生理研究表明,一组蝗虫的小叶巨型运动探测器(LGMDs)对接近的物体具有多种碰撞选择性,在杂乱的环境中,比他们的背景相对更暗或更亮。这种碰撞选择性的多样性可以为蝗虫逃离天敌的攻击提供服务,并在没有碰撞的群中迁移。对于计算研究,已经努力实现多样化的选择性,然而,仍然是最具挑战性的任务之一,尤其是在复杂和动态的现实世界场景中。现有的模型主要表述为仅具有前馈信息处理的多层神经网络,并且不考虑反馈回路中再入信号的影响,这是运动知觉的重要调节回路,然而从未在迫在眉睫的感知中被探索过。在本文中,我们启动了反馈神经计算来构建一个新的基于LGMD的模型,名为F-LGMD,以研究实施不同碰撞选择性时的功效。因此,提出的神经网络模型具有前馈处理和反馈回路的特点。反馈控制将并行开/关通道的输出信号传回其起始神经元,从而使前馈神经网络的一部分,即,ON/OFF通道和反馈回路形成迭代循环系统。此外,反馈控制是瞬时的,这导致存在一个固定点,从而将固定点定理应用于严格推导反馈系数的有效范围。为了验证该方法的有效性,我们进行了涵盖合成和自然碰撞数据集的系统实验,还有在线机器人测试。实验结果表明,F-LGMD,有了统一的网络,可以实现生理学中揭示的不同的碰撞选择性,与以前的研究相比,这不仅大大减少了手工制作的参数,而且还通过反馈神经计算为碰撞感知提供了一种高效和鲁棒的方案。
Physiological studies have shown that a group of locust\'s lobula giant movement detectors (LGMDs) has a diversity of collision selectivity to approaching objects, relatively darker or brighter than their backgrounds in cluttered environments. Such diversity of collision selectivity can serve locusts to escape from attack by natural enemies, and migrate in swarm free of collision. For computational studies, endeavours have been made to realize the diverse selectivity which, however, is still one of the most challenging tasks especially in complex and dynamic real world scenarios. The existing models are mainly formulated as multi-layered neural networks with merely feed-forward information processing, and do not take into account the effect of re-entrant signals in feedback loop, which is an essential regulatory loop for motion perception, yet never been explored in looming perception. In this paper, we inaugurate feedback neural computation for constructing a new
LGMD-based model, named F-
LGMD to look into the efficacy upon implementing different collision selectivity. Accordingly, the proposed neural network model features both feed-forward processing and feedback loop. The feedback control propagates output signals of parallel ON/OFF channels back into their starting neurons, thus makes part of the feed-forward neural network, i.e. the ON/OFF channels and the feedback loop form an iterative cycle system. Moreover, the feedback control is instantaneous, which leads to the existence of a fixed point whereby the fixed point theorem is applied to rigorously derive valid range of feedback coefficients. To verify the effectiveness of the proposed method, we conduct systematic experiments covering synthetic and natural collision datasets, and also online robotic tests. The experimental results show that the F-
LGMD, with a unified network, can fulfil the diverse collision selectivity revealed in physiology, which not only reduces considerably the handcrafted parameters compared to previous studies, but also offers a both efficient and robust scheme for collision perception through feedback neural computation.