EP0289813B1 - Method and device for the course regulation of a position drive - Google Patents

Abstract

A first desired acceleration value (A1) is continuously determined by a non-linear course regulator, and, parallel thereto, a second acceleration value (A2) is continuously determined by a non-linear speed regulator. By means of a simple selection criterion comprising only these two alternative acceleration values, the second alternative desired acceleration value is brought into action by a selection circuit (18) for the running-up, the first alternative desired acceleration value is brought into action for initiating the target braking, and the second alternative desired acceleration value is again brought into action for running into the target position. Changes in the travel target and the speed of the position drive (PA), in particular the realization of creep speeds, are possible to virtually any extent during travel. <IMAGE>

Description

The present invention relates to a method and a device for jerk, acceleration and speed-limited displacement control of a position drive with subordinate speed control, wherein the acceleration, speed and displacement setpoint of the position drive are guided and the jerk value is controlled as a jerk value increased difference between an acceleration setpoint and the time integral of the jerk value limited with respect to its maximum amount is formed. Such a method is known from DE-PS 30 01 778. You can reach the desired position very quickly while observing the longest possible use of the boundary conditions determined by the limitations.

The object of the present invention is to improve the above-mentioned method with simple means with regard to a more flexible driving behavior. Thus, the invention is intended to make it possible to preselect the speed in any way while driving, which e.g. is important for maintaining track-related creep speeds. Furthermore, there should be the possibility of realizing destination changes made while driving.

This object is achieved according to the invention by the features specified in the characterizing part of the main claim.

FIG 1

ein sich auf eine Schachtförderanlage beziehendes Anwendungsbeispiel der Erfindung,

FIG 2a und 2b

einen Ablaufplan des erfindungsgemäßen Verfahrens,

FIG 3 bis 6

Hardware-Beispiele zur Realisation einzelner Verfahrensschritte,

FIG 7

die Streckenführung für eine Hängebahn,

FIG 8 bis 10

für das erfindungsgemäße Verfahren typische Fahrdiagramme.

The invention and its further embodiments, which are reproduced in the subclaims, will be explained in more detail below with reference to the figures. Show

FIG. 1

an application example of the invention relating to a shaft conveyor system,

FIG 2a and 2b

a flowchart of the method according to the invention,

3 to 6

Hardware examples for the implementation of individual process steps,

FIG 7

the route for a monorail,

8 to 10

typical driving diagrams for the method according to the invention.

In the application example in FIG. 1, the position drive PA to be controlled consists of an electric motor 1, which moves the elevator car 3 of an elevator or shaft conveyor system via a rope pulley 2 coupled to it. The current of the electric motor 1 is regulated by means of a current regulator 4, the output variable of which controls a converter arrangement 6 via a headset 5. The actual value I _{A of} the current regulator 4 is obtained by means of a current transformer 7 arranged in the armature circuit. The current controller 4 is superimposed on a speed controller 8, the actual value V _{A of} which consists in the output signal of a tachodynamo 9 coupled to the electric motor. A speed controller 10 is superimposed on the speed controller 8, the actual value S _{A of} which is taken from a travel sensor 11 which is acted upon by pulses which are generated by rotating a pulse disk coupled to the car.

The setpoint position to be approached is given to the position drive PA consisting of the elements 1-11 in the form of a setpoint setpoint S _{F which is} guided according to certain aspects, together with setpoint values V _F and A _{F which are also carried out} for the subordinate speed or. Current controllers 8 and 4. The reference variables A _F , V _F and S _F consist in the output signals of three integrators 12, 13 and 14 arranged one behind the other. S _F is used to specify the setpoint position to be approached to the position drive PA, with the setpoints V _F and A _F for the subordinate speed or current controller 8 or 4 is achieved that one of these values always reaches its maximum value. For this purpose, a position setpoint S * prescribing the target position of the car is compared with the output quantity S _{F of} the integrator 14, which forms the travel setpoint for the position drive PA, and made to coincide with the position setpoint S * by means of a non-linear control. Provided that the car 3 is able to follow the respective changes in the guided travel setpoint S _F without any significant following errors, the difference _Δ S between the travel setpoint S * corresponding to the target position and that of the integrator corresponds not only at the beginning of each travel process, but also continuously 14 output target value S _F the path between the respective position of the position drive PA and the target position. This route is referred to below as the remaining route.

The command variable A _F is formed by means of an acceleration control loop, which consists of a mixer 17, an integrator 12 and a proportional amplifier 15 with a quite large gain factor, the output signal R _F corresponding to the jerk, i.e. the time differential quotient of the acceleration, for both polarities to a maximum Jerk value R _{max is} limited. The output signal A _{F of} the integrator 12, which corresponds to the acceleration to be specified for the drive, is fed back to the input of the amplifier 15 and at the same time acts as a guided correction value for the acceleration on the current controller 4. The combination of the amplifier 15 and the integrator 12 practically sets one Ramp-up controller for the acceleration setpoint A _F and allows this value to be adjusted with a defined rate of change to the respective acceleration setpoint A *, the deceleration values being defined in the case of negative values of these acceleration values. With this method of indirect jerk value specification, you save the otherwise necessary determination of the respective switch-on and switch-off times for the maximum jerk values.

The device described so far, shown in FIG. 1 on the right of line II, corresponds to the prior art shown in DE-PS 30 01 778.

