DE102021108690A1 - Operating unit for a construction machine, construction machine and method for operating a construction machine - Google Patents

Abstract

The invention relates to a control unit (17) for construction machines (1), in particular soil compactors, road finishers or ground milling machines, comprising at least two control elements (19) which are designed for the input of control commands by an operator, a control element support plate (18) on which the control elements (19) are arranged, and an evaluation unit (20) which is connected to the operating elements (19) via a respective signal transmission connection (22), which is arranged separately from the operating element support plate (18) and which is designed to transmit output signals from the operating elements (19) to receive and process, wherein the signal transmission connection (22) is a flexible cable connection or a wireless connection. The invention also relates to a construction machine (1) and a method (35).

Description

The invention relates to an operating unit for construction machines, in particular soil compactors, road finishers or soil milling machines. In addition, the invention also relates to a construction machine with such an operating unit and a method for operating a construction machine.

Generic construction machines are, for example, soil compactors, such as tandem rollers, compactors, rubber-tyred rollers and garbage compactors, as well as road finishers or ground milling machines, for example road milling machines, stabilizers or recyclers. Such construction machines are typically used in road and path construction and for the construction and compaction of landfills. They often include a large number of machine functions that can/must be controlled by an operator during work. The machine functions relate, for example, to the advance speed and the use of various working units of the construction machine. In addition, machine functions can also assume different states, for example speed or intensity levels.

In order to enable the operator to control the construction machine, these comprise at least one operating unit, the operating unit in the present case comprising at least two operating elements which are designed for manual input of control commands by an operator. The operating elements are arranged, for example, on an operating element support plate, in particular a common one, and can be actuated manually by an operator, for example, by pressing, sliding and/or turning. In addition, the operating unit typically includes an evaluation unit which is connected to the operating elements via a respective signal transmission connection and is designed to receive and process output signals from the operating elements. Such an evaluation unit can, for example, be a suitable processor or a data processing device comprising at least one processor. A control unit of this type therefore forms, for example, a control panel or control panel arranged in the driver's cab of the construction machine with at least two and in particular a large number of control elements, via which the operator controls the construction machine or functions of the construction machine.

In such operating units of the prior art, operating elements are regularly used which are structurally designed for the function to be controlled via them. For example, the operating elements are typically limited to a number of possible operating positions that correspond to the number of machine functions or states that can be set using this operating element. For a machine function which, for example, has only two states, for example “on” and “off”, an operating element is typically provided which also has only two operating positions. In particular, constructive limitations, such as mechanical stops, are used for this purpose. The same applies to operating elements that are intended to control different states of a machine function, for example with an adjustable intensity between levels from "0" to "5". The controls then emit output signals that indicate which of the specified switch positions they are currently in. The number of possible switching positions of the operating element corresponds to the possible number of states of the machine function to be controlled. Due to the large number of machine functions to be controlled that are typically present in construction machines of this type, this means that a large number of differently designed special operating elements have to be manufactured, installed and kept in stock. However, if a defect in a control element occurs, for example, an exchange can also only be made with this one special control element, which is designed, for example, for three rotational positions at specific angles to one another, etc. At the same time, the controls must also be exchanged if, for example, the range of functions of the construction machine is to be expanded or if the various states of a machine function are to be reclassified. In this case, the control elements have to be newly developed or at least adapted and often completely replaced, together with the control element support plate and the evaluation unit.

In addition, it is customary in the prior art to arrange the operating elements of the operating unit together with the evaluation unit or units on a common support structure, for example on a common printed circuit board, in a housing. The result of this is that the operating units can only ever be used in the relative position to one another that is predetermined by the circuit board. In addition, such a totality of operating elements and evaluation unit in a common housing requires increased installation space, which is of course only available to a very limited extent, particularly where the operating units are to be installed in the driver's cab of the construction machine. For example, it is customary to provide control units on the armrests of a seat provided for the operator in the driver's cab. Due to the predetermined relative position of the operating units to each other and their common arrangement with the evaluation unit as a coherent module, in particular with a common housing, the flexibility of the arrangement of the operating unit on the construction machine is limited.

Against this background, it is the object of the present invention to improve a construction machine and in particular its operating unit and a method for controlling a construction machine in such a way that a more flexible and more cost-effective operating concept is provided. In particular, the flexibility of the operating elements used should be increased, and a subsequent extension of the range of functions or a change in the assignment of machine functions to the individual operating elements should be made easier. At the same time, measures to increase functional safety should be made possible.

This task is solved with a control unit, a construction machine and a method according to the independent claims. Preferred developments are specified in the dependent claims.

In concrete terms, for an operating unit according to the invention it is initially provided that the evaluation unit is arranged separately from the operating element support plate. The evaluation unit and the control elements arranged on the control element support plate are therefore no longer on a common support plate or support structure, which significantly increases the flexibility of arrangement. It is further provided according to the invention that the signal transmission connection is a flexible cable connection or a wireless connection. This also contributes to increased arrangement flexibility. In the operating unit according to the invention, it is therefore provided overall that the evaluation unit, in which at least part of the evaluation of the input entered via the operating element takes place, is spatially separated from the operating element support plate and in particular also the operating elements. This means that the evaluation unit does not have to have a fixed relative position with respect to the operating elements, but instead, for example, a machine designer can fall back on considerably more degrees of freedom in this regard. The evaluation unit therefore does not have to be arranged, for example, together with the operating elements on the operating element support plate. It is sufficient if the controls are arranged on the control element support plate. The operating elements can be connected to the evaluation unit via the flexible cable connection according to the invention or the wireless connection, in particular they can exchange data, with the evaluation unit being able to be mounted at any point on the construction machine. In this way, the controls can be arranged in relation to each other as desired. It is preferable for the cable connection to have a maximum length of 35 cm in order to ensure adequate signal quality. At the same time, the spatially separate arrangement of the evaluation unit saves installation space directly where the operating elements of the operating unit are provided and where only limited installation space is typically available. The function of the evaluation unit can preferably be to carry out a software-based evaluation and/or sorting of one or more mechanical actuating movements of the operating element or elements. In particular, this can include the processing of the specific adjustment information transmitted by the operating elements to the evaluation unit, for example with regard to its real scope, for example the specific rotary adjustment of a rotary switch in degrees, etc. In addition or as an alternative, a function of the evaluation unit can be to sort adjustment information coming in from the operating elements and to assign it to specific machine functions, for example for forwarding to a machine controller. It goes without saying that the evaluation unit is preferably designed to carry out these functions.

