JP2002144265A - Control method of movable part of robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compliance-control approaching movement of a movable part of a robot to an approaching object by using an optical sensor which is an inexpensive and light weight sensor. SOLUTION: The optical sensors 33-35 to detect light from a ground surface 36 are provided on a walking leg 2 and lowering movement of the walking leg 2 is controlled in speed in three stages before grounding on the ground surface 36 in accordance with a change of output signals of the optical sensors 33-35 by the light from the ground surface 36 at the time of controlling the lowering movement to the ground surface 36 as an approaching object of the walking leg 2 as the movable part of the robot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a control method suitable for controlling a movable portion of a robot, particularly for compliance control of a walking leg of a walking robot.

[0002]

2. Description of the Related Art Conventionally, for compliance control of a walking leg of a walking robot (control for actively realizing softness), an optical distance measuring device such as a laser type distance sensor is mounted on a walking leg as a movable portion. Provided, the distance between the walking leg and the ground surface to be approached was measured. However, since such a sensor is very expensive, it is very difficult to use it for a six-legged robot or the like. Met.

Also, optical distance measuring devices such as laser type distance sensors have large sensor bodies and amplifiers, so that a large load is applied to a motor torque and a driving mechanism for driving a walking leg when a walking robot walks. Gave.

Further, conventionally, since the distance measurement data is used as described above, a complicated program or the like relating to the compliance control is created and executed, so that there is a malfunction and a complicated control.

When a walking robot is used for land mine detection or the like, a sensor for detecting a buried land mine is mounted on the walking leg, so that the installation space for other sensors is limited, and the number of sensors for compliance control is reduced as much as possible. Needed.

[0006]

SUMMARY OF THE INVENTION
The main points are as follows. (1) For a robot such as a walking robot, an optical sensor that is an inexpensive and lightweight sensor is used,
By controlling the approaching movement of a movable part such as a walking leg with respect to an approaching object such as the ground surface, the contact force of the movable unit with the approaching object is controlled, and the reaction force from the approaching object is reduced.

(2) In order to prevent the walking robot from falling during walking, it is possible to recognize the swelling or fragile state of the ground surface by using an optical sensor before the walking leg touches the ground, thereby enabling stable control. I do.

(3) In a walking robot or the like, the distance of a movable portion such as a walking leg to an approaching object such as the ground surface is recognized in several stages using an optical sensor, so that the walking robot can smoothly move. Compliance control.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method that advantageously solves the above-mentioned problems, and a method of controlling a movable part of a robot according to the present invention is as follows. In controlling the approaching movement of the movable part of the robot with respect to the approaching target, an optical sensor is provided on the movable part so as to detect light from the approaching target, and an output of the optical sensor by light from the approaching target. Before approaching the approaching object, the approaching movement of the movable unit is controlled based on a change in the signal.

According to this control method, by controlling the approaching movement of the movable part of the robot with respect to the approaching object by using the optical sensor, which is an inexpensive, lightweight, and small sensor, the moving part of the robot with respect to the approaching object is controlled. Since the contact force can be controlled and the reaction force from the approaching object can be reduced, compliance control of the movable part of the robot can be performed at low cost and without applying a large load to the drive motor and drive mechanism of the movable part. The sensor for compliance control can be easily installed even when the sensor installation space of the movable part is small, and it can be controlled with a relatively simple program, and highly reliable compliance control can be performed. . Here, the light sensor detects the light source provided in the movable portion, or other light sources around the approaching object or reflected light reflected by the approaching object from light from the sun, or the reflected light. Light emitted from a light source provided on the approaching object may be used.

In the control method according to the present invention, the movable portion may be a walking leg, and the approaching object may be a ground surface. In controlling the approaching movement to, the above-described effects can be obtained.

In the control method according to the present invention, the control may be to reduce the speed of the approaching movement. According to such a control method, the contact force of the movable portion with respect to the approaching object is reduced by the speed reduction. Compliance control can be performed.

Further, in the control method of the present invention,
The control may be to determine the stop position of the approach movement, according to such a control method, instead of or in addition to deceleration, the stop position of the approach movement, for example, when the movable part is a walking leg By appropriately determining whether the walking leg is higher or lower than other walking legs, compliance control for controlling the contact force of the movable portion with respect to the approaching target can be performed.

