FR2749716A1 - STEPPER MOTOR DRIVER AND INCORPORATION INTO A VEHICLE STEERING WHEEL DRIVE - Google Patents

Abstract

In a stepper motor driver, an instruction unit produces voltage indicating PWM pulses whose voltage value increases and decreases in a predetermined cycle. A drive unit applies a voltage obtained by chopping with PWM pulses to a stepper motor. Resistors detect the current flowing in the motor. A step change detection unit compares the expected value of the current to pass through the motor when the chopped voltage is applied and the value of the current actually passing through it. If the difference between these values is outside a given range, a step change detection unit produces information on this change. When used for tilt or telescopic flywheel drive, the driver stops the flywheel drive when a change in pitch is detected.

Description

The present invention relates to a stepping motor drive device

for training a

  object and controlling the positioning of the object.

  Stepper motors are often used to drive objects that require relatively precise positioning, for example, for the opening-closing drive of a vehicle engine throttle valve, driving the tilt and telescopic drive of a steering wheel, up-down drive of a cushion seat (i.e. part of the seat on which one sits) , and the command to tilt the back of a seat. In a control mechanism for driving a steering wheel, a cushion seat and the like, the driven object is adjustable to a position corresponding to the optimal attitude of the user (for example, driver), and the optimal position is saved in a memory, so that the object is automatically driven to the optimal position when, for example, the ignition key is inserted, and the object is automatically driven to position

  when the key is removed.

  If there is no overload (load disturbance), the movement of the driven object can be detected by counting the number of steps of the electric attack of a stepper motor. On the basis of the count value obtained by counting the steps of the electric drive, it is possible to recognize the position of the driven object and to place it at the desired position. Thus, the position of the object can be tracked without having to additionally employ a position sensor, a rotary position tracking encoder or the like. However, if there is an increase in the load during training to the optimal position or to the withdrawal position, caused, for example, by an external object or a troublesome person

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  the passage of the driven object, it becomes necessary to stop the attack so as to avoid damage to the steering wheel or the drive mechanism of the seat, of a stepping motor, or of the object or the person causing the discomfort. An overload will cause the step change of the stepper motor, i.e. a situation in which the actual operating speed of the motor (object drive speed) does not match the electric attack step by step. If this change occurs and continues for a duration equal to or exceeds one cycle of the step, there is a difference between the count value which corresponds to the number of drive steps and the position of the object driven , which results in a positioning error based on the count value. In a technology described in the Japanese patent made available to the public N Hei 4-364399, a rotation angle sensor is connected to a motor

  step by step which opens and closes a throttle valve.

  After storing the detection value of the angle of rotation sensor, the stepper motor is driven a number of steps forward, in terms of the number of steps of the electric drive, and is then driven backwards by the same number of steps, in order to obtain another value from the detection of the angle sensor, from which the value of the detection stored is subtracted. The difference thus obtained is examined, and if it exceeds an admissible range, there is determination of the fact that there is a change in pitch. Since this technology additionally requires a rotation angle sensor, the number of elements constituting the mechanism increases and the installation space and costs increase accordingly as in the technologies mentioned above which employ a additional sensor or the like, such as a position sensor for tracking the position of

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  the object being driven, or a rotary position tracking encoder. Accordingly, an object of the present invention is to detect the change in pitch of a stepper motor without employing a sensor for mechanical tracking of the position. Another object of the invention is to precisely position a driven object on the basis of the count value obtained by counting the number of steps of the electric drive of a stepping motor. Another object of the present invention is to provide a count value which accurately indicates the position of a driven object even if the step of the stepper motor changes. Another object of the present invention is to avoid damaging a drive mechanism, a stepping motor, an external object or a person hindering the passage of the driven object s' there is such discomfort or external force which is applied to the driven object. According to one aspect of the present invention, the stepping motor driver comprises a motor driving instruction unit 191 which produces a voltage indicator signal (pulses leaving PA1, PB1), the value of which the indication Val, Vbl increases and decreases (sin, cos) in a given cycle. In response to the voltage indicating signal, a motor drive circuit 199a applies a voltage Val, Vbl indicated by the voltage indicating signal to the stepping motor 171. A current detection unit 1OlAl, 101OA2, 0llB1, 101B2 is supplied to detect a value ial, ibl of an electric current passing through the stepping motor 171. A step change detection unit 191 compares an expected value Ial, Ibl of the current which it is expected to pass through the stepping motor 171 when applying to the stepping motor the voltage indicated by the voltage instruction signal and a value ial, ibl of the current flowing in the stepping motor 171 following the application of a

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  voltage to the stepping motor by the motor driving circuit in response to the voltage indicating signal, the value ial, ibl of the current being detected by the current detection unit 101A1, 101A2, 101B1, 101B2. If the difference Eal, Ebl between the expected value of the current and the detected value is outside a given range Esl, the step change detection unit

  produces information on this change AF = 1.

  When the value ial, ibl of the current actually passing through the stepping motor 171 is detected after the output of the voltage indicator signal to supply the stepping motor with an expected value Ial, Ibl of the current, the expected value of the current Ial, Ibl , that is to say the target value of the current, is compared with the detected value of the current ial, ibl, that is to say with a value of feedback. If there is no change in the pitch, the expected value of the current

  is substantially equal to the detected value ial, ibl.

  If a step change is caused by an overload, the detected value of the current becomes the value of an overload current, so that the difference between the expected value and the detected value of the current, i.e. between Expected current value - detected current value, out of the given range Esl. A change in the step of the stepper motor is therefore detected without using a sensor

  for the continuation of the mechanical position.

  According to another aspect of the present invention, a stepping motor driver - includes a movement instruction unit 31 for giving an instruction to drive an object. In response to this instruction (open or closed state of 31), an instruction unit 191 for attacking the motor produces a voltage indicator signal (pulses leaving PAl, PB1) whose indicator value Val, Vbl increases and decreases (sin, cos) in a predetermined cycle. In response to the voltage indicating signal, a motor drive circuit 199a applies a voltage Val, Vbl indicated by the voltage indicating signal to the stepping motor 171. A position tracking unit 191 present stores information on the positiohi presents and updates this information a given number of times per increase-decrease cycle of the voltage indicator signal. A current detection unit 101A1, 101A2, 101B1, 101B2 is provided for detecting a value ial, ibl of the electric current flowing through the stepper motor 171. A step change detection unit 191 compares an expected value Ial, Ibl of current expected to flow through the stepper motor 171 when applying the voltage Val, Vbl indicated by the voltage instruction signal and a value ial, ibl of the stepper motor current flowing through the stepping motor 171 following the application of a voltage to this motor by the drive circuit of the motor in response to the voltage indicator signal, the value ial, ibl of the current being detected by the current detection unit 101A1, 101A2, 101B1, 101B2. If the difference between the expected value of the current and the detected value of the current is outside a given range Esl, the step change detection unit stops the application of the voltage to the stepping motor 171 by the circuit

engine 199a.

  When the unit 31 instructs the training of an object (that is to say when this unit goes from the open state to the closed state), the training of the object begins. The present position tracking unit 191 then updates this position information in synchronism with the electrical attack of the stepper motor 171, thereby monitoring the position of the object during its training. If the expected value of the current - detected value of the current increases and leaves the range Esl during the drive, the unit 191 stops the application of the voltage to the stepping motor 171 by the drive circuit 199a, hence stopping the attack (application

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  motor voltage or excitation)

step by step 171.

