JP2657174B2 - Travel control device for electric vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a travel control device used for an electric vehicle in which a plurality of DC motors for separately driving at least two wheels of the plurality of vehicles are connected in series. It is about.

BACKGROUND OF THE INVENTION Conventionally, there is an electric vehicle in which two or more wheels are separately driven by two or more DC motors. For example, in a four-wheeled vehicle, two wheels in a pair of left and right or diagonal positions may be driven by separate DC motors, or in a rear two-wheeled vehicle, left and right rear wheels may be driven by separate DC motors. . A two-wheeled vehicle using a DC motor (wheel motor) installed in the wheel of the wheel has also been considered.

In such a case, it is conceivable to connect two or more DC motors in series and control the speed of all the motors with one motor control device. However, in this case, if one drive wheel slips due to wetness or unevenness of the running surface,
The speed of the motor of the slip vehicle is higher than that of the other motors. Generally, in DC motors, the armature rotation speed increases with an increase in the armature voltage, regardless of whether the motor is series-wound, split-wound, or compound-wound.
Also, the torque tends to increase with an increase in the electronic machine current. Therefore, when a plurality of DC motors are operated in series, if any one of the motor loads suddenly decreases and the rotation speed increases (corresponding to wheel slip), the armature back electromotive voltage of the armature increases and this slippage occurs. The motor voltage of the slipping wheel increases, and the motor voltage of the non-slip wheel decreases. For this reason, an imbalance occurs in which the voltage distribution is large for the motor of the vehicle that is slipping and is small for the other motors. This results in the problem that the motor of the wheel that is slipping becomes faster and the motor of the wheel that is not slipping becomes slower, and the imbalance becomes large and the vehicle cannot travel. At this time, there is also a problem that the electric current is reduced and the torque is reduced due to the electric motor of the wheel that is slipping.

(Object of the Invention) The present invention has been made in view of such circumstances,
When a DC motor that drives a plurality of wheels separately is connected in series, even if a slip occurs on one of the wheels, an electric motor that can continue running stably without increasing the speed imbalance of each motor. It is an object of the present invention to provide a traveling control device for a vehicle.

(Constitution of the Invention) According to the present invention, the object is to reduce a speed of the motor, a plurality of wheels, a plurality of motors connected in series to drive at least two wheels of the plurality of wheels separately. In a traveling control device for an electric vehicle provided in an electric vehicle including a speed control device for controlling, a plurality of bypass circuits provided for each of the electric motors and bypassing each electric motor, and each of the plurality of bypass circuits is intermittently connected. A normally open switch for bypassing, a speed detector for detecting the speed of the electric motor, and comparing the speed of each of the motors output from the speed detector, the difference is
Slip determining means for determining whether or not the speed of the low-speed motor exceeds a predetermined ratio, and in the case of exceeding the predetermined ratio, outputting a switching signal for closing the bypass normally open switch of the high-speed motor. The speed control device controls the speed of the low-speed motor to a predetermined speed for a fixed time after the bypass normally-open switch of the high-speed motor is closed by the switching signal, and After the lapse of the predetermined time, the determining means stops the low-speed motor, and outputs a switching signal for opening a normally open switch for bypass of the high-speed motor. Achieved.

(Embodiment) FIG. 1 is a circuit configuration diagram of one embodiment of the present invention, FIG. 2 is a flowchart showing the operation thereof, FIG. 3 is a perspective view of a floor cleaning robot to which this embodiment is applied, and FIG. Is a vehicle layout diagram.

3 and 4, reference numeral 10 denotes four wheels having the same diameter, and each wheel 10 is mounted below the bogie 12 so as to be steerable. That is, each wheel 10 is controlled by a servo motor or the like in an appropriate traveling direction such as straight traveling, lateral traveling, or reverse traveling. Shunt DC motors M ₁ and M ₂ are directly connected to the _two wheels 10 at diagonal positions.

The armatures of the motors M ₁ and M ₂ are connected in series as shown in FIG. 1 to form a closed circuit together with the battery 14, the main switch 16, and the control element 18. The electric motors M ₁ and M ₂ are provided with circuits for bypassing the armature, and the bypass circuits are provided with changeover switches 20 and 22, respectively. That these switches 20, 22 includes a normally closed switch 20a connected in series to the motor M _1, M _2, and 22a, the normally open switch 20b for intermittently bypass circuit, and 22b.

