Hybrid Trajectory Optimization for Autonomous Terrain Traversal of Articulated Tracked Robots

Autonomous terrain traversal of articulated tracked robots can reduce operator cognitive load to enhance task efficiency and facilitate extensive deployment. We present a novel hybrid trajectory optimization method aimed at generating smooth, stable, and efficient traversal motions. To achieve this, we develop a planar robot-terrain interaction model and partition the robot's motion into hybrid modes of driving and traversing. By using a generalized coordinate description, the configuration space dimension is reduced, which provides real-time planning capability. The hybrid trajectory optimization is transcribed into a nonlinear programming problem and solved in a receding-horizon planning fashion. Mode switching is facilitated by associating optimized motion durations with a predefined traversal sequence. A multi-objective cost function is formulated to further improve the traversal performance. Additionally, map sampling, terrain simplification, and tracking controller modules are integrated into the autonomous terrain traversal system. Our approach is validated in simulation and real-world experiments with the Searcher robotic platform, effectively achieving smooth and stable motion with high time and energy efficiency compared to expert operator control.

Quadruped Guidance Robot for the Visually Impaired: A Comfort-Based Approach

A quadrupedal guidance robot that can guide people and avoid various obstacles, could potentially be owned by more visually impaired people at a fairly low cost. In this paper, we propose a novel guidance robot system with a comfort-based concept. We design a leash containing an elastic rope and a thin string, and use a motor to adjust the length of the string to ensure comfort. We use the force-based human motion model to plan the forces experienced by the human. Afterward, the direction and magnitude of the force are controlled by the motion of the robot, and the rotation of the motor, respectively. This allows humans to be guided safely and more comfortably to the target position in complex environments. The system has been deployed on Unitree Laikago quadrupedal platform and validated in real-world scenarios.