JP2008068702A - Traveling body traveling by receiving power assist - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a consumed electric current in a traveling body with a power assist, and to improve operability. <P>SOLUTION: A carrying head which is the traveling body has a hold threshold value HS1 holding input torque. When the input torque of an operator becomes not more than the hold threshold HS1, the input torque is regarded as the hold threshold value HS1 to calculate assisting force during hold time Ht. The assisting force assists force of the operation for pushing/pulling a carrying bed. When the input torque becomes not less than a hold releasing threshold value HL1 during the hold time Ht, holding is released and the assisting force is calculated on the basis of actual input torque. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a traveling body that is used for moving sick people, luggage, etc., and that travels with electric assistance from an electric motor.

  Examples of traveling bodies that can run with electric assistance include transport devices such as electric beds and stretchers used in hospitals, nursing homes, factories, warehouses, food carts, and cargo carts. can give. In the conveyance device as an example of such a traveling body, driving wheels driven by an electric motor are attached in addition to the casters arranged in the main body frame, and assist force at the time of movement is obtained by the driving wheels. . On the main body frame, a mat is placed if it is a bed, and a cargo bed is provided if it is a carriage.

  In the conventional electrically assisted transfer device, as a device for detecting the force (operating force) applied to the operation handle by the operator, the torsion bar detects the torsional displacement when the operation handle is operated and determines the operation angle of the operation handle. There exists what was comprised so that the signal according to it might be output from a potentiometer (for example, refer patent document 1). The input torque is detected based on the signal output from the potentiometer, and the electric motor is driven according to the magnitude of the input torque.

Here, an auxiliary power control method for a battery-assisted bicycle is known as power control in the case of applying assist force with an electric motor (see, for example, Patent Document 2). In this auxiliary power control method, when the pedaling force is equal to or less than the first threshold and this state continues for a predetermined time, the supply of the assist current to the electric motor is stopped, or the assist current is set from a normal set value. Also lower. When the pedal effort exceeds a second threshold value that is greater than the first threshold value, supply of a normal assist current is started. Since current consumption is kept low, the cruising range is extended.
JP 2005-289081 A JP 2000-72080 A

However, if the input torque input from the operator to the transport device, which is the traveling body, increases or decreases in a short time, the assist current changes following this, so the assist force changes frequently and the operation Sexuality gets worse. In particular, unlike a battery-assisted bicycle that is used in a state in which a person rides, a transport device that is manually pressed by an operator tends to fluctuate the operating force input from the operator to the transport device. For this reason, if the assist force is made to respond sensitively to the input torque, the electric motor works like a brake and the transport device feels heavy, increasing the burden on the operator. On the other hand, there is also a desire to improve the followability by changing the assist force when the value falls below the first threshold even within a predetermined time.
The present invention has been made in view of such circumstances, and a main object thereof is to improve operability while suppressing current consumption in a traveling body with electric assist.

The invention according to claim 1 of the present invention that solves the above-described problem is an electric motor that detects an input torque applied by an operator, rotates a driving wheel by an electric motor based on the input torque, and assists an operator's input. A traveling body that generates an assist force, and configured to calculate an electric assist force by regarding the input torque as a constant hold threshold for a predetermined hold time when the input torque falls below the hold threshold. It was set as the traveling body which receives the electric assistance characterized by being run.
A traveling body that travels with this electric assist generates assist force when the input torque falls below the hold threshold even if the actual input torque changes, the constant value (hold threshold) is regarded as the input torque. Let During the hold time, the traveling body is assisted with a stable force without depending on the change of the input torque.

According to a second aspect of the present invention, in a traveling body that travels by receiving the electric assist according to the first aspect, the traveling body has a hold release threshold corresponding to an input torque that is smaller than the hold threshold, and the input torque during the hold time. Is configured to generate an assist force corresponding to the actual input torque when the value becomes equal to or less than the hold release threshold.
When the actual input torque further decreases during the hold and falls below the hold release threshold, the traveling body that receives this electric assist releases the hold and controls the assist force based on the actual input torque.

