KR102371922B1 - Control system of electric assist module and control method for wheelchair driving on stairs and stepped terrain - Google Patents

Abstract

The present invention provides an electric assist system provided in a wheelchair frame in which a seating portion for a passenger to sit is provided on a frame having a footrest and a handle, and driving wheels are provided on both sides of the frame. Caterpillar portion of the caterpillar type traveling member for elevating the steps or steps of the frame; a landing gear unit provided in the caterpillar unit, the free ends of which are raised/lowered before and after the center of gravity of the wheelchair frame as an axis; a 3-axis acceleration sensor for measuring the x, y, and z-axis acceleration of the caterpillar part; and a controller for estimating the yaw angle of the caterpillar part by calculating the roll angle and the pitch angle with the data of the acceleration sensor. , then, by driving the step by driving the caterpillar part, it is characterized in that the step is raised or lowered by the stairs or the slope of the step of the wheelchair frame without an assistant.

Description

Electric assist system including electric assist module for wheelchair driving on stairs and step terrain, and control method of electric assist module

The present invention relates to a system and control method for controlling an electric assist module that assists inclining driving of a wheelchair. It relates to a system and a control method capable of controlling an electric assist module by estimating.

A wheelchair has a structure in which a chair is provided with wheels so that it can be moved in a seated state for a person who does not have free legs or who has difficulty walking due to physical discomfort. Recently, due to the rapid aging of the population and the increase in the number of people with walking disabilities, the number of people with disabilities in transportation has dramatically increased. Accordingly, the demand for wheelchairs, which are the main means of transportation for the transportation disadvantaged, is increasing, and the desire to use wheelchairs in various environments is increasing.

Among those who answered that they felt uncomfortable when going out using a wheelchair, 20.8% had jaws and 20% had stairs. Wheelchair users must use a separate elevator or lift to move on stairs and slopes. However, in the case of a building that has restrictions on the use of lifts due to the size and weight of the existing electric wheelchair and does not have an elevator or lift installed, there is a hassle in that the guardian has to lift the user directly to move the stairs. In addition, although there are cases where a separate slope or lift is installed as a solution to the movement of stairs, additional costs are charged because they must be installed on each main movement path, and installation is difficult due to structural problems. Therefore, in order to secure the mobility rights of wheelchair users, there is a need to develop a device that can climb on its own regardless of location or guardian and can move on stairs by simply attaching it to a manual wheelchair.

Examples of devices that allow wheelchair users to climb stairs on their own are the wheel-type iBot, and the caterpillar-type Scelovo and Topchair. A wheel-type stair climbing device such as the iBot runs the stairs with precise balance control in the form of an inverted pendulum. However, due to the inability to stand up due to power cut off while driving on the stairs. Accidents such as overturning may occur. Therefore, in most of the studies on the development of devices for safe stair climbing, studies using a caterpillar-type mechanism rather than a general wheel are being conducted in parallel. Since the caterpillar-type mechanism has excellent contact performance with curved surfaces and the grounding area is evenly distributed, stable driving is possible in climbing obstacles or stairs compared to other driving methods.

In the case of existing studies, studies on the caterpillar mechanism have focused on stable stair entry and stair climbing, but studies on exceptional situations that may occur during driving are insufficient. In particular, yawing such as misalignment during stair driving may occur due to external factors such as slippage and slippery ground. Yawing loses straightness and causes a phenomenon of driving biased to one side, and it can lead to safety accidents such as overturning, so there is a high need for research.

On the other hand, as a prior art, US Patent No. 7080842 discloses a wheelchair device for stairs. The prior art up to now has a pivot member for landing on the step, but an assistant is required due to safety accidents such as overturning when climbing the stairs. Currently, a commercially available wheelchair and auxiliary assist module for stair climbing is SANO's lift car PTR. Currently, a caterpillar-type product that is applied to a wheelchair and enables the wheelchair to travel up the stairs is also being released, but safety issues such as overturning have not been solved because the liftcar's unique function helps the wheelchair go up and down the stairs alone without an assistant.

