conditions (ie: engine speed, vehicle motion, etc.). The resulting scaled velocity request from block 62 is transferred to the velocity control block 63 where an open or closed control loop determines the hydraulic valve velocity control signals to meet the cylinder velocity request. Such open or closed loop control systems are well known in the field of control theory. The hydraulic control valve signals are complemented with another set of signals to eliminate errors introduced in the Cartesian to link coordinate transformation.

In block 64, the joystick speed requests are scaled by the same factor obtained in proportional flow control. The scaled joystick speed commands are integrated over time to obtain position commands 65 and transformed to the link coordinates 66. This transformation is similar to the transformation process in block 60. The output of the position transformation block 66 is applied to another open or closed control loop. 67 where the hydraulic valve position control signal is detected. The hydraulic valve control signals from both branches are combined at 68 to arrive at the final cylinder valve control signals for the implement.

The Cartesian to link coordinate transformations described above use the bucket pin as the reference point and do not reference the bucket swing position. However, it is more intuitive for the operator to operate the vehicle using the bucket swing because the significant endpoint translation can be easily extended to accommodate the bucket linkage.

To control the implement, the operator moves the joystick controls as if the implement were an extension of his left or right arm. To cause the implement to move outward from the vehicle, the operator pushes the right joystick outward toward the front of the vehicle. To cause the implement to move upward, he raises the right joystick upward. To cause the bucket to close or retract, he turns his wrist in, which in turn rotates the right joystick. In one embodiment, the direction and speed of the implement links independently correspond directly to the movement of the joystick controls. In another embodiment, the joystick movements directly correspond to the movement of the bucket. The second embodiment is preferred because it provides the operator with direct control of the spatial placement of the bucket at the work site. This can be easily imagined by comparing the human arm to the implement, with pivot points at the shoulder, elbow, and wrist. When reaching for an object, the placement and Movement of the arm, forearm and elbow is irrelevant; the focus is on the placement and path of the hand. The left control lever controls the lateral pivoting of the device to a different work location.

Since the control scheme addresses natural expectations, it should take significantly less time to become familiar with and efficient in operating vehicles equipped with the invention. It also reduces operator stress and fatigue since it requires significantly less concentration to operate.

Claims (7)

1. A control system (10) for controlling a work device (11) on a vehicle (34), the work device (11) having the following: a first connection (12) connected to the vehicle (34), a second connection (13) connected to the first connection (12); and a working device (14) connected to the second link (13), the first link (12), the second link (13) and the working device (14) being controllably and pivotably movable in a substantially vertical plane (49) with respect to one another, and hydraulic actuating means (51) for controlling the working device, the second link (13) and the first link (12) in response to control signals from the control system (10), the control system comprising: a joystick (23) movable in first and second directions for generating electrical signals corresponding to the movement; and control means (30) for supplying a plurality of implement control signals to the hydraulic actuating means (51) in response to receipt of the electrical signals; characterized by: the control means are arranged so that the vertical movement of the working device (14) is controlled by movement of the control lever (23) in the vertical direction and the horizontal movement of the working device (14) is controlled by movement of the control lever (23) in the horizontal direction; and the control lever is arranged essentially horizontally and can rotate about its longitudinal axis. 2. Control system according to claim 1, wherein the control means (30) are operable to coordinate the movements of the links (12, 13) and the working device (14) to produce a resultant linear movement of the working device (14). 3. Control system according to claim 1 or 2, wherein the working device is rotatable upon rotation of the control lever. 4. Control system according to claim 1, wherein the movement of the first link (12) is controlled by the movement of the control lever (23) in the substantially vertical direction (26) and the movement of the second link (13) is controlled by movement of the control lever (23) in the substantially horizontal direction (25); and wherein the control means are arranged so that the movement of the working device (14) with respect to the second connection (13) is controlled by rotational movement (27) of the control lever (23) about its longitudinal axis. 5. Control system according to one of claims 1 to 4, further comprising: an upright second joystick (24) movable in a third direction for generating electrical signals corresponding to the movement, wherein the control means (30) for controlling the pivoting movement of the implement (11) in response to the movement of the second joystick in the third direction (28) and wherein the implement (11) is further simultaneously controllable and pivotable is movable about a substantially vertical axis. 6. Control system according to claim 4, wherein the control means (30) controls the speed of movement of the first link (12), the second link (13) and the working device (14) so that it is directly proportional to the amount of movement of the first and/or the second control lever (23, 24). 7. Control system according to one of claims 1 to 6, wherein the first connection (12) is a boom, the second connection (13) is an arm connected to the boom (12) and the working device is a bucket or scoop (14) connected to the arm.