In principle, the operating elements can be designed in different ways. The operating elements are preferably in the form of rotary encoders, toggle switches, pressure switches or slide switches. Particularly in the case of rotary encoders, also known as angle encoders, rotary encoders or rotary encoders, it is preferred that these are designed as rotary push encoders that can be turned by the operator to enter a control command or pressed like a push button. Particularly preferred controls for the present invention are encoders and encoders.

In principle, the at least two control elements can be different control elements, for example a rotary knob and a toggle switch. In addition, two rotary knobs that are structurally different from one another can also be used, for example with a different rotary detent and/or design of the rotary knob. However, it is particularly preferred if the at least two operating elements and in particular all operating elements of the operating unit are designed to be structurally identical to one another. However, this does not only apply to the type of control element, ie rotary knob or toggle switch, for example, but ideally to the entire structural or constructive design of the respective control element. In particular, the operating elements are therefore preferably also not designed individually for the input options for a specific machine function, for example for activating and deactivating a working unit. This therefore also includes very particularly preferred an embodiment of the at least two operating elements in such a way that they are not limited, in particular mechanically, to a specific, fixed number of switching positions provided ex works. As will be explained in more detail below, the assignment of switching positions takes place downstream by the evaluation unit and/or the central machine control. If the at least two operating elements are a rotary encoder, this is preferably designed in such a way that it cannot rotate about its axis of rotation, in other words it therefore has no rotary stops and can rotate freely through 360° about the axis of rotation from any position leaves.

The only difference between the at least two operating elements is preferably exclusively the identification of the operating elements, which is described in more detail below and is particularly unambiguous, although this is preferably a difference at the software level. At the hardware level, on the other hand, the operating elements are preferably designed to be identical or structurally identical to one another. This means that the controls are interchangeable. If, for example, the two operating elements of the operating unit were interchanged and, for example, arranged in the other position on the operating element support plate, the result would be the same operating unit on a purely structural level. The fact that the operating elements assume different control functions or that inputs via the operating elements are assigned to different control functions is implemented by the evaluation unit and/or the central machine control, as described in more detail below. The fact that the operating elements used can be constructed identically to one another means that they can be used for different machine functions, as a result of which the number of different components required for the production of a construction machine is reduced. In this way, costs can be saved both in the production and in the replacement of defective operating elements.

As already mentioned, the operating unit according to the invention preferably uses at least two structurally identical operating elements. There is therefore a deviation from the fact that in the prior art operating elements that are customarily tailored to the respective machine function are used. The operating unit therefore has at least two and in particular a large number, for example three, four, five or six, structurally identical operating elements. The output signals of the operating elements are therefore also no longer tailored to the respective machine function. For example, an operating element therefore does not supply an output signal which directly indicates a state of a machine function desired by the operator (e.g. “vibration drive on”). In contrast to this, it is preferably provided that the at least two operating elements are designed in such a way that they generate output signals which describe a relative movement and/or an absolute position of the respective operating element. The operating elements are thus functionally designed as sensors, for example rotary sensors when rotary encoders are used, which detect their own position and/or change in position. The output signal preferably includes exclusively this unprocessed position signal (relative or absolute). Ideally supplemented by an identification signal, in particular an unambiguous one, for the operating element. In the case of a rotary encoder, the output signal contains, for example, the information that the rotary knob of the rotary encoder has been rotated through a specific angle and/or that the rotary knob is in a specific angular position between 0° and 360°, in particular in relation to a zero crossing position. In the case of a pressure switch, the output signal contains, for example, the information that the pressure switch was pressed and/or how often the pressure switch was pressed. The pressure switch could also be a touch pressure switch. However, the operating elements do not require structurally specified switching positions or stops. The number of possible switching positions of the operating element exceeds the possible number of states of the machine function to be controlled. In concrete terms, the number of theoretically possible physical switching positions of the control element is limited only by the sensitivity of the position detection of the control element, ie for example by a predetermined grid of the possible adjustment movement, in particular for example 12 grid positions for a full revolution of a rotary encoder. The output signals from the operating elements are forwarded to the evaluation unit via the signal transmission connection. The evaluation unit in turn assigns adjustment information of the operating elements to the output signals, ie the received absolute or relative position information of the respective operating elements. The adjustment information thus includes, on the one hand, the absolute or relative position information of the respective control elements and, on the other hand, information about the control element from which the information originates. The evaluation unit thus ensures in particular an assignment and sorting of the signals to the respective operating elements and forwards these assigned signals to the central machine control or places them in a memory for reading out by the central one Machine control ready. The assignment can include, for example, the evaluation unit placing the respective adjustment information, for example using a unique identification of the operating element, at a point in the CAN message provided for this purpose and sending it cyclically to the central machine control. The CAN message designates the information sent from the evaluation unit to the central machine control. From the point in the CAN message where the adjustment information is located, the central machine control can identify from which operating element the adjustment information comes or to which machine function the adjustment information is assigned. In addition or as an alternative, the assignment can include, for example, the evaluation unit storing the respective adjustment information in a memory location that corresponds to a specific machine function assigned to the operating element. If, for example, one of the operating elements is assigned a machine function by the evaluation unit and/or the central machine control that has three possible switching positions, the output signals of this operating element are converted into the corresponding switching positions and into switching processes between these switching positions. The conversion into the switching positions can already be carried out by the evaluation unit when the adjustment information is derived. However, it is also possible that the specific switching position, which corresponds to a machine function desired by the operator, is only determined by the central machine control from the adjustment information provided by the evaluation unit. The extent of the movement of the operating elements that must be applied to them by the operator in order to switch back and forth between the switch positions can be set as desired. For example, the corresponding adjustment paths can be matched to those between the stops of conventional control elements. However, the adjustment paths can also be set to be longer or shorter, taking into account the resolution of the sensors of the operating elements. It is important here that the operating elements are each only designed as sensors, which only forward their respective position, for example rotational position, to the evaluation unit. Adjustment information is only assigned to these signals in the evaluation unit and control commands are in turn assigned in the central machine control. The assignment of adjustment information to the respective output signals by the evaluation unit does not mean that control commands, for example for actuators of the machine, are derived directly from the output signals. The actual machine functions are controlled by the central machine control. However, the evaluation unit already sorts the output signals coming from the control elements and inserts them at the designated point in the CAN message or stores them in a memory, for example, specifically at a memory location that is intended for a specific machine function. This pre-sorted forwarding of the output signals of the operating elements by the evaluation unit as adjustment information to the central machine control means that the central machine control system can use the individual storage locations to identify the actual machine function for which the respective signal is intended. The assignment by the evaluation unit is therefore purely functional and is used for communication between the operating elements and the central machine control.