  Since the updating of the information on the position present by the tracking unit 191 is also stopped when the attack on the stepping motor is stopped, the information on the present position continues, indicating precisely the stop position. In addition, if there is an obstruction by an external object or an external force is applied to the driven object, a new drive of the object is not executed so that the damage of the mechanism drive, stepper motor or

  obstruction can be avoided.

  The stepping motor driver of the present invention may further include a positioning unit 191 which stores the information on the target position and which stops the application of the voltage to the stepping motor 171 by the motor drive circuit 199a when the information on the present position is in accordance with the information on the target position. With this construction, if the step change detection unit 191 does not detect the step change of the stepper motor 171 during the drive, the drive of the stepper motor stops automatically when the object reaches a target position. According to another aspect of the present invention, a stepper motor driver includes a movement instruction unit 31 which instructs the forward drive and the back drive of a object. In response to the forward drive instruction (transition from the open state to the closed state of the unit 31), a motor drive instruction unit 19 produces a voltage indicator signal of drive forward (pulses out of PAl, PB1) whose value of the indication increases and decreases (sin, cos) in a?

  predetermined cycle. In response to the instruction.

  backward drive (change from closed state to open state of unit 31) ,. the unit 191 produces a signal indicating a backward drive voltage, the value of which increases and decreases in a predetermined cycle. In response to the voltage indicating signal, a motor drive circuit 199a applies a voltage indicated by the voltage indicating signal to a stepping motor 171 which drives the object. A present position tracking unit 191 stores information on the present position and updates the information on the present position a given number of times per increase-decrease cycle of the voltage indicator signal. A positioning unit 191 stores the information on the target position and the information on the original position. When the information on the present position is in accordance with the information on the target position during the application of the forward drive voltage to the stepper motor 171 which corresponds to the drive instruction to the front, the positioning unit 191 stops the application of the forward drive voltage. The positioning unit establishes the present position information that exists at the time of the forward drive instruction appearance as home position information. When the present position information matches the original position information during the application of the rear drive voltage which corresponds to the rear drive instruction, the unit positioning stops the application of the backward drive voltage to the stepper motor. A current detection unit 10lA1, 101A2, 101Bl, 101B2 is provided for detecting the value ial, ibl of the electric current passing through the stepping motor 171. A step change detection unit 191 compares an expected value Ial, Ibl of the current which is expected to

  crosses the stepper motor 171 during application.

  to the stepping motor of the voltage indicated by the voltage instruction signal and a value ial, ibl of the current flowing through the stepping motor 171 following the application of a voltage to the stepping motor by the motor drive circuit in response to the voltage indicating signal, the value ial, ibl of the current being detected by the current detection unit 10Al, 101A2, 101Bl, 101B2. If the difference between the expected value of the current and the detected value of the current leaves a given range Esl, the step change detection unit stops the application of the voltage to the stepping motor 171 by the circuit

engine attack 199a.

  When the movement instruction unit 31 instructs forward drive, the stepper motor 171 is driven forward to move the object forward. If this detection unit does not detect a change in the stepper motor step during forward drive, the attack of the stepper motor stops automatically when the object reaches the target position. When the instruction unit 31 instructs a backward drive, the stepper motor 171 is driven backward so as to move the object backward. If the detection unit does not detect a change in the stepper motor step when driving backwards, the attack of the stepper motor stops automatically when the object reaches the

original position.

  The present invention will be well understood

  during the following description made in connection with

  the accompanying drawings, in which: Figure 1 is a side view of a steering device which is controlled by a preferred embodiment of the stepping motor driver according to the present invention;

Figure 2 is a sectional view

  longitudinal of the steering device of Figure 1; Figure 3 is a block diagram of an electronic control unit 19 shown in Figure 1; Figure 4 is a block diagram of a motor drive circuit 199a shown in Figure 3; FIG. 5 is a flow diagram schematically showing the position control of a steering wheel executed by the central processing unit 194 of FIG. 3; FIG. 6 is a flowchart showing part of the content of the "TRAINING TOWARDS THE TARGET POSITION" of step 5 in FIG. 5; Figure 7 is a flowchart showing

  the rest of the contents of the "TRAINING TOWARDS THE POSITION-

  TARGET "of step 5 endfigure 5; and Figure 8 is a flowchart representing the content of" CALCULATE THE TARGET VOLTAGE Val, Vbl "of

step 17 in figure 6.

  A preferred embodiment of the present invention will be described below in connection with the

annexed drawings.

  Figures 1 and 2 show a side view and a longitudinal sectional view of a steering wheel device 1 which is driven by a preferred embodiment of the stepping motor driver of the present invention (shown in Figure 3). The device 1 comprises a mechanism for tilting the steering wheel and a telescopic mechanism for this steering wheel. Stepper motors 171 and 181 for the tilt mechanism and the telescopic mechanism

  are attacked by the embodiment of the invention.

  The device 1 steers the front wheels of a vehicle. The tilt mechanism drives an upper shaft 16 whose upper end (right side in the drawings) is fixed to a steering wheel (not shown) in a downward tilting direction in which the steering wheel is tilted toward the driver's seat at the rear of the steering wheel, and in the upward tilting direction in which the steering wheel is tilted toward. a vertical position away from the conductor. The telescopic mechanism drives the upper shaft 16 in a direction of telescopic sliding upwards (direction of the front) in which the steering wheel moves upwards, and in the direction of telescopic sliding downwards (direction of the rear) in which the steering wheel moves down. The device 1 comprises a stationary column 11, a mobile column 12, a pivoting column 13, a lower shaft 14, a central shaft, and an electronic control unit (which is designated hereinafter by "ECU") 19 which constitutes a main part of the embodiment of the present invention, in addition to the upper shaft 16, the tilt mechanism 17 and the telescopic mechanism 18, as

  this is shown in Figures 1 and 2.

  The stationary column 11 is fixed to the vehicle body (not shown). The mobile column 12 is supported on the stationary column 11 by an axis 20 in such a way that the column 12 is mobile from top to bottom and from front to rear (arrow A) of the vehicle relative to the column 11. The axis 20 prevents the mobile column 12 from rotating relative to the fixed column 11. The pivoting column 13 is mounted in a pin 21 (shown in FIG. 1) fixed to the mobile column 12 in such a way that the pivoting column 13 can pivot in the approximate direction from top to bottom (arrow B) of the

vehicle.

  The lower shaft 14 is rotatably supported by the fixed column 11. The distal end (end of the left side in the figures) of the shaft il 2749716

  lower 14 is connected to the front wheels (non

  shown) of the vehicle. The base end (right side end in the drawings) of the lower shaft 14 has grooves 141 which extend over the outer peripheral surface of the end

  in the direction of the axis of the lower shaft 14.

  The central shaft 15 is disposed in rotation inside the movable column 12 and is coaxially aligned with the lower shaft 14. The central shaft 15 has a tubular part 151 at its end on the left side. Grooves 152 extend over the inner peripheral surface of the tubular part 151 in the direction of the axis of the shaft 15. The end of the right side (in the drawings) of the lower shaft 14 is inserted into the tubular part 151, the splines 141 of the shaft

  lower 14 being engaged in the grooves 152.

  The spline engagement allows the central shaft 15 to rotate with the lower shaft 14 and to move in the direction indicated by the arrow A relative to the lower shaft 14. The upper shaft 16 is supported in rotation by a tubular element 22 fixed to the pivoting shaft 13, and the upper shaft 16 is aligned coaxially with the lower shaft 14 and the central shaft 15. The end on the left side (in the drawings) of the shaft upper 16 is connected to the central shaft 15 by a ball joint 23 which allows the upper shaft 16 to rotate at the same time as the central shaft 15 and to pivot in the direction indicated by the arrow B relative to the 'central shaft 15. The distal end (end of the right side in the drawings) of the upper shaft 16 is fixed to the steering wheel

(not shown).

