JP3099067B1 - Control method and apparatus for object-cooperative transport robot - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To control an object-cooperative transport robot that transports an object in cooperation with a human by intuitively grasping the behavior of the object with a daily sense by limiting the direction in which the object can move. It can be so. In controlling an object-cooperative transport robot, a force applied to the robot from an object is detected by a force sensor, and a rotational force component τ about a vertical axis separated from the sensor signal and a translation in an object long-axis direction. Based on the force component Fx, the rotational motion component about the vertical axis and the translational motion component in the object long axis direction are output with a gain set so that the resistance force of the robot is reduced. On the other hand, the translational force component Fy in the short axis direction of the object is restricted so that no translational movement in the short axis direction of the object occurs. Thereby, the robot arm is driven while giving the same motion limitation to the object 4 as being supported by a virtual wheel oriented in the object long axis direction at one point on the robot side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling an object-coordinated transport robot that can be used for heavy-load transport work in mining, agriculture, forestry and fisheries, construction, distribution, and households.

[0002]

2. Description of the Related Art As a method of transporting an object in cooperation between a human and a robot, there is a method called power assist which has been studied at the University of California, Tohoku University, the Institute of Mechanical Engineering, etc. This is because the robot arm is equipped with two force sensors that detect the load of the object held at the end of the robot arm and the force applied by the operator, and amplifies the force applied by the operator and applies it to the object. Is a technique for reducing the load on the operator while exercising following the movement of the operator.

However, this method requires an operator to grasp and move the force sensor handle at the tip of the robot arm, so that only one of the objects can apply a force.
Limited to only one place. When carrying a long object or an object having a large size, it is desirable that the hand 2 at the tip of the robot arm 1 and the operator (human) 3 hold both ends of the object 4 as shown in FIG. In this case, even if the force sensor 5 is provided on the robot arm 1 side to measure the force, the force applied to the object 4 cannot be directly measured on the operator 3 side. It is difficult to apply the technology.

[0004] On the other hand, a method in which a human and a robot support some places of an object and share and carry a load has been studied at Stanford University, Tohoku University, and the like in the United States. These are mainly based on impedance control. That is, by compensating for the weight of the object, the object is set to a weightless state and supported, and at the same time, the virtual impedance (inertia, viscosity, spring coefficient) is set for the object or the robot,
Change the movement of the object according to the change in the force applied by humans,
This is a method of imitating the movement of an object to the movement of a human.

[0005] However, when the object is a long object, the human can only apply a translational force mainly, and it is difficult to apply a torque (rotational force) at one end of the object.
If impedance control is the basis, it is easy to move straight in the long axis direction connecting the human and the robot, but it is difficult for humans to control the position of the end point on the robot side to the target point in operations involving rotation. Becomes In order for an object to move only by applying a weak force to a human, impedance parameters such as inertia and viscosity need to be set low.
However, in such a case, a drift (shift movement) in the normal direction occurs, and it is difficult to stop the drift. Therefore, there is a problem that the behavior of the object is difficult to intuitively predict.

The above-mentioned problem of the conventional technique arises because the impedance parameters are set uniformly in all directions and in a fixed absolute coordinate space. As a result, the behavior of the object is such that a human does not experience everyday, that is, moving an object floating in a weightless space by applying a force, and it is difficult to move the object to a target position / posture.

[0007]

SUMMARY OF THE INVENTION The present invention addresses such a problem and, in the control of an object-cooperative transport robot that transports an object in cooperation with a human, restricts the direction in which the object can move. An object of the present invention is to simplify the relationship between the force applied by a human and the movement of an object so that the human can intuitively grasp the behavior of the object with a daily sense. Further, another technical problem of the present invention is to make it possible to grasp the behavior of the above-described object with a daily sense without impairing the original purpose of the work of transporting the object to an arbitrary target position and posture. An object of the present invention is to obtain control means of an object cooperative transport robot.

[0008]

In order to solve the above-mentioned problems, a control method according to the present invention is directed to a method in which a human and a robot have a long object.
Or a control method for controlling an object-coordinated transport robot for gripping both ends of a large object and transporting it in a horizontal plane, detecting the force applied to the robot from the object with a force sensor and separating it from the sensor signal Force components around the vertical axis and the gripping points by humans and robots
Based on the translational force component of the object axial direction connecting the bets, the rotational movement component and the translation component of the product body length direction around the vertical axis, is output by setting the gain so that the resistance force of the robot is reduced On the other hand, the translational force component in the short axis direction of the object orthogonal to the long axis direction of the object is constrained so as not to cause the translational motion in the short axis direction of the object, whereby Is provided with a movement restriction equivalent to that supported by a virtual wheel oriented in the object long axis direction at one point on the robot side to drive the robot arm.