In particular, the evaluation unit assigns different machine functions of the construction machine to the output signals of the at least two operating elements. The evaluation unit derives adjustment information assigned to these machine functions from the output or adjustment signals of the two operating elements. Concrete control commands for the working units of the machine affected by the machine function can then in turn be obtained from the adjustment information by the central machine control. For example, the controls are assigned to different working units of the construction machine. The respective machine functions can have the same or a different number of possible switching positions. This makes no difference according to the invention, since the operating elements are preferably designed in such a way that they are suitable for several, in particular all, machine functions. The operating elements, in particular all operating elements, therefore preferably have a number of possible switching positions which is at least as large as the highest number of switching positions of a machine function to be controlled by the operating elements. Conversely, this means that the possible switching positions of the operating elements exceed the necessary number of switching positions for most machine functions. For example, the controls could be designed as a continuous encoder. However, preference is not given to a continuous configuration, but instead, for example, to a configuration of the operating elements as rotary encoders with a 12-step grid. Even with such a design, the possible switching positions of the operating elements typically exceed the number of switching positions required for a given machine function. The switch positions of the operating elements that are not used are preferably interpreted as transitional positions, in particular by the evaluation unit and/or the central machine control. In addition or as an alternative, it is also possible to This means that when the operating element is rotated by 360°, for example, the evaluation unit converts all of the recorded positions into a value that is sent to the central machine controller. This value then corresponds, for example, to the adjustment information, which in turn is assigned to a specific machine function by being assigned to a specific location in the CAN message or by being stored in a specific memory location. The central machine control then recognizes, for example, the direction of rotation, sets the machine function and, if necessary, sends the state that the display devices of the operating element, which are explained in more detail below, are to assume to the evaluation unit. However, any increased manufacturing costs due to the provision of unused switching positions are compensated for by the fact that different operating elements no longer have to be manufactured and stored. Because the possible switching positions of the operating elements exceed the necessary switching positions, which means that all operating elements are suitable for all machine functions, the assignment of the operating elements to the machine functions can be changed, for example by software. In addition, changes to the machine functions, for example additional machine functions or additional switching positions of existing machine functions, can be implemented by software changes without having to replace the operating elements, as is usual in the prior art.

In order to support the assignment of the operating elements to individual machine functions, it is preferably provided that the at least two operating elements are equipped with an identification that can be recognized by the evaluation unit, in particular that is unique. This can be, for example, an identification number, for example a serial number, which is stored in an EEPROM, for example. Alternatively, a corresponding identification could also take place using an RFID chip. The identification is recognized or read out by the evaluation unit and the respective operating element is assigned a machine function on this basis by the evaluation unit. An alternative embodiment provides that the evaluation unit identifies the operating elements via their respective slot provided on the evaluation unit for the flexible cable connection or assigns a machine function assigned to the respective slot to the operating elements.

An advantage of the identification of the operating elements recognizable by the evaluation unit is that, according to a preferred embodiment, it enables the evaluation unit to recognize an exchange of an operating element based on a changed identification. In particular, it is provided that the evaluation unit regularly or continuously reads out the identification of the operating elements. If the identification of an operating element changes here, the evaluation unit recognizes that the respective operating element has been replaced. In response to this, a corresponding message can then be displayed to the operator, for example. The operator can confirm the replacement of the control element in a dialog box so that, for example, operation can be continued with the replaced control element. Alternatively, a teach-in routine can also be started on the software side in order to configure the new control element and the evaluation unit for the new control element. In addition or as an alternative, the central machine control can also monitor the identification of the operating elements. For this purpose, the identification of the operating elements is stored, for example, in a memory area of the evaluation unit that is accessible to the central machine control. When the system starts, the central machine control reads the identifications of the connected operating elements in this memory area of the evaluation unit and can thus recognize general changes to the hardware (e.g. the replacement of operating elements with new parts). In addition, the evaluation unit can independently check whether the identifications learned during initial commissioning still match the currently connected identifications. In this way, the evaluation unit can detect if the slots of the control elements have been mixed up and, for example, rectify this itself by means of autorouting. If the autorouting or the automatic assignment fails, the evaluation unit reports this to the central machine control and initiates appropriate troubleshooting steps (e.g. a manual teach-in process by the operator).

In the state of the art, it is customary to already equip the operating elements with an evaluation unit, which adapts the output signals of the operating elements to the systems used in each case. In this case, either each operating element has its own evaluation unit, for example a microcontroller, or the operating elements are arranged on a common circuit board, this circuit board then also carrying an evaluation unit, for example a microcontroller. In this case, there is an evaluation unit for each group of control elements that are on the same circuit board. According to the present invention, it is now preferred that the control unit exclusively includes a single evaluation unit, which receives and processes the output signals of all control elements. there is it is provided that the evaluation unit, in contrast to the prior art, is not structurally bound to the operating elements, for example via a common circuit board. The individual operating elements are structurally independent of the evaluation unit and can be installed at any location using the flexible cable connection or the wireless connection. In particular, the individual operating elements are therefore designed without a microcontroller or without a microprocessor and, in particular, are not arranged on a common circuit board. The output signals of the operating elements therefore consist of the sensor signals reflecting their respective switching position, for example rotational position. The output signals are not, as is usual in the prior art, processed by an evaluation unit that is installed with the control element. On the other hand, the entire evaluation of the output signals and their conversion into usable adjustment information is carried out by the exclusively one, central evaluation unit, which is connected to the operating elements.

It is preferred that the at least two operating elements are each connected to the evaluation unit via a serial interface. In other words, the signal transmission connection between the evaluation unit and the control elements is designed as a serial interface, in particular via an SPI (Serial Peripheral Interface) or an I2C (Inter-Integrated Circuit). The manufacturing costs of the operating units according to the invention can be greatly reduced through the use of simple serial interfaces. In particular, these interfaces also offer the advantage that the operating elements do not have their own evaluation unit and can forward their output signals directly via the serial interface to the common evaluation unit of the operating unit.

In addition, the invention makes it possible to implement current functional safety requirements on the operating unit in a simple manner. For example, it is preferred that the connections of the at least two operating elements to the evaluation unit are redundant. Each of the operating units is therefore connected to the evaluation unit in parallel via two serial interfaces, for example. Should one of the two serial interfaces actually be defective, error-free control of the machine via the operating unit would continue to be guaranteed. In addition, this can prevent the machine from performing unwanted, dangerous movements in the event of a defect. The redundant design of the signal transmission connection, especially for push and turn inputs, is therefore a measure according to PL e (Performance Level e) in accordance with the EN ISO 13849 standard.

