Joshua R. Smith

• PhD
• Milton and Delia Zeutschel Professor at University of Washington

Achieving negative surgical margins, defined as no tumor found on the edges of the resected tissue, during lumpectomy for breast cancer is critical for mitigating the risk of local recurrence. To identify nonpalpable tumors that cannot be felt, pre-operative placements of wire and wire-free localization devices are typically employed. Wire-free loc...

Highly articulated organisms serve as blueprints for incredibly dexterous mechanisms, but building similarly capable robotic counterparts has been hindered by the difficulties of developing electromechanical actuators with both the high strength and compactness of biological muscle. We develop a stackable electrostatic brake that has comparable spe...

In this work, we demonstrate that it is possible to read UHF RFID tags without a carrier. Specifically, we introduce an alternative reader design that does not emit a carrier and allows reading RFID tags intended for conventional carrier-based systems. While traditional RFID tags modulate a carrier, it is important to note that a modulation circuit...

The octopus coordinates multiple, highly flexible arms with the support of a complex distributed nervous system. The octopus’s suckers, staggered along each arm, are employed in a wide range of behaviors. Many of these behaviors, such as foraging in visually occluded spaces, are executed under conditions of limited or absent visual feedback. In coo...

Wireless power transfer (WPT) using magnetically coupled resonators is being integrated into space vehicles destined for the lunar surface. The dusty soil on the Moon, called lunar regolith, is known to adhere to surfaces and is also known to contain iron, including iron oxides and metallic iron. Regolith samples are limited, and lunar soil simulan...

Autocurricular training is an important sub-area of multi-agent reinforcement learning~(MARL) that allows multiple agents to learn emergent skills in an unsupervised co-evolving scheme. The robotics community has experimented autocurricular training with physically grounded problems, such as robust control and interactive manipulation tasks. Howeve...

The octopus coordinates multiple, highly flexible arms with the support of a complex distributed nervous system. The octopus's suckers, staggered along each arm, are employed in a wide range of behaviors. Many of these behaviors, such as foraging in visually occluded spaces, are executed under conditions of limited or absent visual feedback. In coo...

This paper presents a step-up DC-DC converter that uses a stepwise gate-drive technique to reduce the power FET gate-drive energy by 82%, allowing positive efficiency down to an input voltage of ±0.5 mV—the lowest input voltage ever achieved for a DC-DC converter as far as we know. Below ±0.5 mV the converter automatically hibernates, reducing quie...

We present the design of a passive wireless communication method that does not rely on ambient or generated RF sources. Instead, the method modulates the Johnson (thermal) noise of a resistor to transmit information bits wirelessly. By selectively connecting or disconnecting a matched resistor to an antenna, the system can achieve data rates of up...

p>This paper presents a step-up DC-DC converter that uses a stepwise gate-drive technique to reduce the power FET gate-drive energy by 82%, allowing positive efficiency down to an input voltage of ±0.5 mV—the lowest input voltage ever achieved for a DC-DC converter as far as we know. Below ±0.5 mV the converter automatically hibernates, reducing qu...

p>This paper presents a complete closed-form analytical model for determining the per-cycle energy consumption of a stepwise adiabatic drivers used for driving a capacitive load such as a power FET gate. The model takes into account the number of steps used, the stepwise driver tank capacitance, the load capacitance, and the stepwise driver switch...

Acoustic traps and levitation systems can lift, translate and manipulate a wide range of objects and materials without contact. This enables new manipulation capabilities for robots that may not be possible otherwise. This paper presents an acoustic balance, a contactless method for weighing acoustically trapped objects in air. The method works by...

During in-hand manipulation, robots must be able to continuously estimate the pose of the object in order to generate appropriate control actions. The performance of algorithms for pose estimation hinges on the robot's sensors being able to detect discriminative geometric object features, but previous sensing modalities are unable to make such meas...

p>This paper presents a step-up DC-DC converter that uses a stepwise gate-drive technique to reduce the power FET gate-drive energy by 82%, allowing positive efficiency down to an input voltage of ±0.5 mV—the lowest input voltage ever achieved for a DC-DC converter as far as we know. Below ±0.5 mV the converter automatically hibernates, reducing qu...

p>This paper presents a complete closed-form analytical model for determining the per-cycle energy consumption of a stepwise adiabatic drivers used for driving a capacitive load such as a power FET gate. The model takes into account the number of steps used, the stepwise driver tank capacitance, the load capacitance, and the stepwise driver switch...