  The tilt mechanism rotates the pivoting column 13 in the direction indicated by the

  arrow B relative to the axis 21 of the movable column 12.

  The tilt mechanism 17 includes a stepping motor 171 (described below), a pinion 172, a shaft

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  splined 173, a threaded shaft 174 and a nut element 175. The stepping motor 171 is mounted on a side face of the fixed column 11. The pinion 172 is supported by the column 11 and connected to the output shaft (not shown) of the stepping motor 171 by a belt (not shown). The splined shaft 173, extending in the direction of arrow A, is engaged in the inner peripheral part of the pinion 172 in such a way that the splined shaft 173 can rotate with the pinion 172 and is movable in the direction arrow A with respect to pinion 172. The threaded shaft 174 is connected to the right-hand end (in the drawings) of the splined shaft 173 by a seal 176 in such a way that the threaded shaft 174 can rotate with the splined shaft 173. The threaded shaft 174 is aligned coaxially with the splined shaft 173. The nut element 175 is screwed onto an outer peripheral part of the threaded shaft 174 so that, during rotation of the threaded shaft 174, the nut element 175 moves in the direction of arrow A. The nut element 175 is fixed to the pivoting column 13 by two fixing pins 177

  (one of them is represented in figure 1).

  The telescopic mechanism 18 moves the mobile column 11 in the front-rear direction relative to the fixed column 11. The telescopic mechanism 18 comprises a stepping motor 181 (described below), a pinion (not shown), a shaft threaded (no

  shown) and a nut element (not shown).

  The stepping motor 181 is mounted on a lateral face of the fixed column 11, in juxtaposition with the stepping motor 171. The pinion is connected to the output shaft (not shown) of the stepping motor 181. L The threaded shaft is connected to the pinion in such a way that it can rotate with it. The nut element is screwed onto an outer peripheral part of the threaded shaft so that, when the threaded shaft is rotated, the nut element moves in the direction

  indicated by arrow A. The nut element is attached to.

  the mobile column 12 by a support (not shown).

  The operation of the steering device 1 will now be described. When the driver actuates the steering wheel, the upper shaft 16, the central shaft 15 and the lower shaft 14 rotate together, this

  which has the effect of steering the front wheels of the vehicle.

  When the tilt stepping motor 171 is driven at an angle predetermined by the ECU 19 which is described below, the pinion 172, the splined shaft 173 and the threaded shaft 174 rotate together. As a result of the threaded engagement between the threaded shaft 174 and the nut element 175, the latter moves in the direction of arrow A during the rotation of the shaft 174. The pivoting column 13 and the element tubular 22 thus rotate in the direction indicated by arrow B relative to the movable column 12, the axis 21 being a pivot. The upper shaft also pivots with the pivoting shaft 13 in the direction indicated by the arrow B relative to the central shaft 15 because the upper shaft

  16 is connected to this shaft by the ball joint 23.

  With this operation, the steering wheel is moved in the direction indicated by the arrow B (top to bottom direction of the vehicle), hence the angle adjustment

  angle of the steering wheel.

  When the stepper motor 181 of the telescopic mechanism is driven at an angle given by

  iCEU 19, the pinion and the threaded shaft rotate together.

  As a result of the threaded engagement between the threaded shaft and the nut element, the latter moves in the direction indicated by the arrow A during the rotation of the threaded shaft. The mobile column 12 is thus moved in the direction indicated by the arrow A with respect to the fixed column 11. The tubular element 22 and the pivoting shaft 13 supported on the mobile column 12 by the axis 21 also move together in the direction indicated by the arrow A. The upper shaft 16 and the central shaft 15 also move together in the direction i4

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  indicated by arrow A. Thanks to this operation, the steering wheel moves in the direction indicated by arrow A (front to rear direction of the vehicle), hence the adjustment of the projecting position of the steering wheel. The electronic control unit 19 comprises a microcomputer 191 having entry points 192, exit points 193, a processing unit (hereinafter referred to as "UCT") 194, a read only memory ( ROM) 195, a direct access memory (RAM) 196 and a

  timer 197 which are interconnected by a bus.

  The unit 19 is electrically connected to the ignition key insertion switch 31, to an up tilt switch 32, to a down tilt switch 33, to an up slide switch 34 and a slide switch 35, etc. The ignition key insertion switch 31 is arranged in a key cylinder which receives the ignition key (not shown). The switch 31 switches from the open position to the closed position when the ignition key is inserted into its cylinder, and it switches to the stop position when the ignition key is removed. The up tilt switch 32, the down tilt switch 33, the up slide switch, and the down slide switch 35, located in the driver's compartment, are push button that closes when pressed

  above, and open when released.

  The signals coming out of these switches are applied to the central processing unit 194 via the input points 192 via amplification circuits 198a-198e. Width Modulated Pulses (PWM) for the forward drive and the rear drive come out of the output points 193 to be applied to a motor driver 199a (for the drive of the 'tilt) and

2749716 a motor drive circuit 199b (for telescopic drive. The

  Figure 4 schematically shows the construction of the motor drive circuit 199a. The stepping motor 171 of the tilting mechanism 17 is a two-phase motor of the four-pole type in which a pole of the positive phase A, formed from a winding of a positive phase coil A, of a phase pole positive B formed from a positive phase coil winding B, an opposite phase pole A formed from an opposite phase coil winding A, and an opposite phase pole B formed from a coil winding of

  opposite phase B are distributed in steps of 90.

  Since the winding directions of the coil of the positive phase A and of the coil of the opposite phase A with respect to the poles are opposite to each other, the pole of; the coil of the positive phase A (phase A) and the pole of the coil of opposite phase A become an N pole and an S pole, respectively, when the coils are energized. The poles of phase B are magnetized in a similar way. If a sinusoidal voltage is applied to the coils of phase A and a cosine voltage is applied to the coils of phase B, the stepper motor 171 operates forward (the rotor turns clockwise shown in Figure 4). If a cosine voltage is applied to the coils of phase A and a sinusoidal voltage is applied to the coils of phase B, the stepper motor 171 turns backwards (the rotor turns in the opposite direction

Clockwise).

  The coil of positive phase A and the coil of opposite phase A are connected to a bipolar excitation switching circuit A. The coil of positive phase B and the coil of opposite phase B are connected to a switching circuit of bipolar excitation B.

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  PWM (PWMal) pulses for energizing the positive phase coil A exit from the output point PAl to a switching driver lOCAl. The PWM pulses from the output point PA1 are also inverted, and the inverted pulses are supplied in the form of PWM pulses (PWMa2) for energizing the coil of the opposite phase A to a switching drive circuit 100A2. The switching drive circuits 10A1, 100A2 have rise delay circuits which delay the rise between a low level B and a high level H of the pulses PWM applied to them. Each. pulse rise to go from level B to level H is delayed by the delay circuit and, after a delay time, level H is supplied to switching circuit A or B. On the other hand, each fall of the PWM pulses for switching from level H to level B is immediately transmitted, hence synchronous switching of the output of switching circuit A or B to pass from level H to level B. Switching circuit A connects the coil of the positive phase A to a resistor 101Al for detecting the current only when the output of the driving circuit lO0Al is at level H, so that a current crosses the coil of the positive phase A and that a voltage proportional to the current is produced at the terminals resistance lOlAl. The switching circuit A connects the coil of the opposite phase A to a resistor 101A2 for detecting the current only when the output of the driving circuit 100A2 is at level H, so that a current flows through the coil of the opposite phase A and a voltage proportional to the current is produced at the terminals of the

resistance 101A2.

