JP3423090B2 - Operating force detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an operating force in a power assist device for amplifying and transmitting the operating force to a partner machine, a master / slave control system for controlling the operation of the partner machine by operating a steering wheel, and the like. The present invention relates to an operation force detection device for supplying to a control circuit of a partner machine.

[0002]

2. Description of the Related Art Conventionally, a transfer assisting device for transferring a patient lying on a bed to another bed or the like is known, and a master / slave system is introduced into a control system for such transfer assisting device. It is under consideration.

In a master-slave type transfer assisting device, a transfer plate for carrying a patient is moved by a caregiver operating a master hand,
The patient is taken from the bed or transferred to another bed. The operating force of the master hand is generally detected by using a load cell, and a driving force corresponding to the operating force is applied to the transfer plate.

[0004]

However, due to the structure of the load cell, the acting force in the predetermined uniaxial direction can be accurately detected, but when the force acts in a direction deviating from the uniaxial direction, Hysteresis occurs in the relationship between the force and the detection signal, and the desired measurement performance cannot be obtained. In particular, when applied to a transfer assistance device, the transfer plate moves in an unintended direction due to hysteresis, which is extremely dangerous. Therefore, conventionally, a dead zone of control is provided near the zero point of the relationship between the acting force and the detection signal to avoid the influence of hysteresis, but this makes delicate operation difficult and lowers operability.

An object of the present invention is to provide an operating force detecting device capable of supplying a detection signal corresponding to the operating force to a partner machine without providing a dead zone even if the acting direction of the operating force is slightly deviated. That is.

[0006]

In the operating force detecting device according to the present invention, a torsion acting shaft (17) is erected on a base (11) so that one end is fixed and the other end is freely rotatable. By connecting the handle (16) to the free rotation end of (17) via the arm (14) , the handle (1
6) The operating force for the rotation torque is applied to the torsion acting shaft (17).
A force sensor (20) for detecting the stress caused by the twist is attached to the torsion acting shaft (17), and the output of the force sensor (20) is supplied to the measuring circuit (3) to handle the handle. The operation force in the uniaxial direction acting in the torsion direction of the torsion acting shaft (17) with respect to (16) is detected.

Further, another operating force detecting device according to the present invention is
The torsion acting shaft (17) is fixed on one end and erected at the other end on the base (11), and a handle (16) is attached to the free end of the torsion acting shaft (17) via an arm (14). Twist acting shaft (1
7) includes a force sensor (2
(0) is attached, and near the handle (16),
The changeover switch (4) to be operated when changing the direction of the operating force with respect to the handle (16) is provided, and the force sensor (20)
And the output of the change-over switch (4) is supplied to the measuring circuit (3) to detect the biaxial operation force acting on the handle (16) in the torsion direction of the torsion shaft (17). .

[0008]

In the first operation force detection device, when the handle (16) is gripped and an operation force is applied in one axial direction (for example, horizontal direction), a torque having a magnitude corresponding to the operation force is twisted. By acting on the free rotation end of the shaft (17), a stress due to torsion is generated in the torsion acting shaft (17), and the stress is detected by the force sensor (20). At this time, even if the direction of the operating force slightly changes, the torsion acting shaft (17)
Because of the rotation free end is not at all restricted to the direction of rotation, from the force sensor (20) is output detection signal of a magnitude corresponding to the operating force, occurs hysteresis between the operation force and the detection signal Absent.

The output of the force sensor (20) is supplied to the measuring circuit (3) and converted into a signal corresponding to the operating force acting on the handle (16), and then as a signal for operating the other machine, Output to the control circuit of the partner machine. As a result, the partner machine operates according to the operating force.

In the second operation force detecting device, the handle 16 is selectively actuated in either one of two axial directions (horizontal direction and vertical direction) orthogonal to each other. Power is added. When changing the direction of the operating force, the changeover switch (4) is operated and the output thereof is supplied to the measuring circuit (3). This makes the measurement circuit (3)
Determines in which direction the signal from the force sensor (20) is an operation force detection signal.

The operation of detecting the operating force in each acting direction is exactly the same as that of the first operating force detecting device, and no hysteresis occurs between the operating force and the detection signal. Similarly, the output of the force sensor (20) is supplied to the measuring circuit (3) and converted into a signal corresponding to the operating force acting on the handle (16),
The signal is output to the control circuit of the partner machine as a signal for operating the partner machine. As a result, the partner machine operates according to the change of the changeover switch and the operating force.

