由于它们的时间加工能力及其低交换(尺寸,重量和功率)以及神经形态硬件中的节能实现,尖峰神经网络(SNNS)已成为传统人工神经网络(ANN)的有趣替代方案。然而,培训SNNS所涉及的挑战在准确性方面有限制了它们的表现,从而限制了他们的应用。因此,改善更准确的特征提取的学习算法和神经架构是SNN研究中的当前优先级之一。在本文中,我们展示了现代尖峰架构的关键组成部分的研究。我们在从最佳执行网络中凭经验比较了图像分类数据集中的不同技术。我们设计了成功的残余网络(Reset)架构的尖峰版本,并测试了不同的组件和培训策略。我们的结果提供了SNN设计的最新版本,它允许在尝试构建最佳视觉特征提取器时进行明智的选择。最后,我们的网络优于CIFAR-10(94.1%)和CIFAR-100(74.5%)数据集的先前SNN架构,并将现有技术与DVS-CIFAR10(71.3%)相匹配,参数较少而不是先前的状态艺术,无需安静转换。代码在https://github.com/vicenteax/spiking_resnet上获得。
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由于稀疏,异步和二进制事件(或尖峰)驱动加工,尖峰神经网络(SNNS)最近成为深度学习的替代方案,可以在神经形状硬件上产生巨大的能效益。然而,从划痕训练高精度和低潜伏期的SNN,患有尖刺神经元的非微弱性质。要在SNNS中解决此培训问题,我们重新批准批量标准化,并通过时间(BNTT)技术提出时间批量标准化。大多数先前的SNN工程到现在忽略了批量标准化,认为它无效地训练时间SNN。与以前的作品不同,我们提出的BNTT沿着时轴沿着时间轴解耦的参数,以捕获尖峰的时间动态。在BNTT中的时间上不断发展的可学习参数允许神经元通过不同的时间步长来控制其尖峰率,从头开始实现低延迟和低能量训练。我们对CiFar-10,CiFar-100,微小想象特和事件驱动的DVS-CIFAR10数据集进行实验。 BNTT允许我们首次在三个复杂的数据集中培训深度SNN架构,只需25-30步即可。我们还使用BNTT中的参数分布提前退出算法,以降低推断的延迟,进一步提高了能量效率。
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深度尖峰神经网络(SNNS)目前由于离散二进制激活和复杂的空间 - 时间动态而导致的基于梯度的方法的优化困难。考虑到Reset的巨大成功在深度学习中,将深入了解剩余学习,这将是自然的。以前的尖峰Reset模仿ANN的标准残留块,并简单地用尖刺神经元取代relu激活层,这遭受了劣化问题,并且很难实施剩余学习。在本文中,我们提出了尖峰元素 - 明智(SEW)RESET,以实现深部SNNS的剩余学习。我们证明SEW RESET可以轻松实现身份映射并克服Spiking Reset的消失/爆炸梯度问题。我们在Imagenet,DVS手势和CIFAR10-DVS数据集中评估我们的SEF RESET,并显示SEW RESNET以准确性和时间步长,最先进的直接训练的SNN。此外,SEW Reset通过简单地添加更多层来实现更高的性能,提供一种培训深舒头的简单方法。为了我们的最佳知识,这是第一次直接训练具有100多层以上的深度SNN。我们的代码可在https://github.com/fangwei123456/spike-element-wore-resnet上获得。
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尽管神经形态计算的快速进展,但尖刺神经网络(SNNS)的能力不足和不足的表现力严重限制了其在实践中的应用范围。剩余学习和捷径被证明是培训深层神经网络的重要方法,但以前的工作评估了他们对基于尖峰的通信和时空动力学的特征的适用性。在本文中,我们首先确定这种疏忽导致受阻信息流程和伴随以前的残留SNN中的降解问题。然后,我们提出了一种新型的SNN定向的残余块MS-Reset,能够显着地扩展直接训练的SNN的深度,例如,在ImageNet上最多可在CiFar-10和104层上完成482层,而不会观察到任何轻微的降级问题。我们验证了基于帧和神经形态数据集的MS-Reset的有效性,并且MS-Resnet104在直接训练的SNN的域中的第一次实现了在ImageNet上的76.02%精度的优越结果。还观察到巨大的能量效率,平均仅需要每根神经元的一穗来分类输入样本。我们相信我们强大且可扩展的型号将为进一步探索SNN提供强大的支持。
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我们提出了一种新的学习算法,使用传统的人工神经网络(ANN)作为代理训练尖刺神经网络(SNN)。我们分别与具有相同网络架构和共享突触权重的集成和火(IF)和Relu神经元进行两次SNN和ANN网络。两个网络的前进通过完全独立。通过假设具有速率编码的神经元作为Relu的近似值,我们将SNN中的SNN的误差进行了回复,以更新共享权重,只需用SNN的ANN最终输出替换ANN最终输出。我们将建议的代理学习应用于深度卷积的SNNS,并在Fahion-Mnist和CiFar10的两个基准数据集上进行评估,分别为94.56%和93.11%的分类准确性。所提出的网络可以优于培训的其他深鼻涕,训练,替代学习,代理梯度学习,或从深处转换。转换的SNNS需要长时间的仿真时间来达到合理的准确性,而我们的代理学习导致高效的SNN,模拟时间较短。
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Spiking neural networks (SNNs) are promising brain-inspired energy-efficient models. Recent progress in training methods has enabled successful deep SNNs on large-scale tasks with low latency. Particularly, backpropagation through time (BPTT) with surrogate gradients (SG) is popularly used to achieve high performance in a very small number of time steps. However, it is at the cost of large memory consumption for training, lack of theoretical clarity for optimization, and inconsistency with the