Development of MCU for intelligent remote control wheelchair

With the aging of China's population and the increase in the number of disabled people, the problem is becoming increasingly serious. Smart wheelchairs have gradually become an important means of transportation due to their advantages such as easy operation and the convenience for the elderly and the disabled to better integrate into society. The wheelchair introduced in this article is suitable for those who are inconvenient to move with both hands or below the neck. This wheelchair uses a head-mounted control device to detect the movement state of the user's neck, and transmits the corresponding instructions to the user through a short-distance wireless communication system. wheelchair to make the wheelchair move accordingly. In addition, in order to prevent collisions due to improper operation by users, obstacle avoidance sensors are installed around the wheelchair. In addition, in order to prevent the wheelchair from running out of power, the wheelchair is also equipped with a power detection system, which displays the current power level on the LCD screen in real time. When the wheelchair is feeding power, the wheelchair's LCD screen will display "No Power" to remind the user to charge in time.

1. Intelligent wheelchair design ideas

The wheelchair mainly includes three parts: a neck posture detection unit, a wireless signal transmission unit, and a wheelchair motion control unit. This paper introduces the block diagram of the wheelchair system shown in Figure 1.

1.1 Neck posture detection unit

The main part of the unit is a gy-85 nine-axis gravity acceleration sensor module. This work mainly uses the three-axis accelerometer in gy-85 to measure the user's neck movement state. And the measurement result is transmitted to the control terminal in the form of 16-bit two's complement code. The measurement error of the data obtained by the user's neck movement state through this form will not exceed 1°. These data will be transmitted to the motion unit through the transmission module, so that the motion unit moves according to the command.

1.2 Signal wireless transmission unit

In order to ensure the speed and accuracy of data transmission and to leave enough room for improvement in the design, the device uses the NRF24L01 module as the wireless transmission unit. The unit has the characteristics of fast transmission rate, multiple transmission channels, and compatibility with other NRF series chips. It has excellent measurement accuracy, high confidentiality and huge room for improvement.

1.3 Wheelchair motion control unit

When the control end receives the corresponding data, it will issue corresponding instructions, which will control the motor drive module L298N to work, and the wheelchair will move in the specified direction under the drive of the motor, so that the wheelchair will move in the direction of the human neck. purpose of exercise.

1.4 Other functional units

In order to increase the safety of the device and improve the man-machine relationship of the device, the device also includes two other parts: the front obstacle detection unit and the power detection unit.

(1) Front obstacle detection unit: In order to prevent collision accidents caused by improper operation of the wheelchair user and protect the safety of the user, this wheelchair is specially added with this module. This module is composed of an infrared obstacle avoidance sensor and an ultrasonic sensor. When When the infrared obstacle avoidance sensor detects that the road ahead is uneven, the wheelchair will automatically stop, and the distance between the wheelchair and the obstacle ahead will be displayed on the LCD screen. This system can effectively prevent the wheelchair from colliding with obstacles in front to achieve the purpose of protecting the safety of users.

(2) Power detection unit: This unit compares the measured voltage data with the voltage data at full power through the ADC0804 module, so as to calculate the remaining value of the current power. When the power is insufficient, the LCD will display "No Power" is used to remind the user to charge in time, so as to prevent the embarrassing situation that the user cannot reach the charging place without leaving enough time.

2. The working principle of the intelligent remote control wheelchair

2.1 Principle of attitude detection sensor

This wheelchair uses gy-85 as the detection device for the user's head posture. The sensor, also known as "nine-axis gravity acceleration sensor", is a powerful sensor. Generally, a three-axis accelerometer is used to detect the motion posture of the user's head. The detection method is: based on the gravity direction of the object, the current user's neck posture is judged according to the magnitude of the gravity acceleration components of the sensor on the three axes.

2.2 Technical principle of short-range radio frequency communication

In order to ensure that the car has enough space for transformation and communication channels, the communication of this wheelchair mainly uses the NRF24L01 module. This module has 125 communication channels and communicates with other NRF24L01 modules on the same channel in SPI mode. At the same time, this kind of chip can be compatible with other NRF series chips, so that the wheelchair introduced in this paper has good compatibility.

3. Market prospect of intelligent remote control wheelchair

In a modern society where population aging is becoming an increasingly prominent problem, it has gradually become a social problem to solve the travel problem of the elderly and provide enough companionship for the elderly. According to statistics, in 2010, there were approximately 177.64 million elderly people in China, and a considerable number of these elderly people are disabled in both hands or even unable to exercise below the neck. Assuming that only 3% of these people have the willingness and ability to purchase wheelchairs, the annual demand for wheelchairs will exceed 350,000 units, which is a huge demand.

After a lot of market research, we found that most of the wheelchairs on the market use the hand to apply force to the wheels of the wheelchair to move the wheelchair, even a small number of electric wheelchairs can control the wheelchair by the swing direction of the rocker direction of movement, but this control mode still depends on the direction of the user's hand movement to control.

Based on providing a suitable means of transportation for people with disabilities below the neck and hands, the wheelchair comes with an anti-collision system and a power feed alarm system to make it have better human-computer interaction functions, better practicability, and unique The head control of the mobile phone has enabled some elderly people who have been unable to go out for a long time to see the hope of getting out of the house and integrating into society. The wheelchair introduced in this article only needs to improve the existing electric wheelchairs on the market, and it will have considerable commercial value and extremely superior development space in the future.

The above is the development example of the intelligent remote control wheelchair introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have a solution development demand for a smart wheelchair, you can rest assured to entrust it to us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, microcontroller development, Bluetooth solutions, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.