p>This paper presents a step-up DC-DC converter that uses a stepwise gate-drive technique to reduce the power FET gate-drive energy by 82%, allowing positive efficiency down to an input voltage of ±0.5 mV—the lowest input voltage ever achieved for a DC-DC converter as far as we know. Below ±0.5 mV the converter automatically hibernates, reducing qu...

p>This paper presents a step-up DC-DC converter that uses a stepwise gate-drive technique to reduce the power FET gate-drive energy by 82%, allowing positive efficiency down to an input voltage of ±0.5 mV—the lowest input voltage ever achieved for a DC-DC converter as far as we know. Below ±0.5 mV the converter automatically hibernates, reducing qu...

p>This paper presents a complete closed-form analytical model for determining the per-cycle energy consumption of a stepwise adiabatic drivers used for driving a capacitive load such as a power FET gate. The model takes into account the number of steps used, the stepwise driver tank capacitance, the load capacitance, and the stepwise driver switch...

We present NeuriCam, a key-frame video super-resolution and colorization based system, to achieve low-power video capture from dual-mode IOT cameras. Our idea is to design a dual-mode camera system where the first mode is low power (1.1~mW) but only outputs gray-scale, low resolution and noisy video and the second mode consumes much higher power (1...

Biological and artificial agents are faced with many of the same computational and mechanical problems, thus strategies evolved in the biological realm can serve as inspiration for robotic development. The octopus in particular represents an attractive model for biologically-inspired robotic design, as has been recognized for the emerging field of...

For certain manipulation tasks, object pose estimation from head-mounted cameras may not be sufficiently accurate. This is at least in part due to our inability to perfectly calibrate the coordinate frames of today's high degree of freedom robot arms that link the head to the end-effectors. We present a novel framework combining pre-touch sensing a...

During in-hand manipulation, robots must be able to continuously estimate the pose of the object in order to generate appropriate control actions. The performance of algorithms for pose estimation hinges on the robot's sensors being able to detect discriminative geometric object features, but previous sensing modalities are unable to make such meas...

Highly articulated organisms serve as blueprints for incredibly dexterous mechanisms, but building similarly capable robotic counterparts has been hindered by the difficulties of developing electromechanical actuators with both the high strength and compactness of biological muscle. We develop a stackable electrostatic brake that has comparable spe...

Benchmarks for robot manipulation are crucial to measuring progress in the field, yet there are few benchmarks that demonstrate critical manipulation skills, possess standardized metrics, and can be attempted by a wide array of robot platforms. To address a lack of such benchmarks, we propose Rubik's cube manipulation as a benchmark to measure simu...

This project aims to motivate research in competitive human-robot interaction by creating a robot competitor that can challenge human users in certain scenarios such as physical exercise and games. With this goal in mind, we introduce the Fencing Game, a human-robot competition used to evaluate both the capabilities of the robot competitor and user...

Brain-computer interfaces (BCIs) are neural prosthetics that enable closed-loop electrophysiology procedures. These devices are currently used in fundamental neurophysiology research, and they are moving toward clinical viability for neural rehabilitation. State-of-the-art BCI experiments have often been performed using tethered (wired) setups in c...

Many regions of the world benefit from heating, ventilating, and air-conditioning (HVAC) systems to provide productive, comfortable, and healthy indoor environments, which are enabled by automatic building controls. Due to climate change, population growth, and industrialization, HVAC use is globally on the rise. Unfortunately, these systems often...

This project aims to motivate research in competitive human-robot interaction by creating a robot competitor that can challenge human users in certain scenarios such as physical exercise and games. With this goal in mind, we introduce the Fencing Game, a human-robot competition used to evaluate both the capabilities of the robot competitor and user...

We present the design of a new passive communication method that does not rely on ambient or generated RF sources. Instead, we exploit the Johnson (thermal) noise generated by a resistor to transmit information bits wirelessly. By switching the load connected to an antenna between a resistor and open circuit, we can achieve data rates of up to 26bp...

Proximity perception is a technology that has the potential to play an essential role in the future of robotics. It can fulfill the promise of safe, robust, and autonomous systems in industry and everyday life, alongside humans, as well as in remote locations in space and underwater. In this survey article, we cover the developments of this field f...

Low power long-range networks like LoRa have become increasingly mainstream for Internet of Things deployments. Given the versatility of applications that these protocols enable, they support many data rates and bandwidths. Yet, for a given network that supports hundreds of devices over multiple miles, the network operator typically needs to specif...

Proximity perception is a technology that has the potential to play an essential role in the future of robotics. It can fulfill the promise of safe, robust, and autonomous systems in industry and everyday life, alongside humans, as well as in remote locations in space and underwater. In this survey paper, we cover the developments of this field fro...