online property of biological learning and rules on neuromorphic hardware. Other works connect spike representations of SNNs with equivalent artificial neural network formulation and train SNNs by gradients from equivalent mappings to ensure descent directions. But they fail to achieve low latency and are also not online. In this work, we propose online training through time (OTTT) for SNNs, which is derived from BPTT to enable forward-in-time learning by tracking presynaptic activities and leveraging instantaneous loss and gradients. Meanwhile, we theoretically analyze and prove that gradients of OTTT can provide a similar descent direction for optimization as gradients based on spike representations under both feedforward and recurrent conditions. OTTT only requires constant training memory costs agnostic to time steps, avoiding the significant memory costs of BPTT for GPU training. Furthermore, the update rule of OTTT is in the form of three-factor Hebbian learning, which could pave a path for online on-chip learning. With OTTT, it is the first time that two mainstream supervised SNN training methods, BPTT with SG and spike representation-based training, are connected, and meanwhile in a biologically plausible form. Experiments on CIFAR-10, CIFAR-100, ImageNet, and CIFAR10-DVS demonstrate the superior performance of our method on large-scale static and neuromorphic datasets in small time steps.
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尖峰神经网络(SNN)是一种受脑启发的模型,具有更时空的信息处理能力和计算能效效率。但是,随着SNN深度的增加,由SNN​​的重量引起的记忆问题逐渐引起了人们的注意。受到人工神经网络(ANN)量化技术的启发,引入了二进制SNN(BSNN)来解决记忆问题。由于缺乏合适的学习算法,BSNN通常由ANN-SNN转换获得,其准确性将受到训练有素的ANN的限制。在本文中,我们提出了具有准确性损失估计器的超低潜伏期自适应局部二进制二进制尖峰神经网络(ALBSNN),该网络层动态选择要进行二进制的网络层,以通过评估由二进制重量引起的错误来确保网络的准确性在网络学习过程中。实验结果表明,此方法可以将存储空间降低超过20%,而不会丢失网络准确性。同时,为了加速网络的训练速度,引入了全球平均池(GAP)层,以通过卷积和合并的组合替换完全连接的层,以便SNN可以使用少量时间获得更好识别准确性的步骤。在仅使用一个时间步骤的极端情况下,我们仍然可以在三个不同的数据集(FashionMnist,CIFAR-10和CIFAR-10和CIFAR-100)上获得92.92%,91.63%和63.54%的测试精度。
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基于事件的视觉传感器在事件流中编码本地像素方面的亮度变化,而不是图像帧,并且除了低延迟,高动态范围和缺乏运动模糊之外,还产生稀疏,节能编码。基于事件的传感器的对象识别的最新进展来自深度神经网络的转换,培训背部经历。但是,使用这些事件流的方法需要转换到同步范式,这不仅失去了计算效率,而且还会错过提取时空特征的机会。在本文中,我们提出了一种用于基于事件的模式识别和对象检测的深度神经网络的端到端培训的混合架构,将尖刺神经网络(SNN)骨干组合用于高效的基于事件的特征提取,以及随后的模拟神经网络(ANN)头解决同步分类和检测任务。这是通过将标准的梯度训练与替代梯度训练相结合来实现这一点来实现,以通过SNN传播梯度。可以在不转换的情况下培训混合SNN-ANN,并且导致高度准确的网络,这些网络比其ANN对应物大得多。我们演示了基于事件的分类和对象检测数据集的结果,其中只需要将ANN头的体系结构适应任务,并且不需要基于事件的输入的转换。由于ANNS和SNNS需要不同的硬件范式来最大限度地提高其效率,因此设想SNN骨干网和ANN头可以在不同的处理单元上执行,从而分析在两部分之间进行通信的必要带宽。混合网络是有前途的架构,以进一步推进基于事件的愿景的机器学习方法,而不必妥协效率。
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尖峰神经网络(SNNS)模仿大脑中信息传播可以通过离散和稀疏的尖峰来能够能够通过离散和稀疏的尖峰来处理时空信息,从而受到相当大的关注。为了提高SNN的准确性和能源效率,大多数以前的研究仅集中在训练方法上,并且很少研究建筑的效果。我们研究了先前研究中使用的设计选择,从尖峰的准确性和数量来看,发现它们不是最适合SNN的。为了进一步提高准确性并减少SNN产生的尖峰,我们提出了一个称为Autosnn的尖峰感知神经体系结构搜索框架。我们定义一个搜索空间,该搜索空间由架构组成,而没有不良的设计选择。为了启用Spike-Aware Architecture搜索,我们引入了一种健身,该健身既考虑尖峰的准确性和数量。 Autosnn成功地搜索了SNN体系结构,这些体系结构在准确性和能源效率方面都超过了手工制作的SNN。我们彻底证明了AutoSNN在包括神经形态数据集在内的各种数据集上的有效性。