The acceleration setpoint A * according to the invention is provided by an acceleration transmitter 16, which receives the distance-to-go signal ΔS, the command value V _F for the speed, the command value A _F for the acceleration, an arbitrarily predeterminable speed setpoint V2 *, and the limiting parameters R _max for the jerk for the maximum value a _{bmax of} the acceleration and for the maximum value a _{vmax of} the deceleration are supplied. With a limit value detector 17 acted upon by the path difference ΔS, a travel direction signal FR is provided which has different polarity for upward and downward travel, which, in conjunction with multipliers, can ensure the correct sense of action of the acceleration sensor 16 for both travel directions.

vor der vom Sollwert S* vorgegebenen Haltestelle liegt. Die Größe R_max bedeutet dabei den maximal zugelassenen Ruckwert.In the accelerator 16, two setpoints for the acceleration control loop are now provided with the quantities supplied to it. The first of these alternatively provided acceleration setpoint A1 serves for the targeted reduction of the speed in such a way that the position drive under the effect of this acceleration setpoint would not go beyond a point with a constant deceleration of the size a _v , which is a distance of
${\text{SZ = a}}_{\text{v}}{\text{³. (24 R²}}_{\text{Max}}\text{) ⁻¹}$

is in front of the stop specified by setpoint S *. The size R _max means the maximum permitted jerk value.

With the second acceleration setpoint A2 offered alternatively by the acceleration sensor 16, the position _drive can be brought to _{predeterminable} speeds V2 * without overshoot while observing the limit _values for the acceleration a _bmax or for the deceleration a _vmax .

The basic idea of the method according to the invention is now to start up and, if necessary, to follow it at a constant speed under the effect of to allow the second alternative acceleration value A2 to take place, for which purpose the predeterminable speed V2 * is set to the value V _max , from the point in time at which the targeted deceleration is to occur, to bring the first alternative acceleration setpoint A1 into effect and the regulation in the last part of the journey - to bring the entry into the breakpoint back under the control of the second alternative acceleration setpoint A2. In the run-in phase, the first alternative acceleration setpoint is replaced when there is still a distance of four times the distance SZ mentioned above, while the replacement of the second acceleration setpoint A2 for target braking by the first acceleration setpoint A1 depends on the distance and speed in accordance with the known laws of kinematics can be done. These replacements are carried out by a selection circuit 18.

It is essential that the given speed setpoint V2 * can be changed at any time between zero and a maximum value V * _max after the start, which is important for maintaining technologically-related creeping distances when approaching or entering the target position or with speed restrictions due to the route can. Likewise, the position setpoint S * can also be changed as required, ie here, too, it is possible to deviate from the initially planned course of the journey while driving.

The formation of the two alternative acceleration setpoints A1 and A2 and their selection continuously necessitates a series of arithmetic operations, which can be greatly reduced in terms of time with the variant of the method according to the invention described below, thanks to the simplest selection criteria. This procedure can be described in algorithmic form in connection with FIG. 1 as follows:

Accordingly, the travel direction signal FR is formed from the difference ΔS between the setpoint S * supplied by the setpoint generator 19 and the guided setpoint S _{F of} the position drive PA, which is fed to the accelerator 16, by means of the limit value detector 17 in accordance with equation (1) is a positive signal of size 1 when driving upwards and an equally large signal of negative polarity when driving downwards. As long as a signal ASTOP set to the value 1 at the start of the start maintains this value, limit values for the acceleration a _b and for the deceleration a _v from their value zero in at the start of the start become very small in accordance with equations (2) and (3) The time interval Δt of successive steps increases practically in a linear manner, these increases being continued until either the limit values have reached their maximum permissible, constant values a _bmax or a _vmax or the aforementioned signal ASTOP disappears, ie becomes zero, whereupon the limit values maintain their previously achieved values. In accordance with equation (4a), the amount of the remaining path ΔS, the guided speed setpoint V _F , the guided acceleration setpoint A _F , the respectively reached limit value a _v for the deceleration and the travel direction signal FR, including the limit value R _max for the jerk, becomes a setpoint V1 * and thus the first alternative acceleration setpoint A1 is determined according to equation (4b). If one realizes that the quantity ΔS is represented as the difference between a travel setpoint S * and a value that corresponds practically to the travel actual value S _A , equation (4a) describes a special, non-linear travel controller processing a travel difference, the output variable V1 * of which is the setpoint for a subordinate, also non-linear speed controller - equation (4b) -, which is supplied with the actual speed setpoint V _F as the actual value and the acceleration limit value a _v as the pilot variable.

The second alternative acceleration setpoint A2 is determined in accordance with equation (6), it being ensured that it does not exceed the limits for the deceleration a _v and for the acceleration a _b . Equation (6) in turn conceals a non-linear controller which processes the difference between a speed setpoint V2 * and an actual value in the form of the guided speed value V _F. At the start of the journey, the speed setpoint V2 * is set to any value that can be predetermined up to V _max , which means the speed to be reached by the position drive. If the first alternative acceleration setpoint A1 becomes negative, which is the case in the braking phase that follows the run-up, the speed setpoint V2 * is set to the value zero in accordance with equation (5).

The selection of which of the two alternative acceleration setpoints A1 and A2 acts as the setpoint A * for the acceleration control loop consisting of the amplifier 15 and the integrator 12 is made in the selection device 18 in accordance with the condition equations (7a) and (7b) depending on from the difference A1 - A2 of the two alternative acceleration values, which is evaluated with the sign of the first alternative acceleration value - formed by the signum function. It is essential that the two alternative acceleration setpoints A1 and A2 are sufficient to form this simple selection criterion and that no path or speed monitoring is required.

According to equations (1) to (7), the second alternative acceleration value A2 takes effect at the start of the journey, i.e. when the vehicle is ramping up, at the beginning of the targeted braking phase, the first alternative acceleration setpoint A1 then takes over control and finally the run-in to the intended target position takes place without overshoot according to equation (6) with V2 * = 0 again under the influence of the second alternative acceleration setpoint A2.

Equations (8a) and (8b) represent the conditions under which the time-linear structure of the limit values for the acceleration a _b and for the deceleration a _{v is} terminated. This termination is important for the realization of short travels. It is no longer necessary to differentiate between large and small paths, but a uniform driving strategy can always be used.