Brain-computer interfaces (BCIs) are an emerging strategy for spinal cord injury (SCI) intervention that may be used to reanimate paralyzed limbs. This approach requires decoding movement intention from the brain to control movement-evoking stimulation. Common decoding methods use spike-sorting and require frequent calibration and high computationa...

Despite significant research in backscatter communication over the past decade, key technical open problems remain underexplored. Here, we first systematically lay out the design space for backscatter networking and identify applications that make backscatter an attractive communication primitive. We then identify 10 research problems that remain t...

To increase the transmission distance of Wireless Power Transfer (WPT) systems, we provide guidelines on choosing the optimal location of an Intermediate Coil with respect to size within a standard five-coil axially aligned experimental setup. From our results, for maximum magnitude of S21 at the resonant frequency we found the optimal location to...

Despite significant research in backscatter communication over the past decade, key technical open problems remain under-explored. Here, we first systematically lay out the design space for backscatter networking and identify applications that make backscatter an attractive communication primitive. We then identify 10 research problems that remain...

The energy systems of mechanical circulatory support devices have evolved significantly since the inception of the Artificial Heart Program in 1963. The transition from bulky paracorporeal pulsatile blood pumps to continuous flow devices has facilitated the use of mechanical circulatory support (MCS) in a larger population of heart failure patients...

Brain-computer interfaces (BCIs) for treatment of spinal cord injury (SCI) can be used to reanimate paralyzed limbs. Most approaches stimulate the peripheral nerves or muscles, which has limitations. To overcome these challenges, here we show that a BCI can control spinal stimulation and improve forelimb function in rats with cervical SCI. We decod...

Reliable detection of human occupancy in indoor environments is critical for various energy efficiency, security, and safety applications. We consider this challenge of occupancy detection using extremely low-quality, privacy-preserving images from low power image sensors. We propose a combined few shot learning and clustering algorithm to address...

The increasing number of embedded, plugged-in radios around homes and offices in everyday objects such as appliances, TVs, and smart speakers provides an excellent opportunity to bring ultra-low-power backscatter connectivity to billions of devices. However, backscatter links suffer from high loss due to two consecutive propagations and have to ope...

Although general purpose robotic manipulators are becoming more capable at manipulating various objects, their ability to manipulate millimeter-scale objects are usually very limited. On the other hand, ultrasonic levitation devices have been shown to levitate a large range of small objects, from polystyrene balls to living organisms. By controllin...

Benchmarks for robot manipulation are crucial to measuring progress in the field, yet there are few benchmarks that demonstrate critical manipulation skills, possess standardized metrics, and can be attempted by a wide array of robot platforms. To address a lack of such benchmarks, we propose Rubik's cube manipulation as a benchmark to measure simu...

Existing Internet of Things (IoT) solutions require expensive infrastructure for sending and receiving data. Emerging technologies such as ambient backscatter help fill this gap by enabling uplink communication for IoT devices. However, there is still no efficient solution to enable low-cost and low-power downlink communication for ambient backscat...

This work presents a custom high-performance protocol for bi-directional communication with neural implants, that will eventually enable a closed-loop operation. This protocol presents a flexible configuration to communicate with neural implants with different characteristics. It can support different uplink data rates, variable number of neural ch...

We present MuSHR, the Multi-agent System for non-Holonomic Racing. MuSHR is a low-cost, open-source robotic racecar platform for education and research, developed by the Personal Robotics Lab in the Paul G. Allen School of Computer Science & Engineering at the University of Washington. MuSHR aspires to contribute towards democratizing the field of...

The need for a miniaturized device that can perform closed-loop operation is imminent with the growing interest in brain-controlled devices and in stimulation to treat neural disorders. This work presents the Neural Closed-Loop Implantable Platform (NeuralCLIP), a modular FPGA-based device that can record neural signals, process them locally to det...

The growing interest on the use of RFID tags with battery-free sensors, also known as computational RFID tags, demands an efficient MAC protocol to identify these tags and to stream data from their sensors, while dealing with tags collisions. The current standard for identifying these tags is the EPCglobal Class 1 Generation 2 (EPC C1G2), which res...

We describe a single fingertip-mounted sensing system for robot manipulation that provides proximity (pre-touch), contact detection (touch), and force sensing (post-touch). The sensor system consists of optical time-of-flight range measurement modules covered in a clear elastomer. Because the elastomer is clear, the sensor can detect and range near...

Background: Models of power delivery within an intact organism have been limited to ionizing radiation and, to some extent, sound and magnetic waves for diagnostic purposes. Traditional electrical power delivery within the intact human body relies on implanted batteries that limit the amount and duration of delivered power. The efficiency of curre...