In order to obtain the simplest possible construction, provision can be made for the at least two operating elements to be supplied with electrical energy via the evaluation unit and a corresponding cable connection. It is therefore preferred to use a signal transmission connection that allows the control element to be supplied with electrical energy or current at the same time. When using a serial interface, either a serial interface is used that allows electrical energy to be supplied, or the serial interface is provided with an additional power supply. To assemble the controls, it is therefore sufficient for them to be connected to the evaluation unit after they have been arranged on the control element support plate, which ensures both data transmission and the supply of electrical energy to the control elements.

The evaluation unit receives all output signals from the operating elements used in the operating unit and converts them into adjustment information. In order to actually implement the information available on the evaluation unit for controlling the construction machine, it is preferably provided that the evaluation unit is connected to a central machine control unit (ECU) of the construction machine via a main connection. The main connection is designed in particular as a CAN bus (for example with the CANopen, CANopen safety or J1939 protocol). The information forwarded from the evaluation unit to the central machine control via the main connection is also referred to as a CAN message. The central machine control is, for example, the on-board computer of the construction machine. The central machine control, in turn, is designed in particular to control actuators of the construction machine based on the control commands entered by the operator. In other words, the control commands entered by the operator on the construction machine are actually implemented by the central machine control, in that the machine controls the machine functions, for example via suitable actuators. The control commands, in turn, are obtained from the central machine control from the adjustment information provided by the evaluation unit. The evaluation unit serves as an intermediary between the operating elements and the central machine control, in that the output signals of the operating elements are converted into adjustment information that can be used by the machine control and pre-sorted, i.e. assigned to individual machine functions.

As described above, the controls are simply sensors of their own position (relative or absolute). There is therefore basically no information on the operating elements themselves as to which machine function or which state of a machine function is currently selected via the respective operating element. It is therefore not possible, as is usual in the prior art, based on an existing switch position of the operating elements, for example due to the stop on a mechanical travel limit, to conclude per se that the machine function whose switch position is on this stop should be activated. Nevertheless, the operator of the construction machine must of course be given feedback as to which switching position the control element is currently in from the point of view of the evaluation unit or the central machine control or which machine function or its status is currently selected/assigned. For this purpose, it is preferably provided that display devices, in particular comprising LEDs, are provided, which are assigned by the evaluation unit and/or the central machine control to machine functions and/or their states, which can be set by the at least two operating elements. Since, according to the invention, the operator's control commands are obtained from the adjustment information of the operating elements only in the central machine control, the information about a currently set machine function or its status is only available in the evaluation unit and the central machine control. It is therefore preferably provided that the evaluation unit and/or the central machine control control the display devices provided for visualizing the current operating situation. If the display devices are controlled by the central machine control, then this generates a display command for the corresponding display devices based on the set machine function. The display command is then transmitted from the central machine control to the evaluation unit, which in turn activates the corresponding display device. In order to control the display devices, the evaluation unit is therefore interposed between the central machine control and the display devices. For this purpose, it is initially provided that the evaluation unit and/or the central machine control system assigns the machine functions to be visualized and/or their states to the respective display devices. The corresponding assignment is made by software and can therefore be changed or adjusted quickly and easily. For example, a machine function can be assigned to a different display device by changing the software. It is not necessary to change the hardware for this.

The display devices are preferably visually perceptible display devices, such as one or more displays, one or more switchable lamps, etc. LEDs are particularly preferred here.

In principle, the display devices can be arranged independently of the operating elements and, for example, can be mounted at any point on the operating unit or the construction machine. For example, the display devices can also be arranged together with the operating elements on the operating element support plate. However, since the display devices should be able to be controlled by the evaluation unit and/or the central machine control, this results in a comparatively high connection effort. It is therefore preferred if the display devices are designed as a modular unit together with the operating elements. In particular, the display devices are therefore preferably arranged in a housing of the control element, with this housing preferably exclusively comprising a control element and the display devices as well as the necessary connections for the evaluation unit. In addition, it is preferred that the at least two operating elements are equipped with a number of display devices, in particular LEDs, with the number of display devices preferably being equal to or greater than the number of machine functions and/or their states that can be set using the respective operating element. In other words, each operating element is equipped with a set of display devices assigned to this operating element. The number of display devices is independent of the machine function to be controlled by the respective operating element. The number of display devices can therefore particularly preferably be the same for each of the at least two operating elements, regardless of which machine function is to be controlled by the operating element. If the machine function to be controlled requires only a few switch positions, then the number of display devices on the operating element exceeds the number of switch positions. It can therefore happen that not all display devices of the operating element are necessary for a display of the respectively currently selected switching position. Some of these display devices are therefore not used during operation. However, this disadvantage is compensated for by the fact that no different operating elements, each specifically designed for a machine function, have to be manufactured and stored. In the case of a rotary encoder, for example, it is preferably provided that it is equipped with, for example, twelve LEDs. These can, for example, be arranged in a ring around the rotary knob. The rotary encoder is particularly preferably designed with two such rings of display devices, that is to say with a total of 24 LEDs, for example.

It is optimal if the display devices are controlled exclusively via the evaluation unit and/or the central machine control and in particular not directly by the at least two operating elements, for example by direct signal transmission from the operating element to the display device, for example mechanically. It is therefore preferred if the at least two operating elements transmit a change in position to the evaluation unit and/or the central machine control and the evaluation unit and/or the central machine control then uses this information to control the display devices.

As already indicated, it is preferably provided that the evaluation unit and/or the central machine control activates a selection of the display devices of an operating element that corresponds to the machine functions currently set by the operator and/or their states. On the other hand, a direct transmission of information or control between the display devices and the control element is not provided. At least the evaluation unit and/or the central machine control is always provided between the display device and the operating element. The display devices are therefore controlled by the evaluation unit and/or the central machine control. The flow of information for a currently set machine function or its status runs from the operator, who selects the desired function via the control elements, to the evaluation unit, which converts the output signals of the control element into corresponding adjustment information and forwards this to the machine control system, where the control commands are then obtained from the adjustment information will. The information about the currently set machine function or its status then runs from the central machine control and/or the evaluation unit back to the display devices, which are activated or not depending on the current operating status. The activated display devices inform the operator about the operating status of the construction machine. The display devices are also controlled via the signal transmission connection, in particular the serial interface. A separate connection of the display devices to the evaluation unit and/or the central machine control is therefore not necessary. Provision is particularly preferably made for each operating state or each activated machine function or its state to be visualized via at least two display devices. In other words, the evaluation unit and/or the central machine control always activate at least two display devices in order to display an operating state. This measure also serves to ensure functional safety, since even if one of the two activated display devices fails, visualization of the current operating status of the construction machine is guaranteed for the operator. This is in particular a measure according to PL c (Performance Level c) according to the EN ISO 13849 standard. Additionally or alternatively, the display devices can also be controlled directly by the evaluation unit after receipt of the position and/or position change signals of the at least two control elements .

