JPH07110711A - Moving robot - Google Patents

Abstract

PURPOSE:To provide the moving robot which can easily and quickly avoid an obstacle. CONSTITUTION:A microcomputer 7 outputs a control signal to drivers 8A and 8B, and drivers 8A and 8B output the driving currents based on the control signal to servo motors 9A and 9B to drive right and left driving wheels independently to each other. The control program consisting of an obstacle avoiding algorithm is stored in the memory of the miocrocomputer 7. When the distance to the obstacle is longer than a prescribed reference distance, the microcomputer 7 sets the virtual repulsive force to '0' and moves an electric wheelchair 1 forward/backward or in the turning direction in accordance with the operation of a joystick 11. When the distance to the obstacle is shorter than the reference position, the microcomputer 7 sets the virtual repulsive force supposed by the dumper of a spring-dumper system and moves the electric wheelchair 1 forward/ backward or in the turning direction by the manipulated variable corrected in accordance with the strength and the direction of the repulsive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile robot.

[0002]

2. Description of the Related Art Conventionally, as a mobile robot of this type, for example, Japanese Patent Laid-Open No. 4-271410 has been disclosed. This mobile robot is intended to prevent an unfamiliar operator from making an erroneous operation by switching the steering control direction by the control device to the left and right in accordance with the traveling direction of the mobile robot.

However, in the above mobile robot, unless the operator is proficient in operating the mobile robot, he or she collides against a wall or the like against the intention of the operator, and avoids obstacles in the traveling route well. There was a problem that I could not do it. Therefore, as a conventional mobile robot having an obstacle avoidance function, there is one that includes a sensor that detects the position of an obstacle, and when it detects an obstacle, it slows down and stops to avoid a collision with the obstacle. Are known.

[0004]

However, in the above mobile robot, although the collision with the obstacle can be avoided, the robot is forced to retreat and reestablish its posture after slowing down and stopping,
After that, it moves forward again to reach the destination intended by the worker. As a result, the operation of the mobile robot becomes dull, which causes a problem that the mobile robot cannot move quickly. Also, when moving in a narrow area surrounded by walls on both sides of the traveling path, the moving robot will stop because the distance to the obstacle (wall) becomes a certain value or less and pass between obstacles. There is a risk that it will not be possible.

The present invention has been made in view of the above problems, and an object thereof is to provide a mobile robot capable of easily and promptly avoiding obstacles and moving. is there.

[0006]

In order to achieve the above object, the present invention, as shown in FIG. 9, includes a mobile robot which moves in a forward or backward direction or a turning direction by a predetermined amount of movement, so as to move forward or backward. Drive means M1 for driving the moving means, obstacle detection means M2 for detecting the distance and direction to the obstacle, and the obstacle detected by the obstacle detection means M2 is separated from a predetermined distance. In this case, the first momentum calculation means M3 for calculating the momentum in the forward / backward direction and the momentum in the turning direction according to the predetermined movement amount and the obstacle detected by the obstacle detection means M2 are closer than a predetermined distance. In this case, the amount of movement in the forward / backward direction and the amount of movement in the turning direction are calculated according to the predetermined amount of movement, and the direction opposite to the detection direction of the obstacle by the obstacle detection means M2 is calculated. A second momentum calculation means M4 for correcting the momentum so that the momentum increases, and the driving means M1 is operated by the first or second momentum calculation means M3, M4 in the forward and backward direction and the turning direction. The gist is that the control means M5 for controlling is provided.

Further, as described in claim 2, the second momentum calculation means M4 assumes a predetermined repulsive force in a direction opposite to the detection direction of the obstacle, and determines the magnitude of the repulsive force. It may be configured to correct the momentum according to the direction.

Further, as described in claim 3, assuming a virtual bumper at a predetermined distance from the obstacle, the second
The momentum calculation means M4 calculates the repulsive force by the bumper according to the distance at which the obstacle approaches the predetermined distance, and modifies the momentum according to the magnitude and direction of the repulsive force. May be.

[0009]

According to the above construction, the driving means M1 drives the moving means for moving forward and backward or turning. Obstacle detection means M2
Detects the distance and direction to an obstacle. When the obstacle detected by the obstacle detection means M2 is farther than a predetermined distance, the first momentum calculation means M3 calculates the forward / backward movement amount and the turning direction movement amount according to the predetermined movement amount. . When the obstacle detected by the obstacle detecting means M2 is closer than a predetermined distance, the second momentum calculating means M4 calculates the forward / backward movement amount and the turning direction momentum according to the predetermined movement amount. At the same time, the momentum is corrected so that the momentum in the direction opposite to the detection direction of the obstacle by the obstacle detection means M2 becomes large. Control means M
Reference numeral 5 controls the operation of the drive means M1 by the momentum in the forward and backward movement direction and the turning direction by the first or second momentum calculation means M3, M4.

