Fusing Event-based Camera and Radar for SLAM Using Spiking Neural Networks with Continual STDP Learning

This work proposes a first-of-its-kind SLAM architecture fusing an event-based camera and a Frequency Modulated Continuous Wave (FMCW) radar for drone navigation. Each sensor is processed by a bio-inspired Spiking Neural Network (SNN) with continual Spike-Timing-Dependent Plasticity (STDP) learning, as observed in the brain. In contrast to most learning-based SLAM systems%, which a) require the acquisition of a representative dataset of the environment in which navigation must be performed and b) require an off-line training phase, our method does not require any offline training phase, but rather the SNN continuously learns features from the input data on the fly via STDP. At the same time, the SNN outputs are used as feature descriptors for loop closure detection and map correction. We conduct numerous experiments to benchmark our system against state-of-the-art RGB methods and we demonstrate the robustness of our DVS-Radar SLAM approach under strong lighting variations

Active Inference in Hebbian Learning Networks

This work studies how brain-inspired neural ensembles equipped with local Hebbian plasticity can perform active inference (AIF) in order to control dynamical agents. A generative model capturing the environment dynamics is learned by a network composed of two distinct Hebbian ensembles: a posterior network, which infers latent states given the observations, and a state transition network, which predicts the next expected latent state given current state-action pairs. Experimental studies are conducted using the Mountain Car environment from the OpenAI gym suite, to study the effect of the various Hebbian network parameters on the task performance. It is shown that the proposed Hebbian AIF approach outperforms the use of Q-learning, while not requiring any replay buffer, as in typical reinforcement learning systems. These results motivate further investigations of Hebbian learning for the design of AIF networks that can learn environment dynamics without the need for revisiting past buffered experiences

Millimeter Wave Antennas, Circuits and Systems in MCM-D Technology (Millimetergolf antennes, circuits en systemen in MCM-D technologie)

This work discusses the practical realization, modeling and design of front-ends for emerging (60 GHz WLAN) and next-generation (77 GHz automotive radar) commercial millimeter-wave applications, focusing on IMEC's MCM-D passive integration platform. The MCM-D design and modeling work covers planar and 3D micromachined antenna integration together with fixed frequency and tunable cavity resonators and oscillators. In addition to the work on front-end components, a system level modeling tool was developed to analyze millimeter-wave imagers.status: publishe

Design and Comparison of Resonant and Non-Resonant Single-Layer Microwave Heaters for Continuous Flow Microfluidics in Silicon-Glass Technology

This paper presents a novel concept for the co-design of microwave heaters and microfluidic channels for sub-microliter volumes in continuous flow microfluidics. Based on the novel co-design concept, two types of heaters are presented, co-designed and manufactured in high-resistivity silicon-glass technology, resulting in a building block for consumable and mass-producible micro total analysis systems. Resonant and non-resonant co-planar waveguide transmission line heaters are investigated for heating of sub-micro-liter liquid volumes in a channel section at 25 GHz. The heating rates of 16 and 24 °C/s are obtained with power levels of 32 dBm for the through line and the open-ended line microwave heater, respectively. The heating uniformity of developed devices is evaluated with a Rhodamine B and deionized water mixture on a micrometer scale using the microwave-optical measurement setup. Measurement results showed a good agreement with simulations and demonstrated the potential of microwave heating for microfluidics

Complementary Split-Ring Resonator with Improved Dielectric Spatial Resolution

status: accepte

Effect of Open-Ended Coaxial Probe-to-Tissue Contact Pressure on Dielectric Measurements

Open-ended coaxial probes are widely used to gather dielectric properties of biological tissues. Due to the lack of an agreed data acquisition protocol, several environmental conditions can cause inaccuracies when comparing dielectric data. In this work, the effect of a different measurement probe-to-tissue contact pressure was monitored in the frequency range from 0.5 to 20 GHz. Therefore, we constructed a controlled lifting platform with an integrated pressure sensor to exert a constant pressure on the tissue sample during the dielectric measurement. In the pressure range from 7.74 kPa to 77.4 kPa, we observed a linear correlation of − 0.31 ± 0.09 % and − 0.32 ± 0.14 % per kPa for, respectively, the relative real and imaginary complex permittivity. These values are statistically significant compared with the reported measurement uncertainty. Following the literature in different biology-related disciplines regarding pressure-induced variability in measurements, we hypothesize that these changes originate from squeezing out the interstitial and extracellular fluid. This process locally increases the concentration of membranes, cellular organelles, and proteins in the sensed volume. Finally, we suggest moving towards a standardized probe-to-tissue contact pressure, since the literature has already demonstrated that reprobing at the same pressure can produce repeatable data within a 1% uncertainty interval

A 20 GHz microwave heater for digital microfluidic

This paper reports on a microwave heater at 20 GHz for digital microfluidics. It allows rapid heating of nanoliter fluid samples and simultaneous temperature monitoring by correlating the reflection coefficient of the heater with the temperature dependency of the relative permittivity of the lossy fluid under consideration, in this case demineralized water. Microwave heating was performed with power levels of 20 and 23 dBm at the on-wafer probe tips on samples of 500 nL. Temperature measurements were carried out with a miniaturized type K thermocouple, and a platinum resistor to monitor the reference temperature. Microwave and thermal performances have been characterized using multi-physics software, and measurements obtained with a large signal vector network analyzer showed good agreement with simulated data. An average heating rate of 20 °C/s was observed during the first 4 s of the heating process.status: publishe

Multilayer Compact Grid Antenna Array for 79 GHz Automotive Radar Applications

© 2002-2011 IEEE. A novel wideband compact grid antenna array is developed for 79 GHz multiple-input multiple-output radar applications. The key issue is the stable radiation pattern with flat-gain characteristic along the whole frequency bandwidth, which is very advantageous for the targeted radar applications. The antenna is taped out with the new high-resolution multilayer printed circuit board (PCB) technology called 'Any-Layer PCB.' This technology provides the possibility to stack microvias in PCBs and reduce the fabrication cost compared with other multilayer technologies in millimeter-wave bands. With this feature, the width of the array has been compacted with 17.2%, which leads to a higher sidelobe suppression and an enhancement of the field of view in radar applications. A combined impedance and 3 dB gain bandwidth of 9.6% is achieved. The gain and sidelobe level are 13.52 and-14 dB at 79 GHz, respectively.status: publishe

Wideband Compact Comb-Line Antenna Array for 79 GHz Automotive Radar Applications

© 2002-2011 IEEE. A wideband microstrip comb-line antenna array is developed for 79 GHz multiple-input-multiple-output radar applications. This array is composed of four radiating subarrays, with 180° phase shift. This topology leads to a more stable radiation pattern behavior and broadside gain flatness along the frequency bandwidth. The antenna is taped out with a new high-resolution multilayer printed circuit board (PCB) technology, called 'any-layer PCB.' This technology provides the possibility to stack small microvias, instead of using thick machine-drilled vias. A measured impedance and gain bandwidth of 12.5% is achieved. The sidelobe suppression is higher than 15 dB, and the array gain is 12.36 dBi at 79 GHz.status: publishe