  If the central processing unit 194 changes, in a time series, the duty cycle of the pulses PWMal to be output from the output point PAl to the driving circuit lO0Al, in such a way as the change of the time series

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  of the voltage (VB X duty cycle) applied to the.

  coil of positive phase A in accordance with the changed duty cycle follows a sine wave (a first sine wave which is positively biased and whose lower peak value is greater than the mass of the device), the duty cycle of the inverted pulses PWMa2 applied to the drive circuit 100A2 becomes a duty cycle which corresponds inversely to that of the PWMAl pulses. Consequently, the duty cycle of the PWMa2 pulses changes in time series, according to a second sine wave whose phase is delayed by compared to the first sine wave. In short, if the central unit 194 issues, at the output point PA1 to the driving circuit 1OOA1, pulses PWMal for the application of the pulsed voltage which follows the first sine wave in the time series to the coil of the positive phase A, the driving circuit A2 automatically receives the pulses PWMa2 for application to a pulsed voltage of the coil of the opposite phase A which follows the second sine wave shifted in phase by 180 relative to the first sine wave.

  The previous description was made in

  connection to the forward drive (clockwise rotation in Figure 4) of the stepper motor 171. The operation for the backward drive can be described in a substantially identical manner (counterclockwise, clockwise) except that "sine wave" is

  replaced by "cosine wave".

  The constructions of the switching circuit B connected to the coil of the positive phase B and to the coil of the opposite phase B, and of the driving circuits 10OB1, 100B2 for closing and opening the switching devices provided in the circuit B are substantially identical to the comparable circuit and to the drive circuits connected to the phase coils

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  positive A and of the opposite phase A. When the central processing unit 194 leaves, at the output point PB1 towards the driving circuit lOB1, pulses PWMbl for the application) of pulsed voltages which follow a first cosine wave in a series time to the coil of positive phase B, the drive circuit 10OB2 automatically receives the pulses PWMb2 for application to the pulsed voltage of the coil of opposite phase B which follows a second cosine wave 180 phase out of phase with the first wave cosine. This operation is performed for

  drive the stepper motor. step 171 forward.

  The operation for the backward drive can be described in a substantially identical manner except that "cosine wave" is replaced by "sine wave". Resistors 101Al, 101A2, 101Bl-and 101B2 cause voltages proportional to the currents flowing through the coil of positive phase A, the coil of opposite phase A, the coil of positive phase B and the coil of opposite phase B, respectively . The voltages are clipped and amplified to values which exhibit changes in the rectified sine and cosine waves (pulsed waves) as described above, by low-pass filters and amplifiers. The voltages are then applied to A-D (analog-to-digital) conversion input points.

  iall, i12, ibll and ibl2, respectively, of the micro-

computer 191.

  The stepping motor 181 of the telescopic mechanism 18 has substantially the same construction and the same specifications as the motor 171. The drive circuit of the motor 199b connected to the stepping motor 181 also has a construction and functions substantially identical to those of the driver 199a. The motor drive circuit 199b receives, from an output point PA2 (corresponding to the output point PAl) and from an output point PB2

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  (corresponding to PB1); PWM pulses for applying a voltage in the form of first sine waves, second sine waves, first cosine waves, or second cosine waves, to the coils of phases A and B of the stepper motor 181. Although not shown in the drawings, the driving circuit 199b includes resistors 102A1 (corresponding to the resistance 101Al), 102A2 (corresponding to 101A2), 102B1 (corresponding to 101B1) and 102B2 (corresponding to 101B2) to detect the value ia21 of the current passing through the coil of the positive phase A of the motor 181, the value ia22 of the current passing through the coil of the opposite phase A, the value ib21 of the current passing through the coil of the positive phase B and the value ib22 of the current passing through the opposite phase coil B. The voltages caused by these resistors (current detection signals) are applied to AN conversion input points,

  ia21, ia22, ib21 and ib22, respectively, of the micro-

computer 191.

  Again in connection with FIG. 3, the read-only memory 195 stores programs and reference data to be used for various operations which include the operations illustrated by the flowcharts of FIGS. 5 to 8. The central processing unit 194 executes the programs. Input / output data and / or reference data which are necessary for the execution of the program are written into the RAM 196. Although not shown, there are two supply circuit systems for the supply of electrical power to the electronic control unit 19: a continuous supply circuit which constantly supplies the microcomputer 191, the amplifier 198a and a relay drive circuit (not shown) for the input relay of energy, with operating voltages which allow program execution (input detection), data retention in memory and closing

  (contacts closed) of the relay, even when the key.

  contact is not inserted in its cylinder; and a power supply circuit responding to the insertion of the key which is connected to a battery by an energy input relay only when the ignition key is inserted in its cylinder in order to supply energy to the amplifier circuits 198b-198e and circuits

199a, 199b of the engines.

  FIG. 5 schematically represents the control operation (main program) of the central unit 194 of the microcomputer 191 in accordance with programs. When the unit 194 of the microcomputer 191 (hereinafter referred to as "the microcomputer 191") is supplied with power (for example when a battery is installed in a vehicle and the supply circuit is connected to it immediately before dispatch, so that the supply circuit

  operating voltage), the micro-

  computer 191 sets the signal level at the exit points to a standby level, and initializes an input / output register, a data backup register, a status register (an area in a memory), a timer , a counter, etc., at the initial values (waiting values), hence the execution of the initialization in step 1. It is assumed that at the time of this initialization, the tilt mechanism is found at its origin o it is tilted up to its upper limit position, and the telescopic mechanism is at its origin o the mechanism is extracted or has telescopically slid

  down to its lower limit position.

  However, the original positions of the tilt mechanism and the telescopic mechanism programmed for the position control of the mechanisms are positions of slight tilt down or telescopic sliding up relative to the

origins of mechanisms.

  Thanks to initialization (step 1), each of the current position registers and target position registers assigned to the tilting mechanism and to the telescopic mechanism comes to indicate O (origin of the mechanism). When the ignition key is inserted into its cylinder, the key insertion switch 31 closes and, in response, the microcomputer 191 issues a closing instruction signal to a relay drive circuit, which puts energized the energy input relay. This relay thus closed connects to the battery the supply circuit responding to the insertion of the key, and this circuit supplies energy to the amplification circuits 198b-198e and to the motor drive circuits 199a, 199b . The microcomputer 191 writes "1", indicating the insertion of the ignition key (closed state of the switch 31) in the register of RF indicators (steps 2-4), and then executes the operation "DRIVE UNTIL" AT TARGET POSITION "from step 5. However, since the current position registers and the target position registers assigned to the tilt mechanism and the telescopic mechanism indicate O

  (origin of mechanisms) as mentioned above

  above, the present positions are the same as the target position (variable data), so that there is neither drive of the tilting mechanism nor of the telescopic mechanism. The program then goes to

  DRIVE IN RESPONSE TO THE INPUTS OF THE SWITCHES 32-

  from step 6. Since the closed state of switches 32-35 is not detected, the program returns to step 2, the cycle of steps 2-3-6-2 is repeated while the key contact is in its cylinder. During the cycle, a tilt up or tilt down command or a telescopic slide up or telescopic slide down command is executed in response to the closed state of switches 32-35 in

step 6.

  1. Steering wheel position adjustment.

  direction by switches 32-35 (step 6).

  We suppose in the following description

  have someone operate switches 32-35 to place the steering wheel at a certain tilt angle and telescopic position which are optimal

for her.