That is, when the mobile robot and the obstacle come closer than a predetermined distance, the moving direction of the mobile robot is corrected in a direction opposite to the detection direction of the obstacle. For example, if an obstacle is detected diagonally forward with respect to the forward direction of the mobile robot and the obstacle is closer than a predetermined distance, the mobile robot decelerates with respect to the obstacle and moves in a direction to avoid the obstacle. Turn.

According to the configurations of claims 2 and 3,
Obstacles are avoided depending on the magnitude and direction of the repulsive force.
In particular, according to claim 3, since the repulsive force is calculated by the virtual bumper, the impact at the time of avoiding the obstacle is reduced. In addition, when it is far from the obstacle, the repulsive force required to avoid the obstacle is small, and the closer to the obstacle,
The repulsive force for avoiding obstacles increases.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a control system for an electric wheelchair will be described below with reference to the drawings.

FIG. 2 shows a side view of the electric wheelchair 1 as a mobile robot, and FIG. 3 shows a schematic view of the electric wheelchair 1 seen from above. The electric wheelchair 1 has a pair of left and right drive wheels 3
A and right drive wheels 3B are provided, and left and right drive wheels 3A, 3
Servo motors 9A and 9B are connected to B, respectively. The left and right drive wheels 3A and 3B are rotated by driving the servomotors 9A and 9B. The electric wheelchair 1 moves forward and backward at the average value of the rotational speeds of the left and right drive wheels 3A, 3B (that is, the average value of the rotational speeds becomes the forward speed of the electric wheelchair 1), and the left and right drive wheels 3A, 3B rotate. The vehicle turns by the speed difference (that is, the rotation speed difference divided by the tread becomes the yaw rate of the electric wheelchair 1). The treads of the left and right drive wheels 3A and 3B are "2d". In addition, an auxiliary wheel 4 is provided at the front of the electric wheelchair 1 so as to be rotatable in any direction.

Around the electric wheelchair 1, for example, infrared rays
First to eighth distance sensors S1 to S8, which are sensors
Has been done. In this embodiment, the first distance sensor S1 is
It is arranged in the forward direction of the wheelchair 1 (the y direction in FIG. 3).
The other distance sensors S2 to S8 are counterclockwise and are arranged in numerical order 4
They are arranged at 5 ° intervals. That is, the first to eighth distance sections
Mounting angle of sensors S1 to S8_i(I = 1 to 8) are respectively
θ₁= 0 °, θ₂= 45 °, θ₃= 90 °, θ_Four= 13
5 °, θ_Five= 180 °, θ₆= -135 °, θ ₇= -9
0 °, θ₈= -45 ° and each of the distance sensors S1 to S
The obstacle detection direction of 8 is the above mounting angle θ_i(I = 1 to 1
It conforms to 8). And distance sensor
S1 to S8 are obstacles located around the electric wheelchair 1.
Measure the distance at.

On the other hand, the electric wheelchair 1 includes the same electric wheelchair 1
A joystick 11 for manipulating the is provided. Then, the electric wheelchair 1 moves forward and backward according to the operation amount of the joystick 11 in the front-rear direction, and turns according to the operation amount of the lateral direction.

FIG. 1 shows an electric wheelchair 1 in this system.
3 is a block diagram showing the electrical configuration of FIG. Electric wheelchair 1
Is a well-known CPU (central processing unit), ROM (read only memory), RAM (random access memory), I
A microcomputer (hereinafter abbreviated as a microcomputer) 7 as a logical operation circuit including an / O (input / output) port and the like is provided. The microcomputer 7 outputs a control signal (in this embodiment, a command torque signal described later) to the drivers 8A and 8B, and the drivers 8A and 8B output drive currents to the servomotors 9A and 9B based on the control signals. The servomotors 9A and 9B use the drive current to drive the left and right drive wheels 3
A and 3B are independently driven. Servo motor 9
The rotation of the left and right drive wheels 3A and 3B by A and 9B is performed by an encoder 10A, which is provided on the rotation shaft of each drive wheel 3A and 3B.
It is detected at 10B. The microcomputer 7 has an encoder 10
Based on the detection signals from A and 10B, each drive wheel 3A,
The rotation speeds w _L (t) and w _R (t) of 3B are calculated. Further, the detection signals from the distance sensors S1 to S8 are input to the microcomputer 7, and the microcomputer 7 calculates the distance from the electric wheelchair 1 to the obstacle based on the detection signal.

