优化了平衡，尤其对于向后倾倒的几种极限情况进行优化

Shibo-main-TOMMY/lib/SCServo/examples/STSCL/RegWritePos/RegWritePos.ino

@@ -0,0 +1,36 @@
+/*
+The RegWritePos example passed the test in ST3215 Servo, 
+and if testing other models of ST series servos
+please change the appropriate position, speed and delay parameters.
+*/
+
+#include <SCServo.h>
+
+SMS_STS st;
+
+// the uart used to control servos.
+// GPIO 18 - S_RXD, GPIO 19 - S_TXD, as default.
+#define S_RXD 18
+#define S_TXD 19
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial1.begin(1000000, SERIAL_8N1, S_RXD, S_TXD);
+  st.pSerial = &Serial1;
+  delay(1000);
+}
+
+void loop()
+{
+  st.RegWritePosEx(1, 4095, 3400, 50);//servo(ID1) speed=3400，acc=50，move to position=4095.
+  st.RegWritePosEx(2, 4095, 3400, 50);//servo(ID2) speed=3400，acc=50，move to position=4095.
+  st.RegWriteAction();
+  delay(3000);
+
+  st.RegWritePosEx(1, 0, 3400, 50);//servo(ID1) speed=3400，acc=50，move to position=0.
+  st.RegWritePosEx(2, 0, 3400, 50);//servo(ID2) speed=3400，acc=50，move to position=0.
+  st.RegWriteAction();
+  delay(3000);
+}