在参数过量时代,生物启发模型更适配简单机器人的运动控制。
Benefits of Low-Cost Bio-Inspiration in the Age of Overparametrization
- 对比了CPG与MLP在小规模输入输出下的控制效果
- 浅层MLP和密集连接的CPG表现优于深层网络
- 提出参数影响度量,揭示生物模型的效率优势
尽管中央模式生成器(CPGs)和多层感知机(MLP)广泛用于机器人控制,但针对大规模参数空间在高约束环境中的相对优势尚缺乏系统研究。在输入输出空间有限、性能受限的情况下,更多参数可能阻碍学习而非促进。本文以固定四足形态、感知能力有限的机器人为对象,在进化与强化学习训练框架下,比较了两种生物启发范式(CPGs与MLP)的表现。通过调整不同奖励函数下的参数规模,发现浅层MLP与密集连接的CPG在性能上优于深层MLP或演员-评论家架构。为此引入参数影响度量,显示MLP存在边际效益递减,而CPG无此现象。结果表明,在简单铰链执行器的运动任务中,融入先验偏置的生物启发模型具有显著优势。
原文摘要 · Abstract (English)
While Central Pattern Generators (CPGs) and Multi-Layer Perceptrons (MLP) are widely used paradigms in robot control, few systematic studies have been performed on the relative merits of large parameter spaces in highly constrained settings. As opposed to traditional Machine Learning contexts, our input and output spaces are small and performance is bounded thus having more parameters may actively hinder the learning process instead of empowering it. To empirically measure this, we submit a given robot morphology, with limited proprioceptive capabilities, to controller optimisation under two bio-inspired paradigms (CPGs and MLPs) with evolutionary- and reinforcement- trainer protocols. By varying parameter spaces across multiple reward functions, we demonstrate that shallow MLPs and densely connected CPGs result in better performance when compared to deeper MLPs or Actor-Critic architectures. To account for the relationship between said performance and the number of parameters, we introduce a Parameter Impact metric which showcases diminishing returns for MLPs but not for CPGs. Taken together these results demonstrate, on a fixed quadrupedal morphology, the benefits of integrating prior bias when considering locomotion tasks with simple hinge actuators.
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