JPH1158285A - Force control system of hand mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out multishaft force control without adding a special device such as a force sensor, etc. SOLUTION: Motor generating torque input voltage from a motor driver is transformed (S1) to a digital signal by an A/D board, and a driving shaft external force estimated value is found by using a disturbance observer. A tool head end external force estimated value is found (S3) by applying coordinate transformation (S2) by using a Yacobian matrix against this driving shaft external force estimated value. Force deflection of the tool head end external force estimated value and a tool head end force command value is found (4), this force deflection is transformed to a speed command value, the speed command value is transformed to an analog signal by the D/A board, and it is supplied to the motor driver. The motor driver drives an AC servo motor in accordance with a speed command.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force control system used for a robot hand mechanism having a tool, and more particularly to a force control system which is attached to a robot body and automatically performs a grinding operation, a mold polishing operation, and the like by a tool. The present invention relates to a force control system for a robot hand mechanism used in a processing work robot.

[0002]

2. Description of the Related Art As is well known, a grinder operation is mainly classified into a deburring operation and a leveling operation. The deburring operation is divided into a case where shape accuracy is required and position control is important, and a case where only burrs are processed by force control copying. On the other hand, the leveling operation is a processing method by force control.

[0003] A machine tool (NC machine) having a numerical controller is widely known as a conventional technique for performing a grinder operation. This type of NC machine numerically programs (teaches) a cutter path for a workpiece,
Processing is performed by executing (playback), and is based on the above-described position control method. For this reason,
In such NC processing machines, generally, the control of the processing force is not performed. Variations in the location and size of burrs vary even among works of the same type. In particular, in the case of cast articles, the outer dimensions differ and the degree of burrs also depends on the accuracy of the mold. Therefore, NC is used for such deburring work.
When using a processing machine, it is necessary to correct the teaching data each time. Therefore, there is a practical problem in applying the NC machine directly to the deburring operation.

Next, a description will be given of a conventional technique for performing a machining operation by a force control method.

A method of combining a commercially available articulated robot with a hand having a force control function. In this method, there is an articulated robot in which a hand having a force control axis having one degree of freedom is connected in series to a tip of the articulated robot. In this case, the processing force can be controlled only in one direction by the hand unit alone.

A system in which a shock absorber is provided between the tip of the arm and the grinding grinder. This method is described in, for example,
No. 246619, "Buffer for Grinding Grinder". According to this publication, even if the robot arm is moved linearly on a processing surface with some unevenness, the grinder follows the surface shape and the grinding stone can always contact the processing surface with a constant pressure, and the cylindrical processing surface On the other hand, the grindstone is always brought into contact with the processing surface at a constant pressure by making the robot arm perform an arc movement without rotating. That is, the shock absorber for a grinding grinder disclosed in this publication provides a spherical projection on the outer peripheral surface of a casing in which a transmission shaft is inserted between a rotary driving machine and a grindstone constituting a grinder, and the spherical projection is provided. By supporting with a spherical seat in the housing attached to the robot or manipulator arm, the grinder can swing in all directions with this spherical seat as a fulcrum, even if it is pushed from any direction in the radial direction of the grindstone, It has a configuration that can buffer in the opposite direction.

In the above-mentioned method, an actuator for directly controlling a force is attached to a machining tool, and therefore, there is an advantage that responsiveness and accuracy are high. However, the above-mentioned method has a problem that the mechanical rigidity is low and the position control processing cannot be performed due to the buffering action. Therefore,
It is limited to force control only.

[0008] Therefore, as a method of combining the position control method and the force control method and switching by software means, a force sensor is provided between the tip of a commercially available articulated robot and a grinder motor (rule motor). There is a method of performing multi-axial force control. In this method, when force control is performed in a certain direction, all motors of the robot joint are subject to force control. For this reason, this system has low response and is inferior in dynamic accuracy.

[0009]

In the above method, 3
The robot body performs an operation of changing the posture of the hand on a dimensional machined surface. Generally, when changing the position of the tip of an articulated robot, it is necessary to operate a base-side motor used for a joint that moves the entire robot arm. Therefore, it is disadvantageous when performing high-speed exercise with a small moving distance.

