If you’ve never seen a video of springboks gracefully pronking, have a look below.

Pronking is a gait where all legs are used in synchrony, usually resulting in relatively slow speeds but long flight phases and large jumping heights. Such jumps might be interesting for robots to move around in cluttered environments. The risk is that the robot falls forward or backward if not controlled correctly (pitch control).

For this purpose, Ankaralı et al. propose a special type of feedback controller that has two levels. The top-level takes as an input the desired speed and jump height of the robot. This information is given to a “template” of the robot motion based on the “Spring-Loaded Inverted Pendulum”. A low-level controller then attempts to force the dynamics of the robot to mimic the template as closely as possible.

Experiments were done in simulation on a realistic model of the RHex six-legged robot (see video above). Results show that the user can easily control jump height and forward speed and that the gait is robust to sensor and actuator noise.