Tilt down.

  While the tilt down switch 33 is closed, the microcomputer 191 continues to output at point PA1 PWMal pulses which cause level changes in the form of a sine wave in a time series, and at point PB1 of the PWMbl pulses which cause level changes in the form of a cosineusoid wave in a time series. The stepper motor 171 thus operates forward, so that the flywheel is tilted downward. During this downward inclination, the microcomputer 191 increases by 1 (count increased by 1) the data of the register of the present positions of

  the inclination at each period of the sine wave.

  When the switch 33 is returned to the open state, the microcomputer 191 stops the drive from tilting down. The tilt-down training program contains data on the lower limit position for tilt control, indicating a position slightly tilted upwards relative to the lower limit position of the tilt mechanism. Consequently, when the data of the register of the tilt positions present becomes equal to the data on the lower limit position for the control of the tilt, the microcomputer 191 immediately stops the drive of the tilt down itself if the switch 33 continues to be closed. The

  position indicated by the data for the command of-

  the tilt (limit of the tilt down in the control) is called "lower limit position of

  the tilt "in the following description.

Tilt up.

  When the tilt tilt switch 32 is closed, the microcomputer 191 continues to output at the output point PA1 pulses PWMal which cause changes in level in the form of a cosine wave in a time series, and at the output point PB1 pulses PWMbl which cause level changes in the form of a sine wave in a time series. The stepping motor 171 is thus actuated backwards, so that the flywheel tilts upwards. During the tilting up, the microcomputer 191 decreases by 1 the data of the register of the tilting positions present during each period of the sine wave. When the

  switch 32 is returned to the open state, the micro-

  computer 191 stops the tilt-up drive. The tilt-up training program contains data on the original position for controlling the tilt, indicating a position slightly tilted downwards relative to the upper limit mechanical position (origin of the mechanism). of the tilt mechanism. Consequently, when the datum of the register of the inclination positions present becomes equal to the datum on the original position for controlling the inclination, the microcomputer 191 immediately stops the drive of the inclination downward. even if the switch continues to be closed. The position indicated by the data on the home position for the tilt control is called "home position of

  the tilt "in the following description.

  Telescopic sliding upwards.

  While the slide up switch 34 is closed, the microcomputer 191 continues to output at the output point PA2 pulses PWMa2 which cause level changes in the form of a sine wave in a time series, and at PB2 output point of the PWMb2 pulses which cause level changes in the form of a cosine wave in a time series. The stepper motor 181 is thus driven forward, so that the flywheel telescopically slides upward. During this sliding, the microcomputer 191 increases by 1 the data of the register of the telescopic positions

  present at each period of the sine wave.

  When the switch 34 is returned to the open state, the microcomputer 191 stops the upward sliding drive. The program of the telescopic upward sliding drive contains an upper limit position data for the telescopic control, indicating a slight sliding downwards with respect to the upper limit position of the telescopic mechanism. Consequently, when the datum of the register of telescopic positions present becomes equal to the datum of the limit position

  superior for telescopic control, micro-

  computer 191 immediately stops the upward sliding drive even if the switch 34 continues to be closed. The position indicated by the upper limit position data for the telescopic control (limit of telescopic sliding upwards under control) is called "position

  telescopic upper limit "in description

next.

  Telescopic sliding down.

  While the downward slide switch 35 is closed, the microcomputer 191 continues to output at the output point PA2 pulses PWMa2 which cause level changes in the form of a cosine wave in a time series, and at PB2 output point of PWMb2 pulses which cause level changes in the form of a sine wave in a time series. The stepper motor 181 is thus actuated rearwards, so that the flywheel slides telescopically downwards. During this sliding, the microcomputer 191 decreases by 1 the datum of the register of the telescopic positions present during each period of the sine wave. When the

  switch 35 is returned to the open state, the micro-

  computer 191 stops the sliding down drive. The telescopic sliding down drive program contains original position data for the telescopic control, indicating a position with a slight upward sliding with respect to the lower limit mechanical position (origin of the mechanism) of the telescopic mechanism . Consequently, when the data of the register of the telescopic positions present becomes equal to the data on the original position for the telescopic control, the microcomputer 191 immediately stops the drive for the sliding downwards even if the switch 35 continues to to be closed. The position indicated by the data on the original position for the telescopic control is called "telescopic position

  original "in the following description.

  The steering wheel can thus be placed or adjusted to the position that the operator wishes, by actuation

switches 32-35.

  2. Withdrawal training in response to.

  removing the ignition key (steps 8-9).

  When the ignition key is removed from its cylinder while the steering wheel is in the desired position (hereinafter referred to as "optimal position"), the key insertion switch 31 passes

  from closed state to open state. In response, the micro-

  computer 191 writes the data of the tilt position register present in the register of target tilt positions, and the data of the telescopic position present in the register of target telescopic positions (steps 2-7-8). The microcomputer 191 then erases the RF register of the indicators (step 9), and executes the "DRIVE TO THE

ORIGINAL POSITION "from step 10.

  In the "DRIVE TOWARDS THE ORIGINAL POSITION" of step 10, the microcomputer 191 drives the stepping motor 171 backwards to tilt the steering wheel up until the position register data of inclination present becomes the data indicating the original position of the inclination, in a manner substantially identical to that of the drive of the inclination upwards which has been described above. Significantly in parallel with this operation, the microcomputer 191 also drives the stepping motor 181 backwards so that the steering wheel telescopically slides down until the data in the register of the telescopic positions present becomes a data indicating the position of telescopic origin, in a manner substantially identical to that of the telescopic sliding downward drive which has been described above. When the drive to the original tilt and telescopic positions is completed, the microcomputer 191 reverses the CLOSE instruction signal applied to the relay attack to an OPEN instruction level. The excitement of the relay

  energy input is therefore interrupted, by.

  so that the power circuit that responds to the insertion of the key is disconnected from the battery, interrupting the supply of operating voltage to amplifiers 198b-198e and

  motor drive circuits 199a, 199b.

  Thanks to this operation, the steering wheel is stopped at an extraction position (where the telescopic and tilt positions are the original positions), and the tilt position and the telescopic position corresponding to the optimal position mentioned above. above are written in the target tilt position register and in the target telescopic position register. In addition, the data of the register of the present tilt positions and of the register of the telescopic positions present becomes

  data indicating the original positions.

  3. Training towards the optimal position in

  response to the insertion of the ignition key (step 5).

  When the ignition key is inserted into its cylinder, the switch 31 closes and, in response, the microcomputer 191 issues the closing instruction signal for application to the relay drive circuit, which causes the supply of the energy input relay. This relay thus closed connects to the battery the supply circuit responding to the insertion of the key, and this circuit supplies energy to the amplifier circuits 198b-198e and to the

  motor driver 199a, 199b. The mic-

  computer 191 writes "1", indicating the insertion of the ignition key (closed state of switch 31) in the indicator RF register (steps 2-4) and then executes the "DRIVE TOWARD THE TARGET POSITION" operation

from step 5.

  Figures 6-8 show the contents of the "TARGET-TARGET TRAINING" of step 5. Firstly in connection with Figure 6, a timer Ts set with a time Ts for the determination of a command calculation cycle is started (step 11). Then, the adjustment of the tilt output (COD), the adjustment of the telescopic output (TOD) and the determination of the change of pitch (step 50 in FIG. 7) are carried out repeatedly in a cycle Ts. By repeating the operations, the stepper motors 171 and 181 are driven forward and it is verified that the tilt position has become the target position and that the telescopic position has become the target position. If the target position is reached, the corresponding motor drive is stopped. The motor drive is also stopped if a change in the motor pitch is detected. When the tilt drive and the telescopic drive are stopped, the "TRAINING TO TARGET POSITION" in step 5 is finished and the program goes to step 6

(see figure 5).