According to a third aspect of the present invention, in the traveling body that travels by receiving the electric assist according to the second aspect, an operator can push and pull an input unit that applies input torque, and the hold release threshold value is the input value. The torque is equivalent to the midpoint of the push-pull direction of the part.
The traveling body that travels with this electric assist releases the hold when the operator does not push or pull the traveling body, that is, when the operation unit is in a neutral state, and thereafter assists based on the actual input torque. Generate power.

According to a fourth aspect of the present invention, in the traveling body that travels by receiving the electric assist according to the first aspect, the first threshold corresponding to the input torque when starting the electric assist, and the electric assist during the electric assist. A second threshold value corresponding to an input torque for stopping, and the hold threshold value is between the first threshold value and the second threshold value.
A traveling body that travels by receiving this electric assist has hysteresis at the start and stop of the electric assist so that the electric motor is not frequently turned on and off. Since the hold threshold value is set between the first and second threshold values, the electric motor is frequently turned on and off when the magnitude of the input torque changes minutely or when the change time of the input torque is minute. It will not be done.

According to a fifth aspect of the present invention, in the traveling body that travels by receiving the electric assist according to the second aspect, the first threshold corresponding to the input torque when the electric assist is started, and the electric assist during the electric assist. A second threshold value corresponding to an input torque for stopping, the hold threshold value is between the first threshold value and the second threshold value, and the hold release threshold value is greater than the first threshold value. Is also small.
A traveling body that travels by receiving this electric assist has hysteresis at the start and stop of the electric assist so that the electric motor is not frequently turned on and off. Since the hold threshold value is set between the first and second threshold values, the electric motor is frequently turned on and off when the magnitude of the input torque changes minutely or when the change time of the input torque is minute. It will not be done. In addition, when the operator stops the traveling body or the like, when the input torque changes greatly so as to become the hold release threshold value or less, the hold is released to reflect the operator's intention.

According to a sixth aspect of the present invention, there is provided a traveling body according to any one of the first to fifth aspects, wherein the traveling body lays a mat on the patient, a main body portion on which the mat is placed, and the main body portion. A traveling body is provided that is movably provided and is driven by an electric assist characterized by being a transfer bed provided with a handle for an operator to input torque.
A traveling body that travels with this electric assist, for example, when a patient is transported on it, even if the actual input torque changes when the force pushing the transfer bed (input torque) is below the hold threshold. The assist force is generated by regarding a certain value (hold threshold) as the input torque. During the hold time, the transfer bed is assisted with a substantially constant force without depending on the change of the input torque, so that the ride comfort of the patient and the operability of the operator are improved.

  According to the present invention, when the input torque falls below the hold threshold, the assist force is generated by regarding the torque corresponding to the substantially constant hold threshold as the input torque for a predetermined time. The behavior of the traveling body can be stabilized even when it is slightly reduced or temporarily reduced. For this reason, while being excellent in operativity, a vibration can be suppressed.

  The best mode for carrying out the invention will be described in detail with reference to the drawings. In the following, the traveling body will be described as a transport bed for a hospital. The front-rear direction is the longitudinal direction of the bed, and is the direction in which the transport bed mainly advances and retreats. The width direction means a width direction orthogonal to the front-rear direction.

  As shown in FIGS. 1 and 2, the transport bed 1 has a main body frame 2 (main body portion), and a mat 3 for placing a patient on the main body frame 2 is placed. Further, a safety fence 4 is attached to the main body frame 2 so as to surround the mat 3. Four leg portions 5 are extended downward from the main body frame 2, and casters 6 are attached to the lower ends of the leg portions 5 one by one. Further, a support column 7 is fixed downwardly between the four legs 5 at the bottom of the main body frame 2. An arm 8 is fixed to the lower end of the column 7, and a drive unit 10 is connected to the arm 8 so as to be rotatable in a direction indicated by an arrow X in the drawing.

