JP4461797B2 - Mobile robot - Google Patents

Description

  The present invention relates to a mobile robot that has a moving mechanism and arms composed of a plurality of links and conveys an object.

The legged walking robot with a link mechanism is a mechanism that can move freely even on stairs and uneven road surfaces, and it can move in all directions, so it can move in both directions as well as forward, backward, and turn. It has the characteristic that it is. Since it can be expected to have almost the same movement performance as the walking form of humans and mammals, research and development related to walking has been actively conducted so far, and the impact force generated when the legs land on the ground during walking can be reduced. There is something that can obtain stable walking control. (For example, Patent Document 1)
FIG. 6 is a control block diagram of a conventional example, and is configured to detect and reduce the external force acting on the sole when landing, so that the road surface reaction force can be effectively absorbed, Even if there are irregularities, it can be landed flexibly and a stable landing with less impact can be constructed.
Thus, the conventional walking robot reduces the impact by applying the compliance control when landing on the leg, and realizes stable walking control.
Japanese Patent No. 2819323 (7th page, FIG. 1)

Conventional walking robots reduce the impact force generated when landing on the legs, that is, high-frequency vibrations, and improve walking stability performance. Since the amplitude cannot be reduced, the object held by the arm cannot be stably carried.
The present invention has been made in view of such a problem, and provides a mobile robot capable of significantly reducing the swing of an object gripped by a mobile robot moving with a leg composed of a plurality of links. With the goal.

In order to solve the above problem, the present invention is configured as follows.
The invention according to claim 1 is a movement mechanism portion configured by a plurality of links, an arm portion configured by a plurality of links, a trunk portion to which the movement mechanism portion and the arm portions are attached, and the movement Occurs when the mobile robot has a control unit that drives and controls an actuator attached to each joint of the mechanism part, the arm part, and the trunk part, and the mobile robot moves by an acceleration sensor attached to the trunk part. A vibration calculation unit including an acceleration detection unit that detects an acceleration vector, a state conversion unit that converts the acceleration vector into a velocity vector, and the velocity vector obtained by the vibration calculation unit is multiplied by a coefficient matrix to be opposite to the velocity vector. and a reverse phase calculator for calculating a velocity vector of the phase, when the mobile robot moves, the antiphase Starring the speed command vector of the arms It is intended to superimpose the velocity vector of the inverse phase obtained in part.
According to a second aspect of the present invention, the state conversion unit time-integrates the acceleration vector and then deletes a steady component and converts the acceleration vector into the velocity vector .

According to the first aspect of the present invention, since the vibration having the opposite phase to the low frequency vibration generated by walking is superimposed on the arm hand command, the vibration caused by walking is canceled at the tip of the arm. Therefore, even if the robot is walking, the grasped object is less likely to shake with respect to the ground.
According to the fifth aspect of the present invention, since an anti-phase velocity vector can be multiplied by an arbitrary coefficient vector, the amplitude of oscillation caused by walking can be adjusted.
According to the first and second aspects of the present invention, since the steady component is deleted after the vibration is detected as an acceleration and integrated, the steady speed when moving by walking is not given to the arm. Vibration can be suppressed within the range.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a walking robot showing an embodiment of the present invention. In the figure, reference numerals 11 and 12 denote leg portions and arm portions formed of a plurality of links, and reference numeral 13 denotes a hand portion attached to the distal end of the arm portion, which has a structure capable of gripping an object conveyed by the robot. Reference numeral 14 denotes a trunk part to which the leg part and the arm part are attached, reference numeral 15 denotes a head part attached to the upper part of the trunk part, and reference numeral 16 denotes an acceleration detection part attached to the inside of the trunk part. In this embodiment, an acceleration sensor is used. Reference numeral 17 denotes a control unit that drives and controls an actuator (not shown) attached to each joint of the robot and takes in acceleration sensor information. Reference numeral 18 denotes a reference coordinate system of the robot, which matches the coordinate system of the acceleration sensor. .

FIG. 2 is a control block diagram of the walking robot showing the embodiment of the present invention. In the figure, the acceleration generated by the walking motion is detected by an acceleration detector (acceleration sensor), and the detected acceleration information (acceleration vector) is converted into a velocity vector by an integrator. The converted velocity vector is passed through a high pass filter to remove the steady component. Here, the purpose of passing through the high-pass filter is to include a steady speed component when moving by walking, and if a speed vector that includes this steady speed component is used for the hand command, it deviates from the movable range of the arm, This is to obtain only the velocity component due to vibration. Further, since the cutoff frequency of the high-pass filter is about 0.1 Hz to 1 Hz, the frequency band targeted by the present invention is much smaller than the frequency generated by the impact at the time of landing, which is the subject of Patent Document 1. The velocity vector from which the stationary component has been deleted is multiplied by a negative coefficient matrix K in the antiphase computing unit to generate a vibration velocity vector having a phase opposite to the direction of vibration caused by walking. The antiphase velocity vector generated here and the arm arm speed command vector generated by the command generation unit are superimposed to obtain the final hand speed command vector. The final hand velocity vector is integrated by an integrator and converted into a hand position designation vector, and an angle command vector for each joint can be obtained by inverse kinematic calculation of the arm.
Here, in the figure, I is a unit matrix, s is a Laplace operator, and K is a coefficient matrix.