Further, a control device according to the present invention is a control device for controlling an object cooperative transport robot for a human and a robot to grip both ends of a long object or a large object and transport the object in a horizontal plane. a force sensor for detecting a force applied from the object to the robot, the gripping point by rotational force component, as well as human around the vertical axis from the sensor signals the robot
A coordinate transformation unit for separating the translational force component in the object long axis direction and the object short axis direction that is orthogonal to the object gripping point, and the rotational force component about the vertical axis and the translational force in the object long axis direction based on the component, the force resistance of their rotation and translation direction of the robot and outputs these motion components with a gain smaller - a motion conversion unit, the object of the short axis direction set to these motion components and zero A coordinate conversion unit that synthesizes a translational motion component and outputs a motion command for driving the robot arm.

[0010] According to the control means of the object-cooperative transport robot having the above configuration, the human and the robot can move a long object or a small object.
Upon gripping the ends of the large object of the law controlling the object cooperative transport robot for transporting in a horizontal plane, it is supported by a virtual wheel facing the object longitudinal direction at one point of the robot side relative to the object Give the same exercise restriction as
As a result, since the direction in which the object can move is restricted, the relationship between the force applied by the operator and the movement of the object is simplified, and the operator can intuitively grasp the behavior of the object with a daily sense. It becomes possible. In addition, the original purpose of the operation of transporting the object to an arbitrary target position / posture is not impaired.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The work of placing an object on a truck having passive wheels and pushing the truck on a horizontal floor to carry the object is performed by a unicycle (a so-called cat truck), a shopping cart, a stroller, It is something that humans often experience on a daily basis, such as in table wagons. In these cases, the direction in which the truck can move is momentarily limited by the direction of the wheels. That is, in the direction parallel to the wheels, it is possible to move the bogie back and forth by the rotation of the wheels, but in the direction perpendicular to the wheels, unless the wheels slip against the frictional force between the floor and the wheels. , Can not move. This kind of motion limitation is called nonholonomic constraint.

In spite of such a restriction of the direction of movement, it is possible to finally bring the truck to an arbitrary target position / posture by pushing the truck along an appropriate track.
That has been proven mathematically. In addition, it can be said that humans generally have the skills to realize it from everyday experiences.

Therefore, as shown in FIG. 1, even when the hand 2 of the robot arm 1 and the operator 3 hold both ends of a long object or an object 4 having a large size and cooperate in a horizontal plane to face each other. If the robot is controlled so that the object 4 behaves in the same way as a bogie, humans can intuitively grasp the behavior of the object, and can easily transport the object to the target position / posture. become. For this purpose, as shown in FIG. 2, the object 4 may be limited in motion such that the object 4 is supported by virtual wheels 6 oriented in the long axis direction of the object on the robot side 4a. Accordingly, on the operator side 4b, the same operation as carrying the object by pushing the cart in the appropriate direction exemplified by the arrow becomes possible.

More specifically, as shown in FIG. 3, a force sensor 5 is provided between the robot arm 1 and the hand 2 at the tip of the robot arm. In P, a force applied from the operator side Q to the robot arm 1 side via the object 4 is detected, and the obtained sensor signal is transmitted to the object long axis direction (P
Into a translational force component Fx in the Q direction), a translational force component Fy in the direction perpendicular to it (PR direction), and a rotational force component τ about the vertical axis at the point P. For the rotational force component τ and the translational force component Fx in the long axis direction, the robot moves in each direction without resistance, and the translational force component Fy
For, the movement of the robot is restricted, thereby giving a movement restriction equivalent to that of the object 4 being supported at a point P by a virtual wheel oriented in the direction of the long axis of the object.

For this purpose, a rotational motion component about the vertical axis and a translational component in the object long axis direction based on the rotational force component τ about the vertical axis and the translation force component Fx in the object long axis direction in the sensor signal of the force sensor 5. The motion component is output by setting a gain so that the resistance of the robot is reduced, while the translational force component Fy in the object short axis direction is restrained so that no translational motion in the object short axis direction occurs. Will drive the robot arm. The constraint for preventing the translational movement in the short axis direction of the object may be achieved by outputting a motion command such that the short axis direction motion component becomes substantially zero.

Thus, the point P on the object 4 shown in FIG. 3 can be translated only in the PQ direction. Also,
It is also possible to rotate around point P. Further, the traveling direction can be continuously changed while traveling along a smooth curved trajectory that is in contact with the straight line PQ. Since the behavior of the object 4 is similar to the case where the object is supported by wheels at the point P, the operator intuitively transports the object to the target position / posture using the same skill as when pushing the bogie. Can be.

