概述
小车外形:
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:
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:
定时器示意图:
定时器分配:
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
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:
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
手册中的典型连接:
原理图如下:
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:
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