JP2013031297A - Controller of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of an electric vehicle for detecting a downward step difference.SOLUTION: An electric wheel chair 1 has a drive system 20 and an electronic controller 61. The drive system 20 has a first drive wheel 21 and a second drive wheel 22 on the right side, a first left drive wheel 21 and a second drive wheel 22 on the left side, and a motor 31 for driving the drive wheels 21, 22. The electronic controller 61 detects the downward step difference on the basis on a change in a current value of the motor 31 as a value associated with a torque of the drive system 20.

Description

  The present invention relates to a control device for an electric vehicle including a drive system including drive wheels, and relates to a control device for an electric vehicle that controls the drive system.

  The control device for an electric vehicle disclosed in Patent Document 1 detects an ascending step by an ultrasonic sensor.

JP 2007-168602 A

The control device disclosed in Patent Document 1 cannot detect a descending step.
The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric vehicle control device capable of detecting a descending step.

Means for achieving the above object will be described below.
(1) The first means is the control device for an electric vehicle comprising the invention according to claim 1, that is, the drive system including the drive wheels, and the drive device is a control device for controlling the drive system. The gist is to detect a step difference based on a change in a value related to the torque of the system.

  When the drive wheel of the electric vehicle approaches a descending step, the ground contact area of the drive wheel is reduced, so that the rotational resistance of the drive wheel is reduced. At this time, the torque of the drive system changes according to the change in the rotational resistance of the drive wheels. In this way, the change in the torque of the drive system reflects the change in the rotational resistance of the drive wheel as the drive wheel approaches the lower step, so that the drive wheel is approaching the lower step. It can be detected based on a change in a value related to torque. In the above invention, based on this concept, a configuration is adopted in which a step is detected in accordance with a change in a value related to the torque of the drive system. As described above, according to the present invention, it is possible to provide an electric vehicle control apparatus capable of detecting a descending step.

  (2) The second means performs the descending step corresponding control corresponding to the descending step when the descending step is detected in the control device for the electric vehicle according to the invention of claim 2, that is, the electric vehicle according to claim 1. The gist is to do.

  (3) The third means is the control device for the electric vehicle according to the invention described in claim 3, that is, the control device for the electric vehicle according to claim 2, in which the driving wheel is directly aligned with the descending step as the descending step corresponding control. The gist is to perform pair control.

  When the electric vehicle descends the step with the head not facing the descending step, the posture of the electric vehicle may become unstable due to the operation of descending the step. In the present invention, since the driving wheel is directly opposed to the descending step as the descending step is detected, it is possible to suppress the unstable posture of the electric vehicle when descending the descending step.

  (4) The fourth means is the control device for the electric vehicle according to the invention described in claim 4, ie, the electric vehicle according to claim 3, wherein the electric vehicle includes a drive system A including a right drive wheel as the drive wheel. And a drive system B including a left drive wheel as the drive wheel, and the facing control based on a value related to the torque of the drive system A and a value related to the torque of the drive system B The gist is to do.

  When the electric vehicle approaches the descending step with the right driving wheel and the left driving wheel not facing the descending step, the torque of the drive system including one of the driving wheels approaching the descending step changes greatly. For this reason, it is possible to confirm that the right driving wheel and the left driving wheel are directly facing the step difference based on the change in the value related to the torque of the driving system A and the change in the value related to the torque of the driving system B. it can. In the above invention, the facing control is executed based on the value related to the torque of the drive system A and the value related to the torque of the drive system B based on this concept. For this reason, each drive wheel can be correctly opposed to the descending step.

  (5) The fifth means is the control device for the electric vehicle according to the fifth aspect, that is, the control device for the electric vehicle according to the third or fourth aspect, wherein when the ground contact area of the drive wheel is smaller than a predetermined area, The gist of the step-corresponding control is to perform reverse control for causing the electric vehicle to travel away from the descending step, and then to perform the facing control.

  When the ground contact area of the driving wheel becomes smaller than a predetermined area as the driving wheel approaches the descending step, the electric vehicle may be greatly inclined during the execution of the facing control. In the above invention, since the reverse control is performed before the facing control is performed, the electric vehicle is prevented from being largely inclined during the facing control.

  (6) The sixth means is the invention according to claim 6, that is, in the control device for an electric vehicle according to claim 2, when the ground contact area of the drive wheel is smaller than a predetermined area, The gist of the control is to perform a reverse control in which the electric vehicle travels in a direction away from the descending step.

  When the ground contact area of the driving wheel becomes smaller than a predetermined area as the driving wheel approaches the descending step, the electric vehicle may be largely inclined. In the above invention, since the reverse control is performed as the descending step corresponding control, the electric vehicle is prevented from being largely inclined when the driving wheel approaches the descending step.

  (7) The seventh means is the control device for the electric vehicle according to any one of claims 2 to 6, that is, the speed of change of the value related to the torque of the drive system. The gist of the invention is to change at least one of the operation speed and the start time of the descending step corresponding control according to the above.

