JPH0741559B2 - Master / slave robot control method - Google Patents

Description

The present invention relates to a method for controlling a master / slave robot, that is, a plurality of robots having a master-slave relationship.

[Prior Art] Generally, in tele-existence, an operator who is present at a distant place gives an illusion of being in a place where he / she is working, to give a sense of presence. However, it does not mean that the reaction in the work environment is simply transmitted to the operator. Because the size of the robot arm and the human arm,
This is because the output and the dynamic characteristics of the working environment and the operating environment are generally different. Further, depending on the work environment, there may be a case where the work has a dynamic characteristic that hinders the work, or conversely, a dynamic characteristic required for the work is missing. From the above, in order to obtain an easy-to-use and realistic master / slave system, the operator's work capacity can be expanded to that of the slave manipulator, and the apparent operation feeling in the work environment can be set arbitrarily. It is necessary to do so.

That is, work such as environment identification and control is essential.

As a master-slave method based on such teleagency, "Tate, Sakaki et al .: 27th SICE Academic Lecture Meeting (1988)", "Tate, Sakaki: 6th Robotics Society of Japan Academic Lecture Meeting ( 1988) "," Tachi, Sakaki: 28th SICE Academic Lecture (1989) ".

[Problems to be Solved by the Invention]

In such a conventional bilateral system, the physical meaning of the impedance between the master and the slave, the transmission delay, the operation assistance, and the feeling of operation in environments with different physical conditions become problems.

In each of the above proposals, means for solving the problems of ,,, are presented.

Slaves generally differ from human arms depending on the working environment, and range from micromanipulators to space arms. Conventionally, we operate based on force and motion information based on geometrical relations, but in order to work while grasping the environment realistically, we considered the operation of master / slave and the environment from the viewpoint of physical phenomena. It is necessary to consider it as a physical similarity.

First, when the arm is operated at high speed or low speed exceeding human ability, the operator works at a speed that is normal, but on the slave side, appropriate conversion is performed for this operation and the desired speed is achieved. It is necessary to operate.

Secondly, if the input / output conditions are converted, it becomes possible to easily perform an operation while feeling the blood vessel grasped by the micromanipulator like a rubber hose.

Physical generality is lost if the operation of the master / slave is grasped in a physical similarity relationship and the impedance is adjusted so that the similarity rule is satisfied even when the master and slave have different shapes, different operation speeds, and different input / output conditions. Can provide a sense of presence without

In the present invention, the operating environment model represented by the mass, viscosity, and rigidity of the master arm and the working environment model represented by the mass, viscosity, and rigidity of the slave arm are mutually communicated via a computer, and the operating environment model of both arms is communicated. The purpose of the present invention is to solve the above problems by expanding the basic system that matches apparent dynamic characteristics.

[Means for Solving the Problems]

In order to achieve this object, a control method for a master / slave robot according to the present invention includes a mass of a master arm,
In a control method for a master / slave robot in which an operating environment model represented by viscosity and rigidity and a working environment model represented by mass, viscosity, and rigidity of a slave arm are mutually communicated via a computer, the operating environment model The control impedance is determined by the physical similarity ratio of the work environment model, and the work environment model is modified according to this control impedance.

[Action]

The apparent dynamic characteristics of both arms by communicating with each other via a computer the operating environment model represented by the mass, viscosity and rigidity of the master arm and the working environment model represented by the mass, viscosity and rigidity of the slave arm. In the basic system of matching, the impedance matching between the master and the slave is performed. At this time, the same physical phenomenon occurs in the operating environment and the working environment, and the similarity rule is established.

In the present invention, the physical similarity transformation controls the impedance under different shapes, different input conditions, and different operation speeds to give the operator a sense of reality and increase the degree of freedom in operation.

〔Example〕

 Hereinafter, the present invention will be specifically described based on Examples.

The theorems used in this example are the following three theorems.

[Theorem 1] If the same target impedance is set in both the operating environment and the working environment, the similarity rule is naturally satisfied between the two.

Specifically, the following three dominant physical laws are assumed, and each equation is represented by a relational expression of representative values.

Law of viscosity; F _i = Mα = ρl ⁴ / t ² viscous force; F _v = Dv = μl ² / t spring force; F _e = Kl where ρ is density, l is length, and μ is viscous coefficient , T are representative values of time.

When it is made dimensionless by the pie number, Π ₁ = F _i / F _v = ρl ² / (μt) Π ₂ = F _e / F _v = Kt / (μl) where each slave parameter is each corresponding master parameter Is added with a '.

When the impedances of the master and slave are equal, that is, when M = M ', D = D', K = K ', the following equation holds.

Π ₁ = Π ₁ ′, Π ₂ = Π ₂ ′ Next, the speed at which work is performed is converted to expand the ability of the operator. The target work is simulated in advance only by the master system, the operation content is stored, the work speed is converted according to the similarity rule, and the work content is transmitted to the slave system to perform the work at the target speed.

[Theorem 2] Geometrical similarity ratio between operating environment and working environment l ^*
If the ratio V ^{* of the} operating speeds is specified and the ratio of the impedances in each environment is appropriately determined, the similarity rule is satisfied.

