本帖最后由 天灵灵地灵灵 于 2015-12-24 22:19 编辑
很多人都在抱怨四轴参数难调,刚开始我也使用的是常见的pid控制,发现对参数确实十分敏感,很难达到稳定的效果,甚至直接使用陀螺仪的数据进行角速率反馈得到的效果都比它好。通过查阅资料我发现四轴一般会被简化为一个低阻尼的二阶系统,角速率反馈恰恰可以增加它的阻尼(这个在二代的战斗机比如歼7中广泛采用,是改善阻尼的好方法)。于是我就是用了在固定翼飞机上常常采用的串级pid来调试,经过师兄理论上的指点,四轴已经可以比较稳定的飞行。这个算法有固定翼的控制,和四轴控制原理相同。 首先使用角速率反馈作为内环,在用角度反馈作为外环,只要内环的参数调整合适,外环的参数从个位数变成六七十,四轴都可以稳定的飞行。
void GET_EXPRAD(void) //¼ÆËãÆÚÍû½Ç¶È,²»¼Ó¿ØÖÆʱÆÚÍû½Ç¶ÈΪ0,0
{
EXP_ANGLE.X = (float)(-(Rc_Get.ROLL-1500)/30.0f);
EXP_ANGLE.Y = (float)(-(Rc_Get.PITCH-1500)/30.0f);
EXP_ANGLE.Z = (float)(Rc_Get.YAW);
// printf("%f %f\n",MPU6050_ACC_LAST.Y*cos(Q_ANGLE.X/57.3)-MPU6050_ACC_LAST.Z*sin(Q_ANGLE.X/57.3),MPU6050_ACC_LAST.X*cos(-Q_ANGLE.Y/57.3)-MPU6050_ACC_LAST.Z*sin(-Q_ANGLE.Y/57.3));
// DIF_ANGLE.X = (ACC_AVG.Y*cos(Q_ANGLE.X/57.3)-ACC_AVG.Z*sin(Q_ANGLE.X/57.3))/500;
// DIF_ANGLE.Y = (ACC_AVG.X*cos(-Q_ANGLE.Y/57.3)-ACC_AVG.Z*sin(-Q_ANGLE.Y/57.3)/500);
DIF_ANGLE.X = EXP_ANGLE.X - Q_ANGLE.X;
DIF_ANGLE.Y = EXP_ANGLE.Y - Q_ANGLE.Y;
// DIF_ANGLE.Z = EXP_ANGLE.Z - GYRO_I[0].Z;
// DIF_ANGLE.X = EXP_ANGLE.X - GYRO_I[0].X;
// DIF_ANGLE.Y = EXP_ANGLE.Y - GYRO_I[0].Y;
// DIF_ANGLE.Z = EXP_ANGLE.Z - GYRO_I[0].Z;
}
void CONTROL(void)
{
static float thr=0,rool=0,pitch=0,yaw=0;
static float rool_i=0,pitch_i=0;
static float rool_dif=0,pitch_dif=0;
static float rool_speed_dif=0,pitch_speed_dif=0;
float rool_out,pitch_out;
uint16_t THROTTLE;
GET_EXPRAD();
rool = PID_ROL.P * DIF_ANGLE.X;
rool_i += PID_ROL.I * DIF_ANGLE.X * 0.002;
rool_i = between(rool_i,30,-30);
rool += rool_i;
rool += PID_ROL.D * (DIF_ANGLE.X-rool_dif) * 500;
rool_dif = DIF_ANGLE.X;
///////////
pitch = +PID_ROL.P * DIF_ANGLE.Y;
pitch_i += PID_ROL.I * DIF_ANGLE.Y * 0.002;
pitch_i = between(pitch,30,-30);
pitch += pitch_i;
pitch += PID_ROL.D * (DIF_ANGLE.Y-pitch_dif) * 500;
pitch_dif = DIF_ANGLE.Y;
///////////
//
rool -= GYRO_AVG.X* Gyro_G;
rool_out=PID_PIT.P*rool;
rool_out += PID_PIT.D*(rool- rool_speed_dif)*500;
rool_speed_dif = rool;
pitch -= GYRO_AVG.Y* Gyro_G;
pitch_out=PID_PIT.P*pitch;
pitch_out += PID_PIT.D*(pitch- pitch_speed_dif)*500;
pitch_speed_dif=pitch;
// rool=PID_PIT.I*(rool-GYRO_AVG.X* Gyro_G);
// pitch=PID_PIT.I*(pitch-GYRO_AVG.Y* Gyro_G);
// PID_YAW.dout = 20 * (MPU6050_GYRO_LAST.Z* Gyro_G-(Rc_Get.YAW-1500)/10);
PID_YAW.dout = 10 * (GYRO_AVG.Z* Gyro_G-(Rc_Get.YAW-1500)/10);
PID_ROL.OUT = rool_out;
PID_PIT.OUT = pitch_out;
PID_YAW.OUT = PID_YAW.dout;
/////////////
// GYRO_I[0].Z += EXP_ANGLE.Z/3000;
// yaw = -10 * GYRO_I[0].Z;
//
// yaw -= 3 * GYRO_F.Z;
THROTTLE=Rc_Get.THROTTLE;
if(THROTTLE>1050)
{
// if(THROTTLE>1950)
// {
// THROTTLE=1950;
// }
THROTTLE = THROTTLE/cos(Q_ANGLE.X/57.3)/cos(Q_ANGLE.Y/57.3);
moto1 = THROTTLE - 1000 + (int16_t)PID_ROL.OUT - (int16_t)PID_PIT.OUT - (int16_t)PID_YAW.OUT;
moto2 = THROTTLE - 1000 + (int16_t)PID_ROL.OUT + (int16_t)PID_PIT.OUT + (int16_t)PID_YAW.OUT;
moto3 = THROTTLE - 1000 - (int16_t)PID_ROL.OUT + (int16_t)PID_PIT.OUT - (int16_t)PID_YAW.OUT;
moto4 = THROTTLE - 1000 - (int16_t)PID_ROL.OUT - (int16_t)PID_PIT.OUT + (int16_t)PID_YAW.OUT;
}
else
{
moto1 = 0;
moto2 = 0;
moto3 = 0;
moto4 = 0;
}
if(Q_ANGLE.X>45||Q_ANGLE.Y>45||Q_ANGLE.X<-45||Q_ANGLE.Y<-45)
{
ARMED=0;
LED3_OFF;
}
// printf("moto=%d %d %d %d\n",moto1,moto2,moto3,moto4);
if(ARMED) MOTO_PWMRFLASH(moto1,moto2,moto3,moto4);
else MOTO_PWMRFLASH(0,0,0,0);
}
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