elif obs_type is PyBulletObservationType.LINK_POS \
                    or obs_type is PyBulletObservationType.LINK_LIN_VEL \
                    or obs_type is PyBulletObservationType.LINK_ANG_VEL:
                n_dim = 7 if obs_type is PyBulletObservationType.LINK_POS else 3
                low += [-np.inf] * n_dim