Further, the operation signal of the joystick 11 is input to the microcomputer 7, and the microcomputer 7 calculates the driving force F (t) in the forward and backward directions corresponding to the operation amount of the joystick 11 in the forward and backward directions, and also in the lateral direction. The driving force S (t) in the turning direction corresponding to the operation amount is calculated.

The memory of the microcomputer 7 stores a control program consisting of an obstacle avoidance algorithm. The outline of the obstacle avoidance algorithm in this embodiment will be described. As shown in FIG. 4, a region (region surrounded by a two-dot chain line in FIG. 4) P having a reference distance z ₀ is set around the electric wheelchair 1, and an obstacle (for example, a pillar, a desk, a wall, etc.) is set. ) H enters the area P, the electric wheelchair 1 receives a predetermined repulsive force B _i (t), and the momentum of the electric wheelchair 1 is corrected by the repulsive force B _i (t). There is. here,
A spring-damper system bumper is assumed in the region P, and the bumper generates a repulsive force B _i (t) due to the elastic action of the spring and the buffer action of the damper. Further, in this algorithm, the frictional force μB _i (t) (where “μ is a friction coefficient) is assumed in the direction orthogonal to the repulsive force B _i (t) and in the direction of decelerating the forward speed.

Further, in this case, the reference distance z ₀ is common to all the sensors, and the microcomputer 7 subtracts the reference distance z ₀ from the distance z _i (i = 1 to 8) measured by the distance sensors S1 to S8. Displacement from the reference distance z ₀ Δz _i (Δz _i = z
_i −z ₀ ). Then, the larger the absolute value of the displacement amount Δz _i, the larger the repulsive force B _i (t). The repulsive force B _i (t) acts on the center of gravity of the electric wheelchair 1 in the mounting angle direction of each of the distance sensors S1 to S8 (opposite to the detection direction of the obstacle H).

In this embodiment, the left and right drive wheels 3A, 3B constitute a moving means, and the left and right servomotors 9A, 9B are used.
The drive means is constituted by. Also, the distance sensor S1
S8 to S8 constitute an obstacle detecting means, and the microcomputer 7 constitutes a first momentum calculating means, a second momentum calculating means and a controlling means.

Next, the operation and effect of the control system in this embodiment will be described. FIG. 5 is a flowchart showing a routine executed by the microcomputer 7 at every predetermined cycle (for example, every 10 ms), and the traveling control of the electric wheelchair 1 including the obstacle avoidance algorithm is executed by the routine.

Now, when the routine of FIG. 5 starts,
First, in step 100, the microcomputer 7 determines, based on the operation amount of the joystick 12, the driving force F in the forward / backward direction and the turning direction.
Calculate (t) and S (t). Further, the microcomputer 7 subtracts a predetermined reference distance z ₀ from the measured distance z _i (t) by the first to eighth distance sensors S1 to S8 in step 110 to calculate the displacement Δz _i (t) (= z _i Calculate (t) −z ₀ ).

Further, in step 120, the microcomputer 7 uses the following equation (1) to generate a repulsive force B corresponding to the displacement amount Δz _i (t).
_i (t) is calculated, and the repulsive force B _i (t) is multiplied by a predetermined friction coefficient μ to calculate a friction force μB _i (t). It should be noted that “ζ” and “ω” in the following equations are design parameters when a damper including a spring-damper system is assumed.

[0024]

[Equation 1]

That is, in the above equation (1), "2ζω"
Corresponds to the viscosity coefficient term of the spring-damper system, and “ω ² ” corresponds to the spring coefficient. According to the equation (1), Δz _i (t) <0
In the case of, that is, when the obstacle H is closer than the reference distance z ₀ , the repulsive force B _i (t) is obtained according to the displacement amount Δz _i (t), and when Δz _i (t) ≧ 0 That is, when the obstacle H is separated from the reference distance z ₀ , the repulsive force B _i (t) becomes “0”.

Subsequently, in step 130, the microcomputer 7 defines the movements of the center of gravity of the electric wheelchair 1 in the x and y directions using the following equations (2) and (3). Where (x,
y) is a variable on the coordinate axis of FIG. 3 fixed to the electric wheelchair 1, and the center of gravity of the electric wheelchair 1 is set as the origin. That is, the microcomputer 7 calculates the driving force F (t) in the forward / backward direction (y direction in FIG. 3) and the driving force S (t) in the turning direction (x direction in FIG. 3) calculated in step 100. By combining the repulsive force B _i (t) from the obstacle H and the frictional force μB _i (t), the motion of the center of gravity of the electric wheelchair 1 is defined. In addition, "
D ″ is a viscous resistance coefficient associated with driving the servomotors 9A and 9B.