If the method according to the invention were to be implemented by means of a digital computer, the two alternative acceleration values would be continuously determined, together with the decision as to which one should be used, in the order of equations (1) to (8b) Alternative acceleration setpoint brought into effect, which would connect the provision of the individual guided setpoints A _F , V _F and S _F to be made available to the position drive PA for acceleration, speed or distance. There would then be a new calculation cycle for processing equations (1) - (8b) and provision of a new set of guided setpoints. At the processing speeds of today's microprocessors, the computing cycle time T can be chosen to be very small, for example 5 msec, so that, despite the use of a computer which only works in steps, a quasi-continuous position control results.

The flow chart according to FIGS. 2a and 2b shows the resolution of the algorithmically described method in its individual steps. The state of the relevant quantities is indicated in the rectangular function blocks, which results as a result of the states which are described by the respective upstream function blocks. The diamond-shaped function blocks represent a switch function in the course of the method, in which if the condition specified in this function block is fulfilled, ie, if the question is answered in the affirmative, it proceeds in the other way, while in the other case the path marked "no" is taken. The reference symbols given next to the function blocks indicate the elements of FIG. 1 with the same names.

Starting with the start, the ASTOP signal is first set to the value 1. With the path setpoint S * corresponding to the intended stop and with the value S _F corresponding to the actual path value S _{A of} the position drive PA, the path control deviation ΔS corresponding to the travel or remaining path and the polarity of the direction of travel signal FR are formed therefrom. This is followed by the linear increase in the limit values for the acceleration a _b and a _v for the deceleration - with a subsequent check as to whether the end values a _bmax or a _{vmax have been} reached. The two alternative acceleration setpoints A1 and A2 are calculated in accordance with equations (4) - (6) and the second alternative acceleration setpoint A2 is checked to determine whether it is within the limit values for the acceleration a _b or for the deceleration a _v . Furthermore, it is checked whether the previous value of the ASTOP signal can remain in the next calculation cycle, ie whether the linear increase in these values should be stopped in the event that A1 has become smaller than A2. The functions to be assigned to the accelerometer 16 are thus dealt with.

This is followed by the selection of the acceleration setpoint to be used, a function which is assigned to the selection circuit 18 in the overview picture in FIG. 1 and is described with equations (7a, b). With the signum function applied to the first alternative acceleration setpoint A1, a variable sign (A1) is formed, which has a value of +1 for a positive polarity and a value of -1 for a negative polarity. The variable B thus represents the difference between the first and second alternative acceleration setpoint, which is evaluated with the polarity of the first alternative acceleration setpoint. Depending on whether this variable B is larger or smaller than zero, either the first or the second alternative becomes Acceleration setpoint is brought into effect as setpoint A * of the acceleration control loop.

The selection of the acceleration setpoint A * to be used is followed by its processing in the input circuit of the acceleration control loop consisting of the amplifier 15 and the integrator 12 (FIG. 1). C15 is the quite large gain constant of the proportional amplifier 15, the resulting value R _{F of} the guided jerk value possibly being limited to the maximum jerk value R _max .

The resulting value of the guided jerk R _F is then integrated three times in succession and the intermediate values of the guided acceleration setpoint A _F , the guided speed setpoint V _F and the guided travel setpoint S _{F are} fed to the position drive PA. At the end of a computing cycle, the query is made as to whether the path difference .DELTA.S has become zero, that is to say the predetermined stopping point has been reached, and if the answer to this question is in the negative, that is, if the path difference does not disappear, a new computing cycle begins with the last determined value of the guided path setpoint S _F .

The functions of the elements 12-20 of FIG. 1 can be realized with a digital computer programmed according to this flow chart. In the current state of the art, it also makes sense to also reproduce the control loop elements 4, 5 and 8 to 11 with a corresponding program extension using software. Nevertheless, it can be expedient in individual cases to implement at least partial sections of the method according to the invention by means of discrete, in particular analog, components.

3 shows an example with discrete components in hybrid technology, ie there are both analog and digital components. The part of the system according to FIG. 3 is shown, which is located there on the left of line II. The used switches, which are preferably in electronic switching elements, such as FET transistors, are, unless otherwise noted, each shown in its unactuated position, provided that it can be actuated with a digital H (high) signal of positive polarity are.

The difference between an arbitrarily predeterminable setpoint S *, which corresponds to the intended stop, and the guided travel setpoint S _F , which practically corresponds to the current position of the car 3, is formed in the mixer element 20 and a magnitude generator 21 provided in the accelerometer 16 and the direction indicator 17 fed. The direction indicator 17 consists of an electronic comparator circuit known per se, which emits a constant DC voltage signal with the value +1 when the input signal is positive, ie when driving upwards, and outputs a constant signal of size -1 when the input signal is negative, ie when driving downwards. With this direction of travel signal FR, the correct sense of action of the control device according to the invention is ensured for both directions of travel. The existing in the amount of the remaining distance ΔS of the amount generator 21 is fed to a function generator 22, which together with the direction signal, an acceleration limit value a _v , the guided acceleration setpoint A _F and the maximum jerk value R _{max forms} a function which the radicand, ie the expression under the root sign of equation (4a). Such a function can be easily implemented with the usual components of analog computing technology, such as multipliers, amplifiers and mixing elements. The output signal of this function generator is fed to a square root function generator 23, from whose output signal in a mixer 24 a value corresponding to the guided speed setpoint V _F is subtracted. The maximum jerk The corresponding value R _max is doubled in a further mixer 28 and multiplied by means of a multiplier 25 with the output signal of the mixer 24. The output variable of the multiplier 25 is processed in a further square-root function generator 26 and its output variable - in a mixer 27 reduced by the acceleration limitation value a _v - gives the first alternative acceleration target value A1 in accordance with equation (4b). The structure of a non-linear displacement controller, whose output variable V1 * forms the setpoint for a subordinate, also non-linear speed controller 26, is evident from the arrangement of the elements 20 to 23, in the event that the first acceleration setpoint A1 is effective via the selection circuit 18, The acceleration controller with the setpoint A * is subordinate to this non-linear speed controller 26, as a comparison with the arrangement according to FIG. 1 shows.

