JP5034611B2 - Round-trip X-ray equipment - Google Patents

Description

The present invention relates to a round-trip X-ray imaging apparatus that performs X-ray imaging in a hospital room, and more particularly to travel control.

A conventional round-trip X-ray apparatus includes an operation handle that detects the magnitude and direction of an operation using a pressure sensor, a pair of drive wheels that are driven independently on the left and right sides, a motor provided on the wheel shaft, A driving bridge circuit composed of switching elements with the motor positioned at the center of the bridge, a PWM control circuit for controlling the ON / OFF duty of the motor torque with the bridge circuit, and detecting the rotational speed of the driven wheel And an encoder for controlling the torque of the motor in response to a signal from the pressure sensor and a signal from the encoder in a predetermined cycle (for example, 20 ms), and rotating the drive wheel to move ( For example, Patent Document 1).

For the motor torque, the pulse width of the pulse width control circuit is [(maximum value of pulse control width) / (maximum output torque of motor)] × [(maximum rotational speed of motor) / (maximum rotational speed of motor). -Number of rotations of the motor)] x (force to push the operation handle) is controlled to be proportional to the value calculated. Therefore, the above calculation is performed so as to maintain the relationship of motor output torque T = (amplification factor α) × (pressing force F).

Since the linearity between the operation force and the output torque is improved, the roundabout X-ray imaging apparatus configured as described above can be operated with a natural operation feeling. However, if the operating force is directly output torque, steep acceleration / deceleration occurs particularly during low-speed driving such as at the time of starting, resulting in a jerky operational feeling.

In order to solve such a problem, torque fluctuation is limited. For example, with respect to the right side, when the output torque determined based on the magnitude and direction of the operation is T _r ′, the previous output torque is T _pr , and the maximum allowable torque variation is ΔT _lim , the output is as follows: Torque T is determined.

JP 2001-258872 A

When the torque fluctuation limiting process as in the prior art is performed, the jerky feeling such as rising is reduced, but the speed fluctuation at the time of deceleration also becomes gradual, and even if you try to stop while driving, it will not stop immediately, It becomes a factor giving anxiety. Many operators complained of being pulled by the device.

An object of the present invention is to provide an X-ray imaging apparatus for round trips that can stop the apparatus by natural operation while eliminating the jerky feeling at the time of startup.

In order to solve the above-mentioned problem, an X-ray imaging apparatus for round trip according to claim 1, an X-ray generator, an operation handle, an operation force detection means for detecting an operation force applied to the operation handle, A pair of left and right drive wheels; a rotation drive means for driving the drive wheels; a torque calculation value calculation means for calculating a torque calculation value based on the detected operating force at predetermined intervals; and the torque calculation value Output fluctuation limiting means that performs time fluctuation limiting processing to determine the output, drive control means for controlling the rotation driving means based on the output, and storage means for storing the output as a previous output, In the time variation limiting process, when the direction of the torque calculation value and the direction of the previous output are the same, based on the torque calculation value, the absolute value of the difference from the previous output is a first variation limit value. To be below To calculate the output, otherwise, and performs any processing of the following (A) ~ (C).
(A) Based on the torque calculation value, the output is calculated such that the absolute value of the difference from the previous output is less than or equal to a second fluctuation limit value that is greater than the first fluctuation limit value.
(B) Based on the torque calculation value, the output is calculated such that the absolute value is less than or equal to a predetermined output limit value.
(C) The output is set to zero.
In addition, when the direction of the said torque calculation value and the direction of the said last output are the same, the case where either is 0 is included.

Based on the above configuration, the present invention operates as follows. That is, the torque calculation value calculation means determines the torque calculation value based on the operation force detected by the operation handle. When the difference between the torque calculation value and the previous output exceeds a predetermined output fluctuation limit, the output calculation means corrects the difference to be within the predetermined output fluctuation limit and outputs the result. On the other hand, when the difference between the torque calculation value and the previous output does not exceed the predetermined output fluctuation limit, the torque calculation value is directly adopted as the output.

