基于STM32的自动跟踪小车

140
0
2020年11月2日 09时20分

概述

 

1

 

小车外形:

 

2

 

功能简介
利用摄像头识别前车尾部的AprilTag,得到前车位置,传回stm32主控板处理,使两车在行驶时保持恒定距离,实现自动跟车。

1.openMV4摄像头

1.1 Apriltag识别与串口传输

AprilTag是一个视觉基准库,在AR,机器人,相机校准领域广泛使用。通过特定的标志(与二维码相似,但是降低了复杂度以满足实时性要求),可以快速地检测标志,并计算相对位置。
Apriltag示例:

 

3

 

通过识别Apriltag,可以得到x,y,z三个方向的距离以及偏移角度。这里只需要三维的距离即可,通过串口传回stm32.

 

import sensor, image, time, math,pyb
from pyb import UART

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QQVGA) # we run out of memory if the resolution is much bigger...
sensor.skip_frames(time = 2000)
sensor.set_auto_gain(False)  # must turn this off to prevent image washout...
sensor.set_auto_whitebal(False)  # must turn this off to prevent image washout...
clock = time.clock()
uart = UART(3, 115200)#串口波特率

f_x = (2.8 / 3.984) * 160 # find_apriltags defaults to this if not set
f_y = (2.8 / 2.952) * 120 # find_apriltags defaults to this if not set
c_x = 160 * 0.5 # find_apriltags defaults to this if not set (the image.w * 0.5)
c_y = 120 * 0.5 # find_apriltags defaults to this if not set (the image.h * 0.5)

def degrees(radians):
    return (180 * radians) / math.pi

while(True):
    clock.tick()
    img = sensor.snapshot()
    for tag in img.find_apriltags(fx=f_x, fy=f_y, cx=c_x, cy=c_y): # defaults to TAG36H11
        img.draw_rectangle(tag.rect(), color = (255, 0, 0))
        img.draw_cross(tag.cx(), tag.cy(), color = (0, 255, 0))
        print_args = (tag.x_translation(), tag.y_translation(), tag.z_translation())
            #degrees(tag.x_rotation()), degrees(tag.y_rotation()), degrees(tag.z_rotation()))
        # Translation units are unknown. Rotation units are in degrees.
       # print("Tx %f, Ty %f, Tz %f" % print_args)
        uart.write("A%.2f,B%.2f,C%.2f," % print_args+'\r\n')#设置特定格式,以便于stm32分割取得数据
        #pyb.delay(500)
   # print(clock.fps())

 

2. STM32主控板(型号为F407)

2.1 时钟与中断配置

附上stm32时钟示意图:

 

3

 

定时器示意图:

 

4

 

定时器分配:

 

5

 

所有时钟初始化的函数:(每个函数的详细内容在后面)

 

TIM8_PWM_Init(400-1,20-1);	//用于控制电机,168M/20=8.4Mhz的计数频率,重装载值400,所以PWM频率为 8.4M/400=21Khz. 
	TIM3_PWM_Init(200-1,8400-1);//用于控制舵机,50HZ
	TIM2_Int_Init(400-1,20-1);//定时中断,21KHZ
	TIM7_Int_Init(500-1,8400-1);//用于编码器计数,20HZ,50ms中断一次
	uart_init(115200);	//初始化串口1波特率为115200
	Encoder_Init_TIM4();//编码器接口初始化

 

2.2 串口收发与数据处理

串口中断:USART1,USART2
串口初始化函数(以USART1为例):

 

void uart_init(u32 bound){
   //GPIO端口设置
  GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE); //使能GPIOA时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);//使能USART1时钟
 
	//串口1对应引脚复用映射
	GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1); //GPIOA9复用为USART1
	GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1); //GPIOA10复用为USART1
	
	//USART1端口配置
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10; //GPIOA9与GPIOA10
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//复用功能
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	//速度50MHz
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //推挽复用输出
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; //上拉
	GPIO_Init(GPIOA,&GPIO_InitStructure); //初始化PA9,PA10

