diff --git a/src/custom_robot.cpp b/src/custom_robot.cpp
index 79fe9db..a781c7f 100644
--- a/src/custom_robot.cpp
+++ b/src/custom_robot.cpp
@@ -187,7 +187,7 @@ bool CustomRobot::initializeMqtt() {
         
         mqttClient_->startMessageProcessor();
         
-        if (!mqttClient_->connect()) {
+        if (!mqttClient_->connect(config_.mqtt_username, config_.mqtt_password)) {
             LOG_ERROR("Failed to connect to MQTT broker");
             return false;
         }
@@ -305,12 +305,23 @@ void CustomRobot::publishStatus() {
 std::string CustomRobot::generateRandomClientId() const {
     std::string baseId = config_.mqtt_client_id;
     
+    // 确保base ID只包含ASCII字符
+    std::string safeBaseId;
+    for (char c : baseId) {
+        if (std::isalnum(c) || c == '_' || c == '-') {
+            safeBaseId += c;
+        }
+    }
+    if (safeBaseId.empty()) {
+        safeBaseId = "unitree_go2_client";
+    }
+    
     std::random_device rd;
     std::mt19937 gen(rd());
     std::uniform_int_distribution<> dis(1000, 9999);
     
     std::stringstream ss;
-    ss << baseId << "_" << std::time(nullptr) << "_" << dis(gen);
+    ss << safeBaseId << "_" << std::time(nullptr) << "_" << dis(gen);
     
     return ss.str();
 }
diff --git a/src/mqtt.cpp b/src/mqtt.cpp
index 2f6fd38..95bb83c 100644
--- a/src/mqtt.cpp
+++ b/src/mqtt.cpp
@@ -51,6 +51,35 @@ bool MqttClient::connect(const std::string& username, const std::string& passwor
     username_ = username;
     password_ = password;
     
+    // 验证字符串是否为有效UTF-8（实际上确保为ASCII以避免问题）
+    auto isValidMqttString = [](const std::string& str) -> bool {
+        for (unsigned char c : str) {
+            if (c > 127) { // 非ASCII字符
+                return false;
+            }
+            if (c < 32 && c != '\t' && c != '\n' && c != '\r') { // 控制字符（除了常见的空白字符）
+                return false;
+            }
+        }
+        return true;
+    };
+    
+    if (!isValidMqttString(username_)) {
+        LOG_ERROR("Username contains invalid characters");
+        return false;
+    }
+    
+    if (!isValidMqttString(password_)) {
+        LOG_ERROR("Password contains invalid characters");
+        return false;
+    }
+    
+    // 重置连接选项
+    connOpts_ = MQTTClient_connectOptions_initializer;
+    connOpts_.keepAliveInterval = 20;
+    connOpts_.cleansession = 1;
+    connOpts_.reliable = 0;
+    
     // 设置用户名和密码
     if (!username_.empty()) {
         connOpts_.username = username_.c_str();
@@ -64,6 +93,26 @@ bool MqttClient::connect(const std::string& username, const std::string& passwor
     int rc = MQTTClient_connect(client_, &connOpts_);
     if (rc != MQTTCLIENT_SUCCESS) {
         LOG_ERROR("Failed to connect to MQTT broker, return code: " + std::to_string(rc));
+        switch (rc) {
+            case 1:
+                LOG_ERROR("Connection refused: unacceptable protocol version");
+                break;
+            case 2:
+                LOG_ERROR("Connection refused: identifier rejected");
+                break;
+            case 3:
+                LOG_ERROR("Connection refused: server unavailable");
+                break;
+            case 4:
+                LOG_ERROR("Connection refused: bad user name or password (UTF-8 encoding issue)");
+                break;
+            case 5:
+                LOG_ERROR("Connection refused: not authorized");
+                break;
+            default:
+                LOG_ERROR("Connection error: code " + std::to_string(rc));
+                break;
+        }
         return false;
     }