A larger value is selected as the output fluctuation limit when the direction of the previous output and the calculated torque value are different. The case where the direction of the previous output and the torque calculation value is different corresponds to, for example, a state where the operation handle is pushed forward and the output is reversed after the operation handle is pulled backward. To do.

The drive control means controls the rotation drive means based on the adopted output. By controlling the rotation driving means, the rotation speed of the driving wheel changes, and as a result, the moving speed of the round-trip X-ray imaging apparatus changes. After the reversal operation, the output fluctuation limit is relaxed until the output becomes the reverse direction, so the output suddenly goes to zero. After the output direction is reversed, the normal output fluctuation limit is applied.

Based on the above action, the invention described in claim 1 has an effect that smooth operability is realized by limiting the output fluctuation during acceleration, and the apparatus can be stopped quickly and naturally.

With reference to FIG. 1, an outline of an X-ray imaging apparatus for round trips according to the present invention will be shown.
A roundabout X-ray imaging apparatus 1 according to the present embodiment includes a support column 5 held by a carriage 2 so as to be pivotable, an X-ray tube holding arm 7 held by the support column 5 so as to be movable in a height direction, and an X-ray. An X-ray tube 3 held by a tube holding arm 7, a collimator 4 rotatably held by the X-ray tube 3, an operation handle 6 held movably in the front-rear direction with respect to the carriage 2, The driving wheel 9 includes a pair of left and right tires 91 and a motor 92 disposed on the operation handle 6 side, and a pair of left and right casters 10 disposed on the column 5 side.

A CPU board 8 is disposed inside the carriage 2. The CPU board 8 has a function of performing a predetermined process on the signal from the operation handle 6 and outputting a PWM waveform to the motor 92. Since the other mechanism that holds the X-ray tube 3 and the collimator 4 so as to be movable with respect to the carriage 2 is a well-known technique, description thereof is omitted.

Next, a mechanism for converting an operation force applied to the operation handle 6 into an electric signal will be described. FIG. 2 is a cross-sectional view of the vicinity of the traveling operation handle 6 as viewed from above the apparatus. The pressure sensor 64 and an elastic body 63 that transmits an operation force in the front-rear direction applied to the traveling operation handle 6 to the pressure sensor 64 are configured. In addition, “l” is attached to the reference numerals of the components arranged on the left, and “r” is attached to the reference numerals of the constituents arranged on the right. Further, “f” is attached to the components arranged in front of the traveling operation handle 6, and “b” is attached to the components arranged behind. The pressure sensor 64 has an electric resistance that changes in accordance with the pressure applied to the surface. Signals E _fl , E _fr , E _bl , E _br (hereinafter referred to as an operation force signal E) are converted into voltages. Is detected by the CPU substrate 8.

The hardware configuration of the CPU board 8 will be described with reference to FIG. The CPU board 8 includes an A / D converter 82 that converts the operation force signal E into a digital value, a CPU 81 that processes the digital value, and a PWM control circuit that generates a PWM waveform with a duty according to a command from the CPU 81. 83, an FET bridge circuit 84 for turning on and off the motor drive current by the PWM waveform output from the PWM control circuit 83, and a RAM 85 used by the CPU 81.

Next, a program that operates in the CPU 81 will be described. As shown in FIG. 4, the program includes an operating force detection module 86, a torque calculation value calculation module 87, and an output calculation module 88.

The operation force detection module 86 converts a digital value obtained from the operation force signal E from the A / D converter 82 into operation force values S _fl , S _fr , S _bl , S _br (hereinafter referred to as operation force value S). To do. For example, operating force signals E _fl , E _fr , E _bl , E detected when several types of pressure are applied to the traveling operation handle 6 in advance using a measuring means capable of applying a predetermined pressure such as a spring _alone . The value of _br is stored as a calibration value, and the operation force signal S actually detected can be calibrated to obtain the operation force value S.

Based on the operation force value S thus obtained, the operation direction D _s and the magnitude D _g can be obtained.