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Spiking Neural networks (SNN) have emerged as an attractive spatio-temporal computing paradigm for a wide range of low-power vision tasks. However, state-of-the-art (SOTA) SNN models either incur multiple time steps which hinder their deployment in real-time use cases or increase the training complexity significantly. To mitigate this concern, we present a training framework (from scratch) for one-time-step SNNs that uses a novel variant of the recently proposed Hoyer regularizer. We estimate the threshold of each SNN layer as the Hoyer extremum of a clipped version of its activation map, where the clipping threshold is trained using gradient descent with our Hoyer regularizer. This approach not only downscales the value of the trainable threshold, thereby emitting a large number of spikes for weight update with a limited number of iterations (due to only one time step) but also shifts the membrane potential values away from the threshold, thereby mitigating the effect of noise that can degrade the SNN accuracy. Our approach outperforms existing spiking, binary, and adder neural networks in terms of the accuracy-FLOPs trade-off for complex image recognition tasks. Downstream experiments on object detection also demonstrate the efficacy of our approach.
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Spiking Neural Networks (SNNs) are bio-plausible models that hold great potential for realizing energy-efficient implementations of sequential tasks on resource-constrained edge devices. However, commercial edge platforms based on standard GPUs are not optimized to deploy SNNs, resulting in high energy and latency. While analog In-Memory Computing (IMC) platforms can serve as energy-efficient inference engines, they are accursed by the immense energy, latency, and area requirements of high-precision ADCs (HP-ADC), overshadowing the benefits of in-memory computations. We propose a hardware/software co-design methodology to deploy SNNs into an ADC-Less IMC architecture using sense-amplifiers as 1-bit ADCs replacing conventional HP-ADCs and alleviating the above issues. Our proposed framework incurs minimal accuracy degradation by performing hardware-aware training and is able to scale beyond simple image classification tasks to more complex sequential regression tasks. Experiments on complex tasks of optical flow estimation and gesture recognition show that progressively increasing the hardware awareness during SNN training allows the model to adapt and learn the errors due to the non-idealities associated with ADC-Less IMC. Also, the proposed ADC-Less IMC offers significant energy and latency improvements, $2-7\times$ and $8.9-24.6\times$, respectively, depending on the SNN model and the workload, compared to HP-ADC IMC.