The present applicant intends to propose a method for stably correcting an alignment abnormality caused by yawing as a control system for overcoming the risk of overturning that may occur during elevating of an electric assist module for climbing stairs. In general, the yaw angle is measured through the acceleration and angular velocity data of the inertial sensor, but it is difficult to detect rotation about the Z-axis that matches the direction of gravitational acceleration detected by the accelerometer. It is difficult to measure the yaw angle by The present applicant proposes a system and method capable of estimating the amount of yaw angle change using 3-axis acceleration data rather than rotation detection and controlling the electric assist module using this.

US Patent No. 7080842

An object of the present invention is to provide a system and a control method including an electric assist module that enables the driving of stairs and step elevation of a wheelchair without an assistant. Another object of the present invention is to provide an electric assist system and a control method of an electric assist module having excellent safety by estimating a yaw angle during driving of stairs and step elevation of a wheelchair and correcting the electric assist module.

In order to achieve the above object, the present invention provides an electric assist system provided in a wheelchair frame in which a seating portion for a passenger to sit is provided on a frame having a footrest and a handle, and driving wheels are provided on both sides of the frame, the wheelchair a caterpillar part of a caterpillar type traveling member mounted on a frame to elevate stairs or steps of the wheelchair frame; a landing gear unit provided in the caterpillar unit, the free ends of which are raised/lowered before and after the center of gravity of the wheelchair frame as an axis; a 3-axis acceleration sensor for measuring the x, y, and z-axis acceleration of the caterpillar part; and a controller for estimating the yaw angle of the caterpillar part by calculating the roll angle and the pitch angle with the data of the acceleration sensor. , It is characterized in that, by driving the step by driving the caterpillar part, it is characterized in that the stairs or the slope of the step of the wheelchair frame are raised and lowered without an assistant.

Preferably, the control unit calculates the roll angle by the inverse tangent operation of the ratio of the x-axis acceleration value to the z-axis acceleration value, and calculates the pitch angle by the inverse tangent operation of the ratio of the y-axis acceleration value and the z-axis acceleration value. can

Preferably, the control unit may estimate the yaw angle by calculating the inverse tangent of the ratio of the roll angle and the pitch angle to estimate the yaw angle without analyzing the rotation amount.

Preferably, the electric assist system according to the present invention includes a motor driven by applying the yaw angle estimated by the control unit as proportional control, and may further include a correction controller for correcting the straightness of the caterpillar unit by driving the motor. .

Preferably, the correction controller may receive feedback from the estimated yaw angle of the controller to increase or decrease the input speed of the motor according to a direction in which the caterpillar part is inclined and a rotation amount.

In addition, the present invention provides a method for controlling an electric assist module for wheelchair driving in stairs and step terrain, comprising: (a) measuring, by a controller of the electric assist module, the x, y, z-axis acceleration of the electric assist module; (b) step of the controller of the electric assist module calculating the roll angle of the electric assist module from the x-axis and z-axis acceleration data, and calculating the pitch angle of the electric assist module from the y-axis and z-axis acceleration data; (c) step of the controller of the electric assist module estimating the yaw angle of the electric assist module by calculating the roll angle and the pitch angle calculated in step (b); and (d) the correction controller of the electric assist module receives the feedback of the yaw angle estimated in the step (c) and corrects the straightness of the electric assist module.

According to the present invention, the caterpillar part of the caterpillar track linearly raises and lowers the step of the stairs, and a separate landing gear part for the initial landing of the caterpillar part is provided, so that it is possible to ascend and descend the stairs of the wheelchair without an assistant.

In addition, in the present invention, the landing gear unit has front and rear free ends and raises and lowers the front/rear based on the center of gravity, and the center of gravity is positioned toward the stairs when a continuous step difference such as stairs is raised. make this possible In addition, there is an advantage of assisting the user so that the user can properly respond according to the type of the step by looking at the step in the front and ascending and descending from the obstacle of the hill, such as a step difference of one step rather than the stairs.

In addition, the present invention has the advantage of improving the stability of the electric assist module as the control unit estimates the yaw angle and appropriately corrects the straightness of the caterpillar unit.