   //USART1 初始化设置
	USART_InitStructure.USART_BaudRate = bound;//波特率设置
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
	USART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
	USART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	//收发模式
  USART_Init(USART1, &USART_InitStructure); //初始化串口1
	
  USART_Cmd(USART1, ENABLE);  //使能串口1 
	
	USART_ClearFlag(USART1, USART_FLAG_TC);
	
#if EN_USART1_RX	
	USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//开启相关中断

	//Usart1 NVIC 配置
  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;//串口1中断通道
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3;//抢占优先级3
	NVIC_InitStructure.NVIC_IRQChannelSubPriority =3;		//子优先级3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQ通道使能
	NVIC_Init(&NVIC_InitStructure);	//根据指定的参数初始化VIC寄存器、

#endif
	
}

 

 

串口中断处理函数:

 

void USART1_IRQHandler(void)                	//串口1中断服务程序
{
	u8 Res;
#ifdef OS_TICKS_PER_SEC	 	//如果时钟节拍数定义了,说明要使用ucosII了.
	OSIntEnter();    
#endif
	if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)  //接收中断(接收到的数据必须是0x0d 0x0a结尾)
	{
		Res =USART_ReceiveData(USART1);//(USART1->DR);	//读取接收到的数据
		
		if((USART_RX_STA&0x8000)==0)//接收未完成
		{
			if(USART_RX_STA&0x4000)//接收到了0x0d
			{
				if(Res!=0x0a)USART_RX_STA=0;//接收错误,重新开始
				else USART_RX_STA|=0x8000;	//接收完成了 
			}
			else //还没收到0X0D
			{	
				if(Res==0x0d)USART_RX_STA|=0x4000;
				else
				{
					USART_RX_BUF[USART_RX_STA&0X3FFF]=Res ;
					USART_RX_STA++;
					if(USART_RX_STA>(USART_REC_LEN-1))USART_RX_STA=0;//接收数据错误,重新开始接收	  
				}		 
			}
		}   		 
  } 
#ifdef OS_TICKS_PER_SEC	 	//如果时钟节拍数定义了,说明要使用ucosII了.
	OSIntExit();  											 
#endif
} 
#endif	

 

 

字符串接收与处理(从openMV接收到的数据):

 

/*涉及到的全局变量
float data[3];//x,y,z方向的距离,浮点数形式
unsigned char data_string[3][7];//x,y,z方向的距离,字符串形式
*/
if(USART_RX_STA&0x8000)
		{	
			//清空字符串
			for(i=0;i<2;i++)
			{
				for(j=0;j<6;j++)
				{
					data_string[i][j]=' ';
				}
			}
			len=USART_RX_STA&0x3fff;//得到此次接收到的数据长度
			for(t=0,j=0;t<len;t++)
			{
				j=0;
				if(USART_RX_BUF[t]=='A')
				{
					t++;//去掉首字母
					while(USART_RX_BUF[t]!=',')
					{
						data_string[0][j]=USART_RX_BUF[t];
						t++;
						j++;
					}
				}
				if(USART_RX_BUF[t]=='B')
				{
					t++;//去掉首字母
					while(USART_RX_BUF[t]!=',')
					{
						data_string[1][j]=USART_RX_BUF[t];
						t++;
						j++;
					}
				}
				if(USART_RX_BUF[t]=='C')
				{
					t++;//去掉首字母
					while(USART_RX_BUF[t]!=',')
					{
						data_string[2][j]=USART_RX_BUF[t];
						t++;
						j++;
					}
				}
			}
			//把字符串转化为浮点数
			data[0]=myatof(data_string[0])/100.0;//x
			data[1]=myatof(data_string[1])/100.0;//y
			data[2]=myatof(data_string[2])*(-1)/100.0;//z,输入是负数,转换为正
				//USART2发送数据
//				Usart_SendString( RS232_USART, (uint8_t *)USART_RX_BUF );
				