In FIG. 1, reference numerals 24 and 26 denote rotational speeds of the electric motors M ₁ and M ₂ .
It is a speed detector (TG) that detects S ₁ and S ₂ . The rotation speeds S ₁ and S ₂ are converted into digital signals by an input interface 28 and input to a digital operation device (CPU) 30 as slip determination means. The arithmetic unit 30 performs a predetermined arithmetic operation according to the arithmetic program stored in the memory 32 as shown in FIG. 2, and determines which of the electric motors M ₁ and M ₂ is slipping. The arithmetic unit 30 when the motor M ₁ is slipping sends the switching signal K ₁ through the output interface 34 to the change-over switch 20. The order normally closed switch 20a closes the circuit to the normally open switch 20b as well as open, the motor current so as to bypass the motor M _1.
The arithmetic unit 30 if the electric motor M ₂ is slipping sends out a switching signal K ₂ to the change-over switch 22, the normally closed switch 22
the a and bypasses the normally open switch 22b closes the circuit motor M ₂ current while open.

Reference numeral 36 denotes a subtractor, which calculates a difference between the set speed S ₀ of the speed setting device 38 and the traveling speed S. In this embodiment, determined from the rotational speed S ₁ or S ₂ speed detector 24 or 26 of the motor M ₁ or M ₂ of the set speed S is not slipping is detected. That change-over switch 40, the rotational speed of the rotational speed S ₂ as inputs to the subtractor 36 speed S, when the motor M ₂ is slipping based on the switching signal K ₂ when the motor M ₁ is slipping S ₁ is used as the traveling speed S and the subtractor 36
To enter.

Reference numeral 42 denotes a traveling control circuit, which controls the speeds of the electric motors M ₁ and M ₂ by opening and closing the control element 18 based on the output of the subtractor 36 so that the traveling speed S matches the set speed S ₀ .

In FIG. 3, reference numeral 50 denotes a battery, 52 denotes a rotating pad, 54 denotes a watering / recovery tank, and 56 denotes a control panel. Also
Reference numerals 60, 60 denote suction devices for sucking and collecting the detergent, water, and wax sprayed from the front of the rotary pad 52 during the operation of the robot, behind the rotary pad 52. The robot is automatically controlled by a number of distance sensors and the like so as to move all over the floor while avoiding contact with a wall, and performs cleaning.

Next, the operation of this embodiment will be described with reference to FIG.
When the main switch 16 is closed, the operation starts (step 100), and the electric motor is driven (step 102). The rotation speeds S ₁ and S ₂ output from the speed detectors 24 and 26 are compared (step 104), and if the difference (S ₁ −S ₂ ) is positive,
The difference (S ₁ −S ₂ ) is a predetermined ratio m (usually 0.1 to 1.0) of the rotational speed of the non-slip rotational speed, ie, the rotational speed S ₂ on the low speed side.
(Set to 0.3) is determined (step 106). If (S ₁ −S ₂ )> S ₂ xm, the motor M ₁
There is judged that the slipping (step 108), after pausing the motor M _1, M ₂ and cut off the motor current (step 110), change-over switch based on the switching signal K ₁ 2
0 connects the bypass circuit of the motor M ₁ (step 11
2). And if again supplies the motor current (114), only the electric motor M ₂ non-slipping is driven so that the set speed S _0, this state (which is set to about 3 to 5 seconds) time t ₀ after continued (step 116), again the electric motor M ₂ stops (step 118), said changeover switch 20 is returned to block the bypass circuit of the motor M ₁ (step 12
0). Incidentally, the time t ₀ is for returning the shaft to the idle, a fixed time the traveling device at only one side of the motor (i.e., a predetermined distance) is running, provided for applying a short brake the meantime idling the electric motor Time.

If the difference between the rotation speeds S ₁ and S ₂ is negative (step 10
4), the difference (S ₂ −S ₁ ) is compared with S ₁ xm (step 1)
22) If it is determined that the motor M ₂ is slipping (step 124), a bypass circuit of the motor M ₂ (step 126), and drives only other motor M ₁ (step 12
8). The predetermined time t ₀ after (step 130) again to block the bypass circuit (step 132).

Since the above embodiment is applied to a floor cleaning robot that travels in a regular manner, the motor is stopped when the changeover switches 20 and 22 are switched (steps 110 and 118).
And 134, 136). In addition, only one of the motors is driven for a relatively long time of t ₀ = 3 to 5 seconds with the slip-side motor stopped (steps 114 and 130). However, according to the present invention, steps 110 and 134 for stopping the motor can be omitted, and t ₀ can be set to a shorter time.