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由于它们的低能量消耗,对神经形态计算设备上的尖刺神经网络(SNNS)越来越兴趣。最近的进展使培训SNNS在精度方面开始与传统人工神经网络(ANNS)进行竞争,同时在神经胸壁上运行时的节能。然而,培训SNNS的过程仍然基于最初为ANNS开发的密集的张量操作,这不利用SNN的时空稀疏性质。我们在这里介绍第一稀疏SNN BackPropagation算法,该算法与最新的现有技术实现相同或更好的准确性,同时显着更快,更高的记忆力。我们展示了我们对不同复杂性(时尚 - MNIST,神经影像学 - MNIST和Spiking Heidelberg数字的真实数据集的有效性,在不失精度的情况下实现了高达150倍的后向通行证的加速,而不会减少精度。
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从大脑的事件驱动和稀疏的尖峰特征中受益,尖峰神经网络(SNN)已成为人工神经网络(ANN)的一种节能替代品。但是,SNNS和ANN之间的性能差距很长一段时间以来一直在延伸SNNS。为了利用SNN的全部潜力,我们研究了SNN中注意机制的影响。我们首先使用插件套件提出了我们的注意力,称为多维关注(MA)。然后,提出了一种新的注意力SNN体系结构,并提出了端到端训练,称为“ ma-snn”,该体系结构分别或同时或同时延伸了沿时间,通道以及空间维度的注意力重量。基于现有的神经科学理论,我们利用注意力重量来优化膜电位,进而以数据依赖性方式调节尖峰响应。 MA以可忽略的其他参数为代价,促进了香草SNN,以实现更稀疏的尖峰活动,更好的性能和能源效率。实验是在基于事件的DVS128手势/步态动作识别和Imagenet-1K图像分类中进行的。在手势/步态上,尖峰计数减少了84.9%/81.6%,任务准确性和能源效率提高了5.9%/4.7%和3.4 $ \ times $/3.2 $ \ times $。在ImagEnet-1K上,我们在单个/4步res-SNN-104上获得了75.92%和77.08%的TOP-1精度,这是SNN的最新结果。据我们所知,这是SNN社区与大规模数据集中的ANN相比,SNN社区取得了可比甚至更好的性能。我们的工作阐明了SNN作为支持SNN的各种应用程序的一般骨干的潜力,在有效性和效率之间取得了巨大平衡。
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Spiking neural networks (SNNs) are receiving increasing attention due to their low power consumption and strong bio-plausibility. Optimization of SNNs is a challenging task. Two main methods, artificial neural network (ANN)-to-SNN conversion and spike-based backpropagation (BP), both have their advantages and limitations. For ANN-to-SNN conversion, it requires a long inference time to approximate the accuracy of ANN, thus diminishing the benefits of SNN. With spike-based BP, training high-precision SNNs typically consumes dozens of times more computational resources and time than their ANN counterparts. In this paper, we propose a novel SNN training approach that combines the benefits of the two methods. We first train a single-step SNN by approximating the neural potential distribution with random noise, then convert the single-step SNN to a multi-step SNN losslessly. The introduction of Gaussian distributed noise leads to a significant gain in accuracy after conversion. The results show that our method considerably reduces the training and inference times of SNNs while maintaining their high accuracy. Compared to the previous two methods, ours can reduce training time by 65%-75% and achieves more than 100 times faster inference speed. We also argue that the neuron model augmented with noise makes it more bio-plausible.
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Event-based simulations of Spiking Neural Networks (SNNs) are fast and accurate. However, they are rarely used in the context of event-based gradient descent because their implementations on GPUs are difficult. Discretization with the forward Euler method is instead often used with gradient descent techniques but has the disadvantage of being computationally expensive. Moreover, the lack of precision of discretized simulations can create mismatches between the simulated models and analog neuromorphic hardware. In this work, we propose a new exact error-backpropagation through spikes method for SNNs, extending Fast \& Deep to multiple spikes per neuron. We show that our method can be efficiently implemented on GPUs in a fully event-based manner, making it fast to compute and precise enough for analog neuromorphic hardware. Compared to the original Fast \& Deep and the current state-of-the-art event-based gradient-descent algorithms, we demonstrate increased performance on several benchmark datasets with both feedforward and convolutional SNNs. In particular, we show that multi-spike SNNs can have advantages over single-spike networks in terms of convergence, sparsity, classification latency and sensitivity to the dead neuron problem.