Here, the control may be in accordance with the intensity and color of light detected by the optical sensor.
In this way, conventionally, when the walking robot is active outdoors, it has been very difficult to recognize the state of the ground to be grounded (hard ground or fragile ground) before the walking leg touches the ground. However, by recognizing the intensity of the light reflected from the ground surface and the color of the soil, etc., with the optical sensor, it senses the surface condition of the place where the walking leg touches the ground and feeds back to the control to detect the standard surface condition The stop position can be shifted up to this point. For example, when the color of the soil is black and the reflected light is strong, it is moist, and when the reflected light is white, there is snow, etc.The difference in the ground surface state is that the output signal of the optical sensor in the standard ground state is The identification can be performed by calibrating the amplifier for the optical sensor so as to be in a predetermined state.

Further, in the control method of the present invention,
The movable unit is provided with a plurality of optical sensors so as to have a focal position at a plurality of distances in front of the approaching movement direction from the movable unit, respectively, and light from the approaching object is sequentially detected at the plurality of focal positions. The approach movement of the movable portion may be controlled in a plurality of stages before contacting the approaching object based on a change in output signals of the plurality of optical sensors at the time. Since the distance of the movable part such as the ground surface to the approaching object such as the ground surface can be easily recognized in several stages by the optical sensor, it is possible to easily and inexpensively realize smooth compliance control during walking or the like. it can.

In the control method of the present invention,
A contact detection sensor that detects contact between the approaching target and the movable unit; furthermore, based on output signals from the optical sensor and the contact detection sensor, the movable unit before and during the contact with the approaching target. The approaching movement may be controlled, and in this case, a more precise compliance control can be realized by cooperative control with a contact detection sensor such as a force sensor or a microswitch.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. Here, FIG. 1 is a flowchart showing a control procedure of an embodiment of a method for controlling a movable portion of a robot according to the present invention, and FIG. 2 is a diagram illustrating the control method of the embodiment applied to control of a walking leg as a movable portion. FIG. 3 is a front view showing a walking leg of the mine detection robot and a lifting drive unit of the walking leg, and reference numeral 1 in the figure denotes a main body of the mine detection robot. Denotes a walking leg, and 3 denotes an auxiliary leg having a caster at a lower end. In FIG. 2, the front left portion is the front of the mine detection robot.

The robot for detecting land mines has six walking legs 2 on each of the left and right sides of the main body 1 in total, and four auxiliary legs 3 so as to be located at the four lower corners of the main body 1. The auxiliary leg 3 here serves to support the main body 1 by contacting the ground when the walking leg 2 is not driven. On the other hand, as shown in FIG. 3, each of the walking legs 2 has one columnar portion 4 extending substantially vertically, and two link portions located at two upper and lower stages and each extending substantially horizontally. 5, 6 and one grounding part 7
The outer (leftward in FIG. 3) end portions of the two link portions 5 and 6 are connected to the columnar portion via two swing shafts 8 and 9 which are substantially horizontal and parallel to each other. 4 is connected to the upper part of the column 4 so as to be capable of swinging up and down.
The grounding portion 7 is provided at the lower end of the force sensor 10 with two swinging axes 11, 12 which are substantially horizontal and orthogonal to each other.
Swingably connected via a universal joint 13 having

The above-mentioned landmine detection robot also has three lifting drive mechanisms 14 for supporting and raising and lowering each of the walking legs 2 on the left and right sides of the main body 1, for a total of six lifting drive mechanisms 14. As shown in FIG. 3, the inner (rightward in FIG. 3) ends of the two link portions 5 and 6 of the walking leg 2 corresponding to the lifting / lowering drive mechanism 14 are substantially horizontal and parallel to each other. The swing shaft 15 and the swing shaft 15 are supported so as to be swingable in the vertical direction, and the rotation of the output shaft of the servomotor 17 is controlled by the pulley 1.
8, 19 and a belt 20 to a harmonic drive 21 which is a reduction gear having a large reduction ratio.
23 and a belt 24, the two swing shafts 15,
The upper link portion 5 which is transmitted to the upper swing shaft 15 of the upper link 16 and whose inner end is integrally connected to the upper swing shaft 15 is moved up and down as shown by an arrow A in FIG. Rock it,
The walking leg 2 constituting the four-bar link together with the lifting drive mechanism 14 and the two link portions 5 and 6 is moved up and down with respect to the main body 1 as shown by an arrow B in FIG. At this time, the lower link portion 6 swings up and down as shown by the arrow C in FIG.
The columnar part 4 is maintained in a state of extending substantially vertically.

