JPH0233555B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a traveling device suitable for mobile robots, unmanned carriers, and the like.

[Technical background of the invention and its problems]

Recently, various mobile robots and unmanned carriers have been developed. These types of mobile robots and unmanned guided vehicles are generally configured so that they are moved by a fixed base on which the main body is mounted and a traveling device is installed.
Depending on the type of travel device, the environment in which it can travel is significantly limited. For example, if a vehicle is simply equipped with a plurality of wheels, it will not be able to travel if there are stairs or steps, and the only environment it will be traveling in will be a flat, level surface.

Therefore, in the past, a traveling device using a caterpillar has been developed that can travel on uneven ground including stairs and various types of steps. However, caterpillar type traveling devices generally have problems such as difficulty in smooth steering and large slip loss in the traveling system.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to provide a traveling device that is capable of running on stairs, steps, etc., and that also allows smooth steering and low loss. It is in.

[Summary of the invention]

The traveling device according to the present invention supports a main shaft for steering rotatably with respect to a fixed base, and has first and second sub-shafts provided in parallel so as to be movable forward and backward in the axial direction of the main shaft. The first and second sub-shafts are related to each other so as to be driven forward and backward in opposite directions, and the first and second sub-shafts have rotational axes in a direction perpendicular to the direction of movement of the first and second sub-shafts. The present invention is characterized in that wheels are provided rotatably and parallel to the tips of the first and second subshafts, respectively. In particular, the rotational axis of the first wheel is positioned perpendicular to the turning axis of the steering main shaft, and the first wheel is used as a driving wheel.

〔Effect of the invention〕

Thus, according to the present invention, for example, by lifting the second countershaft so that only the first wheel is in contact with the ground, and in this state turning the main shaft for steering while driving the first wheel, the above-mentioned The running direction of the first wheel changes, and its steering is now performed smoothly. Further, when the rotation of the first wheel and the turning of the main shaft are performed simultaneously under a predetermined condition, the turning is performed on the spot.

In addition, when driving on rough terrain, the force applied to the first and second subaxles changes depending on the situation, so this force is detected and the mutually related force of the first and second subaxles is By controlling the forward and backward movement in the opposite direction, it becomes possible to travel effectively on the uneven terrain. For example, when the vehicle comes into contact with an obstacle and receives stress, this information is used to control the advance and retreat of the subshaft to overcome the obstacle, thereby making it possible to drive on rough terrain.

Therefore, according to the present invention, great practical effects can be achieved, such as making it possible to drive on uneven ground including stairs and steps, and making smooth steering possible.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the schematic configuration of the embodiment device.
(a) is a cross-sectional configuration diagram thereof, (b) is a partial cross-sectional configuration diagram of its side surface, and (c) is a partial plan configuration diagram.

This device is attached to a plurality of locations, for example, four locations, on a vehicle body 1 on which the main body of a mobile robot, an unmanned carrier, etc. is mounted, and constitutes a traveling system thereof.

A fixed base 2 fixed to the vehicle body 1 rotatably supports the upper end of a main shaft 3 for steering via a bearing 4. This main shaft 3 is
A gear 6, which is rotationally driven by a turning actuator (motor) 5 provided on the upper part thereof, meshes with an internal gear 7 fixed to the fixed base 2 and rotates.

This main shaft 3 has a first
and second sub-shafts 8, 9 are provided in parallel. These first and second sub-shafts 8, 9 are supported by guide rollers 10 so as to be able to move forward and backward only in the axial direction, and racks 8a, 9a are integrally formed on the opposing inner surfaces thereof, respectively. It is provided. The racks 8a and 9a may be formed by carving the subshafts 8 and 9 themselves, or may be formed by fixing rack members. The pinions 11 that mesh with the racks 8a and 9a move the subshafts 8 and 9 back and forth in opposite directions in relation to each other by their rotation, and act as actuators for driving the subshafts ( It is designed to be rotationally driven by a motor) 12.