1 is a perspective view of a wheelchair in which an electric assist module is coupled to a wheelchair frame according to an embodiment of the present invention.
Figure 2 shows a perspective view of an electric assist module according to an embodiment of the present invention.
3 is a depiction of a yawing generation model due to external factors during stairway and inclined driving of the caterpillar unit.
4 is a control block diagram of a correction controller according to an embodiment of the present invention.
5 shows an electric assist module for performing an experimental example, an experimental staircase environment, and an experimental progress simulation.
6 is a view showing an experiment performed according to the experimental environment of FIG. 5 .
7 is an experimental example, showing the roll, pitch, and yaw data of the caterpillar part when the proportional coefficient is (K _p =10).
8 is an experimental example, showing the roll, pitch, and yaw data of the caterpillar part when the proportional coefficient is (K _p =200).
9 is an experimental example, showing the speed correction data and angular velocity data of the caterpillar part when the proportional coefficient is (K _p =200).
10 is an experimental example, and shows the roll, pitch, and yaw data of the caterpillar part when the proportional coefficient is (K _p =700).
11 shows, as an experimental example, speed correction data and angular velocity data of the caterpillar part when the proportional coefficient is (K _p =700).

Hereinafter, the present invention will be described in detail with reference to the contents described in the accompanying drawings. However, the present invention is not limited or limited by the exemplary embodiments. The same reference numerals provided in the respective drawings indicate members that perform substantially the same functions.

Objects and effects of the present invention can be naturally understood or made clearer by the following description, and the objects and effects of the present invention are not limited only by the following description. In addition, in the description of the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

1 shows a perspective view of a wheelchair 1 in which an electric assist module 3 according to an embodiment of the present invention is coupled to a wheelchair frame 10 .

Referring to FIG. 1 , the wheelchair 1 according to the present embodiment capable of ascending and descending stairs and steps may include a wheelchair frame 10 and an electric assist module 3 . The wheelchair frame 10 is provided with a seating portion 13 on which a passenger sits on the frame 11 having a footrest and a handle, and driving wheels 15 are provided on both sides of the frame 11 . The electric assist module 3 according to the present embodiment may be supplied by being integrally coupled to the wheelchair frame 10 , or may be supplied separately to be compatible with the wheelchair frame 10 .

The electric assist module 3 is fastened to the lower part of the wheelchair frame 10 . Preferably, the electric assist module 3 may be provided by being fastened to the space between the left and right driving wheels 15 . The electric assist module 3 does not interfere with the driving of the driving wheels 15 on flat ground, but assists the occupant to drive on a slope or a single step of a staircase or sidewalk block.

The electric assist module 3 may include a caterpillar unit 30 , a landing gear unit 50 , and a control unit 70 . In the electric assist module 3 , when one end of the landing gear unit 50 is raised and lowered, the caterpillar unit 30 is raised and lowered by reaction force so that the stairs or step surface and the caterpillar unit 30 come into contact with each other. Thereafter, the step is driven by the driving of the caterpillar unit 30 so that the stairs or the slope of the step of the wheelchair frame 10 can be raised and lowered without an assistant.

Figure 2 shows a perspective view of the electric assist module (3) according to an embodiment of the present invention.

The caterpillar unit 30 is a caterpillar type traveling member provided with a plurality of wheels 31 and a chain belt 33 for rotating the wheels 31 , and is mounted on the wheelchair frame 10 and is a step of the wheelchair frame 10 . Or raise and lower the step. Although not shown in the drawings, the caterpillar unit 30 may be provided with a 3-axis acceleration sensor for measuring x, y, and z-axis acceleration. The acceleration sensor may have a well-known configuration capable of measuring accelerations in the x, y, and z axes, respectively. The acceleration sensor may be provided at the lower center of the caterpillar unit 30 , but is not limited thereto.

