JPH0443747B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device applied to an articulated hand of a robot for extreme work in a nuclear reactor containment vessel.

<Prior Art> FIG. 5 shows a block diagram of a conventional master-slave position control device. In the figure, 1 is a master finger operated by a human, 2 is a slave finger of the same size or similar shape to the master finger that performs the work, 3 is the i-th joint of master finger 1, and 4 is the i-th joint of slave finger 2. , 5 is the j-th joint of master finger 1, 6 is the j-th joint of slave finger 2, 7 is a position detector for the joint angle θ _Mi of the i-th joint 3 of master finger 1, and 8 is the i-th joint of slave finger 2. 4 is a position detector for the joint angle θ _Si ; 9 is a position detector for the joint angle θ _Mj of the j-th joint 5 of the master finger 1; 10 is a position detector for the joint angle θ _Sj of the j-th joint 6 of the slave finger 2. , 11
compares the joint angles θ _Mi and θ _Si , and the joint angle difference Δθ _i = (θ _M
i
−θ _Si ), 12 is the joint angle θ _Mj and θ _Sj
13 is an amplifier that amplifies the joint _{angle difference Δθ i ; 14} is _an amplifier that amplifies the joint angle difference Δθ _j ;
A servo motor 5 drives the i-th joint 4 of the slave finger 2 by the amplifier 13, and a servo motor 16 drives the j-th joint 6 of the slave finger 2 by the amplifier 14.

With these configurations, the joint angles θ Si and θ _Si of each joint 4 and 6 of the slave finger 2 are made equal to the joint angles θ _Mi and θ _Mj of each joint 3 and 5 of the master finger 1 operated by a human being. θ _Sj will be controlled. Therefore, the movement of the master finger 1 is faithfully reproduced in the movement of the slave finger 2, and the slave finger 2 can perform the same operation as the master finger 1.

<Problems to be Solved by the Invention> However, in the control device having the structure shown in FIG. It's impossible. That's slave finger 2
This is due to the fact that the joints lacked the ability to vary compliance (the reciprocal of stiffness). Here, compliance is (θM - θS)/(force exerted by slave finger on object) in Figure 5.
This means that with only the device shown in Figure 5, the joint angle difference (θM - θS) and (the force exerted by the slave finger on the object)
There is always a proportional relationship, and compliance is constant.

Therefore, varying the compliance means changing the ratio between the joint angle difference (θM−θS) and the force acting on the object from the slave finger.

For example, when fitting a rod into a hole in the above-mentioned fitting operation, in addition to the force acting on the slave finger, the rod's position (posture) is determined by using the reaction force from the hole.
In other words, it is necessary to operate the master finger in such a way as to change the ratio between the force acting on the rod from the slave finger and (θM - θS).
This is difficult with the above-mentioned certain compliance.

For example, from the beginning, the i-th joint 4 of slave finger 2
Even if we devised ways to lower the rigidity of the 6th
As shown in the figure, the slave finger 2 shown by the solid line becomes in a state like the master finger 1 shown by the broken line, and due to the increase in the deviation between the master finger 1 and the slave finger 2, the posture of the master finger 1 and the positional relationship of the object This results in a considerable deviation from the actual value, which is not desirable for operation.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a control device for an articulated hand that can perform operations such as grasping fragile objects and fitting rods into holes without any operational hindrance.

<Means for Solving the Problems> The present invention achieves the above-mentioned objects in a multi-finger control device for a multi-jointed hand. The slave finger is equipped with a force operation converter that converts the angular difference into a force command, and a force detector that outputs a reference signal of the force command, which is the output of this force operation amount converter, to perform force control. For the other joints, the joint angle of the master finger and the joint angle of the slave finger at the one joint are input, and the correction amount of the joint angle of the slave finger of the other joint is output for the joint angle of the slave finger. It is characterized by being equipped with a coordinate converter to perform position control.

<Operation> The force that the slave finger is exerting on the workpiece is detected by the force detector at the first joint (i-th joint), and the signal and the force operation amount converter convert the force between the master finger and slave finger. The servo motor is driven so that the difference in force commands created as a function of joint angle deviation becomes zero. This makes the compliance of the first joint variable. In order to reduce the deviation in posture between the master finger and slave finger when compliance is made variable, when the deviation between the master and slave joint angles of the i-th joint exceeds a certain value, the output of the coordinate converter, In other words, the correction value is added to the position command of another joint (j-th joint), and the j-th joint of the slave finger moves, thereby maintaining the positional deviation between the slave and master of the i-th joint and adjusting the position between the object and the slave finger. By making the postures of the master finger and slave finger almost the same near the contact point, the operator can reliably perform operations such as grasping fragile objects and fitting rods and holes with a natural feeling. Can be done.