In the method described above, only the force applied to the grindstone (tool) in the radial direction is buffered, and the force acting from all directions is not buffered.

In the above-mentioned method, errors in the motion accuracy of each joint are accumulated, which causes deterioration of the force control accuracy. Also, when viewed from the joint that moves the entire robot arm, several kgf while moving the entire arm weight of several tens to several hundreds kgw
This is disadvantageous in that the sensitivity of force control is increased because the degree of processing force at the tip is controlled. Further, since the mechanical rigidity of the force sensor is low, there is a problem of durability and reliability of the force sensor when performing a processing operation, particularly a processing involving vibration such as a heavy cutting operation.

Generally, in an articulated robot, since an arm (link) is connected to a series, it is disadvantageous to maintain high mechanical rigidity at the distal end. Therefore, in order to increase the load capacity (the robustness against the processing reaction force), the structure of the robot body tends to be large.

In order to deal with these problems, the present inventors have already provided a robot hand mechanism capable of coping with both processing by position control and processing by force control (Japanese Patent Application Laid-Open No. Hei 9-1491). However, the publication does not disclose any specific example of the force control system for that purpose. Further, as described above, the use of a force sensor causes problems in durability and reliability, and it is not preferable to add a special device such as a force sensor.

Accordingly, an object of the present invention is to provide a force control system of a hand mechanism capable of performing multiaxial force control without adding a special device such as a force sensor.

[0015]

According to the present invention, there is provided a force control system used for a hand mechanism having a tool for processing a workpiece, wherein the hand mechanism comprises:
An end plate that holds the tool on one surface side; a base frame having a center axis that is spaced apart from the end plate on the other surface side and has a central axis; and the base frame that is arranged rotationally symmetrically around the central axis. N (N is an integer of 2 or more) motors each having a drive shaft extending toward the end plate and a means for preventing the drive shaft from rotating and extending and contracting; One end is fixed to the other surface, and the other end is
And N joint mechanisms that are swingably connected at the tips of the drive shafts of the motors. The force control system obtains an estimated value of the tool tip external force from the drive shaft force command value and the drive shaft position. A force estimating device, means for obtaining a force deviation between the tool tip external force estimated value and the tool tip force command value, means for converting the force deviation into a speed command, and means for driving the motor according to the speed command. A force control system for a hand mechanism is provided.

[0016]

According to the present invention, an external force estimated value at the tool tip is obtained from the drive shaft force command value and the drive shaft position by the force estimating device, so that a special device such as a force sensor is not required.
Multi-axial force control can be performed.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 2, a working robot having a robot hand mechanism to which the force control system according to the present invention is applied will be described. The machining robot includes a robot body 1, a robot hand mechanism 2 attached to the robot body 1, a robot controller 3 for controlling the robot body 1 and the robot hand mechanism 2, and a motor generated torque voltage from the robot controller 3. In response, a host computer 4 that performs an operation described later and supplies a speed command voltage to the robot controller 3. The robot hand mechanism 2 has a tool 2a for processing a work (not shown).

In the illustrated working robot, the robot body 1 has four degrees of freedom, and a robot hand mechanism 2
Has three degrees of freedom. That is, the robot body 1 includes a fixed body 1a, a movable body 1b supported to be vertically movable in the Z-axis direction and rotatable about the θ-axis with respect to the fixed body 1a, and the movable body 1b. Robot arm 1c supported for movement and rotation in the R-axis direction with respect to portion 1b
And The robot arm 1c supports the robot hand mechanism 2 rotatably around the T axis. On the other hand, the robot hand mechanism 2 has three drive axes as described later, and the three drive axes are respectively H1 axis, H2 axis, and H axis.
It can expand and contract in two axial directions.

