JPS5946753B2 - Master slave type servo manipulator - Google Patents

Description

[Detailed description of the invention] This invention allows for misalignment due to the control of the master arm.

- This invention relates to a multi-joint master-slave type servo and manipulator that act on a target object by operating a servo arm. In conventional so-called mechanical manipulators, an operator is a slave arm in which a multi-jointed master arm and a slave arm, each having rotational or screw joints such as wrists, elbows, and shoulders, are mechanically connected by links, wires, etc. - Since the torque that acts on each joint of the arm when the arm acts on an object is returned to the master arm via the connection mechanism, the master arm can be maneuvered more reliably.

However, with the above-mentioned type of servo manipulator, when acting on a highly rigid object (hereinafter referred to as an object) that is fixed or has a large inertia, such as an iron ingot or a fixed structure, the servo manipulator of the position servo system A sudden joint torque corresponding to the rigidity torque acts on the operator through the master arm, and the operator feels this as a reflex torque, making the required operation unstable9.
In some cases, it may not be possible at all.

Furthermore, there is a very high risk of destruction of fragile objects such as glass products. An object of the present invention is to provide a multi-joint master-slave type servo manipulator that can perform operations stably and reliably, with less discomfort in master-arm operation due to torque feedback caused by action on a target object.

An embodiment of the invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the invention. First, the operation when the slave arm 1 is not acting on the target object will be described.

V) by the operator manipulating the master arm 2
This joint angle θm changes, and this θm is converted into an electrical signal by the position detector 3. At the same time, the joint angle θs of the slave arm 1 is also converted into an electrical signal by the position detector 4.
Here, as shown in FIGS. 4 and 5, the position detector 3 or 4 is an arm 13 in the case of FIG. , 14 joint rotation axis (or screw axis), the motor 15, the reducer 16, the rotation angle of the rotary potentiometer or synchronizer directly connected to the output shaft 17, the differential transformer, the encoder, etc. A detector 18 is used. In addition, to detect the opening of a finger joint, etc., as shown in FIG. Since it is a joint mechanism for movement, the above-mentioned detector 24 is connected to the rotating part (the output shaft 21 in the figure) before the four-bar link. The electric signals from the two position detection sections 3 and 4 described above become differential inputs to the comparator 5. The output ΔE of the comparator 5, which is proportional to the difference between θm and θs, is input to the amplifier 6 and the position error signal converter 7. As a result, the amplifier 6 and the drive device 8 cause the joint angle θS of the slave arm 1 to follow the change in θm. On the other hand, the output ΔE of the comparator 5 is subjected to a signal conversion process having a predetermined functional relationship described later in the position error signal converter 7, and this output signal Ep converts the joint torque of the master arm 2, that is, the operator's steering torque. A comparator 10 compares the output Et of the torque detector q to be detected, and the result is operated through an amplifier 11 and a drive device 12 so that Ep and Et are balanced.

For example, if Et is greater than Ep, the drive unit 12 attempts to reduce the difference (Et - Ep) and operates to open or close the master arm 2 in the direction of the torque being applied by the operator. . Normally, a very large torque is required to move the drive device 12 from the output side, that is, from the operator side, making it difficult to operate, but since the torque detector 9 is used to construct a loop that operates as described above, This problem is almost solved. Next, a case will be described in which the slave arm 1 acts on a target object. Even if the angle θm changes due to the operation of the operator, θs hardly changes, so the absolute values of both ΔE and Ep become large, and the drive device 12 generates torque in the opposite direction to the operating torque of the operator. , the operator further strengthens the steering torque in order not to succumb to this torque. As a result, E
t and Ep match and the system is in equilibrium. If the slave arm 1 is only touching the surface of the target object in the state of ΔE-O, the operator will not receive any torque feedback, but if the slave arm 1 is pressed further, ΔE and Ep corresponding to the magnitude will occur, and Et = Ep Only a small amount of steering torque is required. in this case,
If the position error signal converter 7 has a linear proportional characteristic, the angle at which the master arm 2 is pressed and the required steering torque are proportional as shown in FIG. Furthermore, in the case of nonlinear characteristics, such as cubic or exponential characteristics, as shown in FIG. 3, the required steering torque increases rapidly as the mass tide/pressing angle of the arm 2 increases. The meaning of providing the position error signal converter 7 with nonlinear input/output characteristics is as follows.

When humans directly act on a target object, they first perceive that they have touched the object through their sense of touch. Next, the torque of each joint required for the desired action is applied to the object, but there is a difference in torque between the magnitude of the torque and the degree of depression of the skin and the amount of deflection of the joint (these are collectively referred to as the pressing angle). There is a relationship such that as the pressing angle increases, the degree of increase in the pressing angle decreases. By providing the position error signal converter 7 with the same or pseudo nonlinear input/output characteristics,
Since the manipulation of the target object by manipulating the master arm 2 is the same or almost the same as the above-mentioned direct human action, the operator can manipulate the master arm very smoothly. This invention has the following effects.

(1) Conventionally, when a high reduction gear was used as the drive device for the master arm, it was difficult to maneuver even when the slave arm was unloaded, but in this invention, the torque detection on the master arm side The presence of the device makes it extremely easy to maneuver, and thus the drive circuit on the master arm side can be made significantly smaller and lighter.

(2) The position error signal converter can stably and reliably act on highly rigid objects that are fixed or have large inertia. In particular, the position error signal converter has non-linear conversion characteristics that allow the operator to handle the master arm with a sensation that closely matches the sensation experienced when directly acting on an object, making it extremely easy for the operator to operate. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG.
FIG. 3 is a graph showing the relationship between the pressing angle and the control torque of the master arm based on the different input/output characteristics of the position error signal converter, and FIGS. 4 and 5 are graphs showing the joint operating angle detection in this invention. FIG. 1... Misalignment ≦ arm, 2... Master ● arm,
3, 4... Position detector, 5... Comparator, 6... Amplifier, 7... Position error signal converter, 8... Drive device, 9- Torque converter, 10... Comparator, 11...Amplifier, 12...1 drive device, 13,14...Arm, 15,19...Motor, 16,20...Reducer,
17, 21... Output shaft, 18, 24... Rotation angle detector, 22... Four-bar link mechanism.

Claims (1)

[Claims] 1 A master arm having rotational or torsional joints such as wrists, elbows, shoulders, etc., a torque detector for detecting the operating torque applied to the master arm by an operator, and a master arm having the same joints as the master arm - A slave arm that acts on a target object by manipulating the arm, and a position error signal converter that inputs a position error signal between this slave arm and the master arm and has an output characteristic of a cubic function or an exponential function. , a comparator input through the position error signal converter and comparing this input signal with the output of the torque detector, and a drive device for driving the master arm according to the output of the comparator. and a drive device for driving the slave arm according to the position error signal.