  When the electric vehicle is approaching a descending step, when the operating speed and start timing of the descending step corresponding control are slow, the electric vehicle may be largely inclined forward. In the above-described invention, at least one of the operation speed and the start time of the descending step corresponding control is changed according to the speed of change of the value related to the torque of the driving system, i.e., the degree to which the contact area decreases due to the driving wheel reaching the descending step. change. For this reason, it can suppress that an electric vehicle inclines largely ahead.

  (8) The eighth means is the control device for an electric vehicle according to any one of claims 1 to 7, that is, in the traveling direction when the electric vehicle is traveling. The main point is to bias the load backward.

  When the ground contact area of the front drive wheel decreases due to the drive wheel reaching the descending step, the electric vehicle may tilt forward so that the front portion of the vehicle body is closer to the ground contact surface than the rear portion of the vehicle body. In the above invention, when the electric vehicle is traveling, the load is biased rearward in the traveling direction, so that the forward tilt of the electric vehicle is unlikely to occur when the drive wheel approaches the descending step.

  (9) The ninth means is the control apparatus for an electric vehicle according to any one of the inventions according to the ninth aspect, that is, any one of the first to eighth aspects, wherein the drive system includes an electric motor for traveling. And the value related to the torque of the drive system is at least one of the torque of the electric motor, the current value of the electric motor, the rotational speed of the electric motor, and the rotational speed of the drive wheel. It is said.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the electric vehicle which can detect a level | step difference can be provided.

The perspective view which shows the perspective structure about the electric wheelchair of one Embodiment of this invention. The block diagram which shows typically an electric structure about the electric wheelchair of the embodiment. The side view which shows operation | movement of the load movement mechanism about the electric wheelchair of the embodiment. The flowchart which shows the procedure of the "descent-step detection time control" performed by the electronic controller about the electric wheelchair of the embodiment. The operation | movement diagram which shows typically operation | movement of the wheelchair accompanying execution of facing control about the electric wheelchair of the embodiment. The operation diagram which shows typically operation of the wheelchair accompanying execution of descending control about the electric wheelchair of the embodiment.

  This embodiment has shown an example of the structure which actualized the control apparatus of the electric vehicle of this invention as a control apparatus of an electric wheelchair. In addition, the traveling state of the electric wheelchair is changed according to the operation of the joystick by the occupant.

The configuration of the electric wheelchair 1 will be described with reference to FIG.
The electric wheelchair 1 includes a vehicle body 10 for an occupant to ride, a drive system 20 for causing the electric wheelchair 1 to travel, a stair mechanism 40 for changing the position of the drive system 20 with respect to the vehicle body 10, and a first drive wheel 21. And a load moving mechanism 50 (see FIG. 3) for moving the load of the second drive wheel 22.

  The drive system 20 includes two first drive wheels 21 provided on the right and left sides of the vehicle body 10, second drive wheels 22 provided on the right and left sides of the vehicle body 10 at positions different from the first drive wheels 21, The first driving wheel 21 and the second driving wheel 22 arranged in the traveling direction are taken as one set, and a traveling mechanism 30 that applies torque to the set of the driving wheels 21 and 22 is provided.

  The stair mechanism 40 rotates one drive wheel with respect to the other drive wheel with respect to the set of the first drive wheel 21 and the second drive wheel 22 arranged in the traveling direction. For this reason, when the stair mechanism 40 is driven, the positional relationship between the first drive wheel 21 and the second drive wheel 22 is switched in the traveling direction. Hereinafter, the driving wheel located in front of the traveling direction of the first driving wheel 21 and the second driving wheel 22 is referred to as a “front driving wheel”, and the traveling direction of the first driving wheel 21 and the second driving wheel 22 is determined. A driving wheel located behind the vehicle is referred to as a “rear driving wheel”.

  The vehicle body 10 includes a support portion 11 for supporting the occupant's body, and a main body portion that is disposed below the support portion 11 and houses the drive system 20, the stair mechanism 40, the load movement mechanism 50, and a battery (not shown). 15. The support part 11 is provided with a seat part 12 on which an occupant sits, an armrest 13 for hanging an elbow, and a footrest 14 for placing a foot.

  The right armrest 13 is provided with an operation unit 16 for an occupant to operate the electric wheelchair 1. The operation unit 16 is provided with a joystick 17 for instructing a traveling direction and a traveling speed, an ascending button 18 for selecting a mode for climbing stairs, and a descending button 19 for selecting a mode for descending stairs. ing.

The electrical configuration of the electric wheelchair 1 will be described with reference to FIG.
The electric wheelchair 1 includes a control unit 60 that performs various calculations in addition to the travel mechanism 30, the stair mechanism 40, and the load movement mechanism 50 of the drive system 20.

  The drive system 20 includes a right drive system 20 corresponding to the right drive wheels 21 and 22 and a left drive system 20 corresponding to the left drive wheels 21 and 22. The right drive system 20 includes right drive wheels 21 and 22 and a right traveling mechanism 30 that rotates the drive wheels 21 and 22. The left drive system 20 includes left drive wheels 21 and 22 and a left traveling mechanism 30 that rotates the drive wheels 21 and 22. The first drive wheel 21 and the second drive wheel 22 on the right side correspond to “right drive wheels”. The left first driving wheel 21 and the second driving wheel 22 correspond to “left driving wheel”. The right drive system 20 corresponds to “drive system A”. The left drive system 20 corresponds to “drive system B”.

