CN109374206B

CN109374206B - Method for judging balance of electric intelligent wheelchair according to acceleration vector ball

Info

Publication number: CN109374206B
Application number: CN201811471799.7A
Authority: CN
Inventors: 饶丰; 程鹏; 张培成; 陈功; 徐安成; 朱锡芳
Original assignee: Changzhou Institute of Technology
Current assignee: Changzhou Institute of Technology
Priority date: 2018-12-04
Filing date: 2018-12-04
Publication date: 2020-06-30
Anticipated expiration: 2038-12-04
Also published as: CN109374206A

Abstract

The invention discloses a method and a device for judging the balance of an electric intelligent wheelchair according to an acceleration vector ball. The wheelchair comprises two bearings with equal radiuses, a front wheel of the wheelchair is placed on one bearing, and a rear wheel of the wheelchair is placed on one bearing, so that the front wheel and the rear wheel of the wheelchair can be driven to roll along with the rolling of the bearings; the bearing is provided with a self-rotation driving motor, the friction force of the two wheels of the wheelchair is adjusted through the speed setting of the motor, and the sensor is buried in iron sheet, cloth or plastic and then wrapped on the rolling bearing to form a sensing layer; or the sensor is wrapped on the outer surface of a tire of the wheelchair and is directly arranged at or close to the contact point of the tire and the bearing, and the sensor does not move along with the rolling of the wheel or the bearing. According to the invention, the position of the sensor is set, the three-dimensional acceleration of the wheelchair in the advancing process is measured, whether the wheelchair is balanced or not is judged according to the shape of the acceleration vector ball, the balance result of the wheelchair can be obtained in the durability test, the slope test and the stability test of the wheelchair are avoided, and the test result is reliable.

Description

Method for judging balance of electric intelligent wheelchair according to acceleration vector ball

Technical Field

The invention relates to a detection method of a mobile trolley, in particular to a method for judging the balance of an electric intelligent wheelchair according to an acceleration vector ball.

Background

With the development of intelligent control and lithium battery technology, the electric vehicle technology has gained rapid development. The electric wheelchair is considered to be the most ideal travel tool for the old or disabled people, and especially becomes a living necessity for the old due to the increasingly severe aging. With the development of economy and improvement of living standard of people in China, the market of electric vehicles in China is very explosive. Because the intelligent electric wheelchair mainly aims at the old and the people with mobility disabilities, the safety of the intelligent electric wheelchair puts forward higher requirements.

Statistically, the wheelchair users are about 1 hundred million people worldwide, wherein about 10% of people have accidents during wheelchair use each year, and more than 60% of the accidents are caused by poor balance of the wheelchair. At the same time, the proportion of these cases is increasing year by year.

At present, according to the national standard GB/T-2012 electric wheelchair, a wheelchair durability test is completed through a double-wheel rolling test, and the test can directly detect the durability of the wheelchair and only indirectly detect the balance. Whether the wheelchair can travel in a straight line or not is finished by a slope free sliding test, and although the wheelchair is visual and simple, a large amount of manpower, material resources and time are needed.

Patent 201710589767.7 discloses a method for calculating the center of gravity of a wheelchair by placing the wheelchair on a platform with sensors at four corners and calculating the center of gravity according to the stress condition of the platform. But cannot solve whether the wheelchair is balanced during traveling (including the consistent height of the two wheels and the parallelism of the left wheel and the right wheel).

Disclosure of Invention

1. The invention aims to provide a novel method.

The invention provides a method and a device for judging the balance of an electric intelligent wheelchair according to an acceleration vector ball, aiming at solving the problem that the diameters of a front wheel, a rear wheel, a left wheel and a right wheel of the wheelchair are not completely the same, and the balance and deflection of the wheelchair are difficult to effectively test.