The controls typically have mechanical components or input elements that are moved by the operator to set a desired machine function. Examples are toggle, rotary, push and/or slide switches. With conventional control elements, which derive the control command desired by the operator directly from their position, for example because they have a certain rotating or tilting position, there is the problem that the operator actually has to move them back to a starting position in order to to terminate or switch off the respective machine function. This can be a problem when restarting the construction machine, for example, if the construction machine has been switched off with activated working units, but these working units should not be activated again immediately after the restart. This can be the case, for example, for security reasons. In the case of conventional control elements, it can happen that they retain their previous switching position even after the machine has been restarted and immediately activate the machine function selected thereby. This problem can now be circumvented with the operating unit according to the invention, since only the central machine control derives the control commands desired by the operator from the adjustment information obtained by the evaluation unit from the output signals of the operating elements. Correspondingly, the evaluation unit and/or the central machine control can, in certain situations, reset control commands that were last set or activated machine functions. For example, it is preferable for the evaluation unit and/or the central machine control to set specific machine functions and/or their states after a restart of the operating unit, independently of a current setting of the operating elements assigned to these machine functions. Also If, for example, after the machine has been restarted, an operating element reports via its output signal that it is in an absolute position in which a specific working unit should actually be activated, the evaluation unit and/or the central machine control can provide for this working unit to switched off after a restart. The switching position of the operating element would therefore be ignored by the evaluation unit and/or the central machine control. In the case of a rotary encoder in particular, this can be done in a simple manner by defining the current rotary position of the rotary encoder as the new neutral position, in which the working unit is switched off. Only after a renewed rotary movement of the rotary encoder in the direction of the rotary position representing the activated machine function would the respective working unit be activated again. In this way, too, work safety can be increased with the operating unit according to the invention.

In order to make the operating unit according to the invention as flexible as possible and in particular to make the operating elements mountable at as many locations as possible, it is preferably provided that the operating elements and/or the evaluation unit are of modular design. For this purpose it is preferred, for example, that the at least two operating elements each have a housing and the evaluation unit is arranged in a separate housing. Each operating element is therefore equipped as a self-contained module or as a self-contained structural unit with its own housing. In particular, this housing also includes the display devices assigned to the operating element, in particular LEDs. The evaluation unit, in turn, is arranged in its own separate housing. The housing of the operating elements and the housing of the evaluation unit are connected exclusively via the signal transmission connection, in particular a data connection and a connection for electrical energy. As already explained, this connection takes place in particular via a flexible cable connection or a wireless connection, so that the operating elements can be mounted in any spatial arrangement relative to the evaluation unit.

In addition, it can be provided that mechanical input elements on the operating elements, ie for example in the case of rotary encoders the rotary knob and the rotary shaft, are designed so that they can be disassembled or assembled. If, for example, the rotary knob and the rotary shaft are removed from the rotary encoder, the sensor for the rotary position of the shaft remains on the control element, but cannot currently be used without the shaft. However, the display devices arranged on the control element, for example LEDs, can still be used. A correspondingly partially dismantled control element can therefore be used as a display device, for example for signal lights on the control element support plate. At the same time, the control element can be quickly and easily converted into a fully functional control element by installing the shaft and the rotary knob, to which a function can then also be easily assigned on the software side with the architecture described above. In this way, a simple and quick expansion or modification of the range of functions of the operating unit according to the invention is achieved. This method thus makes it possible to provide a basic control unit with one or more, in particular at least five, preferably identical, control element subassemblies. A control element subassembly is characterized in that it already has everything that is required to complete the respective control element, such as one or more display devices, preferably a housing element, a connection to the evaluation unit and an actuating element receptacle. What is missing is the actual actuating element, such as a rotary knob, and optionally one or more connecting parts that interact mechanically with the rotary knob, such as a rotary axis. The operating element subassembly is also preferably designed in such a way that it has an essentially planar end towards the operating side, in order to be completely covered, for example, with a cover plate and/or a film. If one or more operating element subassemblies are later to be upgraded/converted to a complete operating element by connecting an actual operating element in each case, the cover plate and/or foil can then be exchanged, for example, in which corresponding recesses are then provided above the operating element subassembly. through which the respective connection part of the actuating element or to the actuating element, such as in particular a rotary axis, can be passed. This approach enables a high degree of flexibility while at the same time requiring a small number of mutually different components when manufacturing and/or converting/upgrading an operating unit. This can be of particular advantage in the field with construction machines, since these are often serviced and/or converted on site.

As explained at the outset, the controls are preferably arranged on a control element support plate. The control element support plate is used, for example, as a front panel for the control unit. Thus, the control element support plate preferably has markings that indicate the machine functions correspond to the inputted control commands. The markings do not have to be arranged directly on the control element support plate itself. For example, it is also possible that the control element support plate is provided with a film on which the markings are arranged. The markings preferably include symbols and/or characters assigned to the operating elements, for example pictograms, which indicate active and/or available machine functions and/or their states. Different switching positions of the operating elements, which correspond to different machine functions and/or their states, are therefore displayed visibly for the operator on the operating element support plate via the markings. In order to also inform the operator which of these machine functions and/or their states are currently active, it is preferably provided that the control element support plate covers the display devices of the control elements and at least partially includes transparent areas that are assigned to at least some of the display devices and through which the display devices and/or the light emitted by them can be seen by the operator. The control element support plate is therefore combined with the display devices in such a way that individual markings arranged on the control element support plate can be highlighted, for example illuminated, by the display devices for the operator. To display a specific machine function and/or its status, the evaluation unit and/or the central machine control activates those display devices that highlight the corresponding marking on the operating element support plate or those display devices that are visible through the at least partially transparent areas or through these light for the Send out operators visible. Due to the fact that all operating elements are configured identically with the display devices assigned to them, it is provided according to the invention that only some of the display devices are assigned markings and/or at least partially transparent areas of the operating element support plate. Other display devices, on the other hand, are covered by the operating element support plate, so that neither they nor the light they emit can be perceived by the operator. Due to the modular design of the operating unit, there are therefore superfluous display devices, which, however, is more than compensated overall by the advantages of the modularity.

Due to the structure of the operating unit, a large number of adjustments to the machine control, for example a new assignment of machine functions to operating elements, a new classification of machine functions into different states or the like, can be made simply by changing the software and the assignment of the operating elements or the display devices to the machine functions and/or their states. However, in the event that changes are planned that also make it necessary to change the markings on the control element support plate, it is preferably provided that the control element support plate is detachably attached to the control unit, in particular detachably in one piece. In this way, the control element support plate can be easily dismantled from the control unit and replaced, for example, with a new control element support plate that has the changed markings.