The mine detecting robot further drives each of the lifting / lowering drive mechanisms 14 and thus each of the walking legs 2 via a pulley 25 and a belt 26, and swings the walking legs 2 substantially vertically. The main body 1 is provided with three drive mechanisms (not shown) for swinging in the front-rear direction around the main body 1 on the left and right sides of the main body 1. Ball nut 2 fixed to the inner end of the outer part 6a (the left part in FIG. 3) 6a
The ball screw shaft 29 screwed into the position 8 is rotated by the servo motor 30 and the ball nut 28 is moved along the ball screw shaft 29 so as to approach and separate from the base (the right portion in FIG. 3) 6b of the link portion 6. A traversing drive mechanism 31 for extending and contracting the length of the link portion 6 is provided.

By the various mechanisms, the mine detection robot moves the six walking legs 2 downward to move the main body 1.
, And two of the six walking legs 2 are sequentially raised and swung forward and downward to move forward, and two of the six walking legs 2 are sequentially raised and rocked. By moving, swinging backward and swinging downward, the robot walks rearward, and while the length of the link portion 6 is appropriately expanded and contracted, the two walking legs 2 are swung to move left and right. The user can walk, and the sequential operation of such various mechanisms can be controlled by a small computer (not shown) mounted on the main body 1 and a program stored in advance in a plurality of programmable controllers 31.

As shown in FIG. 3, the above-mentioned landmine detection robot further includes a buried object sensor 32 for landmine detection substantially downward at the lower end of the columnar portion 4 of each walking leg 2 along with the force sensor 10. Also, three optical sensors 33 to 35 for raising and lowering control of the walking leg 2 are fixedly provided.
Reference numerals 3 to 35 each include a built-in optical system having a focal position at a predetermined distance in front of the optical sensor (downward in the figure), and different distances (100 mm) from the lower surface of the grounding unit 7 below the grounding unit 7. , 50 mm, 30 mm), the focal points are located at three levels, and the level of the output signal is adjusted via an amplifier (not shown). Then, the output signals of the metal sensor 32 and the optical sensors 33 to 35 included in each walking leg 2 are input to the small computer via an analog / digital converter (not shown). Further, among the three optical sensors 33 to 35, an optical sensor 34 having an intermediate height in particular.
For example, by having color filters of three primary colors of light and having light receiving elements corresponding to each of the color filters, it is possible to output a signal indicating the color of light collected from the focal position. .

According to the control method of this embodiment, in order to control the ascending and descending drive of each of the walking legs 2, the descending of the once-raised walking leg 2 is controlled by the programmable controller 31. FIG.
The descent is performed according to the procedure shown in FIG. The control of the servomotor 17 of the lifting drive mechanism 14 by the programmable controller 31 is a rotational motion control at a constant speed.

In the procedure shown in FIG. 1, first, in step S1
The change in the output signal from the optical sensor 33 whose focal point is located at a distance of 100 mm from the lower surface of the grounding unit 7 located at the lowest position among the three optical sensors shown in FIG. When the distance between the ground surface 36 and the lower surface of the grounding portion 7 of the walking leg 2 becomes 100 mm, a signal is sent from the small computer to the programmable controller 31 immediately at the time of the detection, and the servo motor 17 is kept constant. Control to reduce the rotation speed from before is executed. Next, in step S2, an optical sensor 34 located at an intermediate position among the three optical sensors shown in FIG.
The small computer detects that the distance between the ground surface 36 and the lower surface of the grounding portion 7 of the walking leg 2 has become 50 mm based on the change state of the output signal from the small computer. A signal is sent to the controller 31 to execute control for further reducing the constant rotation speed of the servomotor 17.