[0012]

According to the operation force detecting device of the present invention,
Even if the operating direction of the operating force on the steering wheel changes a little, hysteresis does not occur between the operating force and the detection signal, so that the partner machine can be delicately controlled without providing a dead zone for control.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic structure of the operating force detection mechanism (1) according to the present invention will be specifically described with reference to the drawings. In the operating force detection mechanism (1) shown in FIG. 1, a pair of support plates (12) and (13) are erected on a base (11), and both support plates are provided.
A cylindrical torsion acting shaft (17) is provided between (12) and (13). Arms (14) and (15) are attached to both ends of the torsion shaft (17).
The handle (16) is connected via. The torsion shaft (17) is made of aluminum and has a thin thickness of 0.5 mm.

As shown in FIG. 2, the right end of the torsion acting shaft (17).
(17a) is rotatably supported by a bearing (18) fitted in the support plate (12), while the left end (17b) is supported by the support plate (1).
It is fixed to 3). Also, the base end of the right arm (14) is fixed to the right end (17a) of the torsion shaft (17), whereas the base end of the left arm (15) is a support plate ( It is rotatably supported by a bearing (19) fitted to the side portion (13a) of 13).

The two arms (14) and (15) extend at an angle of 45 degrees as shown in FIG. 3, and when a horizontal operating force F is applied to the handle (16), the torsion acting shaft ( A torque T having a magnitude (F × L), which is the product of the operating force F and the vertical height L of the arm, acts on 17).

In the present embodiment, in order to detect the torque T, a force sensor (20) consisting of four strain gauges is adopted. That is, as shown in FIG. 1, two active gauges (2) and (21) are attached to the outer peripheral surface of the torsion shaft (17) so as to intersect each other at an inclination angle of 45 degrees, and the base (11).
Two dummy gauges (22) (23) for temperature compensation on the upper surface of
Is attached to form a force sensor (20). The force sensor (20) is connected to the measuring circuit (3). The measuring circuit
(3) is configured by arranging a signal processing circuit (32) and input / output connectors (33, 34) on a circuit board (31).

FIG. 4 shows a specific configuration of the signal processing circuit (32). The four strain gauges (2), (21), (22) and (23) form a bridge circuit as shown in the figure, and a predetermined voltage is applied to the bridge circuit from the voltage regulator (36). It The voltage generated in the bridge circuit due to the deformation of the active gauges (2) and (21) is amplified by the differential amplifier (35), the noise is removed through the low pass filter (37), and the sensor output S Is supplied to the subsequent circuit. The four signal lines connecting the force sensor (20) and the signal processing circuit (32) are shielded (38) to reduce the influence of noise as much as possible.

Here, the strain ε generated in the active gauge due to the torque T acting on the torsion acting shaft (17),
The relational expression of the following mathematical formula 1 is established between the shear stresses τ acting on the torsion action axis (17). Here, E is the longitudinal elastic modulus, and ν is the Poisson's ratio.

[0019]

[Formula 1] τ = εE / (1 + ν) Further, when the polar section coefficient of the torsion action axis (17) is Zp, the following formula 2 is established. Where d ₁ and d ₂ are the torsion acting axes, respectively.
The inner and outer diameters of (17)

[Expression 2] T = τ · Zp = τ · (π / 16) · (d ₂ ⁴ −d ₁ ⁴ / d ₂ )

Therefore, by measuring the shear stress τ by the force sensor (20), the torque T can be derived from the above equation 2, and the operating force F shown in FIG. 3 is calculated from the torque T. is there.

FIG. 5 is a graph obtained by actually measuring the relationship between the operating force F and the sensor output S. Measure the operating force F
It is changed in the increasing and decreasing directions around = 0,
The sensor output S obtained in the process was sampled. As is clear from FIG. 5, the change in the sensor output in the increasing direction of the operating force and the change in the sensor output in the decreasing direction almost overlap with each other, and no hysteresis occurs.

In the operation force detecting mechanism (1), the operation force F applied to the handle (16) acts on the torsion acting shaft (17) as a rotational torque, and the torsion acting shaft (17) has a bearing at its free end. 1
Since the force sensor (20) is supported by 8) and displacements other than the torsional direction are completely restrained, the force sensor (20) has
Only the distortion due to the twist of 7) is added. Therefore, the sensor output S accurately reflects the magnitude of the operating force F,
Highly accurate force detection can be performed.