The second alternative acceleration setpoint value A2 arises as the output signal of a further square root function generator 29, the input signal of which is multiplied by a factor of 2 by means of a multiplier 30. R _max multiplied difference between an arbitrarily definable speed value V2 * and the guided setpoint V _F. The output variable of the square root function generator 29 is limited to the acceleration limitation value a _b for positive polarity and to the deceleration limitation value a _v for negative polarity. In the position of the switch 31 shown, this predeterminable speed value V2 * is obtained from a suitable setpoint generator 32, which could easily be implemented by means of a potentiometer which is at a constant voltage. In the event that the first alternative acceleration value A1 is greater than zero, the switch 31 assumes the position shown, while in the event that the first alternative acceleration target value becomes less than zero, the switch 31 is actuated so that the speed value V2 * the value zero is specified. As becomes clear again in connection with FIG. 1, in the event that the second alternative acceleration setpoint A2 is selected by the selection circuit 18, the position drive under the action of a non-linear speed controller implemented by means of the function generator 29, the setpoint of which consists of the speed value V2 *. This can be changed during the journey as desired by corresponding actuation of the setpoint generator 32, but it becomes negative when the engaged first alternative acceleration setpoint A1 requires a negative acceleration, ie a deceleration, by actuating the switch 31 from the output signal Limit detector 33 set to the value zero. This prepares the second alternative acceleration value to take the lead in the closing phase of the run-in, which will take place later.

The selection circuit 18 then makes the decision as to which of the two alternative acceleration setpoints A1 and A2 provided intervenes in the acceleration control loop in accordance with the conditions specified in equations (7a) and (7b). Among other things, the difference between the first and second acceleration values must be formed. This difference signal A1-A2 is now also used to have the signal ASTOP output via a limit indicator 34, with which the start-up started at the start of two integrators 35 and 36 providing the acceleration limits a _b and a _{v is} interrupted. At the start, a _b = a _v = 0 and, accordingly, according to equations (4b) and (6), the first alternative acceleration value is greater than the second alternative acceleration value. The signal ASTOP is therefore an H signal with which the switch 37 is actuated, that is to say brought into its closed position. Since the output signal of the limit value indicators 38a and 38b also has an H signal at the start, the switches 39 and 40 are also actuated and the output signals of the integrators 35 and 36 begin to increase linearly starting from the value zero, this change for as long continues until either the output _signals a _b and a _{v reach} the predetermined maximum values a _bmax or a _vmax or before the signal ASTOP has become zero. In both cases, the connection between the voltage source denoted by R _max and the inputs of the integrators 35 or 36 is interrupted by opening one of the switches 37 or 39 or 40.

4 shows an advantageous embodiment of the function generator 29 with its modulation limits determined by the limit values a _b and a _v . It must be suitable for processing input signals of both polarities. However, in the arrangement according to FIG. 4, a square-root function generator 41 of simpler construction is used, which only has to form the square root of a positive input variable. Its input is connected to the output of an absolute value generator 42, which is acted upon by the input variable e, which can have both polarities and which is also fed to a comparator 43, which then emits a signal of size +1 if the input variable has a positive polarity and emits a signal of size -1 if the input size e is of negative polarity. In this respect, the function of this comparator 43, which acts as a polarity transmitter, is similar to that of the direction of travel transmitter 17. The output signal of the polarity transmitter is capable of actuating a switch 47 via a limit indicator 44, with which switch 47 a signal corresponding to the limit value for the acceleration a _b is input to the input of a minimum circuit 45 is switched through, while with a negative input signal e the output signal of the limit value detector 44 has the value zero and brings the switch 47 into the position shown in which the limit value for the delay a _v reaches the input of the minimum circuit 45. The other input of the minimum circuit 45 is connected to the output of the square root function generator 41. The minimum circuit allows each of its two always positive input signals to pass through the smaller one, which is then combined in a multiplier 46 with the output signal of the polarity transmitter 43, thereby achieving is that the output signal A2 always gets the same polarity as the input signal e. With the device shown in FIG. 4, the root function shown in the block symbol 29 of FIG. 3 and running in the first and third quadrants can be realized, although only a simple function generator is used for the first quadrant.

5 shows an implementation of the selection circuit 18 for the two alternatively provided acceleration setpoints A1 and A2. The selection function, as defined in equations (7a) and (7b), would require the use of polarity transmitters for the signal function and multipliers for linking to the difference A1 - A2 if they were to be converted directly into discrete components. According to FIG. 5, however, this selection function is achieved by avoiding multipliers with comparatively simpler components. The choice between the two alternatively provided acceleration setpoints A1 and A2 is effected by the output signal of an exclusive OR gate 48. If the output of the exclusive OR gate 48 carries an H (high) signal, then the switch 49 is actuated so that the previously effective alternative acceleration setpoint A2 is replaced and the alternative acceleration setpoint A1 now takes effect as the acceleration setpoint A *. If, on the other hand, the output of the exclusive OR gate 48 carries an L (low) signal, the switch 49 is in the position shown in FIG. The inputs of the exclusive OR gate are connected to the outputs of two limit value indicators 50 and 51, of which the limit value indicator 51 is acted upon by the alternative acceleration setpoint A1 and then carries an H signal if the alternative acceleration setpoint A1 is of positive polarity. The same applies to the limit value detector 51 with regard to the polarity of its input signal consisting of the difference between the first and second alternative acceleration setpoint, which is formed in a mixing element 52. An H signal only arises at the output of limit detector 51 if said difference A1 - A2 is of positive polarity, ie if A1 is greater than A2. An exclusive OR gate only carries an H signal at its output if its two inputs carry different signals. Taking this mode of action into account, it can be shown that the arrangement shown in FIG. 5 performs exactly the selection function shown in equations (7a) and (7b).

