JP3076345B2 - Method and apparatus for controlling master / slave manipulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method and apparatus for controlling a master / slave manipulator.

(Prior art) In a master-slave manipulator, a slave arm is driven so as to follow the movement of a master arm operated by a pilot. It is used to perform the work by remote control. Conventionally, various devices have been devised to improve the operability of the master / slave manipulator. For example, bilateral control in which an external force acting on a slave arm is fed back to a master arm to give the operator a sense of force is a typical example. Recently, research has been conducted on a master / slave manipulator having a different structure in which a master arm having a structure that is easy for the operator to use and a slave arm having a structure most suitable for work are spatially connected.

Generally, in such a conventional master / slave manipulator, control is performed so that the position and the posture of the grip portion of the master arm and the grip portion of the slave arm are the same. This is because the operation (the operation of holding an object) based on the grip portion (palm) can be most easily performed by a human. However, the work based on the grip portion is often a simple operation, and, for example, work such as screwing with a slave arm cannot be achieved unless a power tool for screwing is attached to the grip portion of the slave arm. Was. It is expected that complicated and detailed work will be performed by the master / slave manipulator in the future, so that control of the master / slave manipulator different from the conventional one is required.

(Problems to be Solved by the Invention) As described above, conventionally, a master-slave manipulator with good operability has been realized by spatially associating the grip of the master arm with the grip of the slave arm. There was still a challenge to do complicated and detailed work. An object of the present invention is to provide a control method and apparatus for a master / slave manipulator that can reliably perform complicated and detailed work.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a master / operator operating a master arm drives a slave arm so as to follow the movement of the master arm.
A method for controlling a slave manipulator, wherein a point at a predetermined distance from a wrist of the slave arm is associated with a position of a wrist of the master arm. Also,
In the control device of the master-slave manipulator for driving the slave arm so as to follow the movement of the master arm by operating the master arm, the position of the wrist of the master arm is separated from the wrist of the slave arm by a predetermined length. The control device is provided with reference position conversion means for converting coordinates so as to correspond to points.

(Operation) With the above-described master-slave manipulator control method and apparatus, since the wrist of the master arm corresponds to an arbitrary point, work at any point can be achieved simply by moving the wrist of the master arm. Is done. Therefore, complicated and detailed work by the slave arm is reliably performed.

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

FIG. 1 is a block diagram of a master / slave manipulator showing an embodiment of the present invention. Specifically, the present invention is applied to a force feedback type master / slave manipulator. When the operator operates the master arm 1, each joint angle θ _m of the master arm 1 changes, and the angle at this time is converted into an electric signal by the angle detector 3. On the other hand, likewise the current of each joint angle theta _s of the slave arm 2 is converted into an electric signal by the angle detector 4. Here, all these joint angles are input to the common coordinate converters 9 and 10, and the positions and postures of both arms 1 and 2 are coordinate-converted to a rectangular coordinate system common to the arms 1 and 2. Then, a multiplier is applied to the output signal from the common coordinate converter 9 by the multiplier 11 so as to be multiplied by an appropriate displacement magnification to the slave arm 2.

The output signal from the common coordinate converter 10 is a reference position converter 12
Is input to The reference position converter 12 is, for example, a device in which each joint is controlled so that the grip portion of the master arm 1 and the grip portion of the slave arm 2 correspond to each other, from the wrist of the master arm 1 and the wrist of the slave arm 2. The coordinates are converted so as to correspond to a point P separated by a predetermined length. Here, P can be arbitrarily changed by an output signal from the reference position input device 13, and P
Can freely input P data. The reference position converter 12 and the reference position input device 13 form a reference position conversion unit. For example, when performing the screwing work by the slave arm 2, the tip position of the screwing driver fixed to the slave arm 2, that is, the position where the screw and the driver are fitted may be set to P, and the length of the driver is set in advance as a reference. The data may be input to the position input device 13 and this data may be output to the reference position converter 12 when performing a screwing operation. It is desirable to prepare a plurality of P data based on the position of the axis of the work or the length of the tool according to the work content.

After associating the positions of the master arm 1 and the slave arm 2 in this way, the deviation is multiplied by a slave inverse Jacobian matrix in the slave coordinate converter 14 to obtain a motor drive unit for each joint of the slave arm 2. Convert to the speed command value to 15. Then, a drive voltage is supplied to the motor 8.

On the other hand, the steering torque T _m given by the pilot to the master arm 1
There is detected by the torque detector 5, also, the torque T _s of the slave arm 2 is subjected to the action on the object torque detector 6
Is detected by These torques are applied to the self-weight compensators 16, 17
, And is compensated by calculating the own weight torque depending on the posture of the arm. Then, in the common coordinate converters 18 and 19, the two arms 1 and 2 are multiplied by the inversely transposed Jacobian matrix to be converted into torque in a common orthogonal coordinate system. Then, a multiplier is applied to the output signal from the common coordinate converter 19 by the multiplier 20 so as to be multiplied by an appropriate feedback rate to the master arm 1. Thus, the master arm 1 and the slave arm 2
After taking the force correspondence, the master coordinate converter 21 multiplies these deviations by a master transposed Jacobian matrix and converts the deviation into a force command value to the motor drive unit 22 of each joint of the master arm 1. Then, a drive current is supplied to the motor 7.