  The right traveling mechanism 30 includes a traveling motor 31 for rotating the right drive wheels 21 and 22. The left traveling mechanism 30 includes a traveling motor 31 for rotating the left driving wheels 21 and 22. The traveling motor 31 corresponds to an “electric motor for traveling”.

  The output shaft of each traveling motor 31 is connected to a speed reducer (not shown). The reduction gear is connected to the rotation shaft of the first drive wheel 21 and the rotation shaft of the second drive wheel 22 on the right side or the left side. Thereby, when the traveling motor 31 rotates, the rotation of the output shaft is transmitted to the first drive wheel 21 and the second drive wheel 22 through the speed reducer. Further, the first drive wheel 21 and the second drive wheel 22 rotate at the same rotational speed.

  The stair mechanism 40 includes a link shaft 42 for rotating one of the first driving wheels 21 and the second driving wheels 22 arranged in the traveling direction with respect to the other driving wheel, and a link shaft 42. And a stair motor 41 for rotation. As the stair motor 41, the right stair motor 41 that rotates the link shaft 42 corresponding to the right drive wheels 21 and 22 and the left stair motor that rotates the link shaft 42 corresponding to the left drive wheels 21 and 22. And a motor 41.

  The load moving mechanism 50 has a load moving motor 51 for tilting the support portion 11 forward or backward. The support portion 11 is inclined forward or backward with respect to the main body portion 15, the first drive wheel 21, and the second drive wheel 22 as the load movement motor 51 rotates.

  The operation of the load moving mechanism 50 will be described with reference to FIG. In the figure, an operation state when the first drive wheel 21 corresponds to the front drive wheel is shown. Since the operation state when the second drive wheel 22 corresponds to the front drive wheel is the same, the description of the operation state is omitted here.

  When the electric wheelchair 1 is stopped, that is, when the operation position of the joystick 17 is in the neutral position, the support portion 11 is held in a horizontal state with respect to the ground as shown by a solid line in the figure. When the electric wheelchair 1 is traveling or when the electric wheelchair 1 descends a descending step, the load moving mechanism 50 holds the support portion 11 in a state of being inclined rearward as indicated by a two-dot chain line in the figure. The When the electric wheelchair 1 climbs the ascending step, the support 11 is tilted forward by the load moving mechanism 50 as indicated by the one-dot chain line in the figure.

  When the support portion 11 is inclined forward, the center of gravity of the occupant is biased forward in the traveling direction, so that the load applied to the first drive wheel 21 is greater than the load applied to the second drive wheel 22. For this reason, when the relationship between the drive wheels 21 and 22 and the contact surface is the same, the contact area of the first drive wheel 21 is larger than the contact area of the second drive wheel 22. Further, when the relationship between the first driving wheel 21 and the second driving wheel 22 and the front driving wheel and the rear driving wheel is opposite to the above, the magnitude of the load applied to each driving wheel 21 and 22 is also opposite. Become.

  On the other hand, when the support portion 11 is tilted rearward, the center of gravity of the occupant is biased rearward in the traveling direction, so that the load applied to the second drive wheel 22 is greater than the load applied to the first drive wheel 21. For this reason, when the relationship between the drive wheels 21 and 22 and the ground contact surface is the same, the ground contact area of the second drive wheel 22 is larger than the ground contact area of the first drive wheel 21. Further, when the relationship between the first driving wheel 21 and the second driving wheel 22 and the front driving wheel and the rear driving wheel is opposite to the above, the magnitude of the load applied to each driving wheel 21 and 22 is also opposite. Become.

  The state in which the support part 11 is inclined forward indicates a state in which the support part 11 is inclined so that the front of the support part 11 is closer to the main body part 15 and the like than the rear of the support part 11 in the traveling direction. The state in which the support portion 11 is inclined rearward indicates a state in which the support portion 11 is inclined so that the rear of the support portion 11 is closer to the main body portion 15 or the like than the front of the support portion 11 in the traveling direction.

The configuration of the control unit 60 will be described with reference to FIG.
The control unit 60 includes an electronic control device 61 that performs various calculations, four drive wheel speed sensors 62 that detect the rotation speeds of the drive wheels 21 and 22 (hereinafter referred to as “drive wheel rotation speed NT”), and the travel motor 31. And a current detection circuit 33 for detecting a current value supplied to the motor (hereinafter referred to as “traveling motor current value IM”). Also, a travel drive circuit 32 that supplies power to the travel motor 31 based on a control signal received from the electronic control device 61, and a staircase drive that supplies power to the staircase motor 41 based on a control signal received from the electronic control device 61. A circuit 43 and a movement drive circuit 52 that supplies power to the load movement motor 51 based on a control signal received from the electronic control unit 61 are included. Drive wheel rotational speed NT and travel motor current value IM correspond to “values related to drive system torque”.