The robot hand mechanism 2 will be described with reference to FIG. 3, (A) is a front view,
(B) is a side view. The robot hand mechanism 2 is attached to a robot arm 1c (FIG. 2) of the robot body 1, and has a tool 2a for processing a workpiece. The robot hand mechanism 2 includes an end plate 10, a base frame 20, first to third linear motion mechanisms 30A,
30B, 30C and first to third joint mechanisms 40A, 4
0B and 40C. First to third linear motion mechanisms 30
Each of A, 30B and 30C is constituted by an AC servomotor.

The end plate 10 holds the tool 2a on one side. A grinder motor 50 is fixed to the end plate 10, and the grinder motor 50 processes the workpiece by rotating the tool 2a.

The base frame 20 has a central axis O, and is arranged opposite to the end plate 10 on the other surface side. The base frame 20 includes a base 21 rotatably supported by the robot arm 1c (FIG. 2),
A head 22 that is spaced from the base plate 21 and faces the end plate 10, and that is opposed to the base 21, and a connecting portion 23 that connects the base 21 and the head 22. The head 22 of the base frame 20 has first to third linear motion mechanisms 30A,
First to third main bearings 24A, 24B, 24C for rotatably supporting 30B, 30C around first to third support shafts A, B, C are fixed. The first to third support shafts A, B, C are rotationally symmetric about the central axis O on a plane orthogonal to the central axis O.

The first to third linear motion mechanisms 30A, 30B,
30C is mounted on the head 22 of the base frame 20 so as to be arranged rotationally symmetrically about the central axis O. That is, the first to third linear motion mechanisms 30A, 30B, 30C
Are arranged such that the first to third support axes A, B, and C form one side of an equilateral triangle. First to third
Each of the linear motion mechanisms 30A, 30B, and 30C has a ball screw spline shaft (drive shaft) 31 extending toward the end plate 10 and a mechanism (not shown) that prevents the ball screw spline shaft 31 from rotating and expanding and contracting. ). Also, the first
Each of the third to third linear motion mechanisms 30A, 30B, 30C
It has two main shafts 32 extending in a direction perpendicular to the axial direction of the ball screw spline shaft 31. The two main shafts 32 of the first to third linear motion mechanisms 30A, 30B, 30C are rotatably supported in the first to third bearings 24A, 24B, 24C, respectively. Act as the first to third support shafts A, B, C.

The first to third joint mechanisms 40A, 40B,
40C has one end fixed to the other surface side of the end plate 10 and the other end respectively connected to the first to third linear motion mechanisms 3.
The ends of the ball screw spline shafts 31A, 30B and 30C are swingably connected. In other words, the ball screw spline shaft 31 of the first to third linear motion mechanisms 30A, 30B, 30C is connected to the end plate via the first to third joint mechanisms 40A, 40B, 40C having three rotational degrees of freedom. 10 is connected. Each of the first to third joint mechanisms 40A, 40B, 40C has a U-shaped first frame 41 rotatably connected to the tip of a ball screw spline shaft 31 around the shaft, and an end plate 10
And a U-shaped second frame 42 fixed to the other surface.

The configuration of the robot hand mechanism controller will be described with reference to FIG. As described above, the robot hand mechanism 2 includes the first to third linear motion mechanisms 30A,
It has three AC servomotors 5 as 30B and 30C. The robot controller 3 includes three motor drivers 6 for controlling these three AC servomotors 5. The host computer 4 has an A / D board 7 and a D / A
It includes a board 8 and a counter board 9.

The motor-generated torque voltage output from the motor driver 6 is taken into the host computer 4 via the A / D board 8. The host computer 4 calculates a tool tip force by estimating a force using a disturbance observer (described later) based on the motor-generated torque voltage and performing coordinate transformation (described later). Force control is performed by feeding back the calculated tool tip force.