  Before describing the content of each step, we will summarize a basic operation. The base clock of the central processing unit 194 is a 4 MHz signal produced by an oscillator. In order to produce PWM pulses, the unit 194 divides the frequency of the signal into l / N, hence the generation of PWM clock pulses, Pa (information on the N counting up), and then divides the frequency pulses Pa (number of appearances of the information on the upward counting N) in 1 / b, hence the generation of periodic pulses PWM, Pb (information on the upward counting b). Consequently, the period of pulses Pb becomes the period of pulses PWM. When a periodic pulse Pb occurs, the central unit 194 establishes a level H in the output point of the pulses PWM and begins to count the pulses Pa. When the count value becomes equal to the value of the width of the level H of the PWM pulses to be output, the central unit 194 sets the output point of the PWM pulses

29 2749716

  at level B and waits for the appearance of another impulse.

  PWM periodic, Pb. When a Pb pulse occurs again, the central unit 194 establishes the output point of the PWM pulses at level H and begins to count the Pa pulses again. By repeating this operation, real electrical pulses leave the PWM pulse output point. This operation is

  called "PWM pulse output".

  Since the period Tb of the periodic pulses Pb is determined from the period Ta of the clock pulses Pa, in the form bx Ta = Tb, the duty cycle of the output pulses can be expressed using the value Ha of the width of level H to be supplied (the number up to which the pulses Pa must be counted), in the following manner: (Ha x Ta) / Tb = (Ha x Ta) / (bx Ta)

= Ha / b.

  Thus, the value Ha is independent of the division ratio of the frequency 1 / N. The value Ha is a value on which the central processing unit 194 acts to apply a voltage in the form of sine and cosine waves to the coils of the motor, while the other values mentioned above are fixed values established in the programs. The loading "PWM pulse output" with the Ha value or the change of the Ha value established in the "PWM pulse output" is called "establishment of the

PWM output ".

  The central unit 194 also divides the base clock into 1 / C to produce pulses of step Pc (information on the counting up c), and then divides the pulses Pc into 1/800 to generate pulses Pd of revolution of the motor (information on upward counting 8000). When the value of the count obtained by counting the pulses of step Pc reaches 160, the microcomputer 191 increases by 1 the data of the position registers present during the drive of the forward motor and decreases the data by 1 of the registers of positions present during the backward drive of the motor, and then erases the value of the counting of the Pc step pulses, and begins to count the Pc step pulses again. This is called "updating the

present position ".

  According to this embodiment, one revolution (360) of the stepping motors is divided into 8000 steps. The resolution of one step is 360/8000 = 0.045, and the value of 160 steps corresponds to a cycle or period (360) of a sine wave. If there are 50 sine wave cycles out, the number of steps becomes 50 x 160 = 8000, which means that the motor rotors undergo a

revolution.

  The "PWM pulse output" and the "updating of the present position" are started by the central processing unit 194 when the attack on the motor begins, and they are stopped when the attack on the motor stops.

engine.

  We will describe in the flowcharts of

  Figures 6-8 the operations of each step.

  The operation "CALCULATE THE TARGET SPEED v1" of step 12 is practically repeated in a cycle Ts so that the speed of inclination drive is controlled in trapezoidal form. In this operation, if the data of an acceleration / deceleration register turns out to be O (acceleration not completed) by reference to it, the difference [target tilt position - present tilt position] is calculated and there is verification whether the calculated value is greater than or not a deceleration drive distance (fixed value). If the

  value is greater than this distance, the micro-

  computer 191 refers to the data of a step increase register (number of steps increased) to which one must refer to increase or decrease the speed of the motor in the form of a trapezoid, and

  then check whether or not the data from the register-

  step increase reached a given value M (fixed value indicating the number of steps increased to obtain a high speed). If the data in this register has not reached the value M, the microcomputer 191 increases the register by 1, and performs the calculation V1 = number of steps increased x dV. The value dV is determined by dV = Vs / M o Vs is the established high speed (fixed value). If there is a determination that the data in the register has reached the value M, the microcomputer 191 writes 1 (completion of the acceleration) in the acceleration register /

  deceleration. The initial setting of the acceleration register

  tion / deceleration is O. The previous operation is executed while increasing the speed to Vs

of the motor.

  After the engine speed has been increased to Vs so that the acceleration / deceleration register keeps 1, the microcomputer 191 calculates [target tilt position - tilt position present] and checks whether the value calculated is or not

  greater than the deceleration drive distance.

  If the value is greater than this distance, the micro-

  computer 191 establishes vl = number of steps increased x V (identical to the previous value) as the value of the target speed, without updating the data in the register of increments of steps. This operation is executed

  during movement at constant speed.

  If the [target tilt position -

  tilt position present] is equal or less

  at the deceleration drive distance, the micro-

  computer 191 refers to the data in the step increment register and checks whether or not the data has returned to O. If the register data has not returned to O, the microcomputer 191 decreases the data from 1 register, and calculate vl = number of steps increased x dV. If there is determination that the data in the register has returned to O, the microcomputer

  191 clears the acceleration / deceleration register.

  This operation is carried out during the reduction of the motor speed to 0. In the operation "CALCULATE THE FREQUENCY DIVISION REPORT C" of step 13 in FIG. 6, the microcomputer 191 calculates a report C frequency division based on vl calculated in step 12, as follows:

C = 4 x 106 / (vl x 8000).

  In step 14, the microcomputer 191 establishes the frequency division ratio C which was calculated in step 13, in a frequency division timer which serves as a clock for a

step counter.

  In step 15, the microcomputer 191 writes the frequency division ratio C in a register 0 of the rotational angles for counting the

Pc pulses.

  In step 16 of Figure 6, the micro-

* computer 191 calculates a target voltage V1 as follows: V1 = In + l * x (R + LS) o In + l * is a value of a target torque which is a fixed value established in programs according to this mode embodiment, and (R + LS) is the impedance of the electric coils of the motor which is also a fixed value established in programs according to this embodiment.

  In step 17 of Figure 6, the micro-

  computer 191 calculates a target instantaneous value Val of the voltage to be applied to the electrical coils of phase A and a target instantaneous value Vbl of the voltage to be applied to the electrical coils of phase B. The content of this operation

is shown in figure 8.

  In FIG. 8, the central unit 194 calculates an angular speed o by subtracting the data from the previous rotational angle Op (occurring before Ts) from the data from the present rotational angle

33 2749716

  O, that is to say co = O - Op, in step 62. The unit

  central 194 then calculates a counter force

  electromotive Vi = Ke-o) in step 63 and calculates a voltage applied to the motor (voltage to be applied to the coils) Vd = V1 + Vi in step 64, and reads a data of sinusoidal amplitude SIN corresponding to the present phase angle data I of a phase angle register in a sine wave amplitude table (a group of sine wave amplitude data, stored in a memory area, corresponding to the data d 'phase angle <ô (0-159) from the phase angle register within the range O-2n, the data being positively polarized values whose lower peak values are greater than 0) in step 65. The central unit 194 then reads a data of cosine amplitude COS corresponding to the data of the phase angle present from the register of phase angles in a table of cosine amplitudes (group of wave amplitude data cosine, stored in an area of the m moire, corresponding to the phase angle datum within the range O-2x, the datum being positively polarized values whose lower peak values are greater than O) in step 66. The central unit 194 then calculates a voltage Val to be applied to the coil of the positive phase A of the stepping motor 171 by Val = Vd-SIN in step 67, and calculates a voltage Vbl to be applied to the coil of the positive phase B of the stepping motor 171 by Vbl = Vd.COS in step 68. During the execution of the "PWM pulse output" (during the attack of the motor 171), the central unit 194 increases the given from the phase angle register of 1 whenever a Pc pulse occurs. When the data becomes 160 following an increment, the central unit 194 erases the register of phase angles. This operation is

34 2749716

  called "update of the phase angle data".

