@misc{9234102,
  abstract     = {{Unmanned ground vehicles (UGVs) operating in uneven and unstructured terrain are often limited by fixed sensor mounting, which can reduce mapping quality, situational awareness, and sensor performance when the vehicle body experiences pitch, roll, and vertical motion. This thesis presents the development of a compact four-degree-of-freedom (4-DOF) gimbal prototype for a terrain-mapping module on a quadruped UGV. The system provides yaw, pitch, roll, and vertical elevation, enabling both self-stabilization and adjustable sensor positioning.

A prototype was developed through an iterative process involving CAD design, 3D printing, assembly, and integration of motors, sensors, and control hardware. The final concept included a screw-driven elevation mechanism, a yaw actuator, and a pitch-roll stabilization structure with IMU-based control. A Raspberry Pi 5 served as the central processing unit, together with a servo driver, a stepper motor driver, and an IMU for angle estimation.

To support stabilization, IMU filtering and control strategies were implemented and tested experimentally. A complementary filter and a Kalman filter were compared for angle estimation, and the Kalman filter provided the most suitable performance in terms of drift reduction and signal quality for this application. For pitch and roll control, a PD controller and two active disturbance rejection control (ADRC) approaches, referred to as Simple ADRC and Hybrid ADRC, were evaluated. The PD controller was not sufficiently responsive to fast tilt disturbances, while the ADRC-based methods provided better stabilization performance. Simple ADRC performed best on the roll axis, whereas Hybrid ADRC gave the best results on the pitch axis.

In addition to self-stabilization, the prototype demonstrated yaw rotation and vertical elevation. The yaw function achieved commanded rotations with an accuracy of approximately plus/minus 2 degrees, while the elevation mechanism raised the system from about 24 cm to 33 cm above the UGV platform in 1 minute and 27 seconds. A simulation study in Adams/View was also carried out to investigate passive vibration mitigation. For three representative walking cases, the simulated spring-damper support reduced transmitted motion in heave, pitch, and roll, suggesting that passive isolation could complement active stabilization and improve performance.

Overall, the thesis demonstrates the feasibility of a compact 4-DOF gimbal system for a quadruped UGV sensor module. The result is a functioning proof-of-concept prototype that combines mechanical design, embedded control, and vibration mitigation in one integrated system. Although limitations remain in structural robustness, packaging, and full system integration, the findings provide a solid basis for further development of a more robust sensor platform.}},
  author       = {{Hellquist Tovar, Vincent and Gruber, Konrad}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Development of Sensor Module for Terrain Mapping in Forest Environment}},
  year         = {{2026}},
}