The basic operation of the electronic control device 61 is shown below.
The electronic control device 61 includes an operation signal output from the operation unit 16 when the operation unit 16 is operated, an operation signal output from the ascending button 18 when the ascending button 18 is operated, and a descending button when the descending button 19 is operated. The operation signal output from 19 is received. Further, the detection signal output from the drive wheel speed sensor 62 and the detection signal output from the current detection circuit 33 are received. Based on at least one of the received operation signal and detection signal, a control signal for controlling the traveling motor 31, a control signal for controlling the stair mechanism 40, and a control for controlling the load moving mechanism 50. At least one of the signals is output to a corresponding drive circuit among the travel drive circuit 32, the staircase drive circuit 43, and the movement drive circuit 52.

Specific contents of control performed by the electronic control unit 61 are shown below.
The electronic control device 61 performs the following control (A) or (B) as control for moving the electric wheelchair 1 forward or backward according to the operation of the joystick 17. Further, as control for turning the electric wheelchair 1 to the right or left according to the operation of the joystick 17, the following control (C) or (D) is performed.

  (A) When the joystick 17 is tilted forward by an occupant, the electronic control unit 61 sends a control signal for rotating the drive wheels 21 and 22 forward at a speed corresponding to the operation amount of the joystick 17. 32. The travel drive circuit 32 supplies power to the travel motor 31 based on the control signal. As a result, the drive wheels 21 and 22 rotate forward at a speed corresponding to the amount of operation of the joystick 17.

  (B) When the joystick 17 is tilted backward by an occupant, the electronic control unit 61 sends a control signal for rotating the drive wheels 21 and 22 backward at a speed corresponding to the operation amount of the joystick 17. 32. The travel drive circuit 32 supplies power to the travel motor 31 based on the control signal. As a result, the drive wheels 21 and 22 rotate backward at a speed corresponding to the operation amount of the joystick 17.

  (C) When the joystick 17 is tilted to the right by the occupant, the electronic control device 61 rotates the drive wheels 21 and 22 forward at a speed corresponding to the amount of operation of the joystick 17 and the left drive wheels A control signal for rotating the wheels 21 and 22 at a rotational speed greater than that of the right drive wheels 21 and 22 is output to the travel drive circuit 32. The travel drive circuit 32 supplies power to the travel motor 31 based on the control signal. As a result, the right and left drive wheels 21 and 22 rotate forward at a speed corresponding to the amount of operation of the joystick 17, so that the right drive wheels 21 and 22 and the left drive wheels 21 and 22 rotate. The electric wheelchair 1 turns right according to the difference in speed.

  (D) When the joystick 17 is tilted to the left by the occupant, the electronic control unit 61 rotates the drive wheels 21 and 22 forward at a speed corresponding to the operation amount of the joystick 17 and the right drive wheels. A control signal for rotating the wheels 21 and 22 at a rotational speed greater than that of the left drive wheels 21 and 22 is output to the travel drive circuit 32. The travel drive circuit 32 supplies power to the travel motor 31 based on the control signal. As a result, the right and left drive wheels 21 and 22 rotate forward at a speed corresponding to the amount of operation of the joystick 17, so that the right drive wheels 21 and 22 and the left drive wheels 21 and 22 rotate. The electric wheelchair 1 turns left according to the difference in speed.

  The electronic control device 61 performs the following control (A) as control for ascending the ascending step according to the operation of the ascending button 18. In addition, the following control (B) is performed as control for descending the descending step according to the operation of the down button 19.

  (A) The electronic control device 61 outputs a control signal for rotating the link shaft 42 forward to the stair drive circuit 43 when receiving an operation signal accompanying the operation of the ascending button 18 by the occupant. The stair drive circuit 43 supplies power to the stair motor 41 based on the control signal. Thereby, since the link shaft 42 rotates forward, when the electric wheelchair 1 is approaching the ascending step, the electric wheelchair 1 travels on the ascending step.

  (B) The electronic control device 61 outputs a control signal for rotating the link shaft 42 forward to the stair drive circuit 43 when receiving an operation signal accompanying the operation of the descend button 19 by the occupant. The stair drive circuit 43 supplies power to the stair motor 41 based on the control signal. Accordingly, since the link shaft 42 rotates forward, the electric wheelchair 1 travels on the descending step when the electric wheelchair 1 is approaching the descending step.

  The electronic control device 61 performs the following (A) as control for adjusting the posture of the support portion 11 according to the traveling state of the electric wheelchair 1, that is, traveling on a flat ground, traveling on an ascending step, and traveling on a descending step. ) To (C) are controlled.

  (A) When the electronic control device 61 receives an operation signal for traveling on a flat ground from the operation unit 16, the electronic control device 61 outputs a control signal for tilting the support unit 11 backward to the movement drive circuit 52. The movement drive circuit 52 supplies power to the load movement motor 51 based on the control signal. Thereby, when the electric wheelchair 1 travels on a flat ground, the support portion 11 is maintained in a rearward tilted state.

