JP2976007B2 - Interaction force generation method between objects in environmental model - 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 for simulating a restraining force generated when an object moving three-dimensionally interferes in an environmental structure model.

[0002]

2. Description of the Related Art In recent years, robot simulators have been used in various fields. For example, in the field of industrial robots, when teaching an operation to a robot, the operation is performed directly by operating the robot with a teaching device on site. However, such methods often require inconvenient measures in terms of production efficiency, such as temporarily stopping the production line, and improvements have been desired. Therefore, offline teaching tends to be widely used. This teaching method uses data such as CAD used in product design.
A simulator of the robot and the working environment where the robot works on computer graphics based on the data
The instructor of the work does not move the robot directly on site,
Work teaching data is created through a graphic system that displays the simulated robot and environment,
In this method, only data is sent to the actual robot. In the field of space robots, the need for such simulators is increasing. For space robots, developing fully autonomous robots still requires considerable work and time. Therefore, as a precedent, the development of a remotely operated space robot that can be operated by a person from a safe ground is desired. When a person remotely controls a robot launched on a geosynchronous orbit by maneuvering from the earth, the distance between the operator and the robot becomes longer,
There is a delay in signal transmission between the two. Therefore, it has been pointed out that in a remotely operated robot that must operate while confirming the movement of the robot, the existence of such a communication delay significantly reduces operability. To solve these problems, recently, as shown in FIG.
Graphic display 105 that can accurately simulate the robot launched into space and its working environment
There has been proposed a remote control system for introducing a simulator using a computer. In FIG. 10, the operator is not a direct robot but a robot 102 displayed on a simulator 101.
And the environment 103 as if it were an actual robot or environment, the pilot 104 controls the robot, and transmits the motion trajectory of the robot thus created to the actual robot 106. If a robot or the like to be displayed on the simulator is displayed in real time without delay, the operator can execute a remote operation without being aware of the delay.

In the above two examples of using a simulator,
For efficient offline teaching of industrial robots and remote control of space robots, it is necessary to provide a simulator that projects the real world as much as possible. Recent advances in computer graphics have made it possible to build very precise simulators for visual information.

[0004]

However, a simulator that provides only visual information, that is, a video of a robot or an environment, is not sufficient for a simulator used for the above-described purpose.

[0005] For example, in the teaching using an offline teaching device by a robot or a simulator for displaying a video of a working environment, a robot operated by an operator on the simulator contacts the working environment and physically enters. If the robot enters an area where it cannot be performed, or if robots interfere with each other in a system that teaches multiple robots simultaneously,
In general, a method is adopted in which an interference portion is displayed in a different color on a display to warn an operator of the occurrence of the interference portion. However, pilots often overlook such warnings, especially when interference occurs in multiple locations,
Therefore, the data created by the current off-line teaching device requires actual trials and some rework.

On the other hand, when remotely controlling the robot, a device such as a TV monitor for monitoring the movement of the robot to be operated is necessary. At the same time, the restraining force which the robot receives from the environment during work is given to the operator. It is generally important to communicate. For this reason, a so-called bilateral master slave remote operation manipulator having a function of transmitting a binding force to an operator has been developed. In the remote operation of the space robot, when the operator performs a maneuvering operation with a simulator that only displays a visual image of the robot or the environment, the operator operates a so-called unilateral manipulator without a force transmission function. Is equivalent to Therefore, it has the same drawbacks as pointed out in the conventional unilateral type remote control manipulator, and the workability is extremely deteriorated particularly when performing a work which receives a force from the environment.

[0007] Therefore, in the case of a simulator as well as a real system, when a constraint or collision occurs in an object in the simulator, a function of calculating a force associated with the constraint and transmitting it to an operator is added. desired. However, no simulator has been developed to date to generate such a force.

The present invention has been made in view of the above-mentioned circumstances, and has been developed in the field of CAD to establish a technology for visually displaying a model on a computer in a visually realistic manner. It is an object of the present invention to provide an efficient method of generating the interference force so as to introduce a function of generating an interference force generated by mutual interference.

[0009]

In order to cope with this object, a method for generating an interference force between objects in an environment model according to the present invention provides a method for generating vertices and surfaces on an environment model using a polyhedral model.
Define two contact elements, ridge and ridge, and
By combining the interference forces calculated by various elements,
Is calculated .

[0010]

According to such a method of generating an interference force, the contact between polyhedrons in various contact forms is determined by, for example, (ridge line and ridge line,
Vertex and face). When such a combination of contact elements is determined, the forces generated by the respective elements are calculated, and the combined forces are calculated to determine the interference force that causes the contact between the polyhedrons.