Note that the direction D _s operations here, corresponds to the twist direction of the operation force of the travel operation handle 6. When the round-trip X-ray imaging apparatus 1 is turned with the minimum radius, the center of the left and right drive wheels 9 is the turning center. As a result, the operator feels that it is natural to turn or turn the device by twisting the traveling operation handle 6 substantially at the top.

In this embodiment, the elastic body 63, the pressure sensor 64, the A / D converter 82, and the operation force detection module 86 are components of the operation force detection means. However, the operating force detection means is not limited to such a configuration, and various modifications can be made as long as it has a function of converting the operating force applied to the operation handle 6 into an electrical signal.

ここで、Ｐ_ｇは、操作の重さを表すゲインパラメータである。また、Ｐ_ｓは、旋回性能を表す旋回パラメータである。 Next, the torque calculation value calculation module 87 receives the operation direction D _s and the magnitude D _g from the operation force detection module 86 and outputs torque calculation values T _r ′, T _l ′ to be output to the left and right drive wheels 9. (Hereinafter, the left and right are collectively referred to as a torque calculation value T ′).

Here, _Pg is a gain parameter representing the weight of the operation. P _s is a turning parameter representing turning performance.

It is preferable to calculate the torque calculation value T ′ in consideration of the gain parameter and the turning parameter because an operation feeling according to the operator's preference can be realized. However, the torque calculation value may be obtained by another method. For example, the torque calculation value T ′ may be obtained by multiplying the operating force value S by a coefficient without using the gain parameter and the turning parameter. In addition, as long as some calculation is performed on the operation force to obtain a torque calculation value, the method can be variously changed.
The torque calculation values T _r ′ and T _l ′ in the present embodiment correspond to the torque calculation values of the present invention.

Next, the output calculation module 88 determines the output torque T with the temporal variation limited based on the previous output T _p and the torque calculation value T ′, and generates the output torque T so as to generate the output torque T. Determine the duty.
Note that the output torque T in the present embodiment corresponds to the output in the present invention. Further, the previous output torque T _p corresponds to the previous output in the present invention.

Hereinafter, an embodiment for _obtaining the output torque T _r corresponding to the right wheel will be described, but the output torque T _l corresponding to the left wheel is also calculated in the same procedure.

[Example 1]
The previous output torque T _pr is read from the RAM 85, and a difference ΔT _r from the calculated torque value T _r ′ is calculated.

ただし、ΔＴ_ｌｉｍ１＜ΔＴ_ｌｉｍ２である。
すなわち、トルク計算値Ｔ_ｒ’の方向と前回出力トルクＴ_ｐｒの方向とが異なる場合には、トルク変動の制限を緩和する（出力トルクＴ_ｒの急峻な変動を許容する）。 Next, the upper limit ΔT _{lim of} torque fluctuation is determined as follows.

However, ΔT _lim1 <ΔT _lim2 .
That is, when the direction of the torque calculation value T _r ′ is different from the direction of the previous output torque T _pr , the torque fluctuation restriction is relaxed (abrupt fluctuation of the output torque T _r is allowed).

ΔT _lim1 and ΔT _lim2 are determined in consideration of a control cycle (in this embodiment, 20 ms), motor inertia, output maximum torque, required response speed, maximum speed, and the like. Since so many parameters are involved, it is desirable to experimentally adjust how much torque limitation needs to be applied.
As a guide, the control cycle is a fraction of the value obtained by multiplying the value obtained by dividing the time required to reach the standard walking speed (approximately 4-5 km / hr) from a stationary state by the maximum output torque. _Is preferably ΔT _lim1 . ΔT _lim2 is preferably several times ΔT _lim1 .

Note that ΔT _lim1 and ΔT _lim2 in the present embodiment correspond to the first fluctuation limit value and the second fluctuation limit value in the present invention.

Based on the determined upper limit ΔT _{lim of} torque fluctuation, the output torque _Tr is determined as follows.