The solution to the task mentioned above is also achieved with a construction machine, in particular a soil compactor, a road finisher or a ground milling machine, with an operating unit according to the above statements. In addition, the solution is also achieved with a method for operating a construction machine, in particular a construction machine of this type. The invention therefore also extends to such a construction machine and such a method. The features, advantages and effects explained above for the operating unit also apply in a figurative sense to the construction machine and the method, and vice versa. The same applies to the construction machine and the procedure among each other. To avoid repetition, reference is made to the present explanations as a whole.

With regard to the construction machine, it is preferred that this has two operating units according to the above statements, both of which are connected to the same central machine control. For example, this can be a control unit on the left armrest of the driver's seat and a control unit on the right armrest of the driver's seat. With this arrangement of the operating units in particular, the small installation space requirement of the operating unit according to the invention is particularly important.

The method according to the invention for operating a construction machine, in particular a construction machine according to the above statements, comprises the steps carried out by the evaluation unit: Recognizing an identification of an operating element; Assigning the operating element to a machine function; receiving output signals from the operating element which describe a relative movement and/or an absolute position of the respective operating element; and deriving adjustment information associated with the machine function from the output signals of the operating element. In addition, the Ver continue the steps: Forwarding the adjustment information from the evaluation unit to a central machine control; and activation of display devices, which are assigned to the machine functions set by the operator and/or their states, by the evaluation unit and/or the central machine control. It is important here that, as already described above, the control of the display devices emanates from the evaluation unit and/or the central machine control depending on the currently activated machine functions and/or their states. The switching positions of the operating elements, on the other hand, have no direct influence on the operation of the display devices.

The modular design of the controls makes them particularly suitable for retrofitting. For example, it can be provided that an operating element is only incompletely pre-installed on the operating unit according to the invention, for example in the case of a rotary encoder without the rotary knob and the shaft. In this case, the display devices of the operating element on the operating unit can already be used, for example to operate warning lights or the like. The slot for the shaft can be covered with a design film, for example. If, for example, a new machine function is then enabled later, for example when a new working unit of the machine was purchased, the operating element can be completed by simply retrofitting the mechanical input elements. It is therefore preferred for the method according to the invention that at least one operating element comprises at least one display device and at least one mechanical input element, for example a rotary knob and/or a shaft. The control element is only operated exclusively using the display device in the absence of the mechanical input element. The mechanical input element, specifically the rotary knob and the shaft, is then retrofitted as soon as there is a need for a new input element. The corresponding function can then be assigned to the fully-fledged input element by software, for example by the evaluation unit and/or the central machine control.

This results in a further advantage of the control unit according to the invention: it is possible to use one and the same control unit in different machines, regardless of how many control elements are required for this type of machine. For example, an operating unit is produced that includes a certain number of operating elements, with all operating elements initially being installed without mechanical input elements. The number of partially mounted input elements on the operating unit is at least as large as the maximum number of necessary operating elements for the type of machine that requires the most operating elements. If this control unit is then to be used in a specific machine, the mechanical input elements only have to be mounted on the control unit for that subset of the control elements that are necessary for the operation of the machine. On the other hand, in the absence of their mechanical input elements, the superfluous operating elements are only operated as display devices. In this way, the same operating unit can be stored for assembly for a large number of different machine types. In addition, the range of functions of the corresponding control units can be expanded quickly and easily by retrofitting or retrofitting additional mechanical input elements on other control elements.

The method is preferably carried out using an operating unit according to the invention.

• 1: eine Seitenansicht einer Tandemwalze;
• 2: eine Seitenansicht eines Walzenzuges;
• 3: eine Seitenansicht einer Gummiradwalze;
• 4: eine Seitenansicht eines Müllverdichters;
• 5: eine Seitenansicht eines Straßenfertigers;
• 6: eine Seitenansicht einer Straßenfräse;
• 7: eine Bedieneinheit und deren Anschluss an eine zentrale Maschinensteuerung;
• 8: eine weitere Ansicht einer Bedieneinheit;
• 9: zwei Bedieneinheiten an einer zentralen Maschinensteuerung; und
• 10: ein Ablaufdiagramm des Verfahrens.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the figures. They show schematically:

• 1 : a side view of a tandem roller;
• 2 : a side view of a compactor;
• 3 : a side view of a pneumatic tire roller;
• 4 : a side view of a refuse compactor;
• 5 : a side view of a road finisher;
• 6 : a side view of a road milling machine;
• 7 : an operating unit and its connection to a central machine control;
• 8th : another view of an operating unit;
• 9 : two operating units on a central machine control; and
• 10 : a flow chart of the procedure.

Components that are the same or have the same effect are denoted by the same reference symbols in the figures. Repeating components are not separately identified in each figure.

the 1-6 show generic construction machines 1. All generic construction machines 1 are self-propelled and include a machine frame 3, a driver's cab 2 and a drive motor 4, typically a diesel combustion engine or an electric motor. In working operation, they typically move in the working direction a on a floor 8. For this purpose, they have different driving devices that are related to the respective function or the area of application. In 1 a tandem roller is shown, for example, which has a roller bandage 5 both at the front and at the rear, with which it compacts the soil 8 . A vibration exciter, for example, can also be provided in the rolled tires 5, via which the rolled tires 5 can be made to oscillate in order to increase the compaction performance of the construction machine 1. 2 shows a compactor, which also has a rolled bandage 5 at the front in the working direction a. In contrast, the compactor has wheels 6 at the rear. In the 3 shown rubber wheel roller has rubber wheels 6 both at the front and at the rear. In 4 again, a refuse compactor is shown. At its front end in working direction a, this has a clearing blade 15, with which waste can be distributed to landfills. 5 shows a road finisher for laying asphalt layers. For this purpose, it has a material bunker 16 and a screed 7 . The road finisher shown includes chain drives 9, but could also have 6 wheels. In 6 Finally, a road milling machine is shown. The road milling machine comprises a milling drum 11 which is mounted in a milling drum box 10 so as to be rotatable about an axis of rotation 12 and is used, for example, to mill off damaged roads. The removed milled material is loaded onto a transport vehicle via a conveyor 13 and transported away. These machine types are familiar to a person skilled in the art, so that their design and function will not be discussed in detail. All of the construction machines 1 have a central machine control unit 14 (ECU), which is the on-board computer of the construction machine 1, for example. The machine controller 14 is designed to control all machine functions, the working units, for example also the driving devices, of the construction machine 1 .