FIG. 1 shows a force control flow according to the present invention executed by the host computer 4. First, the motor-generated torque input voltage from the motor driver 6 is converted into a digital signal by the A / D board 7 (step S1), and a drive shaft external force estimated value is obtained using a disturbance observer described later.
By performing coordinate transformation using the Jacobian matrix on the estimated value of the drive shaft external force (step S2), an estimated value of the tool tip external force is obtained (step S3). A force deviation between the tool tip external force estimated value and the tool tip force command value is obtained (step S
4) The force deviation is converted into a speed command value, and the speed command value is converted into an analog signal by the D / A board 8 (step S).
5) Then, the motor driver 6 is supplied. Motor driver 6
Drives the AC servomotor 5 according to the speed command.

Referring to FIG. 5, a position control system used for the hand mechanism 2 will be described. The position control system shown
Each AC servo motor 5 is configured as an independent control system. The position control system has a position controller 60 and a tool tip / motor position converter 70. The position controller 60 has a motor position / motor rotation angle converter 61, a subtractor 62, and a PI compensator 63. Tool tip /
The motor position converter 70 includes a tool tip / end plate position converter 71 and an end plate / motor position converter 7.
And 2. In Table 1 below, various symbols in the position control system shown in FIG. 5 are shown in the left column, and their meanings are shown in the right column.

[0029]

[Table 1]

In the tool tip / motor position converter 70, the tool tip / end plate position converter 71 converts a tool tip position command value into an end plate position command value. The end plate / motor position converter 72 converts the end plate position command value into a drive shaft length command value. In the position controller 60, a motor position / motor rotation angle converter 61 converts a drive shaft length command value into a motor rotation angle command value. The subtracter 62 subtracts the motor rotation angle feedback value from the motor rotation angle command value and outputs an angle deviation. The PI compensator 63 obtains a motor rotation angular velocity command value from the angle deviation. This motor rotation angular velocity command value is supplied to the motor driver 6.

A series of control calculations in the position control system shown in FIG.

[0032]

(Equation 1)

That is, as shown in FIG. 5, a command transformation is performed on the tool tip position command value by the conversion matrix ^E _Tt to calculate an end plate position command value. Further calculates a driving shaft length command value by performing coordinate transformation by the transformation matrix ^A T _E to the end plate position command value. The drive shaft length command value is converted by a conversion coefficient (K _pg ) ^-1 to calculate a motor rotation angle command value. Hand mechanism 2
A motor rotation angle feedback value is calculated from an output from an encoder (not shown) provided in the motor, and an angle deviation is calculated from a deviation calculation between the motor rotation angle command value and the motor rotation angle feedback value. An angle command value is obtained and output to the motor driver 6. Thus, position control is performed.

FIG. 6 shows a force estimating device using a disturbance observer used in the force control system according to the present invention. The illustrated force estimating device 80 includes a disturbance observer 90 and a force coordinate converter 100. The disturbance observer 90 includes first and second filters 91 and 92, a subtractor 93, and a position calculator 94. The force coordinate converter 100 includes a drive shaft / end plate force converter 101 and an end plate / tool tip force converter 102. In Table 2 below, various symbols in the force estimating device shown in FIG. 6 are shown in the left column, and their meanings are shown in the right column.

[0035]

[Table 2]

In the disturbance observer 90, the first filter 91 applies a secondary filter to the drive shaft force command value to limit the band and obtain a filtered drive shaft force command value. The position calculator 94 determines the position of the drive shaft from the rotational displacement of the motor 5. The second filter 92 uses the reference model of the hand mechanism 2 to be controlled based on the drive shaft position to obtain an estimated acceleration force value of the reference model. The subtractor 93 subtracts the drive shaft direction force command value from the estimated acceleration force value of the reference model to obtain an estimated drive shaft external force value. Force coordinate converter 1
At 00, the drive shaft / end plate force converter 101
Calculates the end plate external force estimated value by performing coordinate transformation on the drive shaft external force estimated value. The end plate / tool tip force converter 102 performs coordinate transformation on the end plate external force estimated value to obtain a tool tip external force estimated value.

In this disturbance estimation, a band is limited by a secondary filter in consideration of measurement noise. The control rules for the first and second filters 91 and 92 in the disturbance observer 90 are given by
It is expressed by the following equation and equation (3).