			//LCD更新显示
			//显示xyz
//			  CLEAR(10);
//			  Gui_DrawFont_GBK16(30,0,BLACK,WHITE,clear);
//			  Gui_DrawFont_GBK16(30,0,BLACK,WHITE,data_string[0]);
//				Gui_DrawFont_GBK16(30,20,BLACK,WHITE,clear);
//			  Gui_DrawFont_GBK16(30,20,BLACK,WHITE,data_string[1]);
//				Gui_DrawFont_GBK16(30,40,BLACK,WHITE,clear);
//			  Gui_DrawFont_GBK16(30,40,BLACK,WHITE,data_string[2]);
				
				USART_RX_STA=0;//清除标志位
		}
}

 

字符串转化为两位小数浮点数(用于后续PID控制):

 

int myatof(const char *str)//此函数仅适用于两位小数的浮点数,返回的是乘100后的int值,因float返回有错误
{
	int flag = 1;//表示正数
	int res =0;
	u8 i=1; //小数点后两位
	while(*str != '\0')
		{
			if( !(*str >= '0' && *str <= '9'))//找到字符串中的第一个数字
			{
				str++;
				continue;
			}
			if(*(str-1) == '-')
			{
				flag=-1;//表示是一个负数
			}

		while(*str >= '0' && *str <= '9')
		{
			res = res *10 + (*str - '0');
			str++;
		}
		if(*str == '.')
		{
			str++;
			res = res *10 + (*str - '0');
			str++;
			res = res *10 + (*str - '0');//保留两位,故加两次
			return res*flag;
		}
		}
}

 

 

2.3 LCD显示模块

LCD模块用于调试时观察数据,调试完成可以删去,因为显示屏很耗时,使处理速度变慢
驱动函数总览:

 

void LCD_GPIO_Init(void);
void Lcd_WriteIndex(u8 Index);
void Lcd_WriteData(u8 Data);
void Lcd_WriteReg(u8 Index,u8 Data);
u16 Lcd_ReadReg(u8 LCD_Reg);
void Lcd_Reset(void);
void Lcd_Init(void);
void Lcd_Clear(u16 Color);
void Lcd_SetXY(u16 x,u16 y);
void Gui_DrawPoint(u16 x,u16 y,u16 Data);
unsigned int Lcd_ReadPoint(u16 x,u16 y);
void Lcd_SetRegion(u16 x_start,u16 y_start,u16 x_end,u16 y_end);
void LCD_WriteData_16Bit(u16 Data);

 

TFT屏幕初始化:

 

void TFT_Init_Show(void)
{
	Lcd_Clear(WHITE);
	Gui_DrawFont_GBK16(16,70,BLACK,WHITE,"by WILL CHAN");
	delay_ms(1000);
	Lcd_Clear(WHITE);
	Gui_DrawFont_GBK16(3,0,RED,WHITE,"X:");
	Gui_DrawFont_GBK16(3,20,RED,WHITE,"Y:");
	Gui_DrawFont_GBK16(3,40,RED,WHITE,"Z:");
	Gui_DrawFont_GBK16(3,60,RED,WHITE,"speed:");
}

 

 

字符串显示函数;

 

void Gui_DrawFont_GBK16(u16 x, u16 y, u16 fc, u16 bc, u8 *s)
{
	unsigned char i,j;
	unsigned short k,x0;
	x0=x;

	while(*s) 
	{	
		if((*s) < 128) 
		{
			k=*s;
			if (k==13) 
			{
				x=x0;
				y+=16;
			}
			else 
			{
				if (k>32) k-=32; else k=0;
	
			    for(i=0;i<16;i++)
				for(j=0;j<8;j++) 
					{
				    	if(asc16[k*16+i]&(0x80>>j))	Gui_DrawPoint(x+j,y+i,fc);
						else 
						{
							if (fc!=bc) Gui_DrawPoint(x+j,y+i,bc);
						}
					}
				x+=8;
			}
			s++;
		}
			