  The drive units 10 are installed one by one in the width direction of the transfer bed 1, and an assist motor 12 that is a DC drive electric motor is provided on the base portion 11, and a speed reducer 13 that decelerates the rotation of the assist motor 12. And are installed. An output shaft of the speed reducer 13 is a rotating shaft 14, and a driving wheel 15 is fixed to the rotating shaft 14. A bracket 20 is fixed to the front side of the base portion 11. The bracket 20 extends in the height direction, and the arm 8 is connected to a proximal end portion close to the base portion 11. A plunger 23 of an elevating actuator 22 is fixed to the upper end portion of the bracket 20 via a compression coil spring 21. The compression coil spring 21 and the lifting actuator 22 are arranged so as to extend forward from the bracket 20. The lift actuator 22 is supported by a bracket 25 extending from the main body frame 2. The lift actuator 22 includes a DC motor 26, and the plunger 23 can be expanded and contracted in the arrow Y direction by the rotation of the DC motor 26. When the plunger 23 extends, the upper end portion of the bracket 20 is pushed through the compression coil spring 21. As a result, the base portion 11 rotates in the X direction starting from the portion connected to the arm 8, and the drive unit 10 is pressed against the floor surface to generate a ground load.

  Further, a battery 30 for power supply and a controller 31 for controlling the assist motors 12 and 26 are attached to the bottom of the main body frame 2 and behind the drive unit 10. The battery 30 supplies power to the assist motors 12 and 26 and the controller 31, and also supplies power to a motor of a reclining mechanism (not shown) of the mat 3. The controller 31 is connected to a control panel (not shown) attached to the main body frame 2, and can also drive the assist motor 12 and the like in accordance with an input instruction from the operator.

A handle mechanism 40 is provided on the safety fence 4 at the rear end of the main body frame 2. A sensor device (operation force detection device) 41 is attached to the handle mechanism unit 40 via a bracket 39. The sensor device 41 is a sensor for detecting an operation load (input torque) applied by the operator when the transport bed 1 moves.
As shown in FIGS. 1 and 3, in the sensor device 41, a hollow shaft 43 is rotatably supported by a housing 42 fixed to a bracket 39. The rotation axis of the hollow shaft 43 substantially coincides with the width direction of the transfer bed 1. A torsion bar 44 is connected to one end of the hollow shaft 43. The torsion bar 44 has one end fixed to the housing 42 and the other end fixed to one end of the hollow shaft 43. A potentiometer 45 that measures the torsional displacement of the torsion bar 44 is disposed on the other end side of the hollow shaft 43. The output of the potentiometer 45 is connected to the controller 31.

  Further, the proximal end portion of the handle 50 is fixed to the hollow shaft 43. The handle 50 is an input portion to which an operation load (input torque) is applied when the operator pushes and pulls the transfer bed 1 and swings around the axis of the hollow shaft 43 in the direction indicated by the arrow Z shown in FIG. Is possible. Here, when the handle 50 is swung, the handle 50 is inclined by the input torque and the hollow shaft 43 is rotated. As a result, a torsional displacement occurs in the torsion bar 44. The potentiometer 45 measures the torsional displacement and outputs it to the controller 31. Here, there is a correlation between the input torque applied to the handle 50 and the torsional displacement of the torsion bar 35, and there is also a correlation between the torsional displacement of the torsion bar 35 and the output of the potentiometer 36. Therefore, the potentiometer 45 outputs a signal corresponding to the input torque of the handle 50. The controller 31 calculates the input torque applied to the transport bed 1 based on this measurement value. If a transmission gear and a driven gear are provided in the housing 42 and the rotation of the torsion bar 44 is amplified and then input to the potentiometer 45, the resolution is increased and the accuracy of detecting the angle change is improved.

  FIG. 4 shows a control block diagram of the transfer bed 1. The output of the potentiometer 45 of the handle mechanism unit 40 is sent to the controller 31 and input to the input calculation unit 61 of the controller 31. For example, a map indicating the relationship between the output value of the potentiometer 45 and the output value is stored in advance in the input calculation unit 61, and a torque value (recognition torque) for calculating the assist force by referring to this map. Is calculated. On the other hand, the vehicle speed detection unit 10a in the drive unit 10 includes, for example, a sensor that detects the rotational speed of the assist motor 12, and detects the vehicle speed of the transfer bed 1 and outputs a pulse signal. This information is input to the vehicle speed calculation unit 62 of the controller 31. The vehicle speed calculation unit 62 calculates the speed of the transfer bed 1 and inputs it to the output calculation unit 63. The output calculation unit 63 receives the recognized torque output from the input calculation unit 61 and the vehicle speed calculated by the vehicle speed calculation unit 62, performs necessary processing, and calculates the driving force to be output as the assist force. Then, the duty required to generate the driving force is input to the assist motor 12 to generate the assist force, which is applied to the operator input torque applied to the handle mechanism unit 40.