  (B) When the electronic control device 61 receives an operation signal for ascending the ascending step from the operation unit 16, the electronic control device 61 outputs a control signal for tilting the support unit 11 forward to the movement drive circuit 52. The movement drive circuit 52 supplies power to the load movement motor 51 based on the control signal. Thereby, when the electric wheelchair 1 climbs the ascending step, the support portion 11 is held in a state of being inclined forward.

  (C) The electronic control device 61 outputs a control signal for tilting the support portion 11 to the movement drive circuit 52 when receiving an operation signal for descending the descending step from the operation portion 16. The movement drive circuit 52 supplies power to the load movement motor 51 based on the control signal. Thereby, when the electric wheelchair 1 descends the descending step, the support portion 11 is held in a state of being inclined rearward.

  By the way, when the front driving wheel approaches the descending step as the electric wheelchair 1 travels, the ground contact area of the front driving wheel decreases, and accordingly, the rotational resistance of the front driving wheel decreases. For this reason, both in the state where the front drive wheel is approaching the descending step (hereinafter referred to as “the initial state of the descending step”) and the state immediately before the forward drive wheel is exposed to the descending step (hereinafter referred to as “the state immediately before the descending step”). When the traveling motor current value IM is assumed to be the same, the driving wheel rotational speed NT in the initial step of the descending step is higher than the driving wheel rotational speed NT in the state immediately before the descending step. Moreover, the torque of the traveling motor 31 in the initial state of the descending step is smaller than the torque of the traveling motor 31 in the state immediately before the descending step.

  Further, when the traveling state of the electric wheelchair 1 shifts from the state immediately before the descending step to the initial step of the descending step, the reduction speed of the ground contact area of the front driving wheel is large, and accordingly, the driving wheel rotational speed NT increases rapidly. In addition, the torque of the traveling motor 31 decreases rapidly. Hereinafter, an event in which the torque of the traveling motor 31 decreases as the state immediately before the descending step shifts to the initial descending step state is referred to as “torque loss”.

  Therefore, by detecting that torque loss has occurred, it is estimated that the traveling state of the electric wheelchair 1 has shifted from the state immediately before the descending step to the initial descending step state, that is, the front drive wheel is approaching the descending step. can do.

  Therefore, the electronic control device 61 of the electric wheelchair 1 determines whether or not the front drive wheel is approaching the descending step based on the torque of the drive system 20. When it is determined that the front drive wheel is approaching the descending step, the descending step detection control including the descending step corresponding control corresponding to the descending step is performed.

With reference to FIG. 4, the procedure of the control at the time of descending step detection is demonstrated.
This control is repeatedly performed by the electronic control device 61 every predetermined calculation cycle. In other words, after the processing of the last step is completed, the execution of the control is suspended until a predetermined calculation cycle elapses, and when the predetermined calculation cycle elapses, the descending step detection time control is executed again from the first step. Is done. Note that a series of processing from step S12 to step S17 corresponds to "falling step correspondence control". Further, the process of step S13 corresponds to “reverse control”. Further, the processing of step S15 and step S16 corresponds to “facing control”.

In step S11, it is determined whether or not the front drive wheel is approaching a descending step. Specifically, when both of the following (Condition A) and (Condition B) are satisfied, it is determined that the front drive wheel is approaching a descending step.
(Condition A) A point determined by the traveling motor current value IM and the drive wheel rotational speed NT belongs to the descending step area of the descending step detection map.
(Condition B) The change speed of the drive wheel rotational speed NT with respect to the travel motor current value IM is equal to or higher than a predetermined change speed.

Details of (Condition A) will be described.
The descending step detection map has an orthogonal coordinate system in which the X axis is the traveling motor current value IM and the Y axis is the drive wheel rotational speed NT. This map shows a descending step region corresponding to the traveling motor current value IM and the driving wheel rotational speed NT when the front driving wheel is approaching the descending step, and traveling when the front driving wheel is outside the descending step. A general region corresponding to the motor current value IM and the drive wheel rotational speed NT is provided.

  In step S11, when the point determined by the traveling motor current value IM and the drive wheel rotational speed NT belongs to the descending step region, it is determined that the above (condition A) is satisfied. On the other hand, when the point determined by the travel motor current value IM and the drive wheel rotational speed NT belongs to the general region, it is determined that the above (condition A) is not satisfied.

Details of (Condition B) will be described.
As described above, when the traveling state of the electric wheelchair 1 shifts from the state immediately before the descending step to the initial step of the descending step, the reduction speed of the ground contact area of the front driving wheel is large. To rise. For this reason, the change speed of the drive wheel rotation speed NT with respect to the travel motor current value IM is compared with a predetermined change speed as a determination value, and when the change speed of the drive wheel rotation speed NT is equal to or higher than the predetermined change speed, the front It can be estimated that the drive wheel is approaching the descending step.

  If it is determined in step S11 that at least one of the right and left front drive wheels is approaching a descending step, the process proceeds to step S12. On the other hand, when a negative determination is made in step S11, the present process is temporarily terminated.