In this embodiment, the caterpillar unit 30 is a wheel that travels up and down the stairs of the wheelchair frame 10 and is distinguished from the driving wheel 15 . Driving when ascending and descending stairs is performed by the caterpillar unit 30 . The caterpillar part 30 is a caterpillar-type traveling member consisting of a wheel 31 and a chain belt 33. Even without precise balance control in the inverted pendulum shape of the driving wheel 15-type stair climbing device, the curved surface contact performance is excellent. It is excellent and has the characteristic that the grounding area is evenly distributed. The caterpillar part 30 of the caterpillar track type is particularly excellent for climbing stairs because the chain belt 33 provides a continuous running surface in the stairs having a continuous step. On the other hand, several studies have focused on stable stair entry and stair climbing of the caterpillar mechanism, but studies on exceptional situations that may occur during driving are insufficient. In particular, yawing, such as misalignment behavior during stair driving, may cause a phenomenon of losing straightness and driving biased to one side, which may lead to safety accidents such as overturning. Accordingly, in the present embodiment, the landing gear unit 50 is configured as a means for stably entering the stairs of the caterpillar unit 30 . In addition, the control unit 70 in which the logic of driving control for stable driving of the caterpillar unit 30 is mounted may be included.

The landing gear unit 50 is provided in the caterpillar unit 30 , and the free ends of the front/rear sides may be raised/lowered around the center of gravity of the wheelchair frame 10 as an axis. The landing gear unit 50 means an auxiliary member for the initial elevation of the caterpillar unit 30 . It is noted that the landing gear unit 50 according to the present embodiment is provided with a gear structure capable of elevating the front or the rear, respectively, based on the wheelchair. When ascending and descending stairs in a wheelchair without an assistant, safety accidents such as falls can be prevented by driving the user to face the rear to ascend and descend with the back of the stairs. Therefore, it is preferable that the landing gear unit 50 is provided to lift the front or rear of the wheelchair so that the front or rear of the wheelchair can be driven separately according to the type of step.

The landing gear unit 50 may include a gear shaft 51 , a front landing wheel 53 , a rear landing wheel 55 , and a driving module 57 .

The landing gear unit 50 is controlled so that the front free end is raised and lowered in a state in which the direction of the wheelchair frame 10 is switched to the reverse direction so that the passenger can have his or her back on the stairs when ascending and descending the stairs. In addition, the landing gear unit 50 is controlled so that the free end of the rear is raised and lowered in a state in which the direction of the wheelchair frame 10 is positioned in the front so that the passenger faces the front when the step is lifted. The landing gear unit 50 may be controlled so that the occupant travels the stepped terrain in a straight line when ascending and descending by a single step, and the passenger travels the stepped terrain in a reverse manner when ascending and descending by a plurality of steps of the stairs.

The gear shaft 51 is located at the center of gravity of the wheelchair frame 10 . Referring to FIG. 2 , the gear shaft 51 is provided under the caterpillar part 30 and provided on both sides with a DC motor driving the gear in the center. The gear shaft 51 may be provided as a parallel frame as shown in FIG. 2 , but may also be provided as a single frame.

The front landing wheel 53 and the rear landing wheel 55 are provided on a body having a length extending in the front-rear direction about the gear shaft 51 . The front landing wheel 53 and the rear landing wheel 55 are provided with wheels at the ends of the body, respectively, and can be driven complementary to each other.

The driving module 57 may include a motor to selectively elevate the front landing wheel 53 or the rear landing wheel 55 around the gear shaft 51 to elevate one side of the caterpillar unit 30 . The driving module 57 may be located at the rear of the caterpillar unit 30 and connected to the rear landing wheel 55 .

The front landing wheel 53 and the rear landing wheel 55 are disposed under the caterpillar part 30, and when the front landing wheel 53 is raised and lowered, the rear end of the caterpillar part 30 is raised and lowered, and the rear landing wheel 55 ), the front end of the caterpillar unit 30 is raised and lowered when this is lifted.

The driving module 57 may raise and lower the front landing wheel 53 when ascending and descending stairs, and may raise or lower the rear landing wheel 55 when ascending or descending a step other than stairs. The driving module 57 may include a correction controller, which will be described below.

The control unit 70 controls the landing gear unit 50 to enable stable stair elevation of the caterpillar unit 30 .