First and second wheels 13 and 14 are respectively provided at the lower end portions of the first and second subshafts 8 and 9 to be rotatable with rotational axes extending in a direction perpendicular to the axis of movement thereof. ing. these wheels 1
3 and 14 are provided parallel to the running direction, and in particular, the first wheel 13 is positioned so that its rotational axis is perpendicular to the turning axis of the main shaft 3. A rotating shaft (spline shaft) 16 that is rotatably driven by a traveling motor 15 is provided on the pivot axis so as to be movable forward and backward in the thrust direction. The first wheel 13 is connected to this rotating shaft 16 via a bevel gear mechanism 17, and the first wheel 13 is rotationally driven by the motor 15 regardless of the forward/backward position of the first subshaft 8. It is becoming more and more common.

The traveling device configured in this way operates as follows.

For example, when steering, the actuator 12 is driven to lower the first subshaft 8,
At the same time, the second subshaft 9 is raised to bring only the first wheel 13 into contact with the ground, as shown in FIG. 2(a). In other words, the restriction of the running direction of the first wheel 13 by the second wheel 14 is released. In this state, the first wheel 13 is driven to rotate at an angular velocity ωw, and at the same time the main shaft 3 is driven to turn at an angular velocity ωc.

At this time, the radius of the first wheel 13 is Rw,
If the distance (turning radius) of the first wheel from the turning center is Rc, and the following condition is satisfied: ωw・Rw=ωc・Rc, since the second wheel 14 is not in contact with the ground, the second wheel 14 is not in contact with the ground. As shown in FIG. b, the first wheel 13 smoothly pivots around the pivot center.

Further, when the running angular velocity ωwr is given to the first wheel 13, that is, when steering with the first wheel 13 being driven at the running angular velocity ωwr, ωw=ωwr+(Rc/Rw )・ωc If the main shaft 3 is driven to rotate so as to satisfy the following condition,
A turning component is given to the first wheel 13, and the first wheel 13 is smoothly steered.
Therefore, if the steering with other traveling devices provided on the vehicle body 1 is performed in conjunction with each other, it becomes possible, for example, to make turns on the spot, and it is also possible to easily perform complicated steering operations such as side-by-side maneuvers. It becomes possible.

On the other hand, when traveling on uneven ground with stairs, steps, slopes, and unevenness, the first and second sub-shafts 8 and 9 are related to each other and the forward and backward drive is controlled in opposite directions depending on the situation. do. The situation of the above-mentioned uneven ground is, for example, as shown in Fig. 3a, each sub-axis 1
The pressure is detected by the pressure sensor 18 provided at the tip of the parts 3 and 14. The pressure sensor 18 includes four strain gauges R1, R2, and R that detect the forces applied to the first and second wheels 13 and 14 in the running direction, respectively.
3 and R4, and are configured by being bridge-connected as shown in FIG.

Therefore, each of the above strain gauges R1, R2, R3,
The resistance values of R4 are all equal R, and the resistance value change of each strain gauge R1, R2, R3, R4 is Δr1,
If Δr2, Δr3, and Δr4 are in an equilibrium state when there is no load, then the output voltage eo of the bridge in this equilibrium state is eo≒ei(Δr1−Δr2+Δr3−Δr4)/4R, where the bridge applied voltage is Ei. Become.

Now, if the forces that the wheels 13 and 14 receive when they are moving in the direction of arrow A in the figure are Fr and Ff, then
The resistance value changes Δr1, Δr2, Δr3, and Δr4 occurring in the strain gauges R1, R2, R3, and R4 provided at the tips of the first and second sub-shafts 8 and 9 are as follows: Δr1→ ΔRbf+ΔRof Δr2→ ΔRbr+ΔRor Δr3→− ΔRbr+ΔRor Δr4→−ΔRbf+ΔRof. However, ΔRb indicates the change in resistance value due to bending of the tip of the subshaft due to external force applied to the wheel.
ΔRo indicates the change in resistance value due to axial force and temperature. The subscripts r and f indicate the first wheel 13 at the rear in the direction of travel and the second wheel 14 at the front in the direction of travel.

Therefore, the output voltage eo of the bridge circuit becomes eo≈ei(ΔRbf−ΔRbr)/2R with respect to the change in resistance value ΔRb caused by the external force. When the external forces applied to each of the wheels 13 and 14 are equal, the output voltage eo of the bridge circuit (pressure sensor) becomes zero. Moreover, each wheel 13,
The above output voltage varies depending on the external force applied to 14.
eo is a positive or negative value.