		else 
		{
		

			for (k=0;k<hz16_num;k++) 
			{
			  if ((hz16[k].Index[0]==*(s))&&(hz16[k].Index[1]==*(s+1)))
			  { 
				    for(i=0;i<16;i++)
				    {
						for(j=0;j<8;j++) 
							{
						    	if(hz16[k].Msk[i*2]&(0x80>>j))	Gui_DrawPoint(x+j,y+i,fc);
								else {
									if (fc!=bc) Gui_DrawPoint(x+j,y+i,bc);
								}
							}
						for(j=0;j<8;j++) 
							{
						    	if(hz16[k].Msk[i*2+1]&(0x80>>j))	Gui_DrawPoint(x+j+8,y+i,fc);
								else 
								{
									if (fc!=bc) Gui_DrawPoint(x+j+8,y+i,bc);
								}
							}
				    }
				}
			  }
			s+=2;x+=16;
		} 
		
	}
}

 

 

2.4 电机、舵机与编码器

定时中断:TIM2,用于修改电机和舵机的PWM占空比
初始化函数:

 

//通用定时器2中断初始化
//arr:自动重装值。
//psc:时钟预分频数
//定时器溢出时间计算方法:Tout=((arr+1)*(psc+1))/Ft us.
//Ft=定时器工作频率,单位:Mhz
//这里使用的是定时器2!
void TIM2_Int_Init(u16 arr,u16 psc)
{
	TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);  ///使能TIM2时钟
	
  TIM_TimeBaseInitStructure.TIM_Period = arr; 	//自动重装载值
	TIM_TimeBaseInitStructure.TIM_Prescaler=psc;  //定时器分频
	TIM_TimeBaseInitStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式
	TIM_TimeBaseInitStructure.TIM_ClockDivision=TIM_CKD_DIV1; 
	
	TIM_TimeBaseInit(TIM2,&TIM_TimeBaseInitStructure);//初始化TIM3
	
	TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE); //允许定时器2更新中断
	TIM_Cmd(TIM2,ENABLE); //使能定时器2
	
	NVIC_InitStructure.NVIC_IRQChannel=TIM2_IRQn; //定时器2中断
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0; //抢占优先级1
	NVIC_InitStructure.NVIC_IRQChannelSubPriority=2; //子优先级3
	NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;
	NVIC_Init(&NVIC_InitStructure);

}

 

 

TIM2中断处理函数:

 

void TIM2_IRQHandler(void)
{	
	if(TIM_GetITStatus(TIM2,TIM_IT_Update)==SET)//溢出中断
	{
		if(motor_flag==1)//反转
		{
			TIM_SetCompare1(TIM8,motor_duty*PID_val_motor*400.0);//和定时器的自动重装载值进行比较,来设置占空比,引脚:PC6
			TIM_SetCompare2(TIM8,0);
		}
		if(motor_flag==0)//正转
		{
			TIM_SetCompare1(TIM8,0);
			TIM_SetCompare2(TIM8,motor_duty*PID_val_motor*400.0);//和定时器的自动重装载值进行比较,来设置占空比,引脚:PC7
		}
		TIM_SetCompare1(TIM3,200-(servo_angle/45.0+1)*5);//设置舵机角度,引脚:PA6
	}
	TIM_ClearITPendingBit(TIM2,TIM_IT_Update);  //清除中断标志位
}

 

PWM输出:TIM3(舵机),TIM8(电机)
初始化函数(以TIM8为例):

 

void TIM8_PWM_Init(u32 arr,u32 psc)
{		 					 
	//此部分需手动修改IO口设置
	
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
	TIM_OCInitTypeDef  TIM_OCInitStructure;
	TIM_BDTRInitTypeDef	TIM_BDTRInitStructure;
	
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8,ENABLE);  	//TIM8时钟使能    
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA|RCC_AHB1Periph_GPIOB|RCC_AHB1Periph_GPIOC, ENABLE); 	//使能PORTA时钟	
	