In this embodiment, the control unit 70 may estimate the yaw angle of the caterpillar unit 30 by calculating the roll angle and the pitch angle using data of the acceleration sensor provided in the caterpillar unit 30 .

)는 Z축 높이 방향의 기울임된 각도를 지칭한다. FIG. 3 depicts a yawing generation model due to external factors during stairs and inclined driving of the caterpillar unit 30 . Referring to FIG. 3, Yaw (ψ) refers to an angle at which the caterpillar unit 30 is inclined to one side due to a rotational movement occurring around the electric assist module 3 as an axis. Roll(ρ) refers to the tilted angle in the XY plane generated at the rear due to the tilt of the front yaw. Pitch(

) refers to the tilted angle in the Z-axis height direction.

In the driving coordinate system of the electric assist module 3, rotation does not exist other than the yaw axis when driving on flat ground, but when the electric assist module 3 is driving on stairs and slopes, the local coordinate system based Roll and Pitch axis rotation occurs. To explain the yawing model in more detail, when the electric assist module 3 travels on the stairs, it travels in a state where pitching is observed as much as the angle α of the stairs. When the electric assist module (3) yawing occurs during stair driving, an alignment abnormality occurs as much as the angle (ψ) of the yaw in the traveling coordinate system (X, Y, Z) of the electric assist module (3). At this time, the degree of freedom is limited due to the nature of the stair topography, and rolling occurs at the same time. In summary, when the yawing of the electric assist module (3) occurs, changes in the local coordinate system standard, roll, and pitch angle are observed.

During the stair driving of the electric assist module (3) for stair climbing, Yaing can detect the situation through the Yaw axis rotation amount analysis. However, as described above, the yaw angle is difficult to detect rotation in the accelerometer and difficult to measure due to the drift phenomenon in the accelerometer. Therefore, in this embodiment, the angle of the yaw is indirectly estimated using the angles of the roll and the pitch to solve this problem.

In this embodiment, the controller 70 may calculate the roll angle ρ by calculating the inverse tangent of the ratio of the x-axis acceleration value to the z-axis acceleration value. Roll(ρ) calculated by the control unit 70 may be expressed by the following [Equation 1].

[Equation 1]

Here, Ax denotes x-axis acceleration data, and Az denotes z-axis acceleration data.

를 산출할 수 있다. 제어부(70)가 산출하는 Pitch(

)는 하기의 [수학식 2]로 나타낼 수 있다.The control unit 70 calculates the pitch angle by calculating the inverse tangent of the ratio of the y-axis acceleration value to the z-axis acceleration value.

can be calculated. Pitch calculated by the control unit 70 (

) can be expressed by the following [Equation 2].

[Equation 2]

Here, Ay denotes y-axis acceleration data, and Az denotes z-axis acceleration data.

The angle ψ of the yaw is difficult to measure in a dynamic model due to acceleration data generated while driving, and errors occur in the gyrometer data due to drift due to time accumulation. Theoretically, the angle of Yaw can be calculated as in [Equation 3] on the same principle.

[Equation 3]

), Yaw(ψ)의 값을 가속도 센서의 데이터를 이용하여 구할 수 있으나, Yaw의 각 ψ은 전동 어시스트 모듈(3)의 주행 중, 중력 가속도 방향과 일치하는 Z축에 대한 회전 감지가 어려워 센서 데이터의 정확도가 낮다. 제어부(70)는 Yaw각을 직접 산출하지 않고, 전동 어시스트 모듈(3)에 부착된 가속도 센서에서 측정된 Ax, Ay 가속도 데이터를 가속도계가 감지하는 중력가속도 데이터 Az를 기준으로 Roll(ρ)과 Pitch(

)를 산출함에 주목한다.As in [Equation 1, 2], Roll(ρ), Pitch(

) and Yaw(ψ) can be obtained using the data of the acceleration sensor, but each ψ of Yaw is difficult to detect rotation about the Z axis that coincides with the direction of gravitational acceleration while the electric assist module 3 is running. Data accuracy is low. The control unit 70 does not calculate the yaw angle directly, but roll (ρ) and pitch based on the gravitational acceleration data Az that the accelerometer senses the Ax and Ay acceleration data measured by the acceleration sensor attached to the electric assist module 3 . (

) is calculated.