This device utilizes the output of such a pressure sensor to control the vertical movement (advance and retreat) of the first and second subshafts 8 and 9, thereby enabling the device to travel on rough terrain. That is, here, when the output voltage eo is positive, the second wheel 14 on the front side in the running direction is raised (the first wheel 13 on the rear side in the running direction is lowered), and when the output voltage eo is negative, the second wheel 14 on the front side in the running direction is lowered. second on the side
(the first wheel on the rear side in the running direction) is lowered.
wheel 13). Also the above output voltage eo
When is zero, the first and second subshafts 8 and 9 are kept in that state (not driven forward or backward).

FIGS. 4 to 7 schematically show representative examples of the control form.

That is, in the case of going up stairs, the wheel 14 on the front side in the traveling direction first comes into contact with the edge of the stairs and receives an external force, as shown in FIG. 4a. As a result, the output voltage eo becomes positive and the wheel 14 is lifted. wheel 14
When the vehicle climbs onto the stairs, the external force disappears, so the output voltage eo becomes zero, and the wheels 13 and 14 run in an inclined state. After that, the wheels 13 on the rear side in the running direction come into contact with the edge of the stairs and receive an external force, so that the output voltage increases.
eo becomes negative and the wheel 13 is lifted. When the wheels 13 reach the top of the stairs, the external force disappears and the output voltage eo becomes zero, so that the wheels 13 run horizontally again. By repeating this process, the wheels 13 and 14 move up the stairs.

Figure 5 shows a model for going down stairs. In this case, since the external force acts in the opposite direction, the above-mentioned output voltage eo is generated with the polarity opposite to that of the model shown in FIG. You will lower the wheels 13 and go down the stairs.

Moreover, FIG. 6 shows a model for going up and down a slope. In this case, when transitioning from a horizontal state to a slope, the wheels 14 on the front side in the traveling direction are first moved up and down in accordance with the slope. After that, when the rear wheel 13 enters the slope, the same external force as the front wheel 14 is applied to the wheel 13, so the wheels 13 and 14 tilt according to the slope. This will allow you to drive stably on that slope.

Note that when the direction of the slope changes as shown in FIG. 7, the polarity of the output voltage eo changes accordingly, so the wheels 13, 1
4 is controlled to move up and down, and travels according to changes in the slope.

In addition, here, the second wheel 14 which is a guide wheel
Although the description has been made assuming that the first wheels 13 are on the front side in the direction of travel, the same effect can be obtained even when the first wheels 13, which are the driving wheels, are on the front side.

Furthermore, when detecting the external force and controlling the vertical movement of the wheels 13 and 14, stable running can be obtained by simultaneously controlling the vertical movement speed using the output voltage eo value of the pressure sensor. . That is, when an external force suddenly acts and the output voltage eo increases, the wheels 13 and 14 move up and down rapidly, and conversely, when the output voltage eo changes slowly, the wheels 13 and 14 move up and down rapidly. The vertical movements of 13 and 14 may be performed gently. Specifically, for example, the output voltage eo may be differentiated to determine the rate of change in its value, and the vertical speed of the wheels 13 and 14 may be controlled in accordance with that information.

By using such control in combination, stable running that closely follows changes in the running surface can be achieved.

8 and 9 schematically show the flow of control of the drive system of the present traveling device, with FIG. 8 showing the normal running mode and FIG. 9 showing the steering mode, etc.

In the normal driving mode, speed control is performed depending on the state of fault detection, and the vehicle runs at high speed when there is no fault, and at low speed when a fault is detected.
During such traveling, the vertical movement of the front and rear wheels is controlled according to the output voltage eo. The control of this secondary axis is
This is done in proportion to or at a speed proportional to the control value e. Then, while detecting a fault by comparing the magnitude of the output voltage eo with a predetermined threshold level, the vehicle is driven to travel while controlling the traveling speed.

In addition, in a control mode such as steering, the front wheels are lifted and only the rear wheels, which are driving wheels, are in contact with the ground, and in this state, the turning axis and the running wheels (rear wheels) are driven according to information about the direction and amount of steering. It will be done as follows.

As described above, the present device enables stable running even on uneven terrain including stairs and steps, and in combination with the above-mentioned steering performance, a great practical effect can be achieved. Moreover, unlike the conventional drive system using a caterpillar, there is less slip loss in the running system, and efficient running is possible by utilizing the back drivability of the subshaft drive system. is played.

