JP3163346B2 - Control method and apparatus for object-cooperative transport robot - Google Patents

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. However, in order to compensate for the gravitational force acting on the object, it is necessary to know in advance the mass and the mass distribution of the object. This hinders flexible application to the transport of various objects.

[0005]

SUMMARY OF THE INVENTION The present invention addresses such a problem and, as described above with reference to FIG. 1, a human and a robot grasp both ends of a long object and load the object by its weight. In the control of the cooperative transport robot that carries the robot in a shared manner, the rotational motion of the hand of the robot arm is controlled to be zero, while the vertical direction of the hand is controlled so that the object remains horizontal. The object of the present invention is to obtain control means for controlling the translational motion of the robot arm so that the robot arm bears about half of the object weight. Another technical problem of the present invention is that it is sufficient to provide only one sensor for measuring a force applied from an object to a robot arm as a force sensor, and a force sensor for measuring a force of an operator. An object of the present invention is to provide a control means of an object-cooperative transport robot which does not require a sensor and further does not need to know the size and mass of an object in advance.

[0006]

In order to solve the above-mentioned problems, a control method according to the present invention is a control method for controlling an object-cooperative transport robot for a human and a robot to grip and transport both ends of an object. Then, the force applied to the robot from the object and the angle of the fingertip are detected by a sensor. Set the gain to and output a motion command to drive the robot arm, and for the detected hand angle,
The present invention is characterized in that a movement command for a vertical translational movement of the hand is output so that the object maintains the horizontal position.

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 and transport both ends of an object, and detects a force applied to the robot from the object. A force sensor and an angle sensor for detecting an object grip angle of the robot's hand, a coordinate conversion unit for separating a rotational force component around a horizontal axis and a translational force component in a horizontal front-rear direction from a sensor signal of the force sensor, Based on the two force components, a force-motion conversion unit that outputs their motion components with a gain that reduces the resistance of the robot in the rotation and translation directions, and a hand angle detected by the angle sensor. A motion conversion unit that outputs a vertical motion component of the hand so that the object remains horizontal, and issues a motion command for driving the robot arm by combining the motion components. Is characterized in that a coordinate conversion unit that.

[0008] According to the control means of the object-cooperative transport robot having the above-mentioned structure, the object-cooperative transport robot in which the human and the robot hold both ends of the object and share and carry the load due to the weight is controlled. At this time, while controlling the rotational motion of the hand so that the rotational force at the hand of the robot arm becomes zero, controlling the vertical translational motion of the hand so that the object remains horizontal, about half of the object weight Can be loaded on the robot arm. As a force sensor, only one sensor that measures the force applied from the object to the robot arm need be provided, there is no need for a force sensor for measuring the force of the operator, and the size and mass of the object are reduced. There is no need to know in advance.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When a human and a robot grip and hold both ends of an object to carry them cooperatively, it is most important how to distribute and bear the weight of the object. In general, if an object is supported only by a translational force without applying a torque (rotational force) at the point where the object is supported, the vertical force is distributed in inverse proportion to the distance from the body weight center. Since long objects often have nearly uniform mass distribution, if the robot tip rotates freely without applying torque to the object at the robot tip, humans and robots can be used regardless of the mass or dimensions of the long object. Will bear almost half the weight.

On the other hand, when transporting long objects, it is considered that the objects are most often moved while being kept horizontal.
Therefore, it is preferable to control the vertical movement of the robot tip so as to cancel the inclination of the object. That is, when the object is tilted by a person lifting the object, if the robot also lifts the object, the tilt of the object is canceled and the horizontal state is maintained. The same applies when the object is lowered.

Regarding the horizontal movement of the object, the robot only has to move so as to follow the force applied by the human to the object. That is, virtual inertia and viscosity are set with respect to the horizontal movement of the robot tip, and if the values are set sufficiently low, human-like movement can be performed without giving a resistance to the human.

More specifically, as shown in FIG. 2, a force sensor 5 is provided between the robot arm 1 and the hand 2 at the tip of the robot arm, and the force sensor 5 supports the object 4 on the robot side. At point P, a force applied from the operator side Q to the robot arm 1 via the object 4 is detected, and the obtained sensor signal is translated into a translational force component Fx in the horizontal front-rear direction (PQ direction) and a vertical direction (PR direction). ) Into a translational force component Fz and a rotational force component τ about the horizontal axis around the point P. Although not shown, each joint of the robot arm is provided with a joint actuator for driving each joint, and an angle sensor for detecting the joint angle is provided. Tilt angle θ
Is detected.

The translational force component Fx and the rotational force component τ in the horizontal front-rear direction are determined so that the robot moves in each direction without resistance in the horizontal direction at the point P of the object 4 and the rotational speed of the hand. Is determined. Further, the velocity in the vertical direction at the point P for leveling the object 4 is determined in proportion to the inclination angle θ of the object 4. For this purpose, based on the rotational force component τ around the horizontal axis and the translational force component Fx around the horizontal axis in the sensor signal of the force sensor 5, the rotational motion component around the horizontal axis and the translational motion component around the horizontal axis are The robot arm is driven by setting and outputting a gain so that the resistance of the hand becomes small, and the hand angle detected by the sensor signal of the hand angle sensor (the tilt angle θ of the object 4) The movement command of the proportional vertical translational movement is output, and the hand of the robot arm is driven up and down so that the object is kept horizontal.