  Thanks to this operation, the data D of the phase angle register is updated to a data indicating a higher value in the range 0-159, in synchronism with the appearance of a pulse Pc. In the "ESTABLISH PWMal OUTPUT" operation of step 18 of FIG. 6, the voltage Val to be applied to the coil of the positive phase A which has been calculated as described above (Val = Vd.SIN) is converted into a value of width of level H, Hall, of the PWM pulses for the application to the coil of the positive phase A. The value thus converted is established as width Ha of level H of the "output of the PWM pulses" for the

  coil of the positive phase A of the stepping motor 171.

  In the "ESTABLISH PWMa2 OUTPUT" operation of step 19, the voltage Vbl to be applied to the coil of positive phase B which has been calculated as described above (Vbl = Vd-COS) is converted to a level H width value, Hal2, of the PWM pulses for application to the coil of the positive phase B. The value thus converted is established as the level H width Ha of the "PWM pulse output" for the

  coil of the positive phase B of the stepping motor 171.

  When the operation of step 19 is executed for the first time, the central processing unit 194 establishes a level H in the output points PA1, PB1 and then begins the "pulse output PWM", "the updating of the data of phase angles "and" updating of the present positions "In the operation" CALCULATE THE IAL VALUE OF THE EXPECTED CURRENT OF PHASE A "of step 20 of FIG. 6, the central unit 194 calculates the Ial value of the current which is expected to flow when applying the voltage Val calculated in step 18 to the coil of phase A, as follows Ial = In + l * .SIN- R / (R + LS) In the same way, in the operation "CALCULATE THE Ibl VALUE OF THE EXPECTED CURRENT IN THE PHASE

2749716

  B "of step 21, the central unit 194 calculates the value Ibl of the current which is expected to flow when the voltage Vbl calculated in step 19 is applied to the coil of phase B, as follows: Ibl = In + l * 'COS'R / (R + LS) - Then, the central unit 194 performs the "ESTABLISHMENT OF THE TELESCOPIC OUTPUT" TOD in a similar manner to 1 '"ESTABLISHMENT OF THE TILT OUTPUT" C02 preceding steps 12-21. The content of the "ESTABLISHMENT OF THE TELESCOPIC OUTPUT" TOD can be described in a manner substantially identical to that of i "ESTABLISHMENT OF THE CO2 TILT OUTPUT, except that the "171 stepper motor" and its

  description are replaced by the "181 stepper motor"

and the description concerning it.

  In connection with FIG. 7, the central processing unit 194 executes the operation for determining that there is a change in the time (step 50) at the end of a time delay between the time of application output voltages Val, Va2 determined by setting the output in steps 18 and 19 to the stepper motor 171 and the instant at which the value of the motor current becomes a value corresponding to the values of the applied voltages (c ' i.e. a delay in the phase of the current with respect to the voltage). The delay time is measured by

unit 194.

  In the "DETERMINE IF THERE IS A CHANGE OF STEP" operation in step 50, the central unit 194 receives the voltages present at the terminals of the resistors lOlAl, 101A2, lOlBl and 101B2, that is to say a value iall of the current passing through the coil of the positive phase A of the stepping motor 171, a value ial2 of the current passing through the coil of the opposite phase A, a value ibll of the current passing through the coil of the positive phase B and a value ibl2 of the current passing through the coil of the opposite phase B, and the voltages across the resistors arranged in the driving circuit 199b

36 2749716

  of the motor in order to detect the current passing through the coils, that is to say, the value ia21 of the current passing through the coil of the positive phase A of the stepping motor 171 the value ia22 of the current passing through the coil of the opposite phase A, the value ib21 of the current passing through the coil of the positive phase B and the value ib22 of the current passing through the coil of the opposite phase

B, during step 51.

  Then, the central processing unit 194 calculates the value ial of the current passing through the coil of phase A and the value ibl of the current in the coil of phase B of the stepping motor 171, and the value ia2 of the current in the coil of phase A and the value ib2 of the current in the coil of phase B of the stepping motor 181 in step 52, as follows: ial = liall ial2I ibl = libll - ibl2 | ia2 = lia2l - ia22 [ib2 = jib2l - ib221 In step 53, the central unit 194 calculates the deviations Eal, Ebl from the values of the current mentioned above (detected values) ial, ibl from the expected value ial of the current in phase A and of the expected value Ibl of the current in phase B of the stepping motor 171 calculated in steps 20 and 21, and the deviations Ea2, Eb2 from the above-mentioned values of the currents (values detected) ia2, ib2 from the expected value Ia2 of the current in phase A and the expected value Ib2 of the current in phase B of the stepping motor 181 calculated in

  1 '"ESTABLISHMENT OF THE TELESCOPIC OUTPUT" TOD.

  If at least one of the deviation Eal of the current of phase A and of the deviation Ebl of the current of phase B of the stepping motor 171 is equal to or greater than an established value Esl (i.e. - say, if the difference between the detected value of the current and the expected value of the current is outside the established range Esl), the central unit 194 writes 1, indicating an overload

37 2749716

  (step change) of the inclination drive in a register AF1, and stops this training in steps 54, 56. More precisely, the central unit 194 establishes a level B in the output points PA1 and PB1. If at least one of the deviation Ea2 of the current of phase A and of the deviation Eb2 of the current of phase B of the stepping motor 181 is equal to or greater than an established value Es2 (i.e. - say if the difference between the detected value of the current and the expected value of the current is outside the established range Es2), the central unit 194 writes 1, indicating an overload (change) of the telescopic drive in an AF2 register and stops the telescopic drive in steps 55, 57. More specifically, the central unit 194 establishes a level B in the output points PA2 and PB2. Although not shown in the drawings, the central unit 194 issues a monitoring signal

  (indicating the data of AF1, AF2), towards the micro-

  computer of a monitor in a display panel installed in an interior panel disposed approximately in front of the driver's seat. If the monitor signal indicates an overload (step change), the monitor's microcomputer indicates an overload on the display panel. This indication is reset when the monitor signal comes to

indicate the absence of overload.

  If no step change occurs during training, the central unit 194 outputs PWM pulses to attack the stepping motor 171 (step 59) (that is to say establishes the exit points PA1, PB1 at level B) when the datum of the register of positions of the inclination present becomes equal to the datum of the register of positions of the target inclination (step 58). In an identical manner, the central unit 194 stops the output of the PWM pulses for the attack of the stepping motor 181 (step 59) (that is to say establishes the output points PA2, PB2 at level B ) when the

  data from the register of telescopic positions present-

  becomes equal to the data in the register of the telescopic target positions (step 58): As long as at least one of the stepping motors 171 and 181 is attacked (or if the continuation of the attack is required), the operation returns in step 11 at the expiration of the timer Ts time. In step 11, the timer Ts is restarted. Then, there is execution of the "ESTABLISHMENT OF THE TILT OUTPUT" COD and / or 1 "ESTABLISHMENT OF THE

  TELESCOPIC EXIT "and subsequent operations.