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;           //GPIOFA
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;        //复用功能
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	//速度100MHz
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;      //推挽复用输出
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;        //上拉
	GPIO_Init(GPIOA,&GPIO_InitStructure);              //初始化PA7

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;
  GPIO_Init(GPIOB,&GPIO_InitStructure);
	
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8;
  GPIO_Init(GPIOC,&GPIO_InitStructure);
	
	GPIO_PinAFConfig(GPIOC,GPIO_PinSource6,GPIO_AF_TIM8); //GPIOA8复用为定时器1
	GPIO_PinAFConfig(GPIOC,GPIO_PinSource7,GPIO_AF_TIM8); //GPIOA9复用为定时器1
	GPIO_PinAFConfig(GPIOC,GPIO_PinSource8,GPIO_AF_TIM8); //GPIOA10复用为定时器1
	GPIO_PinAFConfig(GPIOA,GPIO_PinSource7,GPIO_AF_TIM8); //GPIOB13复用为定时器1
	GPIO_PinAFConfig(GPIOB,GPIO_PinSource0,GPIO_AF_TIM8); //GPIOB14复用为定时器1
	GPIO_PinAFConfig(GPIOB,GPIO_PinSource1,GPIO_AF_TIM8); //GPIOB15复用为定时器1

	TIM_TimeBaseStructure.TIM_Prescaler=psc;  //定时器分频
	TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式
	TIM_TimeBaseStructure.TIM_Period=arr;   //自动重装载值
	TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; 
	
	TIM_TimeBaseInit(TIM8,&TIM_TimeBaseStructure);//初始化定时器1
	
	//初始化PWM模式	 
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
	TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
	TIM_OCInitStructure.TIM_Pulse = 0;
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
	TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
	TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset; 
	TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

	TIM_OC1Init(TIM8, &TIM_OCInitStructure);
	TIM_OC2Init(TIM8, &TIM_OCInitStructure);
	TIM_OC3Init(TIM8, &TIM_OCInitStructure);

	TIM_OC1PreloadConfig(TIM8,TIM_OCPreload_Enable);
	TIM_OC2PreloadConfig(TIM8,TIM_OCPreload_Enable);
	TIM_OC3PreloadConfig(TIM8,TIM_OCPreload_Enable);

	TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable;
	TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;
	TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;
	TIM_BDTRInitStructure.TIM_DeadTime = 0;
	TIM_BDTRInitStructure.TIM_Break = TIM_Break_Disable; 
	TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_Low;
	TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Disable;
	TIM_BDTRConfig(TIM8,&TIM_BDTRInitStructure);

	TIM_Cmd(TIM8,ENABLE);
	TIM_CCPreloadControl(TIM8,ENABLE);
	TIM_CtrlPWMOutputs(TIM8,ENABLE);
										  
}  

 

 

编码器初始化函数:

 

void Encoder_Init_TIM4(void)
{
    GPIO_InitTypeDef         GPIO_InitStructure; 
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
    TIM_ICInitTypeDef        TIM_ICInitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
 
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE);//开启TIM4时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB,ENABLE);//开启GPIOB时钟
  
    GPIO_PinAFConfig(GPIOB,GPIO_PinSource6,GPIO_AF_TIM4);//PB6引脚复用
    GPIO_PinAFConfig(GPIOB,GPIO_PinSource7,GPIO_AF_TIM4);//PB7引脚服用
 
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7; //GPIOB6,GPIOB7
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
    //GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_NOPULL ;
	  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
    GPIO_Init(GPIOB,&GPIO_InitStructure); 
    
    NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; /*它的抢占优先级可以尽量设置低点*/
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = DISABLE;//禁用中断,防止计数溢出而没有相应函数,造成卡死
    NVIC_Init(&NVIC_InitStructure);
 
 
 
    TIM_TimeBaseStructure.TIM_Period = 4095; //设置下一个更新事件装入活动的自动重装载寄存器周期的值
    TIM_TimeBaseStructure.TIM_Prescaler = 0; //设置用来作为TIMx时钟频率除数的预分频值  不分频
    TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
    TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure); 
 