In order to carry out the control method described above, an apparatus as described below with reference to FIGS. 3 and 4 can be used. First, as shown in FIG. 3, a hand 2 for grasping the object 4 and a force sensor 5 for detecting a force applied by the operator via the object 4 are arranged at the tip of the robot arm 1. is necessary. The sensor signal detected by the force sensor 5 is input to a control device (computer). In this control device, as shown in FIG. Component F
x and the translational force component Fy in the short axis direction of the object and the rotational force component τ about the vertical axis are separated.

In the force-motion conversion section, a translational motion component (velocity / acceleration) in the PQ direction at the point P in FIG. 3 is determined based on the translational force component Fx in the longitudinal direction of the object. Based on the surrounding rotational force component τ, the point P
A peripheral rotational motion component (angular velocity / angular acceleration) is determined. These are determined by the setting of the gain that reduces the resistance of the robot in the rotation and translation directions. On the other hand, regarding the short-axis direction translational force component Fy, the translational component (velocity / acceleration) in the PR direction of the point P is set to zero regardless of the output of the force sensor, and the coordinate conversion unit (2) By combining these motion components, a motion command for driving each joint actuator of the robot arm 1 is output. The operation of the joint actuator is detected by a joint sensor provided at each joint, and the position and drive speed of the joint are fed back so that the operation of the robot arm approaches the target value.

[0019]

According to the control method and apparatus of the present invention described in detail above, in the control of an object-cooperative transport robot that transports an object in cooperation with a human, the direction in which the object can move is appropriately restricted. By transporting an object to an arbitrary target position / posture, without impairing the original purpose of the work,
The relationship between the force applied by a human and the motion of the object is simplified, and the human can intuitively grasp the behavior of the object in a daily sense, and the robot side of the object is virtual wheels oriented in the object long axis direction. Can work as well as supporting.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an object-cooperative transport robot controlled based on the present invention.

FIG. 2 is a conceptual explanatory diagram of control according to the present invention.

FIG. 3 is an explanatory diagram of a detection output component of a force sensor used in controlling the object-cooperative transport robot according to the present invention.

FIG. 4 is a configuration diagram of a control system of the object-cooperative transport robot according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot arm 2 Hand 3 Operator 4 Object 5 Force sensor 6 Wheel Fx Translation force component of sensor signal in the long axis direction of object Fy Translation force component in the short axis direction of the same object τ Rotation force component around the vertical axis

Continuation of the front page (56) References JP-A-2000-177682 (JP, A) JP-A-7-205072 (JP, A) JP-A-63-200983 (JP, A) Yasuo Hayashibara (four others), Chief Research on human cooperative behavior when transporting shaku, Proceedings of the 16th Annual Conference of the Robotics Society of Japan, September 18, 1998, Vol. 1, p107-108 Ryojun Ikeura (2 other people), Variable damping control and experimental evaluation of robot cooperating with human, Proceedings of the 47th Annual Meeting of the Japan Society of Mechanical Engineers, Tokai Branch, March 6, 1998 , No. 983-1, p305-306 (58) Fields investigated (Int. Cl. ⁷ , DB name) B25J 13/08 B25J 13/00 B25J 17/00 G05B 19/18 JICST file (JOIS)

Claims (2)

(57) [Claims] A human and a robot are long objects or large in size.
This is a control method for controlling an object-coordinated transport robot for grasping both ends of a movable object and transporting it in a horizontal plane, where a force applied from the object to the robot is detected by a force sensor and separated from the sensor signal. Rotational force component around the axis and
Based on the translational force component in the long axis direction of the object connecting the gripping point by the human and the gripping point by the robot, the rotational motion component around the vertical axis and the translational motion component in the long axis direction of the object are reduced by the resistance of the robot. In such a manner, a translational force component in the object short axis direction orthogonal to the object long axis direction is constrained so as not to cause translational movement in the object short axis direction. Object-cooperative transportation, in which a robot arm is driven with a motion limit being given to the object at a point on the robot side equivalent to that supported by a virtual wheel oriented in the long axis direction of the object. Robot control method. 2. The method according to claim 1, wherein the human and the robot are long objects or large in size.
A control apparatus for controlling an object coordinated transport robot for transporting in a horizontal plane by holding both ends of the deal of the object, a force sensor for detecting a force applied from the object to the robot,
From the sensor signal, the rotational force component around the vertical axis and human
A coordinate conversion unit that separates the translational force component in the object long axis direction and the object short axis direction orthogonal to the object grip point connecting the grip point by the robot and the grip point by the robot, and the rotational force component around the vertical axis and the object long axis direction based on the translational force component, the force resistance of their rotation and translation direction of the robot and outputs these motion components with a gain smaller - a motion converting section, the object short axis set in these motion components and zero A coordinate conversion unit for synthesizing translational motion components in directions and outputting a motion command for driving a robot arm, the control device for an object-cooperative transport robot.