Ambient Backscatter (AB), making use of both energy harvesting and backscattering, has recently become a promising solution to communications among low-power devices and demonstrates its potential application in the Internet of Things (IoT). Existing AB systems adopt two-state amplitude shift keying (ASK) or phase shift keying (PSK), where data are...

This paper presents a passive wireless RF sensor platform (RFSP), with only analog components, that harvests energy from an RF source and reflects data as a direct subcarrier modulation, thus making it battery free. A fully-analog architecture results in an ultra-low power device (under 200 μW) with a low component count, reducing the physical foot...

Wireless video streaming has traditionally been considered an extremely power-hungry operation. Existing approaches optimize the camera and communication modules individually to minimize their power consumption. However, designing a video streaming device requires power-consuming hardware components and video CODEC algorithms which makes battery-fr...

Near-field communication (NFC) readers, ubiquitously embedded in smartphones and other infrastructures can wirelessly deliver mW-level power to NFC tags. Our previous work NFC-wireless internet service provider (WISP) proves that the generated NFC signal from an NFC enabled phone can power a tag (NFC-WISP) with display and sensing capabilities in a...

As the number of IoT devices continue to exponentially increase and saturate the wireless spectrum, there is a dire need for additional spectrum to support large networks of wireless devices. Over the past years, many promising solutions have been proposed but they all suffer from the drawback of new infrastructure costs, setup and maintenance, or...

We introduce inter-technology backscatter, a novel approach that transforms wireless transmissions from one technology to another, on the air. We show for the first time that Bluetooth transmissions can be used to create Wi-Fi and ZigBee-compatible signals using backscatter communication. Since Bluetooth, Wi-Fi and ZigBee radios are widely availabl...

Wireless video streaming has traditionally been considered an extremely power-hungry operation. Existing approaches optimize the camera and communication modules individually to minimize their power consumption. However, the joint redesign and optimization of wireless communication as well as the camera is what that provides more power saving. We p...

We present the first battery-free cellphone design that consumes only a few micro-watts of power. Our design can sense speech, actuate the earphones, and switch between uplink and downlink communications, all in real time. Our system optimizes transmission and reception of speech while simultaneously harvesting power which enables the battery-free...

The vision of embedding connectivity into billions of everyday objects runs into the reality of existing communication technologies --- there is no existing wireless technology that can provide reliable and long-range communication at tens of microwatts of power as well as cost less than a dime. While backscatter is low-power and low-cost, it is kn...

The vision of embedding connectivity into billions of everyday objects runs into the reality of existing communication technologies --- there is no existing wireless technology that can provide reliable and long-range communication at tens of microwatts of power as well as cost less than a dime. While backscatter is low-power and low-cost, it is kn...

For more than two decades, capacitive sensing has played a prominent role in human-computer interaction research. Capacitive sensing has become ubiquitous on mobile, wearable, and stationary devices — enabling fundamentally new interaction techniques on, above, and around them. The research community has also enabled human position estimation and w...

RF-powered devices equipped with general-purpose microcontrollers face energy limitation constraints for performing arbitrarily complex sensing and computation tasks. While richer capabilities such as image capture and processing would enable many new RF-powered use-cases, this energy limitation narrows the application space. Enabling richer sensin...

This paper enables connectivity on everyday objects by transforming them into FM radio stations. To do this, we show for the first time that ambient FM radio signals can be used as a signal source for backscatter communication. Our design creates backscatter transmissions that can be decoded on any FM receiver including those in cars and smartphone...

We present the first power over Wi-Fi system that delivers power to low-power sensors and devices and works with existing Wi-Fi chipsets. We show that a ubiquitous part of wireless communication infrastructure, the Wi-Fi router, can provide far field wireless power without significantly compromising the network's communication performance. Building...

Wi-Fi has traditionally been considered a power-consuming communication system and has not been widely adopted in the sensor network and Internet of Things (IoT) space. We introduce Passive Wi-Fi that demonstrates that one can generate 802.11b transmissions using backscatter communication, while consuming 3-4 orders of magnitude lower power than ex...

In this article, the authors discuss new trends in powering pervasive computing systems and review what we have learned in the last 15 years of building such systems. Major advances in cloud computing, RF, power harvesting, and networking have enabled new asymmetric architectures that reduce our reliance on batteries. Although the authors see a slo...

Sustained exponential improvements in the energy efficiency of microelectronics has recently enabled us to build battery-free camera systems that are powered entirely by propagating radio waves. This paper describes primitive machine vision applications built using this highly constrained, battery-free camera system. After describing the WISPCam sy...