  Next, the operation of the robot based on the angle command obtained by the above method will be described with reference to FIGS. In order to show the effect of the present invention, the operation of the robot is compared between the case where the vibration suppression control of the present invention is not applied (FIG. 3) and the case where the vibration suppression control is applied (FIG. 4).

FIG. 3 shows one walk cycle when the vibration suppression control is not applied, that is, when each element of the coefficient matrix K is zero. The figure sequentially shows the posture change of the robot over time from 3A to 3I, 3A is an upright posture before starting walking, 3B is a posture moving the center of gravity to the right foot, 3C is a center of gravity moved to the right foot Posture with the left foot as a free leg, 3D is a posture with the left foot that was a free leg, 3E is a neutral posture in the middle of moving the center of gravity from the right foot to the left foot, 3F is a posture in which the center of gravity is moved to the left foot, 3G is The posture with the right foot as a free leg after shifting the center of gravity to the left foot, 3H is the posture with the right foot that was a free leg landing, and 3I is the upright posture after walking is completed.
The figure shows a case where an object is gripped using two arms, and shows that the center position of the gripped object shown in the figure is displaced (shifted) from the walking center by a walking motion.
When the control method of Patent Document 1 is applied, vibration due to walking of the grasped object as shown in FIG. 3 occurs.

On the other hand, FIG. 4 shows one walking cycle when the vibration suppression control of the present invention is applied, that is, when each element of the coefficient matrix K is 1. Here, the coefficient matrix can be set to a numerical value between 0 and 1, but here each element is set to 1 for easy explanation.
The figure shows the robot posture changes over time from 4A to 4I. 4A is an upright posture before starting walking, 4B is a posture moving the center of gravity to the right foot, and 4C is a center of gravity moving to the right foot. 4D is a posture in which the left foot was landed, 4E is a neutral posture in the middle of moving the center of gravity from the right foot to the left foot, 4F is a posture in which the center of gravity is moved to the left foot, and 4G is The posture with the right foot as the free leg after shifting the center of gravity to the left foot, 4H is the posture with the right foot landing on the free leg, and 4I is the upright posture after the completion of walking.
FIG. 4 also shows a case where an object is gripped using two arms as in FIG. 3, but when the present invention is applied, the center position of the gripped object shown in the figure does not cause a displacement from the walking center even during walking motion. It shows that it is in a certain position.

FIG. 5 shows experimental data collected for experimental verification of the effects of the present invention. The figure shows the displacement of the center position of the gripping object in the Y direction (see FIG. 1) when the vibration suppression control of the present invention is not applied (upper diagram in FIG. 5) and when the vibration suppression control is applied (lower diagram in FIG. 5, coefficient matrix K). Each element: 0.5).
As described above, if the arm moves in the opposite phase based on the vibration derived from the walking motion, the vibration of the object with respect to the ground can be significantly reduced.
In addition, although the walk operation | movement by a leg was demonstrated here as an example, this invention is effective also in the movement form which used the wheel for the moving mechanism and comprised the spring, the damper, etc. by the link mechanism.

  The present invention can also be applied to other moving mechanisms in which the upper limb vibrates when the link of the moving mechanism is displaced, for example, a moving form in which a wheel is used for the moving mechanism and a spring, a damper or the like is configured by the link mechanism. .

  INDUSTRIAL APPLICABILITY The present invention is useful as a mobile robot that has a moving mechanism and arms composed of a plurality of links and conveys an object.

It is a block diagram of the walking robot which shows the Example of this invention. It is a control block diagram of the walking robot showing an embodiment of the present invention. It is robot operation | movement explanatory drawing when not applying this invention. It is robot operation | movement explanatory drawing at the time of applying this invention. It is an experimental data which shows the effect of this invention. It is a control block diagram which shows the example of a prior art.

Explanation of symbols

11 Legs, 12 Arms, 13 Hands, 14 Trunks, 15 Heads, 16 Acceleration Detectors, 17 Controls, 18 Reference Coordinate System

Claims (2)

A movement mechanism section composed of a plurality of links, an arm section composed of a plurality of links, a trunk section to which the movement mechanism section and the arm sections are attached, the movement mechanism section, the arm section, and the body In a mobile robot having a control unit that drives and controls an actuator attached to each joint of the trunk,
A vibration calculation unit including an acceleration detection unit that detects an acceleration vector generated when the mobile robot moves by an acceleration sensor attached to the trunk, and a state conversion unit that converts the acceleration vector into a velocity vector ;
An anti-phase calculator that multiplies the velocity vector determined by the vibration calculator by a coefficient matrix to calculate a velocity vector having an opposite phase to the velocity vector ;
A mobile robot characterized in that, when the mobile robot moves, a speed vector having an antiphase obtained by the antiphase calculator is superimposed on a speed command vector of the arm. The mobile robot according to claim 1 , wherein the state conversion unit performs time integration on the acceleration vector and then converts the acceleration vector into the velocity vector by deleting a stationary component .

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