[0038]

(Equation 2)

(Equation 3) A subtractor 93 in the disturbance observer 90 obtains an estimated value of the driving shaft external force according to the following equation (4).

[0039]

(Equation 4) As a result, the disturbance force is estimated by the following equation (5).

[0040]

(Equation 5)

FIG. 7 shows a force control system according to the present invention using the disturbance estimating apparatus shown in FIG. However, the disturbance estimating device 80A includes a friction compensator 95 and a disturbance observer 90A.
Is added. The friction compensator 95 is for correcting an estimation error due to the friction torque of the ball screw by calibration.

The illustrated force controller 110 includes a disturbance estimator 80A, a subtractor 111, a PI compensator 112,
It has a tool tip / end plate force converter 113, an end plate / drive axial force converter 114, and an amplifier 115.

In addition to those shown in Tables 1 and 2, Table 3 below shows various symbols in the force controller 110 shown in FIG. 7 in the left column and the meaning in the right column.

[0044]

[Table 3]

In the force controller 110, the subtractor 1
Numeral 11 calculates a force deviation by subtracting the tool tip external force estimated value from the tool tip force command value. The PI compensator 112 calculates a compensation calculation value from the force deviation. The tool tip / end plate force converter 113 converts the compensation operation value into an end plate force command value. End plate / drive axial force converter 114
Converts the end plate force command value into the drive shaft force command value. The amplifier 115 amplifies the driving shaft force command value with a force command gain to obtain a motor rotation angular speed command value.

The control law of the force controller 110 shown in FIG. 7 is shown in the following equation (6).

[0047]

(Equation 6)

That is, the external force value at the tool tip estimated by the above-described force estimating device is used as a feedback value, a deviation calculation is performed with the tool tip force command value, converted into a speed command, and output to the motor driver 6. , Perform force control.

FIG. 8 shows a position and force hybrid control system applied to the hand mechanism 2. In the illustrated hybrid control system, the above-described position control system and a force control system using a disturbance observer are configured simultaneously and independently. The motor rotation angular velocity command value output from the position controller 60 and the motor rotation angular velocity command value output from the force controller 110 are added by the adder 121, and the sum of the velocity command values is supplied to the motor driver 6. Performs position and force hybrid control. The overall control law is given by the following equation (7).
It is expressed by an equation.

[0050]

(Equation 7)

The drive shaft length feedback value from the hand mechanism 2 is converted into an actual position by the hand rigidity 122, and the actual position is subtracted from the work position by the subtractor 123. Stiffness 12
4 converts it to the actual force.

According to the position and force hybrid control system having such a configuration, deburring and leveling operations can be performed without being affected by variations in the shape of the processed workpiece. In addition, during the teaching operation, the force of the tip of the tool 2a is estimated and monitored by the above-described force estimating device, so that contact with the teaching target can be detected.
Thus, teaching can be performed without fine adjustment, and the time for teaching operation can be reduced.

FIGS. 9 and 10 show examples of machining a workpiece by the position and force hybrid control system shown in FIG. In each of FIGS. 9 and 10, (a) shows a machined surface before and after machining, (b) shows a machining method, and (c) shows an estimated force value during machining.

FIG. 9 shows an example in which deburring is performed using a carbide bar as the tool 2a (processing example 1). FIG.
As shown in (b), the position was controlled in a direction horizontal to the surface of the work, and at the same time, the processing was performed by controlling the pressing force against the work. As shown in FIG. 9A, it can be seen that the burrs are removed neatly.

FIG. 10 shows an example in which deburring is performed using a carbide bar having a shank longer than that in FIG. 9 as the tool 2a (processing example 2). As shown in FIG. 10B, force control is performed on two surfaces that come into contact with the work, and the position of the work is also controlled from the lower surface to the upper surface.
A corner portion was machined as shown in FIG.