)는

의 관계를 갖는다. 반면, Yaw(ψ)의 각도가 90°인 상황에서 Roll(ρ)과 Pitch(

)는

의 관계를 갖는다. 상기의 관계식을 고찰해보면, Roll(ρ)과 Pitch(

) 및 Yaw(ψ) 의 각도는 탄젠트 함수의 성질을 갖고 있다. Here, in the situation where the angle of Yaw(ψ) is 0°, Roll(ρ) and Pitch(

)Is

have a relationship of On the other hand, in the situation where the angle of Yaw(ψ) is 90°, Roll(ρ) and Pitch(

)Is

have a relationship of Considering the above relation, Roll(ρ) and Pitch(

) and the angle of Yaw(ψ) have properties of a tangent function.

Based on the above principle, the control unit 70 may estimate the yaw angle by calculating the inverse tangent of the ratio of the roll angle and the pitch angle, and estimate the yaw angle without analyzing the rotation amount. The angle of Yaw(ψ) estimated by the controller 70 may be expressed by the following [Equation 4].

[Equation 4]

The controller 70 may control the correction controller by using the estimated Yaw(ψ) information. The correction controller may be provided on the driving module 57 . The correction controller corrects the straightness of the caterpillar unit 30 by driving the motor included in the driving module 57 .

4 is a control block diagram of a correction controller according to an embodiment of the present invention. Referring to FIG. 4 , the correction controller receives velocities of Velocity_L and _R from motors respectively controlling Left and Right. The correction controller feeds back the Yaw (ψ) angle estimated by the controller 70 while driving, and increases or decreases the input speed according to the inclined direction and the amount of rotation. The correction controller compensates the straightness by inputting the increased or decreased Velocity Control_L,_R to the motor.

The correction logic performed by the correction controller may be expressed by the following [Equation 5].

[Equation 5]

The correction controller corrects the straightness by controlling the speed Velocity Control_L and Velocity Control_R of the motor according to the estimated yaw (ψ) angle according to [Equation 5], and due to the characteristic of the electric assist module (3), β° By setting as Threshold, the range within β° is judged as a stable range, and correction may not be applied. Kp is a proportional constant that determines the sensitivity of the controller and can be selected through performance changes according to experiments.

experimental example . Straightness correction of electric assist module

5 shows an electric assist module for performing an experimental example, an experimental staircase environment, and an experimental progress simulation. 6 is a view showing an experiment performed according to the experimental environment of FIG. 5 .

In this experimental example, in order to verify the performance of the proposed yaw angle estimation technique and the straightness correction controller, the straightness correction is checked by applying the yaw angle estimation technique and the straightness correction system to the actual electric assist module (3). Also, in order to change the performance according to the change of Kp, the value of Kp was changed from 10-700 to investigate whether or not the straightness of the system was corrected and the change in the rotational angular velocity. Through the experiment, data graphs were calculated for three cases showing representative characteristics. For the performance verification experiment, a real-stage experimental environment and experimental apparatus were implemented as shown in FIGS. 5 and 6 . Referring to FIG. 5 , an experimental environment was configured to target stairs of the most common standard that a wheelchair user could come across while moving. The effective width of stairs and landings within the range suggested by Ordinance of the Ministry of Land, Infrastructure and Transport No. 548 was manufactured to be 600mm or more, the step height was 180mm or less, and the step width was 260mm or more. The electric assist module 3 according to this embodiment used the caterpillar-type electric assist module of FIG. 5 to test the proposed yaw angle estimation technique and the straightness correction controller performance, and the assistant arbitrarily caused the yawing to perform the experiment. To do this, a separate landing gear configuration was not added.

Referring to FIG. 6, the electric assist module (hereinafter abbreviated as 'assist module') implemented in the experimental example of FIG. 5 is corrected by intentionally applying an external force during stair movement to verify the performance of the yaw angle estimation technique and the straightness correction controller using the same. was tested whether The assist module showed data graphs that were pre-processed by driving at a slow speed of 0.1 m/s.