  When the two stepping motors 171, 181 are stopped, the "DRIVE TO THE TARGET POSITION" of step 5 is finished, and the operation changes to i "" DRIVE IN RESPONSE TO THE INPUTS OF THE SWITCHES 32-35 " from step 6. The content from step 6 has already been

described above.

  According to this embodiment, since the central unit 194 proceeds to "DRIVE IN RESPONSE TO INPUTS OF SWITCHES 32-35" of step 6 when the tilt drive and the telescopic drive up at the target position are stopped following the detection of an overload

  (step change) or waiting for the position-

  target, it is possible to drive or adjust the steering wheel to the desired position by operating switches 32-35, whether or not the steering wheel drive was stopped following the detection of an overload (step change) caused

  by an obstruction by an external object.

  The operation "DETERMINE IF THERE IS A CHANGE OF STEPS" in step 50 of FIG. 7 is repeated in the cycle Ts while at least one of the stepping motors

171 and 181 is attacked.

  Since the central unit 194 performs substantially the same operation as the "DRIVE TO THE TARGET POSITION" of step 5, the "DRIVE IN RESPONSE TO INPUTS OF SWITCHES 32-35" of step

39 2749716

  and i "DRIVE TOWARDS THE ORIGINAL POSITION" of step 10, the training is stopped if there is detection of an overload (step change) either in step 6 or in step 10 Since the operation returns to step 2 (see FIG. 5) in this case, the steering wheel is not returned to the original position but is simply stopped. When the driver puts the ignition key back into the cylinder, steps 2-34-5 are performed. Therefore, the fault information is cleared in step 4, and the drive

  to the optimal position is started in step 5.

  This embodiment applies a sinusoidal voltage and a cosine voltage to the stepping motor 171 using PWM pulses, and compares the expected values Ial, Ibl of the current which is expected to be

  what it crosses the motor at the instantaneous value-

  target of the voltage (duty cycle of the PWM pulses), and at the values ial, ibl of the current actually passing through the motor and thus determines whether or not there is a change in step of the stepper motor 171. This operation is executed in the Ts cycle. Ts x integer m is exactly or approximately equal to one cycle of sine waves or cosine waves, the determination of the step change is carried out ten times or more during a cycle of sine waves or cosine waves. Thus, the delay time between the appearance of a change in pitch and its detection is very short. In addition, since the motor attack is stopped when a change of pitch is detected, the data of the registers of the present positions, increased or decreased by 1 during a cycle of sine waves, does not deviate from the actual present position even if the pitch changes. Therefore, the embodiment is able to accurately track the present position of the tilt mechanism, and eliminates the need to connect the motor 171 or the mechanism.

2749716

  tilt to a position sensor, to a sensor

angle or the like.

  The present invention is not limited to the embodiments which have just been described, it is on the contrary subject to modifications and

  variants which will appear to those skilled in the art.

41 2749716

Claims (4)

  1 Stepping motor attack device, characterized in that it comprises: - a motor attack instruction means in order to generate a voltage indicator signal whose value of the indication increases and decreases in a predetermined cycle; - a motor drive circuit for, in response to the voltage indicating signal, applying a voltage indicated by the voltage indicating signal to a stepping motor; - a current detection means in order to detect the value of the electric current passing through the stepping motor; and - a step change detection means in order to compare an expected value of the current which is expected to pass through the stepping motor when the voltage indicated by the instruction signal is applied. voltage to the stepping motor and a value of the current flowing through the stepping motor following application of a voltage to the stepping motor by the motor drive circuit in response to the voltage indicator signal, said voltage current value being detected by the current detection means, the step change detection means producing information on the step change if the difference between the expected value of the current and the value   detected current is outside a given range.   2 - Stepping motor attack device, characterized in that it comprises: - a displacement instruction means in order to give as instruction the driving of an object; a motor attack instruction means, in response to the drive instruction, producing a voltage indicator signal whose value increases and decreases in a predetermined cycle; 42 2749716   - a motor drive circuit for, in response to the voltage indicator signal, applying a voltage indicated by this signal to a stepping motor which drives the object; - present position tracking means for storing information on the present position and updating information on the present position   a given number of times per cycle of increase-   reduction of the voltage indicator signal - current detection means for detecting the value of the electric current flowing through the stepping motor; and - a step change detection means in order to compare the expected value of the current which is expected to pass through the stepping motor when the voltage indicated by the is applied to the stepping motor voltage instruction signal and the value of the current flowing through the stepping motor following application of a voltage to the stepping motor by the motor drive circuit in response to the voltage indicator signal, said current value being detected by the current detection means, the step change detection means stopping the application of the voltage to the stepping motor by the motor drive circuit if the difference between the expected value of the current and the detected value of the current is outside a given range.   3 - Attack device according to claim 2, characterized in that it comprises a positioning means for memorizing the information on the target position and for stopping the application of the voltage to the stepping motor by the circuit d engine attack when position information is present   matches the target position information.   4 - Stepping motor attack device, characterized in that it comprises: 43 2749716   - a movement instruction means for giving an instruction to drive forwards or to drive backwards of an object; instruction means for driving the motor for, in response to the forward drive instruction, producing a forward drive voltage indicator signal whose indicative value increases and decreases in a cycle predetermined, and to, in response to the backward drive instruction, generate a backward drive voltage indicator signal whose indicative value increases and decreases in a predetermined cycle; - a motor drive circuit for, in response to the voltage indicator signal, applying a voltage indicated by the voltage indicator signal to a stepping motor which drives the object; - a position tracking means present for storing information on the present position and updating the information on the present position a given number of times predetermined per increase-decrease cycle of the voltage indicator signal; a positioning means for storing information on the target position and information on the original position, and for, when the information on the present position agrees with the information on the target position during the application of the forward drive voltage to the stepper motor corresponding to the forward drive instruction, stop the application of the forward drive voltage, the positioning means establishing the information on the present position which exists at the time of the appearance of the forward drive instruction as information on the original position, the positioning means stopping the application of the backward drive voltage to the stepper motor which corresponds to the rear drive instruction 44 2749716   when the information on the present position agrees with the information on the original position during the application of the backward drive voltage; - current detection means for detecting the value of the electric current flowing through the stepping motor; and - a step change detection means for comparing the expected value of the current which is expected to pass through the stepping motor when the voltage indicated by the voltage instruction signal is applied to the stepping motor and the value of the current flowing in the stepping motor following the application of a voltage to the stepping motor by the motor drive circuit in response to the voltage indicator signal, said current value being detected by the current detection means, the step change detection means stopping the application to the stepping motor of the voltage by the motor drive circuit if the difference between the expected value of the current and the detected value of   current is outside a given range.   - Steering device, characterized in that it comprises: - a stationary member fixed to the body of a vehicle; - a mobile member movably supported by the stationary member; and - a drive means for driving the movable member so that the position of the steering wheel is adjusted by the movement of the movable member relative to the stationary member, the means   drive comprising a stepping motor.   6 - Device for a steering wheel, characterized in that it comprises: - a stationary member fixed to the body of a vehicle; - a rotary member supported by the member   stationary rotatably in the upward direction   down from the vehicle; - a movable member supported on the stationary member movably in the front-rear direction of the vehicle; - a rotary member driving means for driving the rotary member so that the position of the steering wheel in the up-down direction is adjusted by the rotation of the rotary member relative to the stationary member ; and - a movable member driving means for driving the movable member so that the position of the steering wheel in the front-rear direction is adjusted by the movement of the movable member relative to the stationary member, each of the drive means of the rotary member and of the drive member of the movable member comprising a stepping motor.