Working modes of the thus-configured master / slave manipulator of the present embodiment will be sequentially described. As described above, in the present embodiment, the wrist of the master arm 1 and the slave arm 2
The bilateral servo control is realized such that a point P separated from the wrist by a predetermined length corresponds. Now, when the slave arm 2 is schematically illustrated as a manipulator having three rotation axes 31, 32, and 33 as shown in FIG. 2, a method of changing the posture of the hand 34 around the wrist 31 is shown in FIG. It is expressed as a). This is master arm 1 and slave arm 2
Preparative a wrist corresponds showing the correspondence with the wrist, respectively, in this case the point P is at the center P ₁ of the wrist 31. In such a case, when the hand 34 is driven, the rotation shafts 32 and 33 of the slave arm 2 shown in FIG. 2 are not driven, so that the attitude of the slave arm 2 as a whole is kept constant. Therefore, the danger of the slave arm 2 coming into contact with an obstacle at the time of work is extremely reduced, and the slave arm 2 is suitable for inspection work using a camera and complicated and detailed work in a narrow place.

Next, the coordinate transformation to move the point P ₁ to point P ₂ by the reference position transducer 12 by operating a reference position input device 13. Here the point P ₂ is located in the gripping center of the slave arm 2 of the hand 34 as shown in FIG. 3 (b) (grip portion), the center of rotation, such as to the point P _2, for example, bolts and nuts corresponding Suitable for such work. That is, conventionally, both the master arm 1 and the slave arm 2 corresponded to the gripping portions located at positions away from the rotation axis, so that the work was complicated and took a long time. Then, the pilot rotates the wrist (rotation axis) of the master arm 1 to move the wrist 31.
The bolt and nut tightening operation can be achieved only by changing the posture of the bolt. Of course, here, the hand 34 may be a tool such as a spanner or a wrench.

It may also be carried out coordinate transformation to move the point P ₁ to point P _3. Here the point P ₃ is in a more distant space from the point P ₂ as shown in FIG. 3 (c). Such correspondence is hand
In the case of an operation in which a tool or equipment is fixed to 34, for example, a welding operation using a welding torch, the position and orientation at the tip of the torch can be easily adjusted. Of course, here too, the operator simply rotates the wrist of the master arm 1 and changes the posture of the wrist 31 to perform the operation.

In the above-mentioned countermeasures, since the force is also fed back by the bilateral servo control, the operation is performed safely and reliably.

The setting of the point P is performed by inputting parameters such as dimensions and mass of tools and devices attached to the hand 34 to the reference position input device 13 in advance. However, it may be input at the time of work using a button, a lever, a keyboard, or the like. Further, a parameter of a tool or a device may be detected by a sensor. Of course, the point P may be in any positional relationship with the slave arm, and the distance from the wrist may be 0 as in the case of the above-described wrist.

The structure of the master arm 1 and the slave arm 2 is as follows.
Most preferably, the three axes that determine the hand posture have a gimbal structure that is orthogonal at one point. In other words, with the arm structure shown in FIG. 4, the position and posture can be easily separated and operated, so that hand or workpiece handling in a situation where the operating area is narrow is very effective. Becomes possible.

In the above embodiment, the position correspondence is performed with the point P, which is a predetermined distance away from the wrist 31 of the slave arm 2, and the force (or torque) is fed back in accordance with the correspondence. May be arbitrarily selectable. For example, as shown in FIG.
It is assumed that a reference position converter 23 and a reference position input device 24, which are reference position conversion means for force, are provided between the common coordinate converter 19 and the multiplier 20 shown in the drawing. Here, the arbitrary position is set by the reference position input unit 24, but may be shared with the reference position input unit 13 shown in FIG. When the gripping portion of the master arm 1 and the gripping portion of the slave arm 2 correspond to each other,
Even if it was desired to sense the mass of the object grasped at 34, the moment of the wrist 31 acted and the exact mass could not be sensed. According to the structure of the present embodiment, since only the mass of the object can be sensed by making the point P correspond to the object, the bilateral controllability is greatly improved.

Of course, according to the invention, at point P only the position may correspond, only the force may correspond, or both the position and the force may correspond.

As described above, in the master-slave manipulator driven by the slave arm so as to follow the movement of the master arm by operating the master arm, the point separated from the wrist of the slave arm by a predetermined length and the wrist of the master arm are moved. If control is performed so as to correspond spatially, complicated and detailed work can be reliably performed.

〔The invention's effect〕

As described above, according to the present invention, a control method and apparatus for a master / slave manipulator that can reliably perform complicated and detailed operations are realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a master-slave manipulator according to the present invention. FIGS. 2 and 3 are schematic diagrams of a slave arm and an example of correspondence between a master arm and a slave arm according to the present invention. FIG. 4 is a schematic diagram showing an example of a master arm having a gimbal structure, and FIG. 5 is a block diagram showing another embodiment of the present invention. 1… Master arm 2… Slave arm 12,23… Reference position converter 13,24 …… Reference position input device

Claims (6)

(57) [Claims] 1. A method for controlling a master / slave manipulator for driving a slave arm so as to follow the movement of the master arm by operating the master arm, the method comprising: a point separated by a predetermined length from a wrist of the slave arm; A method for controlling a master / slave manipulator, wherein a position of a wrist of a master arm is associated with the wrist position. 2. The control method for a master / slave manipulator according to claim 1, wherein a spatial correspondence is made at least with respect to a position. 3. The method of controlling a master / slave manipulator according to claim 1, wherein a spatial correspondence is made at least with respect to the force. 4. A master / slave manipulator control device for driving a slave arm so as to follow the movement of the master arm by operating the master arm, wherein the position of the wrist of the master arm is shifted from the wrist of the slave arm. A master / slave manipulator control device, comprising: reference position conversion means for performing coordinate conversion so as to correspond to a point separated by a predetermined length. 5. The control device for a master / slave manipulator according to claim 4, wherein said reference position conversion means performs coordinate conversion on at least a position. 6. The control device for a master / slave manipulator according to claim 4, wherein said reference position conversion means performs coordinate conversion on at least a force.