Lidar avoid

The tutorial mainly demonstrates the obstacle avoidance function of the balance car combined with the Tmini-Plus radar.

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The tutorial only introduces the standard library project code

Hardware connection

Since we have configured a special connection line, we only need to install it to the corresponding interface.

Control principle

The program analyzes the radar data and determines the movement direction of the balance car based on the distance information at the specified angle.

• Tmini-Plus radar

Radar angle distribution

The arrow in the center of the radar points to 0°/360°, and the angle increases clockwise.

Communication protocol

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For detailed information, please refer to the "T_Mini_Plus Manual"

Main code

The tutorial mainly explains the code for implementing the radar obstacle avoidance function. For detailed code, please refer to the corresponding project file.

Car_Avoid

The obstacle position of the balance car is determined through the radar's 0°, 90°, and 270° distance data and the movement of the balance car is controlled.

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void Car_Avoid(void)
{
    static u8 avoid_step = 0;// Obstacle Avoidance Steps
    
    // Each time this function is called, the value is dynamically refreshed.
    float get_data_mid = Tminidis[0];   
    float get_data_Lmid = Tminidis[270];// Left
    float get_data_Rmid = Tminidis[90];// Right
    
    switch(avoid_step)
    {
        case 0:
        if(get_data_mid <avoid_dis && get_data_mid >0 )//  Obstacle Avoidance
        { 
            // Car stop
            Move_X = 0,Move_Z = 0;
            delay_time_int(10);
            avoid_step = 1;
        }
        else    
        {
            // Car moving forward
            Move_X = GO_speed,Move_Z = 0;
        }
        break;
        case 1: if(get_time_int()==0) avoid_step ++;break; // Time to go to next step
        case 2: 
        {
            // Trolley backward
            Move_X = -15,Move_Z = 0;
            delay_time_int(100); //1s
            avoid_step = 3;
        }
        case 3: if(get_time_int()==0) avoid_step ++;break; // Time to go to next step
        case 4: 
        {
            if(get_data_Lmid >= get_data_Rmid )
            {
                // left
                Move_X = 0,Move_Z = -450;
                delay_time_int(100);
            }
            else
            {
                // right
                Move_X = 0,Move_Z = 450;
                delay_time_int(100);
            }
            avoid_step = 5;
        }
        case 5: if(get_time_int()==0) avoid_step=0;break; // Time to go to next step
    }
}

Program flow chart

Briefly introduce the process of function implementation:

Experimental phenomenon

Software code

The Balance_Radar_Avoid.hex file generated by the project compilation is located in the OBJ folder of the Balance_Radar_Avoid project. Find the Balance_Radar_Avoid.hex file corresponding to the project and use the FlyMcu software to download the program into the development board.

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Product supporting data source code path: Attachment → Source code summary → 5.Balanced_Car_Extended → 12.Balance_Radar_Avoid

Experimental phenomenon

After the program is started, press KEY1 according to the OLED prompt to start the radar obstacle avoidance function of the balance car: OLED displays start control!

Radar does not detect obstacles (obstacle distance>200mm): the car moves forward

Radar detects obstacles in front (0mm<obstacle distance<200mm): the car stops and moves backward

Judge the distance between left and right obstacles:

Left obstacle distance ≥ right obstacle distance: the car turns left and then moves forward

Left obstacle distance <right obstacle distance: the car turns right and then moves forward

The program has voltage detection. If the voltage is less than 9.6V, a low voltage alarm is triggered and the buzzer will sound.
Common situations that trigger voltage alarms:
1. The power switch of the development board is not turned on, and only the Type-C data cable is connected for power supply
2. The battery pack voltage is lower than 9.6V and needs to be charged in time