A program executed by the host computer 4 to realize the force control flow shown in FIG. 1 may be recorded on a recording medium (not shown). Here, the “recording medium” refers to a computer-readable recording medium on which a program is recorded. Specifically, it includes a magnetic disk such as a CD-ROM and a plexible disk, and a semiconductor memory. Further, the recording medium may be paper on which a program is recorded. In this case, the computer only needs to include a reading device such as an OCR (optical character reading device) and a compiler that translates a character (code) read by the reading device into a machine language that can be recognized by the computer. . In any case, by installing the program recorded on the recording medium into the computer, the computer can perform a predetermined process.

The present invention is not limited to the above embodiment,
Various modifications and changes can be made without departing from the spirit of the present invention. For example, in the above embodiment, an example is shown in which the present invention is applied to a parallel mechanism having three degrees of freedom. However, it is needless to say that the present invention can be applied to a parallel mechanism having four or more degrees of freedom. Further, the present invention can be applied to not only a parallel mechanism but also a serial link mechanism. The processing operation is not limited to deburring, and can be applied to other processing operations such as polishing and grinding, and assembling operations of precision parts.

[0058]

As described above, according to the present invention, since the force is estimated by the force estimating device, the force can be detected and controlled without adding a special device such as a force sensor. Further, since the tip force of the tool is controlled, it is possible to process the work while following the shape of the work. Therefore, there is no need to create teaching data for each work.
Since force control in a plurality of directions can be performed by the hand mechanism, a three-dimensional workpiece can be machined without changing the posture of the robot body (base portion). Furthermore, according to the purpose, the force and position are each defined in the rectangular coordinate system,
The characteristics of the hand mechanism can be freely controlled.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a force control method of a hand mechanism according to an embodiment of the present invention.

FIG. 2 is a front view showing the entire configuration of a processing robot to which the present invention is applied.

3A and 3B are views showing a hand mechanism used in the machining operation robot shown in FIG. 2, wherein FIG. 3A is a front view and FIG. 3B is a side view.

FIG. 4 is a schematic and block diagram illustrating a configuration of a hand mechanism controller for controlling the hand mechanism illustrated in FIG. 3;

FIG. 5 is a block diagram showing a position control system for the hand mechanism shown in FIG. 3;

FIG. 6 is a block diagram showing a force estimating device used in a force control system according to the present invention.

FIG. 7 is a block diagram showing a force control system for the hand mechanism shown in FIG. 3, according to one embodiment of the present invention.

FIG. 8 is a block diagram showing a position and force hybrid control system for the hand mechanism shown in FIG. 3;

FIG. 9 is a view showing Working Example 1 by the hybrid control system shown in FIG. 8;

FIG. 10 is a view showing a working example 2 by the hybrid control system shown in FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Robot main body 2 Hand mechanism 2a Tool 3 Robot controller 4 Host computer 5 AC servomotor 6 Motor driver 10 End plate 20 Base frame 30A, 30B, 30C Linear motion mechanism (AC servomotor) 31 Ball screw spline shaft (drive shaft) 40A, 40B, 40C Joint mechanism 50 Grinder motor

Claims (10)

