The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

The intelligent transportation system is the development trend of the future transportation system, and the intelligent vehicle plays a very important role in the intelligent transportation system. The author proposes that the intelligent tracking vehicle is an important part of the construction of the future intelligent transportation system. Aiming at the autonomous tracking problem of the intelligent vehicle under the assumption of the environmental proposition of the navigation line in the future transportation system, a vision-based intelligent tracking vehicle model design scheme is proposed. , As a solution to this hypothetical problem.

introduction

The intelligent transportation system is the development trend of the future transportation system, and the intelligent vehicle plays a very important role in the intelligent transportation system. The author proposes that the intelligent tracking vehicle is an important part of the construction of the future intelligent transportation system. Aiming at the autonomous tracking problem of the intelligent vehicle under the assumption of the environmental proposition of the navigation line in the future transportation system, a vision-based intelligent tracking vehicle model design scheme is proposed. , As a solution to this hypothetical problem.

The vision-based intelligent tracing car model design scheme can use the vision to autonomously track forward under the condition of complex online models and large uncertainty in the turning radius, and graded and precise steering.

1. The overall design of the system

The vision-based intelligent tracing car model system takes the AVR microcontroller MEGA16 as the core, and is composed of a microcontroller module, a path recognition module, a DC motor drive module, and a steering gear drive module, as shown in Figure 1.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

The DC motor is the driving device of the vehicle, and the steering motor is used to control the direction of the vehicle. The intelligent tracing car model uses vision to track forward autonomously on the runway, and steer in grades and accurately. The road is a 318 mm wide white base plate, with 18 mm wide black tape stuck in the middle.

2. Hardware design

2.1 Control module

The tracing car model uses ATMEGAl6 with AVR core. The chip can work independently without the need for an external crystal oscillator and reset circuit, which is very suitable for the requirements of intelligent tracing car models. The controller module is installed on the Leisudeng 1:24 competition-level remote control car model produced by Guangdong Audi Toy Industrial Co., Ltd.

2.2 Path recognition module

A reflective photoelectric sensor is used to distinguish black and white on the runway. The reflective photoelectric sensor has a light emitting end and a light receiving end. The white background and the black line reflect the light from the emitting end differently, which affects the voltage generated at the receiving end. The sensor module is composed of reflective photoelectric sensor, adjustable Resistor and operational amplifier LM324, as shown in Figure 2. Realize the output of high and low levels on different tracks, independent tracking.

2.3 Steering motor and drive motor drive module

The H-bridge circuit is used to drive the front-wheel steering motor and the rear-wheel drive motor of the smart tracing car to realize the functions of the smart tracing car such as left and right steering, forward, backward, acceleration, and deceleration. The steering motor drive circuit is shown in Figure 3. The front-wheel steering motor control scheme is hierarchical steering control, and the rear-wheel drive motor control scheme is also open-loop control.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

2.4 Hierarchical steering module

In order to achieve precise steering at different angles at different turning radii, a hierarchical steering circuit is designed, as shown in Figure 3. The resistance value of the variable resistance in the steering gear of the car model is 1.8-4.2 kΩ, and 1 is connected to the A/D pin of the single-chip microcomputer. The voltage V is the stable reference voltage on-chip, and it can be seen that:

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

Take the No. 1 sensor as an example to illustrate the calculation of the graded steering angle.

The installation of the sensor module is shown in Figure 4. All dimensions have been designed and calculated in the early stage. Point D is the adjustable resistance steering center of the front wheel steering gear, and Point A is the steering center of the trolley. When the No. 1 sensor detects the black line, the steering angle of the front wheels and the steering angle of the variable resistance in the front steering gear corresponding to the steering angle of the front wheels are calculated as:

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

The V3 value is linearly proportional to the variable resistance angle α1 in the front wheel steering gear. Therefore, different sensor detection positions can calculate different ideal front wheel steering angles and different ideal steering A/D voltages. V3 is measured by the single-chip microcomputer. The variable resistance steering angle a1 in the front-wheel steering gear can be converted and compared with the ideal steering A/D voltage. When V3 reaches the ideal steering A/D voltage, the single-chip microcomputer controls the steering gear to a low level, and the steering gear stops and keeps it. Steering, so as to achieve precise graded steering.

3. Software design

3.1 The main program design

Use C language to program and debug under ICC-AVR development environment. The main program flow chart is shown as in Fig. 5.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

3.2 Program design of hierarchical module

ATMEGAl6 can sample 8 single-ended input voltages from port A. When the REFSl and REFS0 of the ADC multi-function register ADMUX on the chip are set to 1, VAREF = 2. 56 V, which is the on-chip stable reference voltage source, that is, the voltage V in Figure 3. The steering limit of the intelligent tracking vehicle is ±30°. Table 1 shows the corresponding calculation data of 5 photoelectric sensors for grading and precise steering.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

4. Conclusion

The vision-based intelligent tracing car model design scheme can use the vision to autonomously track forward under the condition of complex online type and large uncertainty of the turning radius, and graded and precise steering. For the impact of ambient light, consider adding filter circuits and optimizing control algorithms to increase its anti-interference ability. Experiments have proved that this scheme has a good tracking effect.

introduction

The intelligent transportation system is the development trend of the future transportation system, and the intelligent vehicle plays a very important role in the intelligent transportation system. The author proposes that the intelligent tracking vehicle is an important part of the construction of the future intelligent transportation system. Aiming at the autonomous tracking problem of the intelligent vehicle under the assumption of the environmental proposition of the navigation line in the future transportation system, a vision-based intelligent tracking vehicle model design scheme is proposed. , As a solution to this hypothetical problem.