In the present embodiment, the processing in the output calculation module 88 corresponds to time variation limiting processing. The output calculation module 88 and the hardware necessary for executing it correspond to the output fluctuation limiting means in the present invention.

Based on the output torque T calculated in this way, the duty ratio R of the PWM signal is determined. If the motor is simply output at a duty ratio proportional to the output torque T, a natural operating feeling cannot be obtained due to the motor characteristics that a large torque is output in a low rotation range. Therefore, in order to achieve a natural operation, it is desirable to provide a means for detecting the rotational speed of the motor and correct the duty ratio based on the detected rotational speed. Since the correction method is as described in the prior art, description thereof is omitted.

The duty ratio R thus determined is output from the CPU 81 to the PWM control circuit 83. Further, the PWM control circuit 83 turns the FET gate of the FET bridge circuit 84 on and off according to the duty ratio R.

The motor 92 is supplied with current by turning on and off the FET bridge circuit 84, and generates torque according to the amount of current.

[Example 2]
Another embodiment for calculating the output torque T will be described.

First, the upper limit ΔT _{lim of} torque fluctuation is set to ΔT _lim1 . Note that ΔT _lim1 in the present embodiment corresponds to the first variation limit value in the present invention.

When the signs of T _r ′ and T _pr are the same, the output torque T _r is determined by the following equation.

In other cases, the output torque Tr is determined by the following equation. That is, the absolute value of the torque calculation value torque is limited so as not to exceed the upper limit value Tlim of the predetermined torque. here,
If the upper limit value Tlim is set too large, a large torque is generated in the direction opposite to the traveling direction, which is not preferable. In order to realize control without a sense of incongruity, it is preferable that the upper limit value Tlim is about ΔTlim1 which is set as the upper limit of the normal torque fluctuation. The torque upper limit value Tlim corresponds to a predetermined output limit value in the present invention.

すなわち、出力トルクを０にする。 [Example 3]
In another embodiment, the following formula is adopted instead of the formula 8 in the second embodiment.

That is, the output torque is set to zero.

In any of the above embodiments, a constant of ΔT _lim1 , ΔT _lim2, or T _lim is used as the upper limit ΔT _lim of torque fluctuation, but either or both of them are linked to the magnitude of the previous output torque or the like. It may be.

Next, operational effects of the round-trip X-ray imaging apparatus of the present embodiment will be described in comparison with the conventional example and the comparative example.

FIG. 5A is a graph showing the relationship between the operation force S, the output torque T, and the movement speed V of the round-trip X-ray imaging apparatus according to the present embodiment. FIG.5 (b) is the same graph about the X-ray imaging apparatus for round trips concerning a prior art.
In FIG. 5, the vertical axis of the graph represents the operating force S, the output torque T, and the moving speed V, and represents the forward direction as positive and the backward direction as negative. The horizontal axis is time. Further, the operating force S is indicated by a solid line, the output torque T is indicated by a one-dot chain line, and the moving speed V is indicated by a dotted line.

In FIG. 5, time t _{1 to} t ₂ is a state in which the round-trip X-ray imaging apparatus 1 is moving in the forward direction. Further, by the operation handle 6 drawn forward at time t _2, the inverted output torque T at time t _3, it is seen that apparatus at time t ₄ is led to stop.

In FIG. 5A, the characteristic of the output torque T indicated by (1) is due to the control corresponding to the first embodiment. Similarly, the characteristics of the output torque T shown in (2) and (3) are due to the control corresponding to the second and third embodiments, respectively. As for (2) and (3), only characteristic characteristic portions different from those in Example 1 were described, and other portions were omitted.

FIG. 5 (a), when comparing the (b), in FIG. 5 (a), the comparison with FIG. 5 (b), the time of time _t 2 ~t ₃ is very short. Therefore, the time from time t _{2 to} t ₄ is shortened, and the apparatus is stopped in a short time after the operator pulls the operation handle 6 forward.