In the above embodiment, slip determination is performed by the digital arithmetic unit 30, but the present invention can also be configured by an analog circuit.

FIG. 5 is a circuit diagram of such an embodiment. The slip discriminating means 62 in this embodiment includes a rotational speed S ₁ ,
Comparing S ₂ by the comparator 64, 66, S _1> when the S ₂ compares the output S ₂ xm of the comparator 68 with (S ₁ -S ₂₎ stacker 70. If (S ₁ −S ₂ )> S ₂ xm, the off-delay timer 72 is set to the predetermined time
t ₀ only output the switching signal K _1, a bypass circuit of the motor M ₁ by the change-over switch 20. When S ₁ <S ₂ ,
Comparator 74, integrator 76, and outputs only the switching circuit K ₂ predetermined time t ₀ by off-delay timer 78, a bypass circuit of the motor M ₂ by the changeover switch 22. In this circuit diagram, normally closed switches 80 and 82 are connected to the output terminals of the timers 72 and 78, respectively. The normally closed switches 80 and 82 are connected to a switching circuit K
₁ (or K ₂ ) is output and one motor M ₁ (or
When M ₂ ) is stopped, S ₂ −S ₁ (S ₁ > S ₂ ), so the switching circuit K ₂ (K ₁ ) is also output immediately, and eventually both motors M ₁ and M ₂ are stopped. It functions as an interlock for preventing such a situation.

In FIG. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.

Although each of the above embodiments applies the present invention to a wheeled vehicle having _two electric motors M ₁ and M ₂ , the present invention can also be applied to a case where all the vehicles are separately driven by a wheel motor or the like. The invention can be applied to a two-wheeled vehicle, and the present invention includes such a vehicle. The DC motor may be a shunt, series or compound winding motor.

(Effect of the Invention) According to the device of the present invention, as described above, when any one of the wheels driven by the plurality of DC motors connected in series slips, the motor of the slipped wheel is bypassed to supply the electric current. Therefore, even if one of the wheels slips, the balance of the voltage distribution of the electric motors is not lost, and the speed imbalance is not increased. For this reason, it is possible to obtain a travel control device for an electric vehicle that can perform stable travel even on a slippery operation surface or a travel surface having many irregularities.

Also, after bypassing the slipped motor, for a certain period of time, the speed of the non-slip motor is controlled to be a predetermined speed, and after this certain time has elapsed, the non-slip motor is temporarily stopped, The motor bypasses the slipping motor. For this reason, the electric vehicle can be run for a certain period of time with only the motor that has not slipped, and the idling motor driven by the electric motor can be effectively returned by short-circuiting and braking the idling motor. Becomes

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration diagram of one embodiment of the present invention, FIG. 2 is a flowchart showing the operation thereof, FIG. 3 is a perspective view of a floor cleaning robot to which this embodiment is applied, FIG. 4 is a wheel layout diagram. FIG. 5 is a circuit diagram of another embodiment. 10 ...... wheels, 20b, 20b ...... normally open switch, 24, 26 ...... speed detector, calculating apparatus as 30 ...... slip determination unit, 42 ...... speed controller, 62 ...... slip determination unit, M ₁ , M ₂ …… Normal open switch.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-162903 (JP, A) JP-A-54-5110 (JP, A) JP-A-48-97213 (JP, A) 5056 (JP, B1)

Claims (1)

(57) [Claims] An electric vehicle comprising: a plurality of wheels; a plurality of motors directly connected to each other for separately driving at least two of the plurality of wheels; and a speed control device for controlling a speed of the motor. A plurality of bypass circuits provided for each of the electric motors and bypassing each of the electric motors; a normally-open switch for bypass for intermittently connecting each of the plurality of bypass circuits; and the electric motor. Speed detectors for detecting the speeds of the respective motors, and comparing the speeds of the respective motors output from the speed detectors, to determine whether or not the difference exceeds a predetermined ratio of the speed of the low-speed side motor. And a slip discriminating means for outputting a switching signal for closing the bypass normally open switch of the motor on the high-speed side when the motor speed exceeds the speed. The control device controls the speed of the low-speed motor to be a predetermined speed for a predetermined time after the bypass normally-open switch of the high-speed motor is closed by the switching signal, and the slip determination unit includes: A travel control device for an electric vehicle, wherein after a lapse of the predetermined time, the low-speed motor is stopped and a switching signal for opening a bypass normally open switch of the high-speed motor is output.