- Z (single support, hanging)
- B (double support with backward bar)
- F (double support with forward bar).
Inspired by the typical brachiation of a monkey, the following four atomic behaviors can give rise to robust bidirectional brachiation over horizontal bars. Because of the passive gripper choice, additional behaviors have to be considered to release the swing arm from a bar, which is denoted as Back Release (BR) and Front Release (FR) to initiate a BF or FB atomic behavior, respectively. More info on the gripper's heuristics can be found here.
The unique gripper design offers a large region of attraction, shown in orange color, for grasping a target bar and a well-defined pivot point for the swing maneuvers. The passive gripper imposes a constraint on grasping configuration, which plays a vital role in the robot's final configuration.
The atomic behaviors are generated using the following methods:
- Trajectory Optimization with Direct Collocation (ZF, ZB, FB, BF)
- Reinforcement Learning (BF)