    TIM_EncoderInterfaceConfig(TIM4, TIM_EncoderMode_TI12,TIM_ICPolarity_Rising,TIM_ICPolarity_Falling);
    TIM_ICStructInit(&TIM_ICInitStructure);
    TIM_ICInitStructure.TIM_ICFilter = 10;  //输入滤波器
    TIM_ICInit(TIM4, &TIM_ICInitStructure);
    TIM_ClearFlag(TIM4, TIM_FLAG_Update);  //清除所有标志位
    TIM_ITConfig(TIM4, TIM_IT_Update, DISABLE); //允许中断更新
    TIM4->CNT = 0;
    TIM_Cmd(TIM4, ENABLE);  //使能TIM4
}

 

 

编码器返回速度值:

 

/**************************************************************************
函数功能:单位时间读取编码器计数
入口参数:定时器
返回  值:速度值
**************************************************************************/
float Read_Encoder_Speed(uint8_t TIMX)
{
    int32_t Encoder_TIM;
    float res = 0;
    switch (TIMX)
    {
    case 5:
        Encoder_TIM = TIM_GetCounter(TIM5);
        TIM5->CNT = ENCODER_BASE_COUNT; 
        res = (int32_t)Encoder_TIM - ENCODER_BASE_COUNT;
        break;
    case 4:
        Encoder_TIM = TIM_GetCounter(TIM4);
        TIM4->CNT = ENCODER_BASE_COUNT; 
        res = (int32_t)Encoder_TIM - ENCODER_BASE_COUNT;
        break;
    default:
        Encoder_TIM = 0;
        res = 0;
    }
    if(res>2048.0f)
        res-=4096.0f;
    return res*360.0f/4096.0f;
}

 

 

定时从编码器取数,注意,时间不一样,取回的数值也不一样,取决于实际速度以及编码器线数。这里50ms取一次:

 

void TIM7_IRQHandler(void)//频率20HZ,用于编码器计数
{	
	if(TIM_GetITStatus(TIM7,TIM_IT_Update)==SET)//溢出中断
	{
		speed=Read_Encoder_Speed(4);
	}
	TIM_ClearITPendingBit(TIM7,TIM_IT_Update);  //清除中断标志位
}

 

2.5 PID控制

PID库函数:

 

#define N 2				//需要对多少变量进行pid调节

const float KP[N]={1.3,1.0};//这里只用了比例调节
const float KI[N]={0,0};
const float KD[N]={0,0};


struct _pid{
	float SetVol;				//定义设定值
	float ActVol;				//定义实际值
	float Err;					//定义误差
	float	Err_Next;			//定义上一个误差
	float	Err_Last;			//定义上上一个误差
	float Kp,Ki,Kd;			//定义比例、积分、微分系数
	float integral;			//定义积分值
	float actuator;			//定义控制器执行变量
}pid[N];

void PID_Init(void)
{
	for(int i=0;i<N;i++)
	{
		pid[i].SetVol=0.0;
		pid[i].ActVol=0.0;
		pid[i].Err=0.0;
		pid[i].Err_Next=0.0;
		pid[i].Err_Last=0.0;
		pid[i].integral=0.0;
		pid[i].actuator=0.0;
		pid[i].Kp=KP[i];
		pid[i].Ki=KI[i];
		pid[i].Kd=KD[i];
	}
}

float PID_realize(float set_val,float get_val,int i)			//位置型PID算法实现
{
	pid[i].SetVol=set_val;
	pid[i].ActVol=get_val;
	pid[i].Err=pid[i].SetVol-pid[i].ActVol;
	float IncVol;		//定义增量
	pid[i].integral+=pid[i].Err;
//	IncVol=pid[i].Kp*(pid[i].Err-pid[i].Err_Next)+pid[i].Ki*pid[i].Err+pid[i].Kd*(pid[i].Err-2*pid[i].Err_Next+pid[i].Err_Last);
	pid[i].actuator=pid[i].Kp* pid[i].Err+pid[i].Ki*pid[i].integral+pid[i].Kd*(pid[i].Err-pid[i].Err_Next);
//	pid[i].actuator=adc_val+IncVol;
	pid[i].ActVol=pid[i].actuator;
	pid[i].Err_Last=pid[i].Err_Next;
	pid[i].Err_Next=pid[i].Err;
	
	return pid[i].actuator;
}

 