  Here, when the input from the steering wheel 50 falls below a threshold value, the input calculation unit 61 sets the value for a certain period of time when hysteresis is provided between the torque for starting assist and the torque for stopping assist. The hold torque is maintained and the recognized torque is determined.

  Hysteresis processing refers to differentiating the torque value for starting assist and the torque for stopping assist (providing hysteresis). For example, a case where control is performed using the map shown in FIG. 5 will be described. In this map, the horizontal axis represents the handle input (input torque), and the vertical axis represents the handle input with assist force (motor output) added. In the input calculation unit 61, 15N is set as the first threshold value SU for steering wheel input, and 20N is set as the second threshold value SL. When the input torque gradually increases along the line L1, the transport bed 1 is driven only by the input torque from the operator until the first threshold value SU (20N) is exceeded. When the input torque exceeds the first threshold value SU, the assist motor 12 is driven to start assist. As a result, the transfer bed 1 is driven with a force obtained by adding the motor output to the handle input, as indicated by a line L2. If the input torque from the operator decreases along the line L2 while assisting with the assist motor 12, the motor assist is performed even if the handle input falls below the first threshold value SU (20N). Continue. Further, when the input torque decreases and falls below the second threshold SL (15N), the motor assist is stopped. As a result, the transfer bed 1 is driven only by a handle input, as indicated by a line L1.

  Next, an example of the hold process will be described with reference to FIG. The horizontal axis indicates time, and the vertical axis indicates torque. The torque here is input torque from the operator or torque recognized by the input calculation unit 61 (recognized torque). In the input calculation unit 61, a value between the first threshold value SU and the second threshold value SL, for example, 16N, is set as the hold threshold value HS1. Further, a value smaller than the second threshold SL is set as the hold release threshold HL1. The hold release threshold value HL is set to a value corresponding to the middle point of the handle 50 (a position where the handle 50 is neither pushed nor pulled). However, the hold release threshold value HL1 may be a value other than this.

As shown in line L3, when the input torque from the operator changes over time, the torque recognized by the input calculation unit 61 (recognized torque) matches the input torque until time t1, and based on this value. Generate assist force. Since the handle input becomes equal to or less than the hold threshold value HS1 from time t1, the input calculation unit 61 holds the recognition torque only from the time t1 to a predetermined hold time Ht as indicated by a line L4. As a result, the actual input torque is reduced, but the recognized torque is held at the hold threshold value HS1, and an assist force is generated based on the hold threshold value HS1.
When the actual input torque at time t2 after the hold time Ht has elapsed is below the hold threshold value HS1, the actual input torque value is adopted as the recognition torque as indicated by a line L5. On the other hand, when the actual input torque exceeds the hold threshold HS1 until the hold time Ht elapses, the hold is released and the actual input torque is adopted as the recognition torque. As a result, the intention of the operator to positively push the transfer bed 1 is reflected.

Further, when the actual input torque becomes equal to or lower than the hold release threshold HL1 as shown at time t4 while holding below the hold threshold HS1 at time t3, that is, on the opposite side from the middle point of the handle 50 Is moved, the actual input torque is adopted as the recognition torque by releasing the hold. Such cases include the case where the operator tries to stop the transfer bed 1 or the case where the operator tries to stop pressing the transfer bed 1. Make it easier to reflect.
As a result, in the example of FIG. 6, even if the input torque changes between the times t1 and t2 and between the times t3 and t4, it is regarded as a constant recognition torque, and other regions are values corresponding to the input torque. Is regarded as a recognized torque. Then, the hysteresis processing illustrated in FIG. 5 is performed on the recognized torque, and the assist force is calculated by the output calculation unit 63.