Great demands are placed on the flexibility of the driving program, particularly in the case of passenger transport systems, if individual wishes of the passengers arising after the start of the journey are to be taken into account. This can be achieved with a variant of the method according to the invention, which consists in the fact that, even in the case of more distant travel destinations, a travel setpoint which corresponds to the closest stop is always given first and then shortly before the first alternative acceleration setpoint would intervene at this stop for targeted stopping, it is checked whether there should really be a stop, ie whether, in the absence of a stop request made up to that point, a further stop should be used instead. In this case, the travel setpoint would be increased by a value that corresponds to the next stop. The travel setpoint is therefore increased as required in the individual possible stops until it corresponds to the desired destination. These incremental setpoint increases do not affect the course of the journey; this is the same as if the desired setpoint had been specified at the beginning. This gradual increase in the travel setpoint is of particular importance for driverless traction drives, such as monorails. Here, as possible stops to be approached by the position drive, additional sections with a potential for collision, such as switches or crossings, could be provided, so that the system is regularly prepared to stop in front of these danger points and only in the event that there is a safety signal for this danger point, without stopping and delaying to continue.

6 shows an exemplary embodiment of a travel encoder 19 for the travel setpoint S *, with which such a step change in the setpoint can be carried out under the influence of the two alternative acceleration setpoints A1 and A2. The exemplary embodiment is intended to relate to a passenger transportation system with five stops, for example five floors. Accordingly, five setpoint sources S1 to S5 are provided, the potentials of which can be successively output as setpoint S * by means of switches P1 to P5 which can be actuated by the individual stages of a shift register 53. A shift register is a device in which the signal state of a cell is passed on - shifted - to the neighboring cell each time a signal arrives at the input CL. In the example shown in FIG. 6, the shift register 53 is currently in the state in which its leftmost cell carries an H signal as the output signal and has thus actuated the switch p1 assigned to it. At the output, the setpoint S * therefore shows the value S1, which would correspond to the lowest floor. For an upward travel, the direction of travel signal FR is an H signal, so that the next positive pulse edge arriving at the input CL, ie a change from L to H signal, the H signal of the leftmost cell of the shift register 53 moves one cell to the right leaves, which closes switch P2 while switch P1 opens. The H signal thus moves one cell further to the right on each such pulse edge arriving at the input CL, so that the setpoints S1 to S5 are output in succession as the current setpoint S *. If, on the other hand, the direction of travel signal has the value -1 during downward travel, the shift register 53 is set up in such a way that the H signal of the individual cell is passed on to the neighboring cell on the left. Such registers, which optionally shift the information to the right or left, are known per se. Using a series of selection buttons T1 to T5, bistable flip-flops B1 to B5 can be set and the destinations to be traveled to can thus be saved. These selection buttons are either installed in the driver's cabin and / or stationary. By actuation The buttons T1 to T5 can be used to actuate the switches h1 to h5 assigned to the bistable flip-flops B1 to B5, whereby the setpoint sources S1 to S5 can be connected to a diode selection circuit. S5>S4>S3>S2>S1> 0 applies to the potentials of the setpoint sources. Depending on the position of the switches 55 and 56, which can be actuated simultaneously by the travel direction signal FR via a limit indicator 54, the diode selection circuit is configured either as a minimum selection circuit or as a maximum selection circuit. 6 shows the switches 55 and 56 in their unactuated state, which they assume when driving downwards and the diodes connected to the cathodes are connected to the ground or reference potential via a resistor 57. A maximum selection circuit is then configured which, from the travel destinations stored by means of the bistable flip-flops B1 to B5, enables the one at the input of a mixing element 58 whose setpoint potential is greatest. Conversely, when driving upwards, the direction of travel signal FR will assume the value 1 and thus operate the switches 55 and 56, whereby the diodes connected to one another with their anodes are connected to a positive DC voltage P via the resistor 57. This DC voltage P has a positive potential which is greater than the largest of the setpoint potentials, S5, which corresponds to the most distant stop. A minimum circuit is thus configured, which of the selected stop potentials makes the one on the line 59 connected to the mixing element 58 which has the smallest value effective. The second input of the mixing element 58 is acted upon by the current setpoint signal activated by one of the switches p1 to p5. The output of the mixing element 58 is linked to the direction of travel signal FR via a multiplier 60 and is connected to a limit value detector 61, the output of which acts on an AND gate 63 via an OR gate 62. A second input of the AND gate 63 is connected to the first alternative acceleration setpoint A1 via a further limit indicator 64 and a third input of the AND gate 63 is acted upon by the output signal of a mixer 65 via a further limit detector 66. The difference between the second and the first alternative acceleration setpoint is formed in the mixing element 65 and a small value ΔA, which is smaller than 1,000th of the maximum limiting _value a _bmax for the acceleration, is added to this difference. The output of the AND gate 63 acts via an OR gate 67 on the input CL of the shift register 53. A second input of the OR gate 67 can be connected to a voltage source which supplies an H signal by means of a switch 68 which can be actuated by a start signal.