Next, an example in which the operating force detecting mechanism (1) of the present invention is applied to a two-axis driving device (6) consisting of a horizontal driving mechanism (61) and a vertical driving mechanism (62) as shown in FIG. explain. The biaxial drive device (6) is used, for example, to drive a patient transfer assisting device in the biaxial directions of the horizontal direction and the vertical direction, and the operation force of the caregiver at that time is detected by the operation force detection mechanism (1). To be detected. The operation of the biaxial drive device (6) is controlled by a control circuit (5) such as a microcomputer.

The vertical drive mechanism (62) operates in the vertical direction by the drive of the vertical axis motor (65), and vertically moves the entire horizontal drive mechanism (61). Further, the horizontal drive mechanism (61) operates in the horizontal direction by the drive of the horizontal shaft motor (63), and the transfer plate (not shown) of the transfer assist device is connected to the output part of the horizontal drive mechanism (61). To be done. As a result, the transfer plate is driven in the horizontal and vertical biaxial directions.

A rotary encoder (64) for counting the rotation amount of the horizontal axis motor (63) is attached to the horizontal drive mechanism (61), and a rotation of the vertical axis motor (65) is attached to the vertical drive mechanism (62). A rotary encoder (66) for counting the quantity is attached. Counter values obtained from both rotary encoders (64) and (66) are input to the control circuit (5) via the interface (54).

The operating force detection mechanism (1) is a horizontal drive mechanism (61).
It is arranged above, and its basic configuration is as described above, but in order to select which of the horizontal drive mechanism (61) and the vertical drive mechanism (62) to operate, the chain line in FIG. As shown by, a changeover switch (4) is attached to the upper end of the arm (14). The change-over switch (4) is, for example, in the OFF state when a horizontal operating force is applied to the handle (16) and the horizontal drive mechanism (61) is operated, and a vertical operating force is applied to the handle (16). The above vertical drive mechanism
When operating (62), turn it on. The ON / OFF signal C from the change-over switch (4) is the interface (5
It is input to the control circuit (5) via 2).

The above-mentioned measuring circuit (3) is connected to the force sensor (20) of the operating force detecting mechanism (1), and the measuring circuit (3) is connected.
The sensor output S from is input to the control circuit (5) via the interface (53).

Motor drivers (8) and (9) are connected to the horizontal axis motor (63) of the horizontal drive mechanism (61) and the vertical axis motor (65) of the vertical drive mechanism (62), respectively. These motor drivers (8) and (9) generate drive currents for the respective motors according to the command value supplied from the control circuit (5) through the interface (55).

Thus, based on the operating force detected by the force sensor (20) of the operating force detecting mechanism (1) and the measuring circuit (3), the horizontal axis motor (63) of the two-axis driving device (6) or A control target value (target position) for the vertical axis motor (65) is created, and depending on the deviation between the actual position of the motor (63) (65) and the target position detected by the rotary encoders (64) (65). Then, a command value for the motor drivers (8) and (9) is created, and one of the motors (63) and (65) selected by operating the changeover switch (4) is driven.

Operating force detection mechanism for the above-mentioned two-axis drive device (6)
In (1), when the horizontal drive mechanism (61) is operated by applying a horizontal operating force Fh to the handle (16) as shown in FIG. 7 (A), the arm (14) ( 15) component force parallel to f
Although t is canceled out, the component force fp perpendicular to this is the arm (14).
A torque T acts on the torsion shaft 17 as a force for rotating the shaft 15. In this case, the control circuit (5) is the measurement circuit
Based on the sensor output S from (3), the torque T is derived from the equation 2, and the operating force Fh is calculated from the torque T.

Further, after turning on the changeover switch (4),
As shown in Fig. 7 (B), the vertical operation force F is applied to the handle (16).
When the vertical drive mechanism (62) is actuated by applying v, the component force ft of the operating force parallel to the arms (14) and (15) is canceled, but the component force fp perpendicular to this is the arm force (14). A torque T acts on the torsion shaft 17 as a force for rotating the shaft 15. In this case, the control circuit (5) derives the torque T from the equation 2 based on the sensor output S from the measuring circuit (3), and further calculates the operating force Fv from the torque T.