<Example> Here, an example of the present invention will be described with reference to FIGS. 1 to 4. In FIG. 1, the same parts as those in FIG. 5 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, 100 is a force detector provided on the pad of the i-th joint 4 of the slave finger 2. The force detector 100 converts the force exerted by the finger pad of the slave finger 2 on the workpiece into the torque of the i-th joint 4, and outputs an output signal T _Si .

101 is a force operation amount converter that outputs a target torque value T _Mi , and compares the joint angle θ _Mi of the i-th joint 3 of the master finger 1 with the joint angle θ _Si of the i-th joint 4 of the slave finger 2. A torque target value T _Mi is generated as a function of the output of the joint angle difference Δθ _i from the comparator 11 based on the polygonal line of the conversion function shown in FIG.
In other words, when converting Δθ to TMi, the force manipulated variable converter changes the conversion rate depending on the magnitude of Δθi to convert TMi.
It is converted into .

A comparator 102 compares the output T _Si of the force detector 100 and the target value TT _Mi of the force operation amount converter 101, and outputs a torque deviation ΔT _i (=T _Mi −T _Si ).

103 is the correction of the j-th joint 5 of the master finger 1 from the output θ _Mi of the position detector 7 of the i-th joint 3 of the master finger 1 and the output θ _Si of the position detector 8 of the i-th joint 4 of the slave finger 2. This is a coordinate converter that calculates the value θ^ _Sj . The calculation of this coordinate converter 103 is distinguished depending on whether the deviation of the input joints θ _Mi and θ _Si is less than or equal to a certain value.
That is, take a constant number Δθ _K such that θ _Mi −θ _Si <Δθ _K and θ _Mi− 〓 _Si ≧Δθ _K , and in the former case, the output of the coordinate converter 103 is 0, and the target at the coordinates shown in FIG. Although the joint angle θ _Mj is not converted, the latter θ _Mi −θ _Si ≧
In other words, when Δθ _K is obtained, the target joint angle θ _Mj is corrected by θ^ _{Sj .} In other words, as shown in FIG.
is output. In this case, θ^ _Sj is expressed as follows.

Here, l _i indicates the length of the finger at the i-th joint, and l _j indicates the length of the finger at the j-th joint. (Figure 3) In other words, in order to prevent the deviation Δθi of the i-th joint from increasing and the deviation in the postures of the master finger and slave finger from increasing, the coordinate converter corrects the position of the j-th joint by This is to calculate the correction amount.

Returning to FIG. 1, 104 adds the output (target joint angle) θ _Mj of the position detector 9 of the j-th joint 5 of the master finger 1 and the output (correction amount) θ^ _Sj of the coordinate converter 103 described above. This is an adder that outputs the corrected joint angle θ^ _Mj . Further, 105 is a comparator that outputs the corrected joint angle θ^ _Mj and the deviation Δθ _j (=θ^ _Mj −θ _Sj ) of the joint angle θ _Sj measured by the position detector 10 of the j-th joint 6 of the slave finger 2. It is.

By setting the configuration of the control device to the structure shown in FIG. 1 as described above, as shown in FIG. 4, the master finger 1 shown by the broken line becomes the slave finger 2 shown by the solid line by correcting the angle of the j-th joint. By doing so, it is possible to make the compliance of the slave finger variable, and at the same time to make the deviation in posture between the master finger and the slave finger that occurs when the compliance is made variable to an extent that is permissible for operation.

<Effects of the Invention> When the slave finger is used to grasp objects that are easily torn or to fit a rod into a hole, one joint of the human master finger operates the force, and the other joints operate the position. Therefore, the above-mentioned work can be carried out reliably without any operational hindrance, and in a natural way for the operator.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a characteristic diagram of the force operation amount converter in Figure 1, Figure 3 is an explanatory diagram of the coordinate converter in Figure 1, and Figure 4 is an explanatory diagram of the coordinate converter in Figure 1.
FIG. 5 is a conventional block diagram, and FIG. 6 is a conventional relationship diagram between slave fingers and master fingers. In the figure, 100 is a force detector, 101 is a force operation amount converter, and 103 is a coordinate converter.

Claims (1)

[Claims] 1. In a multi-finger control device for a multi-jointed hand, one joint of each finger includes a force operation amount converter that converts the joint angle difference between the master finger and the slave finger into a force command. The slave finger is equipped with a force detector that outputs a reference signal of the force command which is the output of this force operation amount converter, and performs force control. Position control is performed by including a coordinate converter that inputs a joint angle and a joint angle of a slave finger and outputs a correction amount of the joint angle of the slave finger of the other joint with respect to the joint angle of the slave finger. A control device for an articulated hand.