JPS5933518B2 - Master/slave type servo/manipulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a master-slave type servo manipulator in which a master hand is operated to operate a slave hand to grasp an object.

In conventional so-called mechanical manipulators, in which a master hand arm and a slave hand arm are mechanically connected by links, wires, etc., when performing the most important operational responsibility of grasping an object, the master hand arm and the slave hand arm are When the slave hand grasps an object, the operator controlling the hand receives the grasping force back through the connection mechanism,
Therefore, the grasping operation can be executed more reliably.

However, with the above-mentioned type of servo manipulator, when a rigid object such as an iron ingot or glass product is grabbed, a sudden force corresponding to the servo rigidity force of the position servo system is applied to the operator through the master hand. However, since the operator feels this as a reflex force, the grasping operation not only becomes unstable, but also becomes completely impossible.

Furthermore, there is a very high risk of breakage for fragile objects such as glass products. The purpose of this invention is to create a master system that minimizes the discomfort caused by force feedback that occurs when grasping an object, enables stable and reliable grasping work, and enables grasping force control with excellent maneuverability.
An object of the present invention is to provide a slave type servo manipulator.

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

FIG. 1 shows in block diagram form an embodiment of the invention. First, the operation in a state where the stove hand 1 does not grasp an object will be described.

By the operator operating Master Hand 2,
The opening degree θm changes, and this θm is converted into an electrical signal by the position detector 3. Similarly, the opening degree θs of the slave hand 1 is also converted into an electrical signal by the position detector 4, and these two electrical signals are input 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 comparator 6 and the position error signal converter 7. The comparator 6 includes a force detector 8 for detecting the grasping force of the slave hand 1;
The signal Em extracted through the force signal converter 9 that processes the output of is compared with the previous error signal ΔE, but in this case, Em is zero because the object is not grasped. Therefore, the output of the comparator 6 remains △E, and this is the output of the amplifier 10.
The driving device 11 is moved through θ8 to θ. It acts to make it match. On the other hand, the output △E of the comparator 5 is processed by the position error signal converter 7, and the output signal E is the output of the force detector 12 which detects the grasping force of the P-hand 2, that is, the operating force of the operator. Signal Et
The comparator 15 compares E and Et, and the output thereof becomes the input of the amplifier 13, which acts through the driver 14 so that E and Et are balanced.

For example, if Et is greater than E, the drive unit 14 attempts to reduce the difference E, -Et and operates to open or close the master hand 2 in the direction of the force being applied by the operator at that time. Normally, a very large force is required to move the drive device 14 from the output side, that is, from the operator side, making it very difficult to operate, but since the force detector 12 is used to construct a loop as shown in the figure, This problem is almost solved. Next, a case will be described in which the slave hand 1 grasps a highly rigid object.

θ by the operator's control. Even if θ8 decreases, θ8 hardly changes, so ΔE. The absolute value of both E and E increases, causing the drive device 14 to generate torque in the opposite direction to the operator's control force, and the operator further strengthens the force in order not to be defeated by the torque, so Et and E coincide, and the system Equilibrium. If the slave hand 1 is just touching the surface of the object in the state of △E+O, the operator will not receive any feedback force, but if the operator grasps the object further, the △E.
E, occurs and requires a steering force of EtE. In this case, if the position error signal converter 7 has a linear proportional characteristic, the gripping amount of the master hand 2 and the required control force will be proportional as shown in FIG. Also, nonlinear characteristics,
For example, if the grip has characteristics of a cubic function or an exponential function, as the amount of grip increases, the required steering force increases rapidly, as shown in FIG. The meaning of providing nonlinear input/output characteristics to the position error signal converter 7 is as follows.

When humans directly grasp a hard object, they first perceive that they have touched the object through their sense of touch. Next, grasp the object with the force necessary for the desired action, but there is a difference between the amount of force used at that time and the amount of indentation in the skin and the amount of bending of the joints (this is collectively expressed as the amount of grip). There is a relationship in which the rate of increase in the amount of grip decreases as the amount increases. By providing the position error signal converter 7 with the same or similar nonlinear input/output characteristics, grasping by manipulating the master hand 2 is the same as or similar to the above-mentioned direct grasping by a human. Therefore, the operator can perform grasping work very smoothly. In the above case, the slave hand 1 grasps the highly rigid object with a force that makes EITl equal to ΔE.

If you only want to grasp a highly rigid object with a soft sensation by controlling it only from the master hand side, the force detector 8 and force signal converter 9 are not necessary. A large force corresponding to the rigidity will be applied. Finally, in contrast to the slave hand 1 grasping an object by the master hand 2, the slave hand
The operation when an external force is applied to the hand 1 for some reason will be described.

The external force acting on the slave hand 1 produces an output signal Ern through the force detector 8 and the force signal converter 9,
m is compared with ΔE. At this time, θ. If is fixed, θ8 changes so that ΔE=Eml, and equilibrium is established.
Of course, as described above, a force corresponding to this ΔE acts on the fixed master hand 2. In this invention, the input/output characteristics of the above-mentioned position error signal converter 7 and force signal converter 9 are set to be inverse functions to each other. For example, when the input/output characteristic of the position error signal converter 7 is a cube function or an exponential function, the input/output characteristic of the force signal converter 9 is a cube root function or a logarithmic function. When these mutual relationships exist, the operating force of master hand 2 and the operating force of slave hand 1 are expressed as θ. An example of the parameter of the difference between and θ8 is shown in FIG. That is, since the operating force of the slave hand 1 is proportional to that of the operator, it is possible to grip even highly rigid but relatively fragile objects such as glass products very smoothly and safely. Thus, the present invention has the following effects.

(1) For example, when a high speed reducer is used as the drive device of the master hand, it is difficult to operate the slave hand even when the slave hand is not loaded, but in this invention, the force detection on the master hand side The presence of the device made it extremely easy to operate, and the drive circuit on the master pand side could be made much smaller and lighter.

(2) The position error signal converter can stably and reliably perform the highly rigid object grasping operation, which is an important task for a steerable servo manipulator. In particular, the position error signal converter and force signal converter have nonlinear input/output (conversion) characteristics that are inverse functions of each other.
The grasping motion as a manipulator can be made to be very similar to the motion when a human directly grasps, making it extremely easy for the operator to operate, and the operating force of the slave hand is proportional to the operating force of the operator. This allows for excellent grip control.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIGS. 2 and 3 show the amount of grip and the amount of master hand operation based on different input/output characteristics of the position error signal converter, respectively. FIG. 4 is a graph showing the relationship between master hand operating force and slave hand operating force. 1...Slave hand, 2...Master hand, 3, 4...Position detector, 5, 6...
... Comparator, 7 ... Position error signal converter, 8 ... Force detector, 9 ... Force signal converter, 10 ... - Amplifier, 11... Drive device, 12... Force detector, 13... Amplifier, 14... Drive device, 15... Comparator.

Claims (1)

[Claims] 1 A position error signal converter having linear or non-linear input/output characteristics for inputting position error signals between a master hand and a slave hand that performs an object grasping operation by controlling the master hand;
a force detector for detecting a steering force applied to the hand; a comparator for comparing the output of the force detector with the output of the position error signal converter; and driving the master hand in accordance with the output of the comparator. The input/output characteristics of the drive device for the slave hand, the force detector for detecting the grasping force of the slave hand, and the position error signal converter that receives the output of the force detector as input are in an inverse functional relationship. A force signal converter having input/output characteristics, a comparator for comparing an output signal of the force signal converter with the position error signal, and a driving device for driving the slave hand according to the output of the comparator. A master-slave type servo manipulator comprising: