JP2003063800A - Thee axial force sensor system and power operation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a power operation device such as a small crane or a care lifter without having a feeling of physical disorder according to a move of the hand of an operator by detecting the motion direction of the hand of the operator, that is the force lifting, lowering, or laterally moving, by optimizing the interface between a person and a machine. SOLUTION: This three axial force sensor system 10 is constituted so that a cylindrical griping body 2 having an opened part at one end and strain detecting parts forming pairs in the four directions at the other end is installed, a strain gauge 4 is installed in the strain detecting part, the cylindrical griping body 2 is fixed to a shaft body 1 extending in the cylinder direction through the strain detecting part, and a processing device calculating forces in X, Y, and Z directions by strains detected with the strain gauge 4 is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triaxial force sensor system capable of detecting forces in the x, y and z directions applied by an operator, and industrial equipment and welfare equipment to which the triaxial force sensor system is applied. The present invention relates to a power operation device including a power assist device such as transportation equipment or a switchgear.

[0002]

2. Description of the Related Art Conventional crane devices and care lifters are installed away from an object on which an operation switch moves and a care receiver. Further, since the push-button switch for on and off is configured, the operation is on and off.
The result is f, which is considerably different from the operator's feeling. Especially in the case of a lifter for nursing care, it is important that the caregiver and the cared person touch and operate it to give the caregiver a sense of security and smooth movement. I can't handle these things.

As a publicly known example of the sensor, Japanese Patent Application No. 05-2820 relates to an operating device and an input device for detecting displacement and force.
No. 20, Japanese Patent Application No. 09-362428, Japanese Patent Application No. 08-0
No. 57458 is known.

Further, Japanese Patent Laid-Open No. 11-280332 describes a door opening / closing system in which a door is opened by an auxiliary force.

[0005]

SUMMARY OF THE INVENTION The present invention detects the direction of movement of an operator's hand, that is, the force of lifting, lowering, or moving laterally, so that a small crane or a care lifter can be operated with the operator's hand still moving. It is an object of the present invention to optimize the interface between the operator and the machine so that the power operation device can be operated without a sense of discomfort.

[0006]

[Means for Solving the Problems] A rod-shaped strain detecting portion is provided between the central axes for attaching the grip body to the front, rear, left and right of the central axis.
Three axes, which are installed in a book (two pairs), and the front and / or back of two strain gauges are attached to the rod-shaped strain detection unit to detect forces in the x, y and z directions applied by the operator. Configure the sensor.

The force is detected by calculating the bending moment from the bending strain of the member surface generated in the rod-shaped force detecting portion and calculating the x or y direction force from the pair of rod-shaped detecting portions. The z-direction force is calculated in the same procedure as the x- or y-direction force from one or two pairs of rod-shaped force detection units.

The speed of hoisting and lateral movement is determined by the object moving speed when the object on the floor is moved by the force of the operator to optimize the interface between man and machine.

The above-mentioned sensor system is attached to the vicinity of the hook by a power operation device such as a small crane that lifts and moves an object by a luggage hook or the like at the lower end of the wire rope, and moves in x and y directions and lifting work in z direction. I do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a vertical cross section of a triaxial center used in the embodiment of the present invention, and FIG. 2 shows a II-II cross section of FIG.
In these drawings, the triaxial force sensor 100 has a cylindrical grip body (grip portion) 2, and the grip body 2 is formed with the outer cylinder 21 and four strain (force) measurement hardware 3 (31). , 32, 33,
34) and the shaft 1 which passes through the center of the outer cylinder 21 and to which the strain measurement hardware 3 is fixed. The outer cylinder 21 has an open upper end, and the shaft 1 is allowed to tilt in the lateral direction. In addition, the outer cylinder 21 includes four, that is, two pairs of rod-shaped strain measurement hardware 3 (3
1, 32, 33, 34) are fixed to the shaft 1 and held.

The strain measurement hardware 3 is a pair of left and right strain measurement hardware 3.
1, 32 and a pair of front and rear strain-measuring hardware 33, 34, and two strain gauges 4 are attached to the rod-shaped strain (force) detecting portion, respectively. One strain gauge 4 may be provided for each strain detection unit, but by mounting two strain gauges on the front and back, the measurement accuracy is improved. Reference numeral 51 indicates a welded portion. In FIG. 2, the strain gauge 4 is attached to the left and right strain measurement hardware 31, 32 by a,
b, and c and d are attached to the above-mentioned strain measurement metal parts 33 and 34.

A mounting portion 6 for mounting various power operating devices is provided on the upper end of the shaft 1, and a hook mounting portion 5 for luggage is provided on the lower end.

As described above, the triaxial force sensor 100 has one end open, and the other end includes the strain detecting portions that make pairs in the front, rear, left, and right (having two pairs of strain detecting portions). The detection unit is provided with a cylindrical grip body 2 each having a strain gauge 4, and the cylindrical grip body 2 is fixed to a shaft (body) 1 extending in the cylindrical direction via the strain detection unit. To be done. In the above-mentioned example, the rod-shaped strain measuring hardware 31, 32, 33, 34
However, it may be plate-shaped, and the strain detector 4 is configured by mounting the strain gauge 4 on the connecting material.

The expression "one end is open" means that the grip body 2 is open to allow the tilting of the grip body 2 with respect to the shaft 1 as shown in FIG. If so, it is the same as being open even if it is closed with a soft material, and it is also possible to put a soft object in the outer cylinder 21 and it is also open in this case. .

The triaxial force sensor 10 constructed in this way
Although 0 is arranged in the vertical direction in the above-described example, it may be arranged in the opposite direction, that is, the vertical direction may be reversed, or may be arranged in the lateral direction. Therefore, the front-rear, left-right directions here refer to the case of the example shown in FIG.

The three-axis force sensor 100 for the grip portion has a strain-measuring metal member 3 for connecting the shaft 1 and the grip body 2 (that is, the outer cylinder 21) for lifting the object to the shaft 1 and the grip body 2 at one place.
(A rod-shaped force detection unit is installed on the front, rear, left and right of the central axis). An object is suspended at the lower end of the shaft 1 and the upper end is fastened to the body of a small crane or the like. Strain measurement hardware 3
Has a pair of front and rear and left and right rod-shaped portions, and a strain detection unit is configured by this. Attach two strain gauges to the front and back of each member on each rod-shaped force detection part, and
And the force applied by the operator in the z direction is detected as a voltage value. The reason why the two strain gauges are used is to cancel the thermal expansion of the metal product due to the change in temperature.

The force is detected by a strain gauge, which detects the moments generated in the rod-shaped force detecting portions on the front, rear, left and right of the strain measuring hardware 3 by the force of the operator acting on the grip body 2 (force in the x, y, z directions). By doing. This moment has x, y
And the forces in the z direction both affect. Therefore, the forces in the x, y and z directions are separately obtained by the method described later. x
As the directional force, a moment generated in a pair of left and right rod-shaped members of the strain measurement hardware 3 is used. As the y-direction force, the moment generated in the pair of front and rear rod-shaped members of the strain measurement hardware 3 is used. The z-direction force is obtained from the front, rear, left, and right members of the strain measurement hardware 3 y
It is the sum of the directional force and the x-direction force.

The measurement of the bending moment with a strain gauge is generally carried out by sticking on the front and back.
The reason is as follows. 1. The amount of bending strain generated in the member can be measured even if the strain gauge is attached to either the front or the back. However, the amount of elongation of the member due to a change in temperature or the like is also measured, and the amount of bending strain may not be accurate. 2. Affixing two strain gauges on the front and back sides cancels it by doubling the detection sensitivity as compared with one sheet and by setting the amount of elongation of the member due to temperature as the difference in resistance between the two strain gauges. Therefore, only the bending strain amount can be measured without the influence of temperature.

Next, a method for detecting the force of the operator will be described with reference to FIG. Note that FIG. 3 is a two-dimensional model for easy understanding of the explanation, and the grip body is simply a rod-shaped member arranged on the left and right of the strain measurement hardware 3. The moment diagram is shown assuming that the upper end of this rod-shaped member is a free end and only the lower end is fixed. In FIG. 3, the grip 2 is
It is sized so that it can be grasped by almost the hand, and is grasped by the hand and moved, that is, pressed in the x, y and z directions. now,
It is assumed that Fx force acts in the x direction and Fz force acts in the z direction on the xz coordinate. W indicates the weight of a heavy object, and indicates a fixed portion 59 (corresponding to a pulley 9 shown in FIG. 3D described later). In this case, the measurement principle is that the force Fx that pushes the grip body 2 laterally acts on the bending moment that acts on the connection point (contact point) between the strain detection unit and the shaft 1, and the force Fz that attempts to lift it upwards. It is to calculate Fx and Fz according to the bending moment generated at.

FIG. 3 (a) shows a bending moment distribution in the case of a force Fz for lifting upward.

FIG. 3B shows a bending moment distribution when a lateral force Fx acts.

FIG. 3 (c) shows a bending moment distribution when Fx and Fz act together, and this distribution is shown in FIG.
It is the sum of (a) and FIG. 3 (b).

FIG. 3D shows the bending moment distribution when the grip body 2 is attached to the pulley 9.

When the Fx / 2 and Fz / 2 forces act on the two force application points 11 of the grip body 2, the outer cylinder 21
A bending moment distribution as shown in FIG. 3C is generated on the upper portion, the strain measuring metal piece 3, and the shaft 1.

The bending moments Ma and Mb obtained by the strains generated at the points a and b where the strain gauge 4 is installed are F
The relationship between x and Fz is expressed as orders 1 and 2. The measured strain value is input to the personal computer via the A / D and used for calculation.

[0027]

[Equation 1] Fz∝ (Mb-Ma) ... Equation 1

[Equation 2] Fx∝- (Mb + Ma) ... Equation 2 It is represented by.

Here, the proportional constant is the outer cylinder 21 of the grip body 2.
It depends on the fixed situation of.

In the case of movement in the x, y and z directions, Equation 1
But

[Equation 3] Fz∝ (Mb−Ma + Md−Mc) ... Equation 3 And the number 2

## EQU4 ## Fy∝- (Md + Mc) Equation 4 is obtained, and the force detection in the y direction is calculated. In addition, strain gauge 4
The mounting position of is as shown in FIG.

The three-axis force sensor 100 for the grip and the control method of the system are as follows.

A method of realizing a human-machine interface that gives the operator an easy-to-use natural sensation of assisting the operator with mechanical force using the three-axis force sensor 100 for the grip will be described. Consider a small crane (Fig. 7) as an example.
If the operator installs the axial force sensor 100 and moves the grip body 2 by grasping it, it is possible to detect the intention of the moving direction and speed of a person instead of operating the switch away from the object. If controlled, the above interface can be realized. The method is as shown in FIG. 4, in which an actuator 8 acting in the x, y, z directions of a small crane or the like is used.
A motion model 7 for obtaining the moving speed of the object is created by considering the friction when a force F is applied by virtually placing an object on a flat surface in the control device 10 (up / down, forward / backward, left / right moving mechanism). , A speed calculated as a force F proportional to the operator's force acting on the mass of the motion model 7 is adjusted by a proportional constant k so that the operator can easily use, and a speed command is output to each actuator 8. By doing.

The parameters of ease of use due to the adjustment of the force and the like correspond to the mass and friction coefficient of the motion model 7 being set appropriately. Specifically, the voltage output from the triaxial force sensor 100 is taken into the control device 10, and x,
The forces in the y and z directions are determined, the velocities in the x, y and z direction components are numerically calculated based on these forces, and the moving velocities at each real time are numerically calculated based on the motion model 7. This is done by sending a speed command (for example, a voltage value) every time. This method is different from, for example, a method in which a position command is input and a position (target value) as an output is subjected to PID control or the like, and the velocity due to the force as an input is determined by the motion model 7. There are features that it does not have.
Positioning is performed for the actual movement of the object, but this part is configured by a feedback control system including a person performed by a person. In order to stabilize the control system, it is preferable to perform feedback control so that the speed command value and the speed of the actuator 8 are the same.

Using FIG. 3, three-direction forces (Fx, Fy, F
The measuring method of z) will be described.

Since the three-direction force measurement and the two-direction force measurement have the same principle, FIG. 3 (d) shows a moment diagram generated in the force sensor when the three-axis force sensor is applied to the small crane. Originally, the points of action of Fx and Fz due to the operator's gripping action are distributed in a certain range, but for simplicity, they are shown as concentrated loads. When the forces Fx and Fz are applied to the action point 11 of the operator's force, a bending moment is generated in the strain measuring hardware 3 for force detection via the grip body 2. When only Fz acts, the relationship between Fz and the bending moments Ma and Mb generated at the bending moment measurement points a and b is expressed by the equation 1.
When only Fx acts, the hanging rope and the shaft 1 for lifting the object also tilt, and a bending moment is generated in the shaft 1. The bending moment generated on the shaft 1 here is related to Fx. Further, the bending moment generated in the shaft 1 causes an imbalance in Ma and Mb generated by Fz, but the relationship of the equation 1 can be used as it is. Using this imbalance, Fx is calculated from Equation 2. Although the figure is shown in the form of being hung on a wire rope, the above relationships of Equations 1 and 2 are also established when the apparatus is attached to a rigid body such as a machine body.

Considering that the strain gauge 4 is attached to the shaft 1, the strain gauge 4 is set so as to measure the bending moment and axial force generated on the shaft 1. With this, F
It is possible to measure x or Fy, but it is difficult to measure the lifting force. The reason is that when the object is lifted from the floor, the weight of the object hangs on the shaft 1 and the shaft 1 extends and the lifting force cannot be measured. Therefore, the lifting force is measured using the strain measuring hardware 3.

When the force F (t), the object (m), the friction (μ), and the velocity (V) are used, the velocity (V) of the object at each time with the time change of the force (Ft) is calculated by the following equation of motion. decide.

[Equation 5]

Explaining the shape of the strain-measuring hardware 3,
It is not necessary to be particular about the quantity and rod shape of the strain measurement hardware.
For example, a disc-shaped mounting hardware as shown in FIG. 11 may be used. In this case, the forces in the x and z directions may be separated. Alternatively, the relationship between the x-, y-, and z-direction forces of the strain gauges (front and back of the member) arranged on the front, rear, left, and right sides and the output voltage may be experimentally obtained. Further, the grip body 2 may be formed in a rectangular shape as shown in FIG. Further, the same effect can be obtained by deforming the grip body 2 as shown in FIG. 13 or 14.

FIG. 5 shows a control flow for determining the speed command value when the force of the operator acts. The strain gauges 4 (a), (b), (c), and (d) for bending strain measurement are used to detect the measured value (S1), and the measured value is amplified by the amplifier 31 (S).
2) Input to the control device 10. The measured values are A / D converted (S3), Ma, Mb, Mc, Md are calculated (S4), and Fx, Fy, Fz are calculated from the formulas (1) and (2) (S4).
5), velocity parameters Vx, Vy, Vz from the equation of motion
Is determined (S6). D / A conversion of speed parameter (S
7) The speed command value is output and input to the actuator 8 via the control device 30 (S8), and the actuator 8 is controlled (S9).

FIG. 6 shows a method of controlling the force of the actuator 8 when the force of the operator acts. The force in the Fx direction will be described as an example. In the control device 10, the motor torque is determined (assist coefficient × Fx) by Fx and assist coefficient input (S12) (S11), and the rotation speed of the encoder or the tachogenerator motor is input (S1).
3) Calculate the motor applied voltage from the motor speed and torque (S14), and calculate the motor driver applied voltage (S14).
15). The obtained calculated value is D / A converted (S7), the motor driver is controlled (S16), and the movement by power assist is performed (S17). This movement will be a total of human and motor power. The rotation speed of the encoder or the tachogenerator motor is fetched (S13).

The speed is determined by the intention (force) of the operator, and feedback control via the operator is performed (S1).
8). This control is reflected in the strain gauge for measuring bending strain (S1).

FIG. 7 shows a small crane device as an example in which an object is moved by power assisting (assisting) using the triaxial force sensor 100. A small crane is a typical example of a power operation device that has good operability when moving an object and is effective for assembly work and unloading of luggage for elderly people.

In the figure, the main body 12 of the small crane device is shown.
Is provided with a wire winding device 13 (servo motor), and the wire 14 is connected to a pulley receiving portion 17 via a relay pulley 15 to enable the lifting pulley 9 to move in the vertical direction. The tip of the wire 14 is connected to the end 31 of the body.

A horizontal moving device 16 is provided on the upper part of the main body 12.
Is provided, which drives the lateral movement timing belt 18, and the lateral movement timing belt 1
The pulley receiving portion 17 can be moved laterally by 8.

A luggage is hung on the luggage hook 19 and is vertically moved and laterally moved by a power assist system including a motor.

A three-axis force sensor 100 is attached to the shaft 1 of the luggage hook 19, and the measured values are input to the personal computer which is the control device 10. Here, x and y are calculated by calculating the bending moment as described above. And the force F acting in the z direction
x, Fy, Fz are obtained, and a command signal is generated.

The command signal is input to the motor controller 20. The motor controller 20a drives the wire 14 to move the luggage hook 19 in the vertical direction by the command signal in the Fz direction, and the motor controller 20b in response to the command signal in the Fx direction.
Controls the lateral movement device 16 to drive the lateral movement timing belt 18 to move the luggage hook 19 in the x-axis direction.

To move in the y-axis direction, another motor control device may be provided to drive the motor in the same manner as in the x-axis direction.

FIG. 8 shows a control device for moving in an arbitrary direction.

In the figure, the measured value (0 to 5 V) from the triaxial force sensor 100 is input to the control device 10, and the control device 10 uses the input value to perform the motion model as shown in FIG. 7 is operated to perform calculation, and the calculated value is input to the motor control device 20. The input value is converted into a pulse by the pulse oscillator 32 and is input to the driver 33 together with an instruction of the operation direction.

The driver 33 outputs the power assist force to be applied in the x, y and z directions as a command value (speed command) to the wire winding device 13 and / or the lateral moving device 16.

As described above, a small-sized power assist transfer device is provided for the purpose of saving labor for assembling parts having a maximum weight of about 10 kgf, reducing operator fatigue, and working for the elderly.

This device has a Z-axis (vertical direction) and a horizontal direction.
Have freedom. The control method is as described above, and it is possible to smoothly hoist it gently with one hand under the same load, move it there, and install it quietly. It can also be moved diagonally upward and diagonally downward. Since it is not a switch operation like the existing crane, it works in cooperation with the operator's will. It fits very well with one's natural feeling. Moreover, the complexity of the switch operation is released.

FIG. 9 shows a care lifter as another application example.

The care lifter 40 includes a main body 41, a universal joint 69, a chair 42 lifted by the universal joint 69, and a uniaxial actuator 13. Universal joint 6
9 and / or the lower end 4 of the chair 42
The three-axis force sensor 100 (100a, 100b) is installed in the No. 3 unit. The reason for providing the two places is to apply force to the upper and lower portions of the chair 42 when lifting the care chair 42. As described above, the force applied to the care chair 42 is detected by the triaxial force sensor 100.

The force signals detected by the triaxial force sensors 100a and 100b are input to the control device 10 and output to the driver 33 as a speed command in the same manner as shown in FIG. 8, and the wire winding device 13 is output by the driver 33. To move the chair 42 up and down.

The triaxial force sensor 100 is attached to the lifter 40 for care.
The a and 100b are attached in the vicinity of or in contact with the cared person, and the cared person and the cared person are given a natural feeling to the cared person to move from the bed or the like. The conventional device has a switch at a remote place, and if only the switch is operated, the cared person feels anxious as he / she falls into the feeling of being lifted as a thing. In addition, in order for the person to operate a little away, it moves at a very slow constant speed set in the care lifter. Since the caregiver can freely decide the speed of the care lifter 40, the moving time can be shortened. Further, by disposing the three-axis force sensor as shown in FIG. 9, it is possible to operate with one hand of the sensor, or one hand in a natural posture in which the care recipient is placed. For this reason, both the caregiver and the cared person become care lifters that match the natural sense of human beings. It is also released from the complexity of switch operation.

FIG. 10 shows an installation example of the triaxial force sensor 100 using the grip body 2 on the chair 42.

[0058]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the grip body 2 is sized so that the forces applied in the x-, y-, and z-axis directions can be held by the hand.
Since it is detected by the power assisting force, the interface between the operator and the machine can be optimized, and the power operation device can be operated smoothly.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a triaxial force sensor that is an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a bending moment distribution diagram.

FIG. 4 is a flowchart showing how to determine a moving speed by operating force.

FIG. 5 is a control flowchart.

FIG. 6 is a flow chart diagram in which the force of the actuator is controlled by the operating force.

FIG. 7 is a configuration diagram of a power assist transfer device as an application example.

FIG. 8 is a configuration diagram of a control device for performing control in an arbitrary direction.

FIG. 9 is a configuration diagram of a care lifter as another application example.

FIG. 10 is a diagram showing an installation example of a triaxial force sensor.

FIG. 11 is a view showing a modified example of the triaxial force sensor.

FIG. 12 is a view showing a modified example of the triaxial force sensor.

FIG. 13 is a view showing a modified example of the triaxial force sensor.

FIG. 14 is a view showing a modified example of the triaxial force sensor.

[Explanation of symbols]

1 ... Shaft, 2 ... Grip body (grip part), 3 ... Strain (force) measuring hardware, 4 ... Strain gauge, 5 ... Luggage hook mounting part, 6 ... Mounting part, 7 ... Motion model, 8 ... Actuator, 9 ... Lifting pulley, 10 ... Control device, 11 ... Point of action, 12 ... Main body, 1
3 ... Wire winding device, 14 ... Wire, 15 ... Relay pulley,
16 ... Lateral movement device, 17 ... Pulley receiving part, 18 ... Lateral movement timing belt, 19 ... Luggage hook, 20 ... Motor control device, 40 ... Care lifter, 41 ... Main body, 100 ...
3-axis force sensor.

Claims (5)

[Claims] 1. A grip body, which is open at one end and has paired front and rear and left and right strain detection sections, and each strain detection section is provided with a strain gauge and is sized to be gripped by a cylindrical hand. , The tubular grip is fixed to a shaft extending in the tubular direction via the strain detecting section, and X, Y and Z directions are detected based on the strains in the X, Y and Z directions detected by the strain gauge. And a processing device for calculating the force in the Z direction, the three-axis force sensor system. 2. The strain gauge according to claim 1, wherein the shaft body is penetrated through the center of a cylindrical grip body, and strain gauges are provided symmetrically in the front-rear direction and the left-right direction about the fixing point between the shaft body and the strain detecting section. A three-axis force sensor system. 3. The processing device according to claim 1, wherein the processing device calculates a bending moment based on a bending strain of a member surface generated in the strain detection unit, and calculates an x or y direction force by a pair of strain detection units, A triaxial force sensor system characterized in that the force in the z direction is calculated by two pairs of strain detection units. 4. A power operating device having a lifting device provided at the lower end of a wire rope and a power assist device for assisting the lifting force, wherein x, y and a force generated by a force applied in the vicinity of the lifting device. Calculating means for providing a hand-held triaxial force sensor having a strain detecting means for detecting a strain in the z direction, and calculating forces in the x, y and z directions based on the strain detected by the triaxial force sensor And a power assisting device configured to operate the lifting device in the x, y, and z directions with a variable assisting force according to the calculated force. 5. A nursing lifter provided with a main body and a lifting device for lifting a nursing chair on the main body, and a power assist device for assisting the lifting force, wherein the force applied to the nursing chair x, y and z
A three-axis force sensor having a strain detecting means for detecting a strain generated in the direction is provided, and a means for calculating the forces in the x, y and z directions by the three-axis force and the strain detected above is provided and calculated. The lifting device can be moved in x, y with a variable auxiliary force according to the force.
And a care lifter in which the power assist device is configured to be operated in the z direction.