2. The technical scheme adopted by the invention is disclosed.

The invention provides a method for judging the balance of an electric intelligent wheelchair by an acceleration vector ball in order to accurately test the balance problem of the wheelchair, and the method is based on a device for judging the balance of the electric intelligent wheelchair by the acceleration vector ball, wherein the device is a device which is provided with two bearings with equal radius in parallel, a front wheel of the wheelchair is arranged on one bearing, a rear wheel of the wheelchair is arranged on one bearing, and the front wheel and the rear wheel of the wheelchair can be driven to roll along with the rolling of the bearings; the bearing is provided with a self-rotation driving motor, the friction force of the two wheels of the wheelchair is adjusted through the speed setting of the motor, and the motor is wrapped on the outer surface of the tire of the wheelchair; the sensor is directly or closely arranged at the contact point of the tire and the bearing, the sensor does not move along with the rolling of the wheel or the bearing, and the sensor is buried in iron sheet, cloth or plastic and then wrapped on the rolling bearing to form a sensing layer; the method is characterized by comprising the following steps:

step 1, starting the electric intelligent wheelchair, setting the speed, and driving a motor of a bearing to determine the set power according to the test requirement along with the rotation of the bearing;

step 2, the acceleration sensor starts to work, three-dimensional acceleration is measured, the measuring frequency is not lower than 10 times per revolution, namely, the tire rotates once, and the measurement is carried out for 10 times at least; the relative error of the measurement is not higher than 10%;

step 3, starting measurement after the running speed of the wheelchair is unchanged, and inputting a measurement result to form a three-dimensional acceleration spherical graph; judging balance according to the volume of the ball:

(1) if the volume of the ball is small, the balance of the wheelchair is good in the running process, namely up-down, left-right and front-back balance, and the wheels and the bearings do not need to give a lot of external force to keep the wheelchair running in balance;

(2) if the volume is larger, the required external force is larger;

(3) if the center of the acceleration is not at the origin, the external force in a certain direction is needed to keep balance for a long time;

step 4, judging whether the wheels deflect or not according to the average acceleration of the left wheel and the right wheel:

(1) the vertical upward average acceleration directions of the left wheel and the right wheel are opposite, which indicates that the wheels are not as high;

(2) the average acceleration values of the left wheel and the right wheel are in a balance range, and the directions are the same, which indicates that the wheelchair deviates towards the same direction, and deviates to the left or to the right; the opposite direction, either outward or inward.

Furthermore, the radius of the bearing is 25-100 cm.

Furthermore, in the step 4, the volume of the acceleration sphere is set as V, and the corresponding radius is set as R;

(1) if the acceleration value corresponding to the sphere center of the acceleration vector ball is larger than 15% R, or the volume change of the acceleration vector ball after multiple measurements is larger than 15% V, determining that the acceleration vector ball is seriously unbalanced;

(2) judging the wheelchair to be unbalanced by 10 percent; (3) and 5%, judging that the balance of the wheelchair is qualified.

3. The technical effect produced by the invention.

On the basis of the existing double-wheel rolling technology, the sensor is arranged at a specific position, the three-dimensional acceleration of the wheelchair in the advancing process is measured, and whether the wheelchair is balanced or not is judged according to the shape of an acceleration vector ball. According to the invention, the balance result of the wheelchair can be obtained in the durability test, so that the slope test and the stability test of the wheelchair are avoided; the instrument and equipment are simple, the required cost is low, and the test result is reliable.

Drawings

Figure 1 is a schematic view of a wheelchair bearing installation.

Fig. 2 shows a first embodiment of the installation of the acceleration sensor.

Fig. 3 shows a second embodiment of the installation of the acceleration sensor.

Fig. 4 shows a third embodiment of the acceleration sensor mounting.

Fig. 5 is a three-dimensional acceleration spherical diagram.

Fig. 6 shows the acceleration in the X direction.

Fig. 7 shows the acceleration in the Y direction.

Fig. 8 shows the Z-direction acceleration.

Fig. 9 is an acceleration vector diagram (acceleration ball).

FIG. 10 is a graph of ball lift radius analysis.

Reference numerals:

1. bearing, 2, wheelchair front wheel, 3 heavy objects, 4 wheelchair rear wheels.

Detailed Description

Example 1

The measuring method comprises the following steps: and starting the electric intelligent wheelchair, wherein the speed is determined by the test requirement, and the bearing rotates along with the rotation to drive the motor of the bearing to determine the injection power according to the test requirement. The acceleration sensor starts to work, measures the three-dimensional acceleration, and the measuring frequency is not less than 10 times per revolution, namely, the tire rotates once, and the measuring frequency needs to be measured for 10 times at least. The relative error of the measurement is not higher than 10%.