Further, here, in step S3, the output signal of the optical sensor 34 whose focal point is located at a distance of 30 mm from the lower surface of the grounding portion 7, which is located at the highest position among the three optical sensors shown in FIG. According to the change state, the small computer detects that the distance between the ground surface 36 and the lower surface of the grounding portion 7 of the walking leg 2 has become 30 mm, and immediately sends a signal from the small computer to the programmable controller 31 at the time of the detection. Then, control is performed to reduce the constant rotation speed of the servo motor 17 to the limit. Thereafter, in step S4, the distance between the walking leg 2 and the ground surface 36 is sequentially estimated based on an output signal from a potentiometer (not shown) for measuring the rotation angle (joint angle) of the swing shaft 15, and the force is determined. As soon as the contact between the walking leg 2 and the ground surface 36 is detected by the output signal from the sensation sensor 10, the servomotor 17 is stopped, and the walking leg 2 is brought into contact with the ground surface 36 at the lowest speed. That is, in this embodiment, the compliance control is performed by such stepwise reduction of the speed.

In step S2, the light sensor 34 simultaneously detects and outputs the color of the ground surface 36, and the small computer detects snow (white) on the ground surface 36 from the output signal of the light sensor 34. In this case, the grounding control, that is, the stopping of the walking leg 2 at a lower stop position in consideration of the sinking of the walking leg 2 on the ground surface 36 is performed by the pluggram, and the ground surface 36 is exposed to water (transparent). If it is recognized that there is a water-related control by the pluggram, that is, the walking leg 2 is moved laterally by the traversing drive mechanism 31 without further descending, or further swung back and forth by the advance / retreat driving mechanism, A place where landing is possible is automatically detected from an output signal of the optical sensor 34, and control for lowering the walking leg 2 to the place where landing is possible is performed.

The ground surface 36 due to such a difference in color
For example, the colors of the ground surface in different states are arranged in advance at the focal position, and the output signal of the optical sensor 34 at that time is stored in the small computer. This can be performed by calibrating the output signal in the case of the ground and the output signal in the case where the same strong ground is detected in the present use of the robot.

Further, although not shown in FIG. 1, in this embodiment, in step S2, the metal sensor 32
When the output signal of the buried object sensor 32 indicates the presence of an underground mine, the mine corresponding control, that is, the walking leg 2 is not further lowered, and an alarm is output. Of the mine below the walking leg 2 is displayed on a small display device or a display device such as a light emitting diode.

Therefore, according to the control method of the above-described embodiment, the ground sensor 36 of the walking leg 2 of the mine detection robot is provided by using the optical sensors 33 to 35, which are inexpensive, lightweight and small sensors.
By controlling the approaching movement of the walking leg 2 against the ground surface 36, the ground force of the walking leg 2 on the ground surface 36 can be controlled and the reaction force from the ground surface 36 can be reduced, so that the compliance control of the walking leg 2 of the mine detection robot can be performed. Can be performed inexpensively and without applying a large load to the servomotor 17 for driving the walking leg 2 and the lifting / lowering drive mechanism 14. The sensors 33 to 35 can be easily installed, and can be controlled by a relatively simple program, and highly reliable compliance control can be performed.

In the above embodiment, the optical sensors 33 to 3
5 detects the reflected light from the ground surface 36 which reflects the light from the sun, but the present invention is not limited to this.
For example, the light from a light source provided on the ground surface 36 or another light source grounded around the ground surface 36 may be reflected light reflected by the ground surface 36. When the present invention is applied to the control of a movable part other than a walking leg, an optical sensor may detect light emitted from a light source provided for an approaching object.

Further, according to the control method of the above embodiment, the control based on the output signals of the optical sensors 33 to 35 is performed on the ground surface 3.
Since the speed of approach movement of the walking leg 2 with respect to the ground surface 6 is reduced, compliance control for controlling the contact force of the walking leg 2 with respect to the ground surface 36 can be performed by the reduction.