In this way, the object can be freely rotated around the point where the robot supports the object (point P in FIG. 2), and no torque is applied to the object.
The vertical force between humans and robots is reduced by almost half according to the mass distribution of long objects. Furthermore, when a human applies a horizontal force to an object, the robot moves horizontally without any resistance. Also, when a human lifts the object and tilts the object, a vertical upward speed is generated at the robot hand so that the tilt angle becomes zero, so that the object rises while keeping the horizontal. The same applies to the case where an object held by a human is lowered. Such control may be such that impedance control is performed in the horizontal direction and the initial state of the object is maintained in the vertical direction.

In order to carry out the control method described above, an apparatus as described below with reference to FIGS. 2 and 3 can be used. First, as shown in FIG. 2, a hand 2 for grasping the object 4 and a force sensor 5 for detecting the force applied by the operator via the object 4 may be arranged at the tip of the robot arm 1. is necessary. Also, as mentioned above,
Each joint of the robot arm is provided with a joint actuator for driving the joint and an angle sensor for detecting the joint angle. As these joint actuators and angle sensors, those generally provided in a robot arm that is driven and controlled are used as they are.

The sensor signal detected by the force sensor 5 is input to a control device (computer). In this control device, as shown in FIG. The translational force component Fx and the vertical translational force component Fz, and the rotational force component τ about the horizontal axis are separated. On the other hand, the angle sensor of each joint of the robot arm measures the inclination angle θ of the object 4.

Then, in the force-motion conversion unit, based on the translational force component Fx in the horizontal front-rear direction, the translational motion component (speed / speed) at the point P in FIG. Acceleration), and a rotational motion component (angular velocity / angular acceleration) around the point P is determined by a calculation as in the following equation (2) based on the rotational force component τ about the horizontal axis. These are determined by the setting of the gain that reduces the resistance of the robot in the rotation and translation directions.

[0018]

(Equation 1) In this case, to reduce the resistance by the robot,
The target inertia coefficient M, the target inertia moment coefficient I, the target viscous friction coefficient _Bx , and the target viscous friction coefficient _Bd are set low.

On the other hand, based on the tilt angle θ detected by the angle sensor and obtained by the coordinate conversion unit (b), the point P is proportionally proportional to the tilt angle θ of the object in the motion conversion unit as shown in Expression (3). Is determined in the vertical direction.

(Equation 2) K in the equation is a proportional coefficient between the inclination angle and the speed.

The coordinate conversion unit (c) combines the above-described motion components to determine the motion of the hand of the robot arm 1,
A motion command to drive each joint actuator is output, and the operation of each joint actuator is detected by an angle 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. Is done.

[0021]

According to the control method and apparatus of the present invention described in detail above, a human and a robot can grasp both ends of a long object and carry the load by sharing the load due to its weight. In a robot, while controlling the rotational movement of the hand so that the rotational force at the hand of the robot arm becomes zero, controlling the vertical translational movement of the hand so that the object remains horizontal, the weight of the object is reduced. Control can be performed so that half of the load is placed on the robot arm. According to the present invention, only one sensor for measuring the force applied from the object to the robot arm needs to be provided as a force sensor, and a force sensor for measuring the force of the operator is required. In addition, it is possible to obtain control means for an object-cooperative transport robot that does not need to know the dimensions and mass of the object in advance.

[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 an explanatory diagram of a detection output component of a force sensor used in control of the object-cooperative transport robot according to the present invention.

FIG. 3 is a configuration diagram of a control system of the object cooperative transport robot according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 robot arm 2 hand 3 operator 4 object 5 force sensor Fx translational force component in the horizontal front-rear direction of sensor signal Fz translational force component in the vertical direction of sensor signal τ Rotational force component around the same horizontal axis θ tilt angle

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, 16th Annual Meeting of the Robotics Society of Japan, September 18, 1998, Vol1, p107-108 Ryojun Ikeura (2 other people), cooperating with humans Variable damping control and experimental evaluation of robot, 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 19/00 G05B 19/18 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A control method for controlling an object cooperative transport robot for a human and a robot to grip and transport both ends of an object, wherein a force applied to the robot from the object and an angle of a hand are detected by a sensor. Based on the sensor signal, for the rotational motion component around the horizontal axis and the translational motion component in the horizontal front-rear direction, the gain is set so that the resistance of the robot is reduced,
Object coordination characterized by outputting a motion command for driving the robot arm, and outputting a motion command for a vertical translation of the hand in accordance with the detected angle of the hand so that the object remains horizontal. Control method of transport robot. 2. A control device for controlling an object-cooperative transport robot for holding and transporting both ends of an object by a human and a robot, comprising: a force sensor for detecting a force applied to the robot from the object; An angle sensor that detects an object gripping angle, a coordinate conversion unit that separates a rotational force component around a horizontal axis and a translational force component in a horizontal front-rear direction from a sensor signal of the force sensor, and based on the two force components, A force-motion conversion unit that outputs a motion component of the robot with a gain that reduces the resistance of the robot in the rotation and translation directions, and based on the angle of the hand detected by the angle sensor, the object maintains a horizontal position. A motion conversion unit that outputs a vertical motion component of the hand, and a coordinate conversion unit that synthesizes the motion component and outputs a motion command for driving the robot arm. A control device for an object-cooperative transport robot characterized by the following.