The mode of operation of the device shown in FIG. 6 is as follows: It is assumed that the position drive is in the stop assigned to the setpoint S1 and that the fourth floor is selected as the destination by pressing the button T4. With the signal START, the switch 68 is actuated and the shift register is advanced one stage, so that the resultant closing of the switch p2 presets the position drive as the setpoint S * as the setpoint S2. The direction of travel signal FR has the value 1, the switches 55 and 56 are therefore in their position, not shown, in which a minimum circuit is configured. The position drive now begins to move towards the stop according to setpoint S2. Shortly after the start of the journey, the stop corresponding to the setpoint S3 should also be selected by pressing the selection button T3, which initially has no further consequence for the driving behavior. In the course of the approach to the closest stop corresponding to the setpoint S2 activated by the state of the shift register 53, target braking would be initiated if the difference between the second alternative acceleration setpoint and the first alternative acceleration setpoint becomes negative if the first alternative acceleration setpoint is positive. Shortly before the occurrence of this condition, whereby this short time is determined by the small additional value ΔA, two of the three AND conditions of the AND gate 63 are fulfilled. If the third AND condition were also fulfilled at this point in time, a shift signal would be generated for the shift register 53 which increases the setpoint and consequently prevents the use of target braking. With the third condition, which consists in an H signal of the limit value detector 61, it can thus be checked whether there is a need for a further switching, that is to say a setpoint increase, or whether the drive is to be stopped at the stopping point S2. There is such a need for a setpoint increase while suppressing target braking whenever the smallest stored stop point is greater than the currently output setpoint S *. In this case, the output signal of the mixing element 58 becomes greater than zero, which, when the limit value detector 61 moves upward, responds with an H signal at its output. After the next stopping point has been stored in the minimum circuit corresponding to the setpoint S3, the target braking with respect to the stopping point S2 is suppressed by stepping on the indexing mechanism 53 and the stop S2 is passed over. If the position drive is between the stops S2 and S3, then the output signal of the mixing element 58 has an L (low) signal. The step-by-step mechanism 53 is prevented from advancing and the position drive comes to a standstill at the intended holding position S3. After a new start, this game of increasing the setpoint as required continues until the position drive at the next stored stop is brought to a standstill.

The same applies to the downward movement, ie a movement from the stop S5 to S1. As already mentioned, a maximum circuit is configured for this purpose, which in each case brings the largest of the stored setpoint potentials to the line 59 connected to the mixing element 58.

In the event that e.g. In the case of guideless traction drives connected to the guideway, certain danger points are present, for example in the form of switches and crossings, which may require an emergency stop, the extensions shown in dashed lines can be provided in FIG. 6. These are that e.g. between the normal stops, two additional setpoints (W1 and W2) are permanently fed into the maximum or minimum circuit and corresponding stages of the shift register 53 are provided for outputting these setpoints. A stop at these points is thus initially programmed, which is then canceled when an enable signal OK is given to the second input of the OR gate 62.

7 shows a route of a monorail (H-Bahn) suitable for the travel setpoint shown in FIG. 6. The final stops on the route are labeled S1 and S5, with the intermediate stops S2 to S4 in between. Between the stops S1 and S2, a passenger cabin designated 69 is indicated, which moves in the direction of the final stop S5. In order to avoid collisions at critical danger points, junctions or switches 70 or 71 in the example shown, emergency stops designated W1 or W2 are provided. In the given direction of travel, it must therefore be checked after passing stop S2 whether a collision situation is to be expected at switch 70 and, if this question can be answered in the negative, an H (high) signal should be given as an OK signal , so that the emergency stop W1 is run over while stopping at an L (low) value of the OK signal at point W1. The next emergency stop W2 is irrelevant in the direction of travel of the passenger cabin. Immediately after passing the demand stop S3, the release signal OK can be an H (high) signal and the collision check in this case would have to be carried out in an analogous manner in a passenger cabin located on the route section 72 and moving towards the switch 71.

FIGS. 8 to 10 show typical driving diagrams for the method according to the invention. Depicted in time dependence are the guided jerk value R _F , the guided speed value V _F , the speed setpoint V2 *, the speed setpoint V1 * for the speed controller 25, 26 subordinate to the travel controller 22, 23 and the two alternative acceleration setpoints A1 and A2.

/2 . R_max, so daß sich entsprechend der Gleichung (6) der Wert des zweiten alternativen Beschleunigungssollwertes von seiner Begrenzung -a_vmax zu lösen beginnt und die Bedingung gemäß Gleichung (7b) wieder erfüllt ist. Es löst also der zweite alternative Beschleunigungssollwert A2 den zuvor wirksam gewesenen ersten alternativen Beschleunigungssollwert A1 ab und die Beschleunigung des Positionsantriebs wird zeitlinear bis auf den Wert Null vermindert, womit sich der verrundete Geschwindigkeitsverlauf von V_F ergibt, bis dann schließlich der Positionsantrieb zum Zeitpunkt t₄ zur Ruhe kommt. Dann hat sowohl die Wegregelabweichung ΔS den Wert Null, als auch die Beschleunigung und die Geschwindigkeit des Positionsantriebs. Würde der erste alternative Beschleunigungssollwert A1 zum Zeitpunkt t₃ nicht vom zweiten alternativen Beschleunigungssollwert A2 abgelöst werden, dann würde der Positonsantrieb mit konstanter Verzögerung zum Zeitpunkt ${\text{t₃ + t}}_{\text{e}}\text{/2}$

nur bis zu einer Stelle gelangen, die um eine Wegstrecke SZ vor dem vorgesehenen Haltepunkt liegt, wobei SZ dem Wert

entspricht. Rechtzeitig zum Zeitpunkt t₃, was einer Wegstrecke entspricht, welche um den vierfachen Betrag von SZ vor dem vorgesehenen Haltepunkt liegt, gerät der Positionsantrieb wieder unter die Kontrolle des zweiten alternativen Beschleunigungswertes A2 und kommt zum Zeitpunkt ${\text{t₃ + t}}_{\text{e}}$

am vorgegebenen Haltepunkt (S_F = S*) zur Ruhe, wie aus dem rechts oben in der FIG 7 dargestellten Weg-Zeit-Teildiagramm hervorgeht.According to FIG. 8, the position drive is first started up with the second alternative acceleration setpoint A2 to a speed V2 *, which may correspond to the maximum permissible speed. By changing the speed setpoint V2 * at time t 1, the speed of the position drive PA is reduced to any intermediate value, which could also consist of a so-called creep speed. Up to the time t₂, the position drive is under the effect of the second alternative acceleration setpoint A2 in accordance with the condition according to equation (7b). From the time t₂, the condition according to equation (7a) is fulfilled and the target braking under the effect of the first alternative acceleration setpoint begins. The guided speed setpoint V _F is now brought into congruence with the path controller described with equations (4a) and (4b) with the straight line designated by BP in the FIGURE and is guided along it until the time t 3. The straight line BP would correspond to the so-called brake parabola in a path-speed diagram. At time t₃, the guided speed setpoint V _F becomes smaller than the value a $\genfrac{}{}{0ex}{}{\text{2nd}}{\text{v}}$