However, during the period from t _{3 to} t ₄ , the direction of the torque calculation value T ′ determined based on the operating force S and the actual output torque T are both backward, so that the normal variation limiting process is applied. It should be noted that. If the purpose is only to stop in a short time, such a control should not be performed, and if the operation in the direction opposite to the traveling direction is being performed, the variation limiting process should be relaxed. However, when such control is performed, as described below, another adverse effect occurs.

FIG. 6A is the same graph as FIG. On the other hand, FIG. 6B is a graph similar to FIG. 6A in the comparative example in which the variation limiting process is relaxed when the operation in the direction opposite to the traveling direction is performed.

Comparative example is able to shorten the time time t ₂ ~t _4. However, still at the time of t _4, the results of output torque T is in the rear, thus further moves in the opposite direction, so-called hunting occurs. In this case, a natural feeling of operation cannot be obtained, and this is a fall.

Even with a device like the comparative example, if the operator is skilled, it may be possible to stop the device without causing hunting. However, when the device is turned, a considerable sense of incongruity is produced. .

For example, when turning to the right while traveling forward, an operation of pulling the right hand backward is performed while pushing the left hand holding the operation handle 6 forward. At this time, on the left side, the rotation direction of the motor matches the operation direction, while on the right side, they are in the opposite direction. In the comparative apparatus, the left and right torque fluctuation limits are completely different until the right wheel rotates in the reverse direction. This leads to not rotating at the curvature intended by the operator. Moreover, as soon as the right wheel starts to rotate in reverse, both torque fluctuation limits become the same. With this, it is difficult to achieve a natural operation feeling.

On the other hand, according to the present embodiment, the direction of the output torque T is reversed immediately after the reverse operation, and thereafter, the limitation on the torque fluctuation is the same on the left and right, so that the operation can be performed without a sense of incongruity.

It is a figure explaining the outline | summary of the X-ray imaging apparatus for round trips concerning this invention. It is a figure explaining the detail of the operation force detection means concerning this invention. It is a figure showing an example of hardware constitutions of CPU board 8 in an embodiment. It is a figure showing an example of software composition which operates with CPU board 8 in an embodiment. It is a graph explaining the difference of this embodiment and the effect of a prior art. It is a graph explaining the difference of the effect of this embodiment and a comparative example.

Explanation of symbols

X-ray imaging apparatus for single visit 2 Cart 3 X-ray tube 4 Collimator 5 Strut 6 Operation handle 63 Elastic body 64 Pressure sensor 7 X-ray tube holding arm 8 CPU board 81 CPU
82 A / D converter 83 PWM control circuit 84 FET bridge circuit 85 RAM
86 Operating force detection module 87 Torque calculation value calculation module 88 Output calculation module 9 Drive wheel 91 Tire 92 Motor 10 Caster Tp Previous output Tlim Output fluctuation limit T Output S Operating force value D Direction and magnitude of operation T ′ Torque calculation value torque T Output torque R Duty ratio

Claims (1)

An X-ray generator, an operation handle, an operation force detection means for detecting an operation force applied to the operation handle, a pair of left and right drive wheels, and a rotation drive means for driving the drive wheels,
Torque calculation value calculation means for calculating a torque calculation value based on the detected operating force for each predetermined period;
An output fluctuation limiting means for performing a time fluctuation limiting process on the torque calculation value and determining an output;
Drive control means for controlling the rotation drive means based on the output;
Storage means for storing the output as a previous output,
In the time variation limiting process, when the direction of the torque calculation value and the direction of the previous output are the same,
Alternatively, when either the torque calculation value or the previous output is 0, the absolute value of the difference from the previous output is less than or equal to the first fluctuation limit value based on the torque calculation value. Calculating the output,
In other cases, the round X-ray imaging apparatus is characterized by performing any one of the following processes (A) to (C).
(A) Based on the torque calculation value, the output is calculated such that the absolute value of the difference from the previous output is less than or equal to a second fluctuation limit value that is greater than the first fluctuation limit value.
(B) Based on the torque calculation value, the output is calculated such that the absolute value is less than or equal to a predetermined output limit value.
(C) The output is set to zero.

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