7 shows an operating unit 17, as can be arranged, for example, in the driver's cab 2 of the construction machine 1. The control unit 17 includes a control element support plate 18 on which a plurality of control elements 19 are arranged. The control element support plate 18 can be made of glass, plastic or metal, for example. In the exemplary embodiment shown, rotary encoders, toggle switches, pushbutton switches and slide switches are shown from left to right, with a pair of identical operating elements 19 of the respective type being shown in each case. However, it is initially only essential for the invention that at least two operating elements 19, which are ideally structurally identical to one another, are present. Markings 21 can be arranged on the operating element support plate 18 in the vicinity of the respective operating elements 19 , which symbolize the machine functions that can be controlled via the operating element 19 and/or their states. Depending on the machine function, a different number of markings 21 can be assigned to the respective operating elements 19, even if the operating elements 19 are otherwise identical. For example, links in 7 two identical controls 19, each designed as a rotary encoder, are shown. A total of three markings for different switching or operating positions of this operating element 19 are assigned to the operating element 19 shown above. In contrast, a total of four markings for different switching or operating positions of this operating element 19 are assigned to the operating element 19 shown below.

The operating unit 17 also includes an evaluation unit 20, which includes a microcontroller or a microprocessor, for example. The evaluation unit 20 is designed to receive the output signals of the operating elements 19 . For this purpose, the evaluation unit 20 is connected to each of the operating elements 19 via a signal transmission connection 22 . In the embodiment shown 7 the signal transmission connections 22 are designed as flexible cable connections, with a separate slot 23 being provided on the evaluation unit 20 for each operating element 19 . Alternatively, the signal transmission connections 22 could also be in the form of radio connections. In a preferred embodiment, the signal transmission connections 20 are designed as serial interfaces, which also supply the operating elements 19 with electrical energy via the evaluation unit 20 . The evaluation unit 20 itself can in turn be connected to the central machine controller 14 via a main connection 24 , for example a CAN bus, and can also be supplied with electrical energy from the on-board network of the construction machine 1 . The evaluation unit 20 can also have a data connection with the machine control 14 via the main connection 24 and this can in particular forward the adjustment information obtained from the output signals of the operating elements 19, from which the machine control 14 then determines the control commands entered by the operator. The central machine control 14 in turn is connected to actuators 25 of the construction machine 1 via control lines 26 and controls them according to the control commands.

The exemplary basic principle of the operating unit 17 is based on the 8th explained in more detail. This shows two identical operating elements 19, each designed as a rotary encoder, which are shown in a lateral sectional view, transverse to the control element support plate 18 are shown. The controls 19 include a knob 29 which may be connected to a shaft 34 such that the shaft 34 rotates with the knob 29 when an operator rotates the turret 29 . The shaft 34 can reach into a rotary sensor 33, from which the absolute rotary position and/or the relative rotary position of the shaft 34 and thus of the rotary knob 29 is determined. In addition, the operating element 19 has display devices 30 which, as shown by way of example, can be in the form of LEDs. Finally, the control element 19 can have a housing 31 on or in which the components of the control element 19, in particular the rotary knob 29, the shaft 34, the rotary sensor 33 and the display devices 30 are arranged. The operating elements 19 are arranged on the operating element support plate 18 , for example in such a way that the operating element support plate 18 is penetrated by the shaft 34 . The rotary knob 29 is therefore arranged on the operator-facing side of the operating element support plate 18, while the rest of the operating element 19 and partially also the shaft 34 can be seen from the operator behind the operating element support plate 18. In particular, the display devices 30 can be covered by the operating element support panel 18 and/or a design film. Some of the display devices 30 can be visible through the markings 21 and/or through at least partially transparent areas of the operating element support panel 18 and/or the design film.

The evaluation unit 20 can be arranged with its own housing 32 separately from the operating elements 19 and separately from their housing 31 . In addition, the evaluation unit 20 can also not be arranged on the operating element support plate 18 . In principle, the evaluation unit 20 can be arranged at any point on the construction machine 1 , for example inside the driver's cab 2 . As indicated by the arrows, the signal transmission connections 22 between the evaluation unit 20 and the operating elements 19 include different portions, in which data are each transmitted in different directions. In this way, the position data of the shaft 34 recorded by the rotary sensor 33 can be transmitted to the evaluation unit 20 . At the same time, the display devices 30 can be controlled by the evaluation unit 20 and/or the machine controller 14 via the signal transmission connection 22 . In particular, those display devices 30 are selectively actuated which correspond to or are assigned by the evaluation unit 20 and/or the machine control 14 to the currently set or activated machine function and/or its status and for this purpose, for example on the operating element support plate 18, also with a corresponding, preferably backlit, Marker 21 are provided.

In 9 a situation is shown by way of example in which two operating units 17 are provided, which are each connected to the central machine control 14 . For the sake of clarity, only one control element 19, specifically designed as a rotary encoder, is shown per control unit 17. In addition, the control element support plate 18 is not shown for reasons of clarity. 9 12 therefore shows a perspective view of the housing 31 of the operating elements 19 from the operator's perspective. Each of the operating elements 19 is equipped with a large number of display devices 30 which are arranged in two concentric rings around the rotary knob 29 . Due to the large number of display devices 30, any position around the rotary knob 29 can be highlighted by activating the respective display devices 30. The selection of display devices 30 required for the respectively activated setting is controlled by the evaluation unit 20 and/or the machine control 14 via the signal transmission connection 22 . In the exemplary embodiment shown, the signal transmission connections 22 are designed to be redundant. Each operating element 19 is connected to the evaluation unit 20 via two signal transmission connections 22 . In addition, each signal transmission connection 22 includes, in particular, a serial data connection 27 and a power line 28 for supplying electrical energy. The functional safety can be improved by the redundant connection of the operating elements 19 to the evaluation unit 20 . In addition, a large number, in particular at least two, of the display devices 30 of an operating element 19 can be activated for each setting to be displayed. This is also a redundancy in terms of functional safety.