/ 2nd R _max , so that according to equation (6) the value of the second alternative acceleration _setpoint begins to be released from its limitation -a _vmax and the condition according to equation (7b) is fulfilled again. The second alternative acceleration setpoint A2 thus replaces the previously used first alternative acceleration setpoint A1 and the acceleration of the position drive is reduced in a time-linear manner to the value zero, thus rounding off the rounded speed curve of V _F until the position drive finally comes to rest at time t₄. Then the displacement control deviation ΔS has the value zero, as well as the acceleration and the speed of the position drive. If the first alternative acceleration setpoint A1 at time t₃ would not be replaced by the second alternative acceleration setpoint A2, then the position drive would have a constant deceleration at the time ${\text{t₃ + t}}_{\text{e}}\text{/ 2nd}$

only get to a point that is a distance SZ before the intended stop, where SZ is the value

corresponds. Just in time at time t₃, which corresponds to a distance that is four times the amount of SZ before the intended stop, the position drive comes under the control of the second alternative acceleration value A2 and comes at the time ${\text{t₃ + t}}_{\text{e}}$

to rest at the predetermined stop (S _F = S *), as can be seen from the path-time partial diagram shown at the top right in FIG.

9 shows a driving diagram for "small paths", that is to say for stopping points which are so close to the starting point that the maximum acceleration a _{bmax is} not reached in the course of the journey because the destination braking must take place beforehand. Again, the position drive from the start to the time t₂ under the effect of the second alternative acceleration setpoint A2, from the time t₂ the target braking begins under the effect of the first alternative acceleration setpoint A1 and at time t₃ this is used to enter the intended stop from the second alternative acceleration setpoint A2 replaced. The switchover of the speed setpoint V2 * to the value zero, which will later be required for the entry into the stop, takes place at the time t₂ʹ and is coupled according to equation (5) with the negative of the first alternative acceleration setpoint A1. This ensures that the condition according to equation (7a) remains valid even after the zero crossing of A1 and that the Target braking with the first alternative acceleration setpoint A1 can take place.

FIG. 10 shows a course of travel as it results in the variant of the stepwise setpoint adjustment described in connection with FIG. 6. Sections S1 to S5 in the course of the first alternative acceleration setpoint A1, which result from the effect of these setpoints, are noted. In accordance with the example in FIG. 6, S5> S4> S3> S2> S1 applies. It can be seen that shortly before the condition according to equation (7a) is met and the first alternative acceleration setpoint is reached for the purpose of target braking, the setpoint is increased by one step so that the first alternative acceleration setpoint does not come into play and target braking does not take place. At setpoint S5, there is finally no further increase in setpoint and the first alternative acceleration setpoint A1 takes control at time t₂. If, on the other hand, the setpoint increase from S1 to S2 were omitted, in principle there would be a driving course as shown in FIG. 9.

FIGS. 8 to 10 make it clear that travel setpoint or speed setpoint adjustments can be carried out in a rather permissive manner while driving and practically any desired driving requests can thus be implemented in a simple manner.

Claims (9)

1. A method for providing a stepwise, acceleration and velocity limited path control for a positioning drive having a subordinated velocity control, wherein with a triplicate time integration of a step value (R_F) a control of the acceleration specified value, the velocity desired value, and the path desired value of the positioning drive occurs, and the amplified difference between an acceleration reference value (A*) and the time integral of the step value is formed as a step value in an acceleration control circuit (12, 15, 17), wherein the absolute value of the step value is restricted to a maximum value (R_max), characterised by the following steps:

   a) forming a first alternative acceleration specified value (A1) in dependence on the residual path (ΔS), still to be travelled, with which the positioning drive does not go beyond a point that lies at a given path distance (S_Z) ahead of a predetermined path desired value (S*), using a constant deceleration (a_v);

   b) forming a second alternative acceleration specified value (A2), the absolute square of which is proportional to the difference between a predeterminable velocity (V2*) and the controlled velocity desired value (V_F), with which the positioning drive can be brought to this predeterminable velocity (V2*) without overshoot;

   c) after the start the second alternative acceleration specified value (A2) is firstly effected; the first alternative acceleration specified value (A1) is used to initiate destination braking; and the second alternative acceleration specified value is again used for approaching the predetermined stopping point with the predetermined path desired value (S*) if the positioning drive has reached a point, that is located four times the value of the determined path distance (S_Z) ahead of the predetermined stopping point.
2. A method according to claim 1, characterised by the following steps:

   (a) increasing, from zero, limiting values for the acceleration (a_b) and deceleration (a_v) up to their maximum maximum values a_bmax and a_vmax, linearly in time, beginning with the start of the positioning drive;

   (b) continuously determining the first alternative acceleration specified value (A1) in dependence on the residual path (ΔS), the controlled velocity desired value (V_F), the controlled acceleration specified value (A_F), the respective limiting signal for the deceleration (a_v), the maximum step signal (R_max) and a travel direction signal (FR) (Equations 4a and 4b);

   (c) continuously in dependence on the guided velocity desired value (V_F), the travel direction signal (FR), the predeterminable velocity (V2*) and the maximum step value (R_max) a second alternative acceleration specified value (A2) is determined, restricted between the limited values for the acceleration (a_b) or for the deceleration (a_v), (Equation 6), wherein the predeterminable velocity desired value (V2*) is set at zero, if the first alternative acceleration specified value (A1) is smaller than zero;