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尖峰神经网络是低功率环境的有效计算模型。基于SPIKE的BP算法和ANN-TO-SNN(ANN2SNN)转换是SNN培训的成功技术。然而,尖峰碱BP训练速度很慢,需要大量的记忆成本。尽管Ann2NN提供了一种培训SNN的低成本方式,但它需要许多推理步骤才能模仿训练有素的ANN以表现良好。在本文中,我们提出了一个snn-to-ang(SNN2ANN)框架,以快速和记忆的方式训练SNN。 SNN2ANN由2个组成部分组成:a)ANN和SNN和B)尖峰映射单元之间的重量共享体系结构。首先,该体系结构在ANN分支上训练重量共享参数,从而快速训练和SNN的记忆成本较低。其次,尖峰映射单元确保ANN的激活值是尖峰特征。结果,可以通过训练ANN分支来优化SNN的分类误差。此外,我们设计了一种自适应阈值调整(ATA)算法来解决嘈杂的尖峰问题。实验结果表明,我们的基于SNN2ANN的模型在基准数据集(CIFAR10,CIFAR100和TININE-IMAGENET)上表现良好。此外,SNN2ANN可以在0.625倍的时间步长,0.377倍训练时间,0.27倍GPU内存成本以及基于SPIKE的BP模型的0.33倍尖峰活动下实现可比精度。
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尖峰神经网络(SNNS)是一种实用方法,可以通过模拟神经元对时间信息的杠杆作用来进行更高的数据有效学习。在本文中,我们提出了时间通道联合注意(TCJA)架构单元,这是一种有效的SNN技术,依赖于注意机制,通过有效地沿空间和时间维度沿着尖峰序列的相关性来实现。我们的基本技术贡献在于:1)通过采用挤压操作,将尖峰流压缩为平均矩阵,然后使用具有高效1-D卷积的两种局部注意机制来建立时间和渠道关系,以在频道和渠道关系中进行特征提取灵活的时尚。 2)利用交叉卷积融合(CCF)层在时间范围和通道范围之间建模相互依赖性,从而破坏了两个维度的独立性,并实现了特征之间的相互作用。通过共同探索和重新启用数据流,我们的方法在所有测试的主流静态和神经形态数据集上,在包括时尚量的所有测试的主流静态数据集上,最高可先进的(SOTA)高达15.7% ,CIFAR10-DVS,N-Caltech 101和DVS128手势。
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尖峰神经网络(SNNS)是脑激发的模型,可在神经形状硬件上实现节能实现。然而,由于尖刺神经元模型的不连续性,SNN的监督培训仍然是一个难题。大多数现有方法模仿人工神经网络的BackProjagation框架和前馈架构,并在尖峰时间使用代理衍生物或计算梯度来处理问题。这些方法累积近似误差,或者仅通过现有尖峰被限制地传播信息,并且通常需要沿着具有大的内存成本和生物言行的时间步长的信息传播。在这项工作中,我们考虑反馈尖刺神经网络,这些神经网络更为大脑,并提出了一种新的训练方法,不依赖于前向计算的确切反向。首先,我们表明,具有反馈连接的SNN的平均触发速率将沿着时间的时间逐渐发展到均衡状态,这沿着定点方程沿着时间延续。然后通过将反馈SNN的前向计算作为这种等式的黑匣子求解器,并利用了方程上的隐式差异,我们可以计算参数的梯度而不考虑确切的前向过程。以这种方式,向前和向后程序被解耦,因此避免了不可微分的尖峰功能的问题。我们还简要介绍了隐含分化的生物合理性,这只需要计算另一个平衡。在Mnist,Fashion-Mnist,N-Mnist,CiFar-10和CiFar-100上进行了广泛的实验,证明了我们在少量时间步骤中具有较少神经元和参数的反馈模型的方法的优越性。我们的代码是在https://github.com/pkuxmq/ide-fsnn中获得的。
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Deep spiking neural networks (SNNs) offer the promise of low-power artificial intelligence. However, training deep SNNs from scratch or converting deep artificial neural networks to SNNs without loss of performance has been a challenge. Here we propose an exact mapping from a network with Rectified Linear Units (ReLUs) to an SNN that fires exactly one spike per neuron. For our constructive proof, we assume that an arbitrary multi-layer ReLU network with or without convolutional layers, batch normalization and max pooling layers was trained to high performance on some training set. Furthermore, we assume that we have access to a representative example of input data used during training and to the exact parameters (weights and biases) of the trained ReLU network. The mapping from deep ReLU networks to SNNs causes zero percent drop in accuracy on CIFAR10, CIFAR100 and the ImageNet-like data sets Places365 and PASS. More generally our work shows that an arbitrary deep ReLU network can be replaced by an energy-efficient single-spike neural network without any loss of performance.
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The term ``neuromorphic'' refers to systems that are closely resembling the architecture and/or the dynamics of biological neural networks. Typical examples are novel computer chips designed to mimic the architecture of a biological brain, or sensors that get inspiration from, e.g., the visual or olfactory systems in insects and mammals to acquire information about the environment. This approach is not without ambition as it promises to enable engineered devices able to reproduce the level of performance observed in biological organisms -- the main immediate advantage being the efficient use of scarce resources, which translates into low power requirements. The emphasis on low power and energy efficiency of neuromorphic devices is a perfect match for space applications. Spacecraft -- especially miniaturized ones -- have strict energy constraints as they need to operate in an environment which is scarce with resources and extremely hostile. In this work we present an overview of early attempts made to study a neuromorphic approach in a space context at the European Space Agency's (ESA) Advanced Concepts Team (ACT).
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