  In step S12, the amount by which the front drive wheel approaching the descending step falls downward from the top surface of the descending step, that is, the distance between the top surface of the descending step and the lower end surface of the front drive wheel is defined as the indentation amount E. It is determined whether the amount E is equal to or greater than a predetermined drop amount. Here, when the difference between the driving wheel rotational speed NT immediately before the descending step and the driving wheel rotational speed NT in the initial state of the descending step is equal to or greater than a predetermined speed, it is determined that the ground contact area of the front driving wheel is smaller than the predetermined area. . Note that, as the predetermined drop amount, for example, one third of the outer diameter of the front drive wheel can be set.

  In step S12, when it is determined that the amount of depression E of the front drive wheel approaching the descending step is less than the predetermined amount of depression, step S13 is omitted and the process proceeds to step S14. On the other hand, when it is determined that the amount of depression E of the front drive wheel is equal to or greater than the predetermined amount of depression, reverse control is performed in step S13. In the reverse control, the right and left drive wheels 21 and 22 are rotated by a predetermined rotation amount RA in a direction away from the descending step, that is, rearward. As the predetermined rotation amount RA, for example, one third of the outer diameter of each of the drive wheels 21 and 22 can be set.

  In step S14, it is determined whether or not the down button 19 is pressed. When it determines with the down button 19 having been pressed, it transfers to step S15. In step S15, as a preparatory operation for stabilizing the posture of the electric wheelchair 1 when descending a descending step, a facing control for causing the right and left front drive wheels to face the descending step is executed.

  In the front-facing control, the front drive wheel that is approaching the descending step is rotated backward. When both the right and left front drive wheels are approaching a step, both the right and left front drive wheels are rotated backward.

  In step S16, it is determined whether or not the right and left front drive wheels are directly facing the descending step. Specifically, for the front drive wheel determined to be approaching a descending step, the traveling motor current value IM and the driving wheel rotational speed NT are plotted on the descending step detection map, and when the plotted point belongs to the general region, It is determined that the right and left front drive wheels face the descending step. On the other hand, when it is determined that the right and left front drive wheels are not directly facing the descending step, the facing control is continued until a determination result indicating that the right and left front driving wheels are facing directly is obtained.

  When it is determined that the right and left first driving wheels 21 are approaching the descending step when detecting the descending step, the traveling motor current value of one of the right and left front driving wheels is determined in step S16. When IM and driving wheel rotational speed NT are plotted in the descending step region, the rotation of the front driving wheel is stopped and the other front driving wheel is rotated backward.

  In step S <b> 17, the descending control for descending the descending step by the electric wheelchair 1 is executed. In descending control, the link shaft 42 is rotated to cause the rear drive wheel to revolve around the front drive wheel.

  With reference to FIG. 5, the operation of the traveling mechanism 30 during the facing control will be described. Note that an arrow AT in the figure indicates the rotation direction of each drive wheel 21, 22. In addition, an arrow AM in the figure indicates the traveling direction of the electric wheelchair 1.

  In the figure, the operating state of the traveling mechanism 30 when the left first driving wheel 21 as the front driving wheel is approaching a step is shown. Note that the traveling mechanism 30 operates in the same manner even when the first drive wheel 21 on the right side is approaching the descending step, and thus description of the operation of the traveling mechanism 30 in the same state is omitted.

  In the facing control, as shown in FIG. 5A, the left driving wheels 21 and 22 are rotated backward by the left traveling motor 31. Further, the right driving wheels 21 and 22 are held in a locked state by the right traveling motor 31. Thereby, the electric wheelchair 1 rotates counterclockwise.

  As shown in FIG. 5 (b), when the drop amount E of the left first drive wheel 21 changes to “0”, the right and left front drive wheels are moved in the process of step S16 of the step detection control. It determines with having faced the descending level | step difference, and the rotation of the 1st driving wheel 21 on the left side is stopped.

  With reference to FIG. 6, operation | movement of the staircase mechanism 40 at the time of descending control is demonstrated. Note that when the stair mechanism 40 operates, the drive motors 21 and 22 are held in a locked state by the travel motor 31.

  In descending control, torque is applied to the link shaft 42 by the stair motor 41 as shown in FIG. Thereby, the 2nd driving wheel 22 as a rear driving wheel begins to revolve with respect to the 1st driving wheel 21 as a front driving wheel.

  As shown in FIG. 6B, the rotation of the link shaft 42 lifts the second drive wheel 22 away from the ground contact surface. Then, as shown in FIG. 6C, when the link shaft 42 further rotates, the second driving wheel 22 rotates forward with respect to the first driving wheel 21 and contacts the lower stage. Note that the control of the link shaft 42 continues even after the second drive wheel 22 contacts the lower stage until the operation signal indicating that the traveling corresponding to the lowering step is stopped by the operation of the lowering button 19 is output. Is called.

(Effect of embodiment)
According to the electric wheelchair 1 of the present embodiment, the following effects can be obtained.
(1) When the driving wheels 21 and 22 of the electric wheelchair 1 are approaching the descending step, the ground contact area of the driving wheels 21 and 22 is reduced, so that the rotational resistance of the driving wheels 21 and 22 is reduced. At this time, the torque of the drive system 20 changes according to the change in the rotational resistance of the drive wheels 21 and 22. Thus, the change in the torque of the drive system 20 reflects the change in the rotational resistance of the drive wheels 21 and 22 as the drive wheels 21 and 22 approach the step. Based on this concept, the electronic control device 61 of the electric wheelchair 1 can detect a step difference in accordance with changes in the drive wheel rotational speed NT and the travel motor current value IM as values related to the torque of the drive system 20. it can.