Note that the present invention is not limited to the embodiments described above. For example, as shown in FIG. 10, a pinion 11 fixed to a subshaft drive actuator 12
The racks 8a provided on the countershafts 8, 9,
9a may be directly driven.
Furthermore, since the driving of the subshafts 8 and 9 and the rotation of the main shaft 3 are not performed at the same time, one actuator 21 is shared, as shown in FIG. 11, for example.
Clutches 22a and 22 are connected to this actuator 21.
b, brakes 23a, 23b, and further reducer 24
The gear 6 for rotating the main shaft and the pinion 12 for vertically moving the countershaft may be selectively driven through the gears a and 24b, respectively.

Furthermore, as shown in FIG. 12, the vertical movement of the first subshaft 8 is controlled by the rotation of the ball screw 25 and the subshaft 8.
Driven by a screw nut 26 which is provided in and meshes with the ball screw 25,
The vertical movement of this first sub-shaft 8 is controlled by the racks 8a and 9.
The first and second countershafts 8, 9 may be driven in opposite directions in relation to each other by transmitting the signal to the second countershaft 9 via the pinion 11 and the first countershaft 8, 9.

With such a configuration, the secondary shaft 8,
It becomes possible to improve the driving efficiency of the device 9, and the driving power can be reduced to simplify the device. Further, according to the configuration shown in FIG. 12, since the vertical movement of the sub-shaft is controlled and positioned only by the rotation of the ball screw 25, effects such as accurate and stable control of the sub-shaft can be achieved. It will be done. As described above, the present invention can be implemented with various modifications without departing from the gist thereof.
It has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention;
Fig. 2 is a diagram for explaining the steering action of the embodiment device, Fig. 3 is a diagram showing the configuration of a pressure sensor responsible for controlling the vertical movement of the subshaft, and Figs. 4 to 7 are diagrams for explaining the vertical movement of the subshaft. Figures 8 and 9 are diagrams each showing a model of rough terrain driving under dynamic control, respectively, and Figures 10 to 1 are diagrams showing a schematic flow of device control, respectively.
FIG. 2 is a main part configuration diagram showing a modification of the present invention. 1...Vehicle body, 2...Fixed base, 3...Main shaft for steering, 8, 9...Subshaft, 8a, 9a...
Rack, 10... Guide roller, 11... Pinion, 13, 14... Wheel, 16... Spline shaft, R1, R2, R3, R4... Strain gauge.

Claims (1)

[Scope of Claims] 1. A main shaft for steering rotatably supported on a fixed base, first and second sub-shafts provided parallel to the main shaft so as to be movable in the axial direction thereof, and these sub-shafts. means for driving the first and second sub-shafts forward and backward in opposite directions in relation to each other; and a means for driving the first and second sub-shafts forward and backward in opposite directions; A traveling device comprising first and second wheels rotatably and parallel to each other at the tip of a subshaft. 2 The first wheel is positioned such that its rotation axis is orthogonal to the rotation axis of the steering main shaft,
The traveling device according to claim 1, wherein the traveling device is rotatably driven. 3. The means for driving the first and second sub-shafts forward and backward in opposite directions in relation to each other is configured to detect the force applied to the first and second sub-shafts when the main shaft for steering is turned, or when the force is applied to the first and second sub-shafts. The traveling device according to claim 1, which is driven. 4. Drive control of the first and second countershafts is performed by controlling the force applied in the running direction of the first and second wheels by pressure-sensitive sensors provided at the tips of the first and second countershafts. The traveling device according to claim 3, wherein the traveling device is operated by detection. 5 The means for driving the first and second sub-shafts forward and backward in opposite directions in relation to each other is
2. The traveling device according to claim 1, comprising pinions for driving racks provided on countershafts of the racks in opposite directions, and an actuator for rotationally driving the pinions. 6 The means for driving the first and second sub-shafts forward and backward in opposite directions in relation to each other is
Claim 1, which comprises a pinion that drives racks provided on each sub-shaft in opposite directions to each other, and an actuator that drives the first or second sub-shaft forward and backward through a ball screw mechanism. The traveling device according to item 1. 7. The actuator selectively drives the first and second countershafts forward and backward, or the main shaft for steering, through a drive power transmission system consisting of a brake and a clutch, or a brake and a differential gear. A traveling device according to claim 5 or 6.