feat: 更新第九章

chapt9/example_ultrasound/lib/PidController/PidController.h

@@ -0,0 +1,30 @@
+#ifndef __PID_CONTROLLER_H__
+#define __PID_CONTROLLER_H__
+
+
+class PidController
+{
+    public: 
+        PidController() = default;
+        PidController(float kp, float ki, float kd, float dt);
+    
+    private:
+        float target_;
+        float kp_;
+        float ki_;
+        float kd_; 
+        // pid
+        float error_;
+        float error_sum_;
+        float derror_;
+        float prev_error_;
+        float intergral_up_ = 2500; // 积分上限
+    
+    public:
+        float update(float current); // 提供当前值，返回下次输出值，也就是PID的结果
+
+
+}
+
+
+#endif // __PID_CONTROLLER_H__