[0027]

[Equation 2]

[0028]

[Equation 3]

In step 140, the microcomputer 7 determines the forward speed v (t) and the yaw rate r as control variables based on the motion state of the electric wheelchair 1 defined in step 130.
Calculate (t). That is, in this embodiment, the electric wheelchair 1
Is driven by driving the left and right drive wheels 3A and 3B, and the direction of the electric wheelchair 1 is always in the tangential direction of the locus. Therefore, the forward speed v (t) of the electric wheelchair 1 and the yaw rate r
(t) is calculated by the following equations (4) and (5).

[0030]

[Equation 4]

[0031]

[Equation 5]

Next, the microcomputer 7 determines in step 150 the target rotational speeds wτ _L (t) and wτ _R of the left and right drive wheels 3A and 3B.
Calculate (t). Specifically, the microcomputer 7 uses the forward speed v (t) and the yaw rate r (t) calculated in the above step 140 to calculate the left and right target rotational speeds according to the following expressions (6) and (7). Calculate w τ _L (t) and w τ _R (t). Here, “d” is the drive wheels 3A, 3 from the center of gravity of the electric wheelchair 1.
Distance to B (1/2 of tread).

[0033]

[Equation 6]

[0034]

[Equation 7]

Thereafter, the microcomputer 7 proceeds to the next step 16
0 the left and right servo motors 9A, command torque T _L as the control amount of 9B (t), calculates the T _R (t). In particular,
The microcomputer 7 determines the actual rotational speed w _L (t) of the left and right drive wheels 3A and 3B based on the detection signals of the encoders 10A and 10B.
, W _R (t) are the target rotational speeds wτ _L (t), wτ described above.
_In order to match _R (t) with each other, the command torque _TL (t) is calculated by the following equations (8) and (9) using PI control, for example.
, T _R (t) is calculated. Note that “K _PL ” and “K _PR ” are proportional gains, and “K _IL ” and “K _IR ” are integral gains.

[0036]

[Equation 8]

[0037]

[Equation 9]

Thereafter, the microcomputer 7 outputs the command torques T _L (t) and T _R (t) in step 170 to drive the servo motors 9A and 9B. Then, the servo motor 9A,
The electric wheelchair 1 runs as the 9B is driven.

FIG. 6 shows an obstacle avoiding operation of the electric wheelchair 1 according to the above algorithm. The joystick 11 is fixed in the forward direction, and the electric wheelchair 1 is initially moving diagonally with respect to the obstacle H (wall surface).
Further, FIG. 7 shows the forward speed v when avoiding the obstacle of FIG.
(t) and yaw rate r (t) are shown with time.

That is, in FIG. 7, the distance between the electric wheelchair 1 and the obstacle H is the reference distance z ₀ (FIG. 4) during the period from time t1 to t2.
(Refer to FIG. 4), and the repulsive force B _i (t) is set according to the distance between the electric wheelchair 1 and the obstacle H within the same period.
At this time, the forward speed v (t) gradually changes according to the forward direction component (the y direction component in FIG. 3) of the repulsive force B _i (t).
Further, the yaw rate r (t) changes according to the turning direction component (the x direction component in FIG. 3) of the repulsive force B _i (t) (when the counterclockwise direction is set to + in FIG. 7, the yaw rate r (t) ) Is a minus value). As a result, the electric wheelchair 1 can gradually correct the posture in the turning direction with respect to the obstacle and smoothly avoid the obstacle H.

When a plurality of obstacles H are scattered in the traveling area, the electric wheelchair 1 smoothly meanders while avoiding the obstacles H as shown in FIG. You can follow the route. In addition, electric wheelchair 1
When there are obstacles H on both sides of the obstacle, the obstacles can be decelerated in accordance with the repulsive force B _i (t) from both obstacles and the middle of both obstacles can be advanced. There is no stopping between things.

As described above in detail, the electric wheelchair of this embodiment
In the control system of the child 1, the obstacle H has a predetermined reference distance z.
₀Virtual repulsive force B_i(t) = 0
(Step 120 in FIG. 5), the joystick 11
Operate the electric wheelchair 1 according to the operation
I moved it to. Also, the obstacle H is the reference distance z ₀
If it is closer than the
Repulsive force B_iWhile setting (t),
120), repulsive force B_iDepending on the size and direction of (t)
Rotate the electric wheelchair 1 in the forward / backward direction and turn with the corrected operation amount.
It was moved in the turning direction (step 13 in FIG. 5).
0).