That is, the dominant physical law is the same as Theorem 1, the geometrical similarity ratio l ^* and the density ratio ρ ^* are determined, and the operating speed ratio V ^*
When you specify, the ratio of impedance in each environment, If you decide, the similarity rule is satisfied. However, l ^* = l / l ′,
Let ρ ^* = ρ / ρ ′ and V ^* = V / V ′.

Further, the conversion of the working speed is considered to be specifically the conversion of the operating force of the master into the internal torque of the slave. The principle of this is shown below.

[System 2-1] In the master and the slave satisfying Theorem 2, ρ ^* = 1, l ^* = 1 and the work speed ratio is V ^*, and the time history _Fm (t) of the operating force to the master is The time history F _s (t) of the internal torque of the slave has the following relationship.

F _s (t) = (1 / V ^* ) F _m (t / V ^* ) Next, input / output conditions are converted from not only the geometrical ratio but also the physical similarity including the material of the object. .

[Theorem 3] When the geometrical similarity ratio l ^* of the operating environment and the working environment is determined, the impedance ratio that appropriately determines the ratio of the physical properties (density, viscosity, rigidity) of the object in each environment Exists and satisfies the rule of similarity. At this time, the master
The slave input / output condition ratio is determined.

That is, the dominant physical law is the same as that of Theorem 1, the geometrical similarity ratio l ^* is determined, and one of the density ratio ρ ^* , the viscosity ratio μ ^* , and the rigidity ratio K ^* is designated. At this time, the ratio of the impedances of the master and slave is determined as M / M ′ = D / D ′ = K / K ′ = ρ ^* l ^{* 3} , for example, by the density ratio ρ ^* , and the similarity rule is satisfied. At this time, the input / output conditions of the master and slave are F / F '= ρ ^* l ^{* 4} .

The above processing is shown in the flowchart of FIG. A portion surrounded by a broken line frame is a characteristic portion of the present invention.

Next, the results of the work speed conversion experiment and the input / output condition conversion experiment will be described.

1) Work speed conversion experiment.

Using the principle shown in Theorem 2 and Corollary 2-1, a conversion experiment of the working speed between the master and slave is performed. ρ ^* = 1, l ^* = 1
If the ratio of the working speed is V ^* = 2/3, the impedances of the master and slave can be set as follows.

M _o = 0.5 [kg], B _o = 20.0 [N / (m / s)], K _o = 40.0 [N /
m] M _s = 0.5 [kg], B _s = 30.0 [N / (m / s)], K _s = 90.0 [N /
m] Operate the DD (direct drive) arm as a master, convert the operating force and use it as the internal torque of the slave.
Add to the same arm. FIGS. 2 (a) and 2 (b) show respective time histories of the operating force to the master, the displacement of the master, the internal torque to the slave and the displacement of the slave. With respect to the impedance and the internal torque converted according to the similarity rule, the slave maintains the physical similarity and the V ^{* of the} master operation ^.
= 2/3 compressed in time to operate.

2) Input / output condition conversion experiment Set ρ ^* = 2 and l ^* = 10, and set each impedance of the master arm and the object model as follows. From Theorem 3, the slave side has an impedance of 1 / ρ ^* l ^{* 3} = 0.5 × 10 ^-3 times.

M _o = 0.05 [kg], B _o = 1.0 [N / (m / s)], K _o = 0.1 [N / m] M = 0.01 [kg], B = 5.0 [N / (m / s)] , K = 5.0 [N / m] Using the bidirectional force information transmission method, the master operates the direct drive arm and the slave simulates in the computer. FIGS. 3 (a) and 3 (b) show the time history of the positions and forces of the master and slave. The slave follows the master at a position of 1 / l ^* = 0.1 times as shown in Theorem 3, and returns a reaction force of ρ ^* = l ^{* 4} = 2.0 × 10 ⁴ times to the operator.

〔The invention's effect〕

As described above, the present invention has the following effects.

By grasping the operation of the master / slave in a physical similarity relationship, and adjusting the impedance to satisfy the similarity rule even when the master and slave have different shapes, different operation speeds, and different input / output conditions, the physical generality can be improved. It is possible to provide a sense of presence without losing.

That is, when operating the arm at high speed or low speed exceeding human ability, the operator performs work at a speed that feels normal, and the slave side performs appropriate conversion to this operation and operates at the target speed. Can be made.

In addition, by converting the input / output conditions, it becomes possible to easily perform an operation while feeling the blood vessel grasped by the micromanipulator like a rubber hose.

[Brief description of drawings]

FIG. 1 is a flow chart showing the procedure of the control method of the present invention, FIG. 2 is a time chart showing the conversion experiment result of working speed, and FIG. 3 is a time chart showing the conversion experiment result of input / output conditions.

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Claims (1)

[Claims] 1. A master / slave in which an operating environment model represented by mass, viscosity and rigidity of a master arm and a work environment model represented by mass, viscosity and rigidity of a slave arm are mutually communicated via a computer. A control method for a robot, wherein a control impedance is determined by a physical similarity ratio between the operation environment model and the work environment model, and the work environment model is modified according to the control impedance.