Add neutral hold mode (key 'n') for joint inspection

Bypasses NN output and commands default_angles directly at 500Hz.
Used for visual diagnosis of hardware joint offsets on new pelvis.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/include/input_interface/gamepad_manager.hpp

@@ -67,6 +67,10 @@ inline std::atomic<double> g_knee_offset_deg{0.0};
 /// Applied post-NN to motor commands only (NN is blind to this adjustment).
 inline std::atomic<double> g_hip_pitch_offset_deg{3.0};
 
+/// Neutral hold mode: bypass NN, command default_angles directly. Key 'n' to toggle.
+/// Used for visual joint inspection (diagnosing hardware offsets).
+inline std::atomic<bool> g_neutral_hold_mode{false};
+
 #if HAS_ROS2
 #include "ros2_input_handler.hpp"
 #endif
@@ -198,6 +202,14 @@ class GamepadManager : public InputInterface {
             is_manager_key = true;
             break;
           }
+          case 'n':
+          case 'N': {
+            bool cur = g_neutral_hold_mode.load();
+            g_neutral_hold_mode.store(!cur);
+            std::cout << "[NEUTRAL] Hold mode: " << (!cur ? "ON (default angles)" : "OFF (NN active)") << std::endl;
+            is_manager_key = true;
+            break;
+          }
           case '1': {
             double val = g_hip_pitch_offset_deg.load() - 1.0;
             g_hip_pitch_offset_deg.store(val);

gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/src/g1_deploy_onnx_ref.cpp

@@ -2827,6 +2827,17 @@ class G1Deploy {
       float* floatarr = action_buffer.data();
       
       MotorCommand motor_command_tmp;
+
+      // Neutral hold mode: bypass NN, command default angles directly (key 'n')
+      if (g_neutral_hold_mode.load()) {
+        for (int i = 0; i < G1_NUM_MOTOR; i++) {
+          motor_command_tmp.q_target.at(i) = static_cast<float>(default_angles[i]);
+          motor_command_tmp.tau_ff.at(i) = 0.0;
+          motor_command_tmp.kp.at(i) = kps[i];
+          motor_command_tmp.kd.at(i) = kds[i];
+          motor_command_tmp.dq_target.at(i) = 0.0;
+        }
+      } else {
         for (int i = 0; i < G1_NUM_MOTOR; i++) {
           const double action_value = static_cast<double>(floatarr[isaaclab_to_mujoco[i]]) * g1_action_scale[i];
           last_action[i] = static_cast<double>(floatarr[i]);
@@ -2836,6 +2847,7 @@ class G1Deploy {
           motor_command_tmp.kd.at(i) = kds[i];
           motor_command_tmp.dq_target.at(i) = 0.0;
         }
+      }
       // Optional waist pitch offset (keys 7/8). Default 0°.
       double waist_offset_rad = g_waist_pitch_offset_deg.load() * M_PI / 180.0;
       if (waist_offset_rad != 0.0) {