10 shows a flow chart of the method 35. The method 35 begins with the recognition 36 of an identification of an ideally clearly defined operating element 19 by the evaluation unit 20. This can be done, for example, by reading out an EEPROM in which a particularly unique identification number is stored . Next, the operating element 19 is assigned 37 to a machine function by the evaluation unit 20. The evaluation unit 20 can, for example, identify the operating element 19 and/or the arrangement of the signal transmission connections 22 coming from the operating element 19 at a special slot 23 of the evaluation unit for assigning the Use machine functions. There is a receiving 38 of output signals of Operating element 19 on evaluation unit 20. The output signals of operating element 19 describe in particular a relative movement and/or an absolute position of operating element 19. In relation to a rotary encoder, the output signals therefore include, for example, an angle by which the rotary encoder was rotated by an operator, or the Absolute position of a shaft 34 of the rotary encoder measured by a rotary sensor 33. These output signals are used by the evaluation unit 20 for deriving 39 adjustment information associated with the machine function. According to the invention, it is therefore only the evaluation unit 20 that assigns an information content that goes beyond this to the pure sensor data of the operating elements 19, which exclusively describe the position of the operating elements 19, for example by storing the corresponding signals in the memory positions assigned to the respective machine functions or at corresponding locations stored in the CAN message and forwarded to the central machine control 14 pre-sorted in this way. The adjustment information obtained by the evaluation unit 20 is transferred to a central machine control 14 by forwarding 40 . The central machine control 14 uses the adjustment information in order to derive from them the control commands entered by the operator for the corresponding machine functions. The control commands, in turn, are used by the central machine controller 14 to control actuators of the construction machine 1, which implement the control commands during operation. In order to provide the operator with appropriate feedback on the operating state of construction machine 1, display devices 30, which are assigned to the machine functions set by the operator and/or their states, are simultaneously activated 41 by evaluation unit 20 and/or central machine control 14. Overall, the invention therefore makes it possible to provide a particularly flexible and cost-effective operating concept for a construction machine 1, which is easily adaptable and at the same time is able to meet increasing functional safety requirements.

Claims (23)

Control unit (17) for construction machines (1), in particular soil compactors, road finishers or ground milling machines, comprising - at least two control elements (19) which are designed for the input of control commands by an operator, - a control element support plate (18) on which the control elements (19 ) are arranged, and - an evaluation unit (20) which is connected to the operating elements (19) via a respective signal transmission connection (22) and is designed to receive and process output signals from the operating elements (19), characterized in that the evaluating unit ( 20) is arranged separately from the operating element support plate (18), and the signal transmission connection (22) is a flexible cable connection or a wireless connection. Operating unit (17) according to claim 1 , characterized in that the at least two operating elements (19) are constructed identically to one another. Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are designed as rotary controls, in particular as rotary push controls, toggle switches, push switches or slide switches. Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are designed in such a way that they generate output signals which describe a relative movement and/or an absolute position of the respective operating element (19) and via the signal transmission connection (22) to the evaluation unit (20), and that the evaluation unit (20) assigns adjustment information of the operating elements (19) to the output signals. Operating unit (17) according to one of the preceding claims, characterized in that the evaluation unit (20) assigns the output signals of the at least two operating elements (19) to different machine functions of the construction machine (1), and in that the evaluation unit (20) assigns adjustment information to these machine functions from the Output signals of the two controls (19) derives. Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are equipped with an identification which can be recognized by the evaluation unit (20), in particular a unique identification. Operating unit (17) according to the preceding claim, characterized in that the evaluation unit (20) recognizes an exchange of an operating element (19) on the basis of a changed identification. Operating unit (17) according to one of the preceding claims, characterized in that there is only a single evaluation unit (20) which receives and processes the output signals of all operating elements (19). Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are each connected to the evaluation unit (20) via a serial interface. Operating unit (17) according to one of the preceding claims, characterized in that the connections of the at least two operating elements (19) to the evaluation unit (20) are designed to be redundant. Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are supplied with electrical energy via the evaluation unit (20). Operating unit (17) according to one of the preceding claims, characterized in that the evaluation unit (20) is connected via a main connection (24), in particular a CAN bus, to a central machine control (14) of the construction machine (1), the central Machine control (14) is designed to control actuators (25) of the construction machine (1) using the adjustment information provided by the evaluation unit (20). Operating unit (17) according to one of the preceding claims, characterized in that display devices (30), in particular LEDs, are provided which are assigned to machine functions and/or their states by the evaluation unit (20) and/or the central machine control (14), which can be adjusted by the at least two operating elements (19). Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are equipped with a number of display devices (30), in particular LEDs, the number of display devices (30) being greater than the number of machine functions and/or their states that can be set by the respective control element (19), and wherein the display devices (30) are arranged in particular in a housing (31) of the control element (19). Operating unit (17) according to the preceding claim, characterized in that the evaluation unit (20) and/or the central machine control (14) activates a selection of the display devices (30) corresponding to the machine functions currently set by the operator and/or their states. Operating unit (17) according to one of the preceding claims, characterized in that the evaluation unit (20) and/or the central machine control (14) after a restart of the operating unit (17) certain machine functions and/or their states independently of a current setting of these controls (19) assigned to machine functions. Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) each have a housing (31) and the evaluation unit (20) is arranged in a separate housing (32). Operating unit (17) according to one of the preceding claims, characterized in that the at least two operating elements (19) are designed without a microcontroller and are in particular not located on a common circuit board. Operating unit (17) according to one of the preceding claims, characterized in that the operating element support plate (18) has at least one of the following features: - it has markings (21) which correspond to machine functions which are assigned to the control commands which can be entered; - The markings (21) include symbols and/or characters assigned to the operating elements (19) which indicate active and/or available machine functions and/or their states; - It covers the display devices (30) of the operating elements (19) and comprises at least partially transparent areas which are assigned to at least some of the display devices (30) and through which the display devices (30) and/or light emitted by them for the operator is visible; - It is detachable, in particular detachable in one piece, attached to the operating unit (17). Construction machine (1), in particular a soil compactor, road finisher or soil milling machine, with an operating unit (17) according to one of the preceding claims. Construction machine (1) according to the preceding claim, characterized in that it has two operating units (17), both of which are connected to the same central machine control (14). Method (35) for operating a construction machine (1), in particular a construction machine (1) according to claims 20 - 21 , comprising the steps carried out by an evaluation unit (20): - recognizing (36) an identification of an operating element (19); - Assigning (37) the control element (19) to a machine function; - Receiving (38) of output signals of the operating element (19), which describe a relative movement and/or an absolute position of the respective operating element (19); and - deriving (39) adjustment information assigned to the machine function from the output signals of the operating element (19), and further comprising the steps of: - forwarding (40) the adjustment information from the evaluation unit (20) to a central machine control (14); and - activation (41) of display devices (30), which are assigned to the machine functions set by the operator and/or their states, by the evaluation unit (20) and/or the central machine control (14). Method (35) according to Claim 22 , characterized in that at least one operating element (19) comprises at least one display device (30) and at least one mechanical input element, for example a rotary knob (29) and/or a shaft (34), the operating element (19) only being activated exclusively using the Display device (30) is operated in the absence of the mechanical input element and the mechanical input element is subsequently retrofitted.

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