FIG. 8 shows a control procedure by the control circuit (5). First, in step S1, torque data obtained from the force sensor is sampled. Step S
At 2, it is judged whether or not the vertical drive is selected by the operation of the changeover switch (4). If NO, the process proceeds to step S3, and if YES, the process proceeds to step S6.

In step S3, the horizontal force Fh is calculated from the torque data as described above, and in step 4, the command value to the driver (8) of the horizontal axis motor (63) is calculated, and then in step S5. Then, the calculated command value is output to the driver (8).

On the other hand, in step S6, the vertical force Fv is calculated from the torque data, and in step 7, the command value to the driver (9) of the vertical axis motor (65) is calculated.
In step S8, the driver (9) uses the calculated command value.
Output to.

The operating force detecting mechanism (1) is not limited to the conventional operating force detecting system using a load cell, but is used when the operating force is deviated from a predetermined horizontal or vertical direction. Also, the sensor output according to the operating force can be obtained without causing hysteresis. That is, the force exerted on the handle (16) of the operating force detection mechanism (1) is a rotational force applied to the torsion acting shaft (17) without any restriction of the component force in the torsion direction with respect to the torsion acting shaft (17). Acting, the force sensor (20) detects the shear stress due to the torsion of the torsion axis (17), whereas the force component in the direction along the arms (14) (15) is the bearing on the base (11). It is completely received by (18) (19) and does not act on the force sensor (20). Therefore, the force sensor (20) issues an output signal S of a magnitude proportional to the operating force as shown in FIG. 5, regardless of the magnitude of the operating force and the acting direction.

Further, according to the operating force detecting mechanism (1) having the changeover switch (4) shown in FIG. 6, the operating force in the biaxial directions with respect to the biaxial driving device (6) is shared by one force sensor ( It can be detected by 20), and can be made smaller and lighter than the conventional device that requires two load cells.

The above description of the embodiments is for explaining the present invention and should not be construed to limit the invention described in the claims or to limit the scope thereof. The configuration of each part of the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external appearance of an operating force detection mechanism according to the present invention.

FIG. 2 is a partially cutaway front view of an operating force detection mechanism.

FIG. 3 is a diagram illustrating a force and a torque that act on an operating force detection mechanism.

FIG. 4 is a block diagram showing a configuration of a signal processing circuit.

FIG. 5 is a graph showing the relationship between operating force and sensor output.

FIG. 6 is a block diagram showing a configuration of an example in which an operating force detection mechanism is applied to a biaxial drive device.

FIG. 7 is a diagram for explaining a relationship between an operating force on the handle in two axial directions and a torque generated thereby.

FIG. 8 is a flowchart showing a control procedure of a control circuit.

[Explanation of symbols]

(1) Operating force detection mechanism (11) Base (14) (15) Arm (16) Handle (17) Torsion acting axis (20) Force sensor (2) (21) Active gauge (22) (23) Dummy gauge (3) Measuring circuit (4) Changeover switch

Claims (2)

(57) [Claims] 1. A torsion acting shaft (1) is provided on a base (11).
7) is fixed at one end and is rotatably installed at the other end, and a handle (16) is connected to the free rotation end of the twisting shaft (17) via an arm (14).
Rotate the operating force for the lever (16) on the torsion axis (17)
A force sensor (20) is attached to the torsion acting shaft (17) to detect the stress caused by the twist, and the output of the force sensor (20) is measured by a measuring circuit (3).
To the handle (16) and the torsion acting shaft (1
7) An investigative force detection device characterized by detecting an operation force in a uniaxial direction acting in the twist direction. 2. A torsion acting shaft (17) is fixed on one end and is freely erected on the other end on a base (11), and an arm (14) is provided at a free end of the torsion acting shaft (17). The handle (16) is connected, and a force sensor (20) for detecting the stress caused by the twist is attached to the torsion acting shaft (17) and the handle is also attached.
A changeover switch (4) to be operated when changing the direction of the operating force with respect to the handle (16) is provided in the vicinity of (16), and the output of the force sensor (20) and the changeover switch (4) is measured. An operation force detecting device characterized in that it is supplied to (3) and detects an operation force in two axial directions acting on a handle (16) in a torsion direction of a torsion acting shaft (17).