According to the interference force generation method of the present invention, a convex polyhedron is divided into a surface, a vertex, and a ridge line, and various contact forms in which two objects described by the convex polyhedron can be generated are described as contact between a vertex and a surface.
Ridge-to-ridge contact, expressed as one of the two elements or a combination of the two elements, and the above-mentioned element used to define the generating force for each of the above-mentioned contacts and to describe the contact between objects By synthesizing all the forces generated by each of the contacts, the force generated by the contact between the polyhedrons, which can assume various contact states, is efficiently simulated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on one embodiment.

As shown in FIG. 1, a simulation is performed in which a rectangular parallelepiped A exists on the floor 100 and a hand 107 of the robot grips and transports another rectangular parallelepiped B. Here, it is assumed that contact between the rectangular parallelepipeds occurs as shown in FIG. 2, FIG. 3, FIG. 4, and FIG. However, the floor and the hand of the robot are omitted in FIGS. 2, 3, 4, and 5.
Here, FIG. 2 shows contact between the vertices of the rectangular parallelepiped B and the surface of the rectangular parallelepiped A, FIG. 3 shows contact between the ridge line of the rectangular parallelepiped B and the surface of the rectangular parallelepiped A, and FIG. In FIG. 5, contact between a part of the surface of the rectangular parallelepiped B and contact of a part of the surface of the rectangular parallelepiped A occurs. To investigate these interferences,
In this embodiment, first, numbers are assigned to all vertices, edges, and faces of each rectangular solid. That is, the vertices are denoted by reference numerals
5, 6, 7, and 8, each ridge is denoted by 9, 10, 11, 1
2,13,14,15,16,17,18,19 and 2
0, each surface is denoted by reference numeral 21, 22, 23, 23, 25, and 2
6 Then, using a method usually used in CAD or the like, a search is made for which vertices, ridges, and faces of the rectangular parallelepiped A are in contact with which vertices, ridges, and faces of the rectangular parallelepiped B, respectively. However, the contact state is adopted only for a combination of a vertex and a face and a ridge line. When such a search is performed, the surface 24 (rectangular solid A) -vertex 8 (rectangular solid B) (interference between the surface and the vertex) in FIG. 2, and the surface 24 (rectangular solid A) in FIG.
-Vertex 8 (rectangular solid B) (interference between surface and vertex), Surface 24 (rectangular solid A)-Vertex 7 (rectangular solid B) (interference between surface and vertex), FIG. 4 shows surface 24 (rectangular solid A)-vertex 5 (rectangular solid) B) (interference between surface and vertex), surface 24 (rectangular solid A) -vertex 6 (rectangular solid B) (interference between surface and vertex), surface 24 (rectangular solid A) -vertex 7
(Rectangular B) (Interference between surface and vertex), Surface 24 (Rectangular A)
-Vertex 8 (rectangular solid B) (interference between surface and vertex); FIG. 5 shows surface 24 (rectangular solid A)-Vertex 5 (rectangular solid B) (interference between surface and vertex); B) (interference between face and vertex), ridge line 19 (rectangular solid A)-ridge line 13 (rectangular solid B) (interference between ridge line and ridge line), ridge line 19 (rectangular solid A)-
All contact can be represented by a combination of a face and a vertex or a ridge and a ridge, such as a ridge 15 (a rectangular parallelepiped B) (interference between the ridge and the ridge). Therefore, next, the interference force generated by the two types of elements is obtained as follows.

(1) Interference between surface and vertex FIG. 6 shows the state of interference between surface S and vertex V. Before interference occurs on the geometric model, the interference force acting on the object is zero. At the moment when the interference occurs, the interference force is zero because the interference force is not calculated. When interference occurs between the geometric models, a vector dx corresponding to a perpendicular from the vertex to the surface is defined as an intrusion vector. Here, it is assumed that when such intrusion occurs, the interference force occurs in proportion to this dx. That is, the rigidity matrix K is assumed on the object surface, and the interference force f is calculated by the following equation. f = Kdx (1) Here, the stiffness matrix is a quantity specified according to physical properties assumed in the geometric model. For example, when a hard object close to a rigid body is assumed, a very large value is set. In general, a diagonal matrix is employed for the structure. After calculating the above f,
A force f is generated on the object to which the vertex V belongs in a direction that prevents the vertex V from entering. On the other hand, a force f is generated on the object to which the plane S belongs in the direction of the approach vector.