  Further, since the descending step is detected based on the driving wheel rotational speed NT and the traveling motor current value IM, it is not necessary to mount special sensors such as an ultrasonic sensor and an image sensor for detecting the descending step. For this reason, the number of parts of the electric wheelchair 1 can be reduced.

  (2) When the electronic control unit 61 detects the step, the right and left front drive wheels are directly opposed to the step. According to this structure, it can suppress that the attitude | position when the electric wheelchair 1 descends a descending level | step becomes unstable. In addition, since the electronic control device 61 causes the right and left front drive wheels to face the descending step, it is possible to save the driver from performing an operation of causing the right and left front drive wheels to face the descending step.

  (3) The electric vehicle has a right side and a left side based on the driving wheel rotational speed NT and the traveling motor current value IM of the right driving system 20 and the driving wheel rotational speed NT and the traveling motor current value IM of the left driving system 20. The front drive wheel of is directly facing the descending step. According to this configuration, the right and left sides of the drive wheel rotation speed NT and the traveling motor current value IM of the right drive system 20 and the changes of the drive wheel rotation speed NT and the travel motor current value IM of the left drive system 20 are changed. Therefore, it is possible to confirm that the front drive wheels of the right side and the left side of the front drive wheels are directly facing the descending step, so that the right and left front drive wheels can be more accurately opposed to the descending step. Further, it is possible to reduce a burden of visually judging that the driver is facing the right and left front drive wheels to the descending step.

  (4) The electronic control unit 61 has a predetermined area when the amount E of the forward drive wheel approaching the descending step is larger than the predetermined amount of depression, that is, the contact area of the front drive wheel approaching the descending step is a predetermined area. When it is smaller, as the descending step corresponding control, the backward control for causing the electric wheelchair 1 to travel away from the descending step is performed, and then the facing control is performed. According to this structure, it is suppressed that the electric wheelchair 1 inclines largely by approaching a descent | fall level | step difference. Moreover, it is suppressed that the electric wheelchair 1 inclines largely during the period when the right and left front drive wheels are directly opposed to the descending step.

  (5) When the electric wheelchair 1 is traveling, the electronic control device 61 biases the load backward in the traveling direction. According to this configuration, the electric wheelchair 1 is unlikely to be tilted forward when the front drive wheel approaches the step in the traveling direction.

  (6) The electronic control unit 61 detects that the vehicle is approaching a step when the change speed of the drive wheel rotational speed NT with respect to the traveling motor current value IM of the front drive wheel is equal to or higher than a predetermined change speed. According to this configuration, it is possible to suppress erroneous detection of a descending step due to an increase in the drive wheel rotational speed NT accompanying the electric wheelchair 1 traveling on a low friction road and a downhill.

(Other embodiments)
The embodiment of the present invention is not limited to the above embodiment, and can be modified as shown below, for example. The following modifications are not applied only to the above-described embodiment, and different modifications can be combined with each other.

  In the above embodiment (FIG. 4), when the descending step is detected, the facing control is executed based on the depression button 19 being pressed, but when the descending step is detected, the descending button 19 The facing control can be executed regardless of whether or not the button is pressed.

  -The following process can also be added with respect to the facing control of the said embodiment (FIG. 4). That is, at least one of a process of increasing the operating speed of the facing control according to the change speed of the driving wheel rotational speed NT with respect to the traveling motor current value IM and a process of advancing the start timing of the facing control according to the changing speed. It can also be added. Further, when the change speed of the drive wheel rotational speed NT with respect to the travel motor current value IM is equal to or higher than a predetermined change speed, at least one of the two processes can be performed. According to this structure, the effect which suppresses that the electric wheelchair 1 inclines largely toward the front before completion of facing control is heightened.

In the above embodiment (FIG. 4), the reverse control, the direct control, and the descending control are executed as the descending step corresponding control, but one or two of these controls may be omitted. Further, instead of or in addition to these three controls, at least one of the following controls (A) and (B) may be executed as the descending step corresponding control.
(A) Notification control for notifying an occupant that a descending step has been detected.
(B) Stop control for stopping traveling of the electric wheelchair 1 when a descending step is detected.

In the above embodiment (FIG. 4), the travel motor current value IM and the drive wheel rotational speed NT are used as values related to the torque of the drive system 20, but the following values (A) to (F) are used. It can also be used as a value related to the torque of the drive system 20, and the descending step can be detected based on at least one change in these values.
(A) Traveling motor current value IM and rotational speed of traveling motor 31.
(B) The command value of the current value of the traveling motor 31 and the rotational speed of the traveling motor 31.
(C) The command value of the current value of the traveling motor 31 and the drive wheel rotational speed NT.
(D) The rotational speed of the traveling motor 31 and the traveling motor current value IM.
(E) A detection value of a sensor that detects the torque of the traveling motor 31.
(F) A detection value of a sensor that detects the torque of the front drive wheel.