In FIG. 6 , the assist module has the same initial stage as section ① of FIG. 6 . After that, an experiment protocol was devised to show the process of generating yawing counterclockwise and clockwise while moving and intentionally applying an external force as in sections ② and ④, and correcting straightness as in sections ③ and ⑤. In the experiment, for posture estimation, roll and pitch angles and yaw angles through estimation techniques are collected, and driving speed and angular velocity data are presented to determine whether straightness is corrected or not.

), Yaw(ψ) 데이터를 나타낸다. 도 7의 실험은 제안하는 보정 제어기의 성능을 낮게 수행할 때 상태 확인을 위해 낮은 Kp를 적용하여 실험하였다. 도 7을 참조하면, 비례계수 Kp를 10으로 설정하여 계단 주행중인 기구가 외부 환경으로 인하여 Yawing이 일어나 직진성을 보정하는 모습과 Roll, Pitch 데이터, Yaw 각도 추정 기법의 결과를 나타낸다. 어시스트 모듈은 ①번 구간의 초기단계에서 주행을 실시하며, 주행 중 의도적으로 반시계방향으로 Yawing을 발생시켜 ②번 구간에서 각도에 급격한 변화가 생기게 된다. ③번 구간에서는 Yawing을 감지하였지만 낮은 Kp에 의해 거의 보정이 되지 않음을 확인하였다.7 is an experimental example, when the coefficient of proportionality is (K _p =10), Roll (ρ), Pitch (

) and Yaw(ψ) data. In the experiment of FIG. 7 , a low Kp was applied to confirm the state when the performance of the proposed correction controller was low. Referring to FIG. 7 , by setting the proportional coefficient Kp to 10, yawing occurs due to the external environment of the instrument running on the stairs to correct straightness, and the results of the roll, pitch data, and yaw angle estimation technique are shown. The assist module drives in the initial stage of section ①, and intentionally generates counterclockwise yaw while driving, resulting in a sudden change in angle in section ②. Yawing was detected in section ③, but it was confirmed that there was hardly any correction due to the low Kp.

), Yaw(ψ) 데이터를 나타낸다. 도 8을 참조하면, ②,④번 구간에서의 급격한 데이터 변화는 의도적으로 발생시킨 Yawing을 나타내고, ③,⑤번 구간에 의해 직진성 보정 과정을 확인하였다. 8 is an experimental example, when the coefficient of proportionality is (K _p =200), Roll (ρ), Pitch (

) and Yaw(ψ) data. Referring to FIG. 8, abrupt data changes in sections ② and ④ indicate intentionally generated yawing, and the straightness correction process was confirmed by sections ③ and ⑤.

9 is an experimental example, showing the speed correction data and angular velocity data of the caterpillar part when the proportional coefficient is (K _p =200). In the speed correction data section ③ and ⑤, as an experimental example according to FIG. 7, the straightness correction of the assist module was confirmed differently from the uncorrected form. During the straightness correction process, the instantaneous angular velocity was measured to be -67 [deg/s] and 67 [deg/s].

), Yaw(ψ) 데이터를 나타낸다. 도 10은 더욱 신속한 보정을 위하여 더 높은 Kp로 적용하여 동일한 조건으로 실험을 진행하였다. 10 is an experimental example, when the coefficient of proportionality is (K _p =700), Roll (ρ), Pitch (

) and Yaw(ψ) data. 10 shows that the experiment was conducted under the same conditions by applying a higher Kp for more rapid correction.

Referring to FIG. 10, by setting Kp to 700, the electric assist module generates yaw in the same counterclockwise and clockwise directions to correct straightness and the yaw data estimated through the roll, pitch data, and yaw angle estimation technique. can be checked

11 shows, as an experimental example, speed correction data and angular velocity data of the caterpillar part when the proportional coefficient is (K _p =700). Referring to FIG. 11 , compared with the experimental example of FIG. 8 , it was possible to confirm the rapid straightness correction process of the assist module in sections ③ and ⑤, and the instantaneous angular velocity in the angular velocity data graph in the straightness correction process was 141 [deg/s ], ?220[deg/s].