Further, according to the control method of the above embodiment,
The control based on the output signal of the optical sensor 34 not only reduces the speed of the approaching movement of the walking leg 2 with respect to the ground surface 36, but also lowers the stop position when snow is present on the ground surface 36. Compliance control for preventing the robot from tipping over by controlling the contact force of the walking leg 2 against the snow on the surface 36 can be performed. In addition, here, the control based on the output signal of the optical sensor 34 is in accordance with the intensity of light detected by the optical sensor 34 and the type of color. By recognizing the soil color and the like, the ground state of the place where the walking leg 2 touches the ground is fed back to the control, and the stop position can be automatically shifted until the standard ground state is detected.

Further, according to the control method of the above embodiment,
The walking leg 2 is provided with three optical sensors 33 to 35 so as to have respective focal positions at three steps below the grounding portion 7 of the walking leg 2, and the light from the ground surface 36 is focused on the three steps. Three light sensors 33 to 3 when sequentially detected at positions
5, the descending movement of the walking leg 2 is controlled in three stages before coming into contact with the ground surface 36 based on the change in the output signal of the ground signal 36. 35, the recognition can be easily performed in three stages, so that smooth compliance control during walking can be easily and inexpensively realized.

According to the control method of the above embodiment,
Further provided is a force sensor 10 as a contact detection sensor for detecting contact of the grounding portion 7 of the walking leg 2 with the ground surface 36, and based on output signals from the optical sensors 33 to 35 and the force sensor 10, Since the descending movement of the walking leg 2 is controlled before and during touchdown, the force sensor 10
With the cooperative control with the above, compliance control with higher accuracy can be realized as compared with a case based on the output signal of only the optical sensor.

Although the present invention has been described with reference to the illustrated examples, the present invention is not limited to the above-described examples. For example, the control method of the present invention uses a hand as a movable portion of an industrial robot as an approaching object. The present invention can be applied to various cases such as a case where the work is moved closer to the work to grip or process the work.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a control procedure of one embodiment of a method for controlling a movable portion of a robot according to the present invention.

FIG. 2 is a perspective view showing a mine detection robot in which the control method of the embodiment is applied to control of a walking leg as a movable part.

FIG. 3 is a front view showing a walking leg of the mine detection robot and an elevation drive unit of the walking leg. In the drawing, reference numeral 1 denotes a main body of the mine detection robot, 2 denotes a walking leg, and 3 denotes an auxiliary leg having a caster at a lower end.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Walking leg 3 Auxiliary leg 4 Columnar part 5, 6 Link part 6a Outer part 6b Base 7 Grounding part 8, 9, 15, 16 Swing axis 10 Force sensor 11, 12, 27 Swing axis 13 Universal joint 14 Elevating drive mechanism 17, 30 Servo motor 18, 19, 22, 23, 25 Pulley 20, 24, 26 Belt 21 Harmonic drive device 28 Ball nut 29 Ball screw shaft 31 Traverse drive mechanism 32 Buried object sensor 33-35 Optical sensor 36 Ground surface

Claims (7)

[Claims] When controlling the approaching movement of a movable portion of a robot with respect to an approaching object, an optical sensor is provided on the movable portion so as to detect light from the approaching object. A method for controlling a movable part of a robot, wherein the approach movement of the movable part is controlled before contacting the approach target based on a change in an output signal of an optical sensor. 2. The method according to claim 1, wherein the movable part is a walking leg, and the approach target is a ground surface. 3. The method according to claim 1, wherein the control is to reduce the speed of the approach movement. 4. The method according to claim 2, wherein the control is to determine a stop position of the approach movement. 5. The control of the movable part of the robot according to claim 1, wherein the control is performed in accordance with at least one of a light intensity and a color type detected by the optical sensor. Method. 6. A plurality of optical sensors are provided on the movable portion so as to have respective focal positions at a plurality of distances in front of the movable portion in the approaching movement direction, and light from the approaching object is focused on the plurality of focal positions. And controlling the approaching movement of the movable section in a plurality of steps before contacting the approaching object based on a change in output signals of the plurality of optical sensors when the detection is sequentially performed in the step (c).
6. The method for controlling a movable part of a robot according to any one of items 1 to 5. 7. A contact detection sensor for detecting contact between the approaching object and the movable portion, based on output signals from the optical sensor and the contact detection sensor, before and during contact with the approaching object. Controlling the approaching movement of the movable portion of
A method for controlling a movable part of a robot according to any one of claims 1 to 6.