The vision-based intelligent tracing car model design scheme can use the vision to autonomously track forward under the condition of complex online models and large uncertainty in the turning radius, and graded and precise steering.

1. The overall design of the system

The vision-based intelligent tracing car model system takes the AVR microcontroller MEGA16 as the core, and is composed of a microcontroller module, a path recognition module, a DC motor drive module, and a steering gear drive module, as shown in Figure 1.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

The DC motor is the driving device of the vehicle, and the steering motor is used to control the direction of the vehicle. The intelligent tracing car model uses vision to track forward autonomously on the runway, and steer in grades and accurately. The road is a 318 mm wide white base plate, with 18 mm wide black tape stuck in the middle.

2. Hardware design

2.1 Control module

The tracing car model uses ATMEGAl6 with AVR core. The chip can work independently without the need for an external crystal oscillator and reset circuit, which is very suitable for the requirements of intelligent tracing car models. The controller module is installed on the Leisudeng 1:24 competition-level remote control car model produced by Guangdong Audi Toy Industrial Co., Ltd.

2.2 Path recognition module

A reflective photoelectric sensor is used to distinguish black and white on the runway. The reflective photoelectric sensor has a light emitting end and a light receiving end. The white background and the black line reflect the light from the emitting end differently, which affects the voltage generated at the receiving end. The sensor module is composed of reflective photoelectric sensor, adjustable resistor and operational amplifier LM324, as shown in Figure 2. Realize the output of high and low levels on different tracks, independent tracking.

2.3 Steering motor and drive motor drive module

The H-bridge circuit is used to drive the front-wheel steering motor and the rear-wheel drive motor of the smart tracing car to realize the functions of the smart tracing car such as left and right steering, forward, backward, acceleration, and deceleration. The steering motor drive circuit is shown in Figure 3. The front-wheel steering motor control scheme is hierarchical steering control, and the rear-wheel drive motor control scheme is also open-loop control.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

2.4 Hierarchical steering module

In order to achieve precise steering at different angles at different turning radii, a hierarchical steering circuit is designed, as shown in Figure 3. The resistance value of the variable resistance in the steering gear of the car model is 1.8-4.2 kΩ, and 1 is connected to the A/D pin of the single-chip microcomputer. The voltage V is the stable reference voltage on-chip, and it can be seen that:

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

Take the No. 1 sensor as an example to illustrate the calculation of the graded steering angle.

The installation of the sensor module is shown in Figure 4. All dimensions have been designed and calculated in the early stage. Point D is the adjustable resistance steering center of the front wheel steering gear, and Point A is the steering center of the trolley. When the No. 1 sensor detects the black line, the front wheel steering angle and the variable resistance steering angle in the front wheel steering gear corresponding to the front wheel steering angle are calculated as:

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

The V3 value is linearly proportional to the variable resistance angle α1 in the front wheel steering gear. Therefore, different sensor detection positions can calculate different ideal front wheel steering angles and different ideal steering A/D voltages. V3 is measured by the single-chip microcomputer. The variable resistance steering angle a1 in the front-wheel steering gear can be converted and compared with the ideal steering A/D voltage. When V3 reaches the ideal steering A/D voltage, the single-chip microcomputer controls the steering gear to a low level, and the steering gear stops and keeps it. Steering, so as to achieve precise graded steering.

3. Software design

3.1 The main program design

Use C language to program and debug under ICC-AVR development environment. The main program flow chart is shown as in Fig. 5.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

3.2 Program design of hierarchical module

ATMEGAl6 can sample 8 single-ended input voltages from port A. When the REFSl and REFS0 of the ADC multi-function register ADMUX on the chip are set to 1, VAREF = 2. 56 V, which is the on-chip stable reference voltage source, that is, the voltage V in Figure 3. The steering limit of the intelligent tracking vehicle is ±30°. Table 1 shows the corresponding calculation data of 5 photoelectric sensors for grading and precise steering.

The design of intelligent tracing car model system based on ATMEGAl6 and hierarchical steering module

4. Conclusion

The vision-based intelligent tracing car model design scheme can use the vision to autonomously track forward under the condition of complex online type and large uncertainty of the turning radius, and graded and precise steering. For the impact of ambient light, consider adding filter circuits and optimizing control algorithms to increase its anti-interference ability. Experiments have proved that this scheme has a good tracking effect.