  According to this embodiment, when the input torque of the operator falls below the hold threshold HS1, the input torque is regarded as the hold threshold HS1 for a predetermined time (hold time Ht), and the hold threshold HS1 is pseudo-input. Since the assisting force (driving force) is generated to assist the operation of pushing and pulling the transfer bed 1, it is not sensitive to such a change when the actual input torque is slightly reduced. become. In the transfer bed 1, the operator pushes it by hand from the rear end to drive it, and the weight of the transfer bed 1 on which the patient is placed is heavier than the weight of the operator, so the input torque is likely to vary in a very small range. In this embodiment, when the input torque fluctuates slightly, it is possible to prevent the assist force from fluctuating and impairing the operator's operational feeling. Further, it is possible to suppress vibration that occurs when the assist force frequently fluctuates. Furthermore, it becomes easy to advance the conveyance bed 1 by inertia. Since such processing is different from filter processing, the processing load is small and there is almost no delay with respect to input.

Further, since the hold release threshold value HL1 is provided so that the hold can be released even during the hold time Ht, when the operator's intention is clear, it can be reflected in the behavior of the transport bed 1. In particular, since the hold release threshold value HL1 is set to a value corresponding to the middle point of the handle 50, it is possible to accurately reflect the operator's intention when the transport bed 1 is to be stopped.
By performing a hysteresis process with a difference between the first threshold value S1 and the second threshold value S2, power consumption can be suppressed.

Note that the present invention can be widely applied without being limited to the above-described embodiment.
For example, the traveling body is not limited to the transport bed 1. A transport cart used in factories or the like may be used. Other traveling bodies may also be used.
The hold threshold value HS1 and the hold time Ht may be configured to change according to the input direction of the handle 50, the vehicle speed, and the weight. Specifically, it has a map and a calculation formula for each of the above-described parameters, and is configured to determine the assist force by selecting as appropriate.
The form of the input unit is not limited to the handle 50. Various modes such as a pushable / pullable lever can be selected.

It is a side view which shows the structure of the conveyance bed which is an example of this invention. It is the figure which looked at the conveyance bed from the bottom. FIG. 2 is a diagram showing a configuration of a handle mechanism section, as viewed from an arrow A in FIG. 1. It is a control block diagram of a conveyance bed. It is a figure explaining a hysteresis process. It is a figure explaining a hold process.

Explanation of symbols

1 Transfer bed (traveling body)
2 Body frame (body part)
3 mat 12 assist motor (electric motor)
15 Driving wheel 31 Controller 50 Handle (input part)
HS1 hold threshold HL1 hold release threshold Ht hold time SU first threshold SL second threshold

Claims (6)

A traveling body that detects an input torque applied by an operator, rotates a drive wheel with an electric motor based on the input torque, and generates an electric assist force that assists an operator's input,
An electric assist is configured to calculate the electric assist force by regarding the input torque as a constant hold threshold for a predetermined hold time when the input torque becomes less than the hold threshold. A traveling body that receives and travels.   A hold release threshold value corresponding to an input torque smaller than the hold threshold value is provided, and an assist force corresponding to the actual input torque is generated when the input torque falls below the hold release threshold value during the hold time. The traveling body that travels by receiving the electric assist according to claim 1.   The operator according to claim 2, wherein an operator provides an input unit for applying input torque so that the input unit can be pushed and pulled, and the hold release threshold value is a torque corresponding to a midpoint of a push-pull direction of the input unit. A traveling body that travels with electric assistance.   A first threshold value corresponding to an input torque when the electric assist is started, and a second threshold value corresponding to an input torque when the electric assist is stopped during the electric assist, wherein the hold threshold is the first threshold value. The traveling body that travels by receiving electric assistance according to claim 1, wherein the traveling body is between the threshold value and the second threshold value.   A first threshold value corresponding to an input torque when the electric assist is started, and a second threshold value corresponding to an input torque when the electric assist is stopped during the electric assist, wherein the hold threshold is the first threshold value. The traveling body that travels with electric assistance according to claim 2, wherein the hold release threshold value is smaller than the first threshold value.   The traveling body according to any one of claims 1 to 5, wherein the traveling body is provided with a mat for laying a patient, a main body portion on which the mat is placed, and a swingable movement with respect to the main body portion. Is a transport bed provided with a handle for applying an input torque, and a traveling body that travels with electric assistance.

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