According to the above configuration, when the obstacle H is approached, the electric wheelchair 1 is turned in a direction away from the obstacle H, and the obstacle H can be avoided and the movement can be continued. As a result, without the need for advanced maneuvering skills,
The object of the present invention can be achieved by easily and promptly avoiding obstacles and moving. Further, in this embodiment, the repulsive force B _i is assumed assuming a spring-damper system bumper.
Since (t) is calculated, the impact during the avoidance motion of the electric wheelchair 1 is reduced, and a smoother motion can be realized.

The present invention is not limited to the above embodiment, but can be embodied in the following modes. In the above embodiment, the repulsive force setting parameters (“ζ” and “” in the equation (3)) in the obstacle avoidance algorithm are used.
ω ″) is the same on the left and right, but it may be set separately on the left and right. In this case, when avoiding the obstacle on the left side, drive closer than when avoiding the obstacle on the right side. Will be possible.

In the above embodiment, the repulsive force is set assuming a spring-damper type bumper, but this may be changed to a spring type or damper type bumper. Further, instead of the repulsive force by the bumper, a repulsive force having a constant magnitude generated in a direction opposite to the obstacle detection direction may be assumed.

In the above embodiment, the mobile robot is embodied as an electric wheelchair, but it may be embodied as another robot such as a transfer robot or a guide robot. In addition, as a configuration of the mobile robot, a pair of left and right drive wheels connected by a drive shaft may be driven by a drive means (servo motor or the like), and a steerable wheel that can be turned may be separately provided.

Further, instead of the operation amount from the control device, C
Control may be performed using the amount of movement from image information or the like in an autonomous mobile robot including a CD camera or the like. In the above embodiment, the distance sensor S1 having a constant detection direction.
Although S8 is used, a swing type distance sensor may be used. In this case, the direction of the obstacle can be detected by the swing angle of the distance sensor.

[0048]

According to the present invention, when the distance to an obstacle is closer than a predetermined distance, the mobile robot moves in a direction to avoid the obstacle, that is, in a predetermined turning direction, thereby easily and Obstacles can be avoided quickly.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a control system for an electric wheelchair in this embodiment.

FIG. 2 is a side view showing a configuration of an electric wheelchair.

FIG. 3 is a schematic diagram showing a configuration of an electric wheelchair viewed from above.

FIG. 4 is a schematic diagram showing a state in which an electric wheelchair and an obstacle approach each other.

FIG. 5 is a flowchart showing a traveling control routine of the electric wheelchair.

FIG. 6 is a schematic diagram showing a trajectory of an obstacle avoidance operation of the electric wheelchair.

FIG. 7 is a time chart showing changes in forward speed and yaw rate with time when avoiding an obstacle.

FIG. 8 is a schematic diagram showing obstacle avoidance traveling of the electric wheelchair.

FIG. 9 is a block diagram corresponding to the claims of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric wheelchair as a mobile robot, 3A ... Left drive wheel as a moving means, 3B ... Right drive wheel as a moving means,
7 ... First momentum calculation means, second momentum calculation means, microcomputers as control means, 9A, 9B ... Servo motors as drive means, S1 to S8 ... Distance sensors as obstacle detection means, H ... Obstacles object.

Claims (3)

[Claims] 1. A mobile robot which moves in a forward or backward direction or a turning direction by a predetermined movement amount, a driving means for driving a moving means for forward or backward movement, and an obstacle for detecting a distance and a direction to an obstacle. When the object detecting means and the obstacle detected by the obstacle detecting means are apart from each other by a predetermined distance, a first momentum in a forward and backward direction and a momentum in a turning direction according to the predetermined movement amount are calculated. Momentum calculation means, when the obstacle detected by the obstacle detection means is closer than a predetermined distance, while calculating the momentum in the forward and backward directions and the momentum in the turning direction according to the predetermined movement amount, Second momentum calculation means for modifying the momentum so that the obstacle detection means increases the momentum in a direction opposite to the detection direction of the obstacle, and the first or second momentum performance Mobile robot is characterized in that a control means for controlling operation of said drive means in forward and backward direction and the turning direction of the momentum by means. 2. The second momentum calculation means assumes a predetermined repulsive force in a direction opposite to the detection direction of the obstacle,
The mobile robot according to claim 1, wherein the momentum is corrected according to the magnitude and direction of the repulsive force. 3. A virtual bumper is assumed at a predetermined distance from an obstacle, and the second momentum calculation means uses the bumper according to the distance at which the obstacle approaches the predetermined distance. The mobile robot according to claim 1, wherein the repulsive force is calculated, and the momentum is corrected according to the magnitude and direction of the repulsive force.