   (d) effecting either the first or second alternative acceleration specified value as reference value (A*) of the acceleration control circuit, depending on whether a difference, when valued with the polarity of the first alternative acceleration specified value (A1), between the first and second alternative acceleration specified values (A1-A2) is smaller or equal or greater than zero (Equations 7a and 7b);

   (e) stopping the time-linear increase of the limiting values for acceleration a_b and for deceleration a_v if the first alternative acceleration specified value (A1) becomes smaller than the second alternative acceleration specified value (A2). (Equation 8a);
3. A method according to claim 1 or 2, especially for passenger transport systems, characterised in that the path desired value (S*) is always set in accordance with the respective nearest lying stopping point; and the predeterminable path desired value (S*) is enlarged as required during the journey with the positive first alternative acceleration specified value (A1) shortly before the difference between the first alternative acceleration specified value and the second alternative acceleration specified value (A2) becomes nil.
4. A method according to claim 3 for roadway-bound, in particular track-bound, traction drives without drivers, characterised in that switchpoints, crossings or other danger points are provided as stopping points.
5. A device for a stepwise, acceleration and velocity limited path control for a positioning drive with subordinated velocity regulation, wherein with a triplicate time integration of a step value (R_F) a control of the acceleration specified value, the velocity desired value and the path desired value of the positioning drive occurs and the amplified difference between an acceleration reference value (A*) and the time integral of the step value are formed as a step value in an acceleration control circuit (12,15,17), wherein the absolute value of the step value is limited to a maximum value (R_max), characterised by the following features:

   a) there are provided two integrators (35, 36) acted upon with a voltage corresponding to the maximum step value (R_max), for generating limiting values for the acceleration (a_b) and for the deceleration (a_v), the output voltages of which, beginning with the start of the positioning drive (PA), are increased from the value nil in a time-linear manner to the maximum values (a_bmax or a_vmax), wherein the input voltages of the integrators (35, 36) are deactivated by the output signal (ASTOP) of a limiting value indicator (34) to which is supplied on the input side the difference between the two alternative acceleration specified values (A1-A2);

   b) for detecting the first alternative acceleration specified value (A1), which is dependent on the residual path ( S), still to be travelled, the controlled velocity desired value (V_F), the guided acceleration specified value (A_F), the respective limiting desired value for the deceleration (A_v), a maximum step value (R_max) and a travel direction signal (FR) (Equations 4a and 4b), a function generator (22) is provided with a subsequent root-extracting function generator (23), the output signal (V1*) of which is supplied together with the controlled velocity desired value (V_F) to a mixing element (24), wherein the output signal of the mixing element (24) acts on a further root-extracting function generator (26);

   c) for detecting the second alternative acceleration specified value (A2), which is dependent on the controlled velocity desired value (V_F), on the travel direction signal (FR), a predeterminable velocity (V2*) and the maximum step value (R_max) (Equation 6), a third root-extracting function generator (29) is provided, the output signal of which is restricted to the respective limiting values for the acceleration (a_b) or for the deceleration (a_v);

   d) both alternative acceleration specified values (A1, A2) are connected to the inputs of a selection circuit (18), which, depending on whether the difference between the first and second alternative acceleration specified value (A1-A2), valued with the polarity of the first alternative acceleration specified value (A1), is smaller than or equal to or larger than nil, connects through either the first (A1) or the second (A2) alternative acceleration specified value as reference value (A*) for the acceleration control circuit (12, 15, 17) (Equations 7a and 7b).
6. A device according to claim 5 or one of the following, characterised in that the selection circuit has a reverse switch (49), able to be actuated by the output signal of an exclusive-OR-gate (48), wherein the inputs of the exclusive-OR-gate are acted upon, in each case by way of limiting value identifiers (50, 51), by the first alternative acceleration specified value (A1) and by the difference (A1-A2) between the first and second alternative acceleration specified value.
7. A device according to claim 5, characterised in that for forming the second alternative acceleration specified value (A2) a root-extracting function generator (41) is used, to which is supplied an input value (e) by means of an absolute-value generator (42), and the output of which is connected to the one input of a minimum value selection circuit (45), the second input of which is acted upon, depending on the polarity of the input size of the absolute-value generator (42), by the limiting signal for the acceleration (a_b) or by the limiting signal for the deceleration (a_v), wherein the polarity of the output signal of the minimum value selection circuit is brought into conformity with the polarity of the input signal of the absolute-valve generator by means of a multiplier (46).
8. A device according to one of claims 5 to 7, for incremental enlarging of the path desired value, corresponding in each case to the nearest-lying possible stopping point, in particular for passenger transport systems, characterised by the following features:

   a) a shift register (53) is provided, able to be stepped up further by the output signal of an AND-gate (63), the cells of which actuate switches (p1 to p5), with which the path desired values (S1-S5) corresponding to the individual stopping points are able to be activated one after the other;

   b) path desired values selected by means of selective keys (T1 to T5) and bistable flip-flops (B1-B5) act on an extreme value selection circuit;

   c) the AND-gate (63) has three inputs which are acted upon in each case by the output signal of a limiting value identifier, wherein supplied to the first limiting value identifier (61) is the difference between the output signal of the extreme value-selection circuit and the respectively activated desired value, the second limiting value identifier (64) is supplied with the first alternative acceleration specified value (A1) and the third limiting value identifier (66) the difference, formed in a mixing element (65), between the second alternative specified value (A2) and the first alternative specified value (A1), wherein the mixing element (65) is acted upon in addition by a value, which is smaller than a thousandth of the maximum limiting value for the acceleration (a_bmax).
9. A device according to claim 8, characterised in that the extreme value-selection circuit contains diodes which are connected to each other at the cathode or the anode side, respectively.

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