The measurement is started after the operating speed of the wheelchair is unchanged, and the measurement result is input into computer software to form a three-dimensional acceleration spherical graph, as shown in figure 5.

If the ball volume is small, the balance is good in the running process, namely up and down, left and right, and front and back, and the wheels and the bearings do not need to give a lot of external force to keep the wheelchair running in balance.

If the volume is large, the external force required is large.

If the center of acceleration is no longer at the origin, it indicates that an external force in one direction is required for a long time to maintain balance.

1. The average acceleration directions in the Z direction of the left wheel and the right wheel are opposite, which indicates that the wheels are not as high;

2. the average value of the acceleration of the left wheel and the acceleration of the right wheel are not zero, and the directions are the same, which indicates that the wheelchair deviates towards the same direction, and deviates to the left or to the right; the opposite direction, either outward or inward.

Setting the volume of an acceleration sphere as V and the corresponding radius as R, and if the acceleration (vector composite value in XYZ direction) corresponding to the sphere center is more than 15%, determining that the acceleration is seriously unbalanced; judging the balance to be unbalanced when the voltage is 10 percent; 5%, the balance was judged to be acceptable.

The testing method of the measuring device comprises the following steps: as shown in figure 1, the front wheel and the rear wheel of the wheelchair are placed on bearings with the radius of 25-100 cm, the bearings roll along with the advancing of the wheelchair, and the bearings are also provided with motors and can rotate by themselves. The wheelchair has a 100 kg weight to simulate an adult sitting on the wheelchair. The friction force of the bearing to the two wheels of the wheelchair can be adjusted by adopting the motor to drive the bearing, so that the rotating speed of the bearing is changed.

The sensor is buried in iron sheet, cloth or plastic and then wrapped on the rolling bearing to form a sensing layer, as shown in fig. 2.

Example 2

Wrapped around the outer surface of the wheelchair tires, as shown in figure 3.

Example 3

The sensor is mounted directly at or near the point of contact of the tire with the bearing, as shown in fig. 4, and does not move as the wheel or bearing rolls.

Experimental verification

A sensor is added on a wheel chair tire, and the measured acceleration is as follows: the acceleration in the X direction is shown in fig. 6, the acceleration in the Y direction is shown in fig. 7, the acceleration in the Z direction is shown in fig. 8, and the acceleration vector diagram (acceleration ball) is shown in fig. 9.

And (3) analysis: as shown in fig. 10, sphere radius, center position (0.1,0,1.12), conclusion: the X-direction balance is within 10%, the left and right of the tire need to be adjusted, and the tire can automatically turn when running for a long time. The acceleration in the Z direction is too large, the heights of the two wheels of the wheelchair are inconsistent, and the adjustment is needed before leaving the factory.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A method for judging the balance of an electric intelligent wheelchair according to an acceleration vector ball is based on a device for judging the balance of the electric intelligent wheelchair according to the acceleration vector ball, the device is provided with two bearings with equal radiuses which are arranged in parallel, a front wheel of the wheelchair is placed on one bearing, a rear wheel is placed on one bearing, and the front wheel and the rear wheel of the wheelchair can be driven to roll along with the rolling of the bearings; the bearing is provided with a self-rotation driving motor, the friction force of the two wheels of the wheelchair is adjusted through the speed setting of the motor, and the motor is wrapped on the outer surface of the tire of the wheelchair; the sensor is directly or closely arranged at the contact point of the tire and the bearing, the sensor does not move along with the rolling of the wheel or the bearing, and the sensor is buried in iron sheet, cloth or plastic and then wrapped on the rolling bearing to form a sensing layer; the method is characterized by comprising the following steps:

(2) if the volume is larger, the required external force is larger;

2. The method for determining the balance of the electric intelligent wheelchair according to the acceleration vector ball as claimed in claim 1, wherein the method comprises the following steps: the radius of the bearing is 25-100 cm.

3. The method for determining the balance of the electric intelligent wheelchair according to the acceleration vector ball as claimed in claim 1, wherein the method comprises the following steps: in the step 4, the volume of the acceleration sphere is set as V, and the corresponding radius is set as R;