(2) Interference between Edge Line and Edge Line FIG. 7 shows interference between the edge line E1 and the edge line E2. Now, ridgeline E
Assume that interference has occurred as 2 approaches the ridgeline E1. If such interference between the ridge lines occurs on the geometric model, a line segment QR connecting the ridge lines with the shortest distance is considered, and a vector dx from the point Q to the point R is defined as an intrusion vector. As in the case of the face and the vertex in the above (1), a rigidity matrix K is assumed for the edge portion, and the equation K is obtained from K determined according to the physical properties.
The interference force f is calculated using (1). In addition, the interference force is generated along the line QR in a direction that hinders the intrusion at the position of the ridge line E2 and the point R on the object side to be cut close. On the object side including the ridge line E1, a force f is generated at the position of the point Q in the direction of entry of the object.

Finally, in order to determine the interference force between the objects, the forces calculated for the individual contact elements are combined. The object coordinate system is set on the object, the force calculated by each contact element is described in this object coordinate system, the force is synthesized using a conventional mathematical method, and the force at the origin of the object coordinate system is calculated. The interference force between objects is expressed by a torque component. FIG. 8 shows an example of the combination of the forces by taking the combination of the forces of the two contact elements as an example. For the translational force, the vector composition method is used as shown in the figure, and for the rotational direction torque, the rotational moment is synthesized from the origin of the coordinate system in consideration of the point of action of the force. Calculate by

The interference force calculated as described above is transmitted to the operator via a control rod having a built-in motor for generating force as shown in FIG. If the force acting on the object gripped by the robot is calculated, the hardware and calculation method for transmitting the restraining force to the operator can be achieved by using the conventional technology.

[0018]

As described above, according to the present invention, in the method for generating an interference force between objects in an environment model, the contact that occurs between polyhedrons is represented by a combination of vertices and faces, and ridges and ridges. And calculation of the interference force generated between the polyhedrons as a synthesis of the interference force generated by each of the ridge lines. All the various contact states generated between the polyhedrons can be described by the two types of contact elements. Therefore, the method of the present invention can obtain a general method of calculating the interference force.

According to the present invention, an interference force between objects can be generated from the mutual interference amount of objects on a geometric model on a computer. Therefore, in the field of remote control in which there is an artificial reality and information transmission time delay. In order to more realistically simulate the environment, it becomes necessary to generate an interference force between objects on an environment model in a computer. Thus, by applying the present invention to the field of remote manipulation / offline teaching, the operator can experience the state of the work environment, and the workability can be improved. In general, an interface between a model in a computer and an operator is used.
A conventional visual graphic interface as a face
In addition to the face, it becomes possible to experience the force sensation of the restraining force generated by the interference between the models, thereby improving the man-machine interface.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view illustrating a working state of a robot hand.

FIG. 2 is a perspective explanatory view showing interference between a surface of a rectangular parallelepiped and a vertex.

FIG. 3 is an explanatory sectional view showing interference between a ridge line and a surface of a rectangular parallelepiped.

FIG. 4 is a perspective explanatory view showing interference between the entire surface of a rectangular parallelepiped and a part of the surface;

FIG. 5 is an explanatory cross-sectional view showing interference between a part of a plane of a rectangular parallelepiped and a part of the plane;

FIG. 6 is an explanatory diagram showing a state of interference between a surface and a vertex.

FIG. 7 is an explanatory perspective view showing a state of interference between ridge lines.

FIG. 8 is a diagram showing an example of force combination.

FIG. 9 is an explanatory diagram showing a state of transmission of an interference force.

FIG. 10 is an explanatory diagram showing a conventional remote control system.

[Explanation of symbols]

S plane V vertex dx penetration vector E1, E2 side 1,2,3,4,5,6,7,8 vertex 9,10,11,12,13,14,15,16,1
7, 18, 19, 20 ridgelines 21, 22, 23, 24, 25, 26 faces

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akio Fujikawa 1-2-2 Namiki, Tsukuba, Ibaraki Pref. Machinery Research Laboratory, Industrial Technology Institute (56) References JP-A-63-196388 (JP, A) JP-A-61 -127007 (JP, A)

Claims (1)

(57) [Claims] 1. An environment model using a polyhedral model,
Define two contact elements, vertices and faces, ridges and ridges,
It is necessary to combine the interference forces calculated by these individual elements.
A method for generating an interference force between objects in an environment model, wherein the method calculates an interference force between the objects by using the method.