 

主函数中的PID调节:

 

		z_get=data[2];
		x_get=data[0];
		if(z_get-z_set>0.5||z_get-z_set<-0.5)//电机PID
		{
			LED1=0;	//调节时灯亮
			PID_val_motor=PID_realize(z_set,z_get,0);
			PID_val_motor=PID_val_motor/10.0;
			if(PID_val_motor<=0)
				motor_flag=0;//motor_flag控制电机正反转,PID_val_motor用于改变占空比,范围0~1
			if(PID_val_motor>0)
				motor_flag=1;
			PID_val_motor=abs_float(PID_val_motor);
			if(PID_val_motor>2)PID_val_motor=0;//标志太远,让车停止
			if(PID_val_motor>1&&PID_val_motor<=2)PID_val_motor=1;
			if(PID_val_motor<0.2)PID_val_motor=0;
		}
		if(x_get-x_set>0.1||x_get-x_set<-0.1)//舵机PID
		{
			LED1=0;	
			PID_val_servo=PID_realize(x_set,x_get,1);
			servo_angle=((140-35)/6)*PID_val_servo+35;//线性映射,把PID的值转化为角度35~140的舵机转角
			if(servo_angle<35)servo_angle=35;
			if(servo_angle>140)servo_angle=140;
		}
		LED1=1;

 

 

定时器TIM2中断里改变占空比:

 

void TIM2_IRQHandler(void)
{	
	if(TIM_GetITStatus(TIM2,TIM_IT_Update)==SET)//溢出中断
	{
		if(motor_flag==1)//反转
		{
			TIM_SetCompare1(TIM8,motor_duty*PID_val_motor*400.0);//和定时器的自动重装载值进行比较,来设置占空比,引脚:PC6
			TIM_SetCompare2(TIM8,0);
		}
		if(motor_flag==0)//正转
		{
			TIM_SetCompare1(TIM8,0);
			TIM_SetCompare2(TIM8,motor_duty*PID_val_motor*400.0);//和定时器的自动重装载值进行比较,来设置占空比,引脚:PC7
		}
		TIM_SetCompare1(TIM3,200-(servo_angle/45.0+1)*5);//设置舵机角度,根据舵机手册得到占空比与转角的关系,引脚:PA6
	}
	TIM_ClearITPendingBit(TIM2,TIM_IT_Update);  //清除中断标志位
}

 

 

3.电源与电机驱动

3.1 L298N电机驱动板

 

6

 

因为后面两路电机要求同速,故把AB两通道用线短接,用一路PWM控制两路电机
下面是使用说明:

 

7

 

具体控制代码见上面TIM2中断处理函数中,利用两路定时器轮流输出PWM(另一路为零),即可控制电机正反转

3.2 LM2596降压模块

 

8

 

手册中的典型连接:

 

9

 

原理图如下:

 

10

 

3.3 电源部分注意事项

1.电池用的是12v航模锂电池,为了防止过放导致电池损坏,必须要在电池输入端加一个电压表模块,如下图:

 

11

 

2.控制部分电源和电机舵机电源分开,因为电机舵机启动时会过大电流,导致电压不稳定,影响芯片供电。这里LM2596给电机供电,一个LM2596给舵机供电,另一个LM2596给单片机和openMV供电

3.控制电源和电机舵机电源分别加开关,下程序的时候先关闭电机和舵机的电源。因为此时控制器没有给信号,电机和舵机可能会不受控制的运动

 

 

发表评论

后才能评论