  In the above embodiment (FIG. 1), a set of the first driving wheel 21 and the second driving wheel 22 is driven by one traveling motor 31, but the traveling motor that drives these driving wheels 21 and 22 individually. Can also be provided.

  -At least one of an ultrasonic sensor and an image sensor can also be provided in the electric wheelchair 1 of the said embodiment (FIG. 2). In this case, in addition to the detection control of the descending step based on the torque of the drive system 20, control for detecting the descending step using at least one detection value of the sensor can be added. Further, the facing control can be executed using the detection value of at least one of the sensors.

  In the above embodiment (FIG. 3), the load moving mechanism 50 for tilting the support portion 11 forward or backward is provided, but instead of or in addition to this, by moving the weight forward and backward in the traveling direction It is also possible to provide a load moving mechanism that can bias the load forward and backward in the traveling direction.

  In the above embodiment (FIG. 1), the first drive wheel 21 and the second drive wheel 22 are provided on the right side and the left side of the vehicle body 10, respectively, but the number of drive wheels provided on the right side and the left side of the vehicle body 10 is one. It can also be changed to one or more than two.

  In the above embodiment (FIG. 1), the vehicle body 10 is provided with a pair of drive wheels 21 and 22 on the right and left sides, respectively, but instead of the right and left drive wheels 21 and 22, the vehicle body 10 A pair of drive wheels can be provided at or near the center in the width direction. Further, it is possible to omit the one drive wheel from the configuration including the one set of drive wheels and change the configuration to include only one drive wheel. Also in these modified examples, when torque loss occurs, this is reflected in the torque of the drive system. Therefore, by monitoring the value related to the torque of the drive system, the level difference is reduced in a manner according to the above embodiment. Can be detected.

  -The electric vehicle used as the application object of this invention is not restricted to the electric vehicle illustrated to the said embodiment. For example, the present invention can be applied to an electric vehicle in which an occupant stands in a standing position as a single-person vehicle, and an electric vehicle as a multi-person vehicle. That is, the present invention can be applied to a control device for an electric vehicle having any configuration as long as it is an electric vehicle including a drive system including a drive wheel and an electric motor for traveling. Also in that case, the effect according to the effect of the above embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Electric wheelchair (electric vehicle), 10 ... Car body, 11 ... Support part, 12 ... Seat part, 15 ... Main-body part, 16 ... Operation part, 17 ... Joystick, 18 ... Rise button, 19 ... Down button, 20 ... Drive System 21... First drive wheel 22. Second drive wheel 30. Travel mechanism 31 Travel motor (electric motor for travel) 33 Current detection circuit 40 Stair mechanism 41 Stair motor 42 ... link shaft, 50 ... load moving mechanism, 60 ... control unit, 61 ... electronic control unit, 62 ... driving wheel speed sensor.

Claims (9)

A control device for an electric vehicle including a drive system including a drive wheel, wherein the control device for the electric vehicle controls the drive system.
A control device for an electric vehicle, wherein a descending step is detected based on a change in a value related to the torque of the drive system. In the control apparatus of the electric vehicle according to claim 1,
A control device for an electric vehicle, wherein when detecting the descending step, the descending step corresponding control corresponding to the descending step is performed. In the control apparatus of the electric vehicle according to claim 2,
A control device for an electric vehicle, characterized in that as the descending step corresponding control, a facing control for causing the driving wheel to face the descending step is performed. In the control apparatus of the electric vehicle according to claim 3,
The electric vehicle includes a drive system A including a right drive wheel as the drive wheel and a drive system B including a left drive wheel as the drive wheel.
And the facing control is performed based on a value related to the torque of the drive system A and a value related to the torque of the drive system B. In the control apparatus of the electric vehicle according to claim 3 or 4,
When the ground contact area of the driving wheel is smaller than a predetermined area, as the descending step corresponding control, reverse control is performed for causing the electric vehicle to travel away from the descending step, and then the facing control is performed. A control apparatus for an electric vehicle characterized by the above. In the control apparatus of the electric vehicle according to claim 2,
When the ground contact area of the driving wheel is smaller than a predetermined area, the control method for the electric vehicle is characterized in that as the descending step corresponding control, the electric vehicle is moved backward in a direction away from the descending step. In the control apparatus of the electric vehicle as described in any one of Claims 2-6,
A control device for an electric vehicle, wherein at least one of an operation speed and a start time of the descending step corresponding control is changed according to a change speed of a value related to the torque of the drive system. In the control apparatus of the electric vehicle as described in any one of Claims 1-7,
When the electric vehicle is traveling, the load is biased backward in the traveling direction. In the control apparatus of the electric vehicle as described in any one of Claims 1-8,
The drive system includes an electric motor for traveling;
In addition, the value related to the torque of the drive system is at least one of the torque of the electric motor, the current value of the electric motor, the rotational speed of the electric motor, and the rotational speed of the drive wheel. Control device for electric vehicle.

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