[Claims] 1. A force control system used for a hand mechanism having a tool for performing processing on a workpiece, the hand mechanism comprising: an end plate that holds the tool on one surface side; A base frame having a central axis, which is spaced apart and opposed on the other surface side; and is attached to the base frame so as to be rotationally symmetric about the central axis, and each extends toward the end plate. N (N is an integer of 2 or more) motors having a drive shaft and a means for expanding and contracting the drive shaft while preventing rotation; one end is fixed to the other surface of the end plate, and the other end is And N joint mechanisms that are swingably connected at the tips of the drive shafts of the N motors. The force control system is configured to determine a tool tip external force based on a drive shaft force command value and a drive shaft position. A force estimating device for obtaining a constant value, a means for obtaining a force deviation between the tool tip external force estimated value and the tool tip force command value, a means for converting the force deviation into a speed command, and driving the motor according to the speed command. And a force control system for a hand mechanism. 2. The apparatus according to claim 1, wherein the force estimating device includes a disturbance observer that obtains an estimated drive shaft external force value from the drive shaft force command value and the drive shaft position; 2. The force control system for a hand mechanism according to claim 1, further comprising a coordinate conversion unit for obtaining an estimated external force. 3. The disturbance observer includes means for obtaining a filtered drive shaft direction force command value by performing a band limitation of the drive shaft force command value, and an acceleration force of the reference model of the hand mechanism from the drive shaft position. Means for determining an estimate;
3. The force control system for a hand mechanism according to claim 2, further comprising: a unit that obtains the estimated value of the drive shaft external force from a difference between the estimated acceleration force of the reference model and the drive shaft direction force command value. 4. 4. The disturbance observer includes means for obtaining a filtered drive shaft direction force command value by limiting a band of the drive shaft force command value, and an acceleration force of a reference model of the hand mechanism from the drive shaft position. Means for determining an estimate;
Means for calculating an estimated error due to friction torque from the position of the drive shaft, and means for calculating the estimated value of the drive shaft external force from the estimated acceleration force of the reference model, the drive shaft direction force command value, and the estimated error. Item 3. A force control system for a hand mechanism according to Item 2. 5. The coordinate conversion means includes: first coordinate conversion means for converting the drive shaft external force estimated value into an end plate external force estimated value; and converting the end plate external force estimated value to the tool tip external force estimated value. 3. The force control system for a hand mechanism according to claim 2, further comprising a second coordinate conversion means for performing conversion. 6. A force estimating device used for a hand mechanism having a tool for processing a workpiece, the hand mechanism comprising: an end plate for holding the tool on one surface side; A base frame having a central axis, which is spaced apart and opposed on the other surface side; and is attached to the base frame so as to be rotationally symmetric about the central axis, and each extends toward the end plate. N (N is an integer of 2 or more) motors having a drive shaft and means for expanding and contracting the drive shaft by preventing rotation; one end is fixed to the other surface of the end plate;
The other end has N joint mechanisms that are swingably connected at the tip ends of the drive shafts of the N motors, respectively. The force estimating device is configured to calculate a drive shaft force command value and a drive shaft position. A force estimating device for a hand mechanism, comprising: a disturbance observer for obtaining an estimated external drive shaft force; and coordinate conversion means for performing coordinate conversion on the estimated external drive shaft force to obtain an estimated external force at a tool tip. 7. The disturbance observer includes means for obtaining a filtered drive shaft direction force command value by performing a band limitation of the drive shaft force command value, and an acceleration force of a reference model of the hand mechanism based on the drive shaft position. Means for determining an estimate;
7. The force estimating device for a hand mechanism according to claim 6, further comprising: means for obtaining the estimated value of the drive shaft external force from the difference between the acceleration force estimated value of the reference model and the drive shaft direction force command value. 8. The disturbance observer includes means for obtaining a filtered drive shaft direction force command value by performing band limitation of the drive shaft force command value, and an acceleration force of a reference model of the hand mechanism from the drive shaft position. Means for determining an estimate;
Means for calculating an estimated error due to friction torque from the position of the drive shaft, and means for calculating the estimated value of the drive shaft external force from the estimated acceleration force of the reference model, the drive shaft direction force command value, and the estimated error. Item 7. A force estimating device for a hand mechanism according to Item 6. 9. The coordinate conversion means includes: first coordinate conversion means for performing coordinate conversion of the drive shaft external force estimated value to an end plate external force estimated value; and coordinate conversion of the end plate external force estimated value to the tool tip external force estimated value. 7. The force estimating device for a hand mechanism according to claim 6, further comprising a second coordinate converting means for converting. 10. A process for inputting a motor-generated torque input voltage from a motor driver, a process for obtaining an estimated value of a drive shaft external force from the motor-generated torque input voltage, and using a Jacobian matrix for the estimated drive shaft force value. By performing a coordinate transformation which has been performed, a process of obtaining a tool tip external force estimated value, a process of calculating a force deviation between an externally applied tool tip force command value and the tool tip external force estimated value, and converting the force deviation into a speed command value. A recording medium recording a program for causing a computer to execute a process of converting and outputting.