Data comparison summarizing the results of FIGS. 7 to 11 is shown in [Table 1].

K _p Yaw
calculation Straightness correction Calibration time instantaneous angular velocity 10 O X not corrected not corrected 200 O O 0.7[sec] 64 [deg/s], -67 [deg/s] 700 O O 0.3[sec] 141 [deg/s], -220 [deg/s]

experimental result.

All three experiments performed by changing the proportional coefficient successfully estimated the yaw angle. When the Kp was 10, the straightness could not be corrected successfully, but when the proportional coefficient was set to 200 or more, it was confirmed that the straightness was corrected in all cases.

Although the present invention has been described in detail through representative embodiments above, those of ordinary skill in the art to which the present invention pertains will understand that various modifications are possible within the limits without departing from the scope of the present invention with respect to the above-described embodiments. will be. Therefore, the scope of the present invention should not be limited to the described embodiments and should be defined by all changes or modifications derived from the claims and equivalent concepts as well as the claims to be described later.

1: wheelchair
8: Stairs
9: sidewalk block
10: wheelchair frame
11: frame
13: seating area
15: drive wheel
3: Electric assist module
30: caterpillar part
31: wheel
33: chain belt
50: landing gear unit
51: gear shaft
53: front landing wheel
55: rear landing wheel
57: drive module
70: control unit

Claims (6)

In the electric assist system provided in a wheelchair frame in which a seating portion for a passenger to sit is provided on a frame having a footrest and a handle, and driving wheels are provided on both sides of the frame,
a caterpillar part of a caterpillar-type traveling member mounted on the wheelchair frame to ascend and descend stairs or steps of the wheelchair frame;
a landing gear unit provided in the caterpillar unit, the free ends of which are raised/lowered before and after the center of gravity of the wheelchair frame as an axis;
a 3-axis acceleration sensor for measuring the x, y, and z-axis acceleration of the caterpillar part; and
Including a control unit for estimating the yaw angle of the caterpillar part by calculating the roll angle and the pitch angle with the data of the acceleration sensor,
When one end of the landing gear part is raised and lowered, the caterpillar part is raised and brought into contact with the step or step surface, and then the step is driven by driving the caterpillar part to raise and lower the stairs or the inclined surface of the step of the wheelchair frame without an assistant, characterized in that Electric assist system.
The method of claim 1,
The control unit is
Calculate the roll angle by calculating the inverse tangent of the ratio of the x-axis acceleration value to the z-axis acceleration value,
Electric assist system, characterized in that the pitch angle is calculated by calculating the inverse tangent of the ratio of the y-axis acceleration value and the z-axis acceleration value.
3. The method of claim 2,
The control unit is
By estimating the yaw angle by the inverse tangent operation of the ratio of the roll angle and the pitch angle,
Electric assist system, characterized by estimating the yaw angle without analyzing the amount of rotation.
The method of claim 1,
The electric assist system comprising a motor driven by applying the yaw angle estimated by the control unit as proportional control, and further comprising a correction controller for correcting the straightness of the caterpillar part by driving the motor.
5. The method of claim 4,
The correction controller is
The electric assist system, characterized in that by receiving the feedback of the estimated yaw angle of the control unit, the input speed of the motor is increased or decelerated according to the inclination direction and the rotation amount of the caterpillar unit.
In the control method of the electric assist module for wheelchair driving of stairs and step terrain,
(a) the control unit of the electric assist module measuring the x, y, z-axis acceleration of the electric assist module;
(b) calculating, by the control unit of the electric assist module, the roll angle of the electric assist module from the x-axis and z-axis acceleration data, and calculating the pitch angle of the electric assist module from the y-axis and z-axis acceleration data;
(c) estimating, by the control unit of the electric assist module, the yaw angle of the electric assist module by calculating the roll angle and the pitch angle calculated in step (b); and
(d) the correction controller of the electric assist module receiving feedback of the yaw angle estimated in step (c), and correcting the straightness of the electric assist module.

Images