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For the realization of an Internet of Things (IoT) with high densities of devices it is necessary that wireless communication protocols are developed that offer 1) low energy consumption; 2) simplicity of encoding and decoding; 3) an asynchronous mode of communication; and 4) an effective but simple method to deal with interference between transmissions. This paper presents the implementation, experimentation, and analysis of a protocol on the MAC sublayer that encodes information in terms of silent intervals between pulses. Based on the representation of patterns of sparse pulses, this encoding has the potential for extremely low power consumption at the transmitter side. It also results in only few conflicts between messages that are broadcast on the same band overlapped in time, while no synchronization between transmitters and receivers is necessary. The protocol is demonstrated experimentally on the 315 MHz band with 100 senders and one receiver configured in a Star topology. Theoretical analysis confirms that the probability of conflicts between messages is low, even if the number of devices increases to the order of ten thousand. This protocol facilitates the implementation of IoT devices that are restricted in terms of hardware and energy resources.

As IoT devices are becoming more and more common, it has become necessary to develop new Low Power Wide Area (LPWA) technology to support massive IoT devices. In our previous work, Asynchronous Pulse Code Multiple Access (APCMA) has been proposed as a pulse-based power-saving communication protocol. In this paper, we propose a low-power and interference-resistant communication method by using Chirp Spread Spectrum (CSS) modulation for APCMA. CSS-based APCMA can communicate with a wider coverage than APCMA that is based conventional On-Off Keying of Continuous Waves (CW). We have implemented the proposed protocol using Software-Defined Radio (SDR) and confirmed that communication is possible. Comparing with LoRa, we found that the proposed communication method has less packet loss under a high duty cycle.

For the realization of an Internet of Things (IoT) with high densities of nodes it is necessary that wireless communication protocols are developed that offer (1) low energy consumption, (2) simplicity of encoding and decoding, (3) an asynchronous mode of communication, and (4) an effective but simple method to deal with interference between transmissions. This paper presents the implementation, experimentation, and analysis of a protocol on the MAC sublayer that is based on the encoding of information by the silent intervals between pulses. This encoding allows for few conflicts between messages that are broadcast on the same band overlapped in time. This is demonstrated experimentally, while no adverse effect is detected on transmissions from broadcasts of a different group of nodes using the same 315 MHz band but with a different code length as coding parameter. Theoretical analysis confirms that the probability of conflicts between messages is low, even if the number of nodes increases to the order of ten thousand. This protocol facilitates the implementation of IoT nodes that are restricted in terms of hardware and energy resources.

For robot teleoperators, replicating head motion in a remote environment is often necessary to complete monitoring and face-to-face service tasks. Especially in the case of a stereoscopic camera rig, remote cameras need to be moved to match the operator's head position and optical axes in order to interact with a remote entity, follow targets, or reorient. However, mechanical, computational, and network delay in such teleoperation can cause intersensory conflict, perceptual deficits, and reduction in performance, especially during activities that require head rotation. In this article, we evaluate the effects of view reconstruction on performance and perception for remote monitoring tasks. To do so, we first implemented a panoramic reconstruction method to reduce perceived latency in a humanoid robot, which allows us to compare and contrast latency. Next, we designed a bidirectional remote control system for the robot and set up a series of experiments where participants had to conduct focused head control tasks through the perspective of the robot. This allowed us to compare the effects of latency on head movement, accuracy, and subjective perception of the interface and remote teleoperation. Results showed that panoramic reconstruction significantly improved perception and comfort during teleoperation, but that performance only improved for tasks requiring slower head movements.

In recent years, robots have become more commonplace as a method for humans to remotely conduct observations or interactions, with commercial applications ranging from customer service to assembly line work. Virtual and augmented reality have shown much promise as methods to visualize and assist with teleoperation of these robots. However, a number of problems still exist with such bidirectional teleoperator relationships, including the intersensory conflict induced by delay of images received on the teleoperator side of a remote session. This can result in nausea, simulation sickness, and unnatural interaction, especially when stereoscopic cameras are present. As a step towards addressing this problem, we introduce the use of stereo panoramic reconstruction in conjunction with an augmented reality interface to improve both the interaction and the sense of embodiment of a teleoperator working through a robot's perspective. Unlike current methods that send latent streams of the robot's eye-cameras to the user, we view reconstruction that also incorporates direct control of the robot's head. This algorithm uses queued time and angle stamped images to reconstruct the robot's stereoscopic view for the teleoperator, which allows for low-latency viewing and field of view expansion. We then conduct experiments comparing our method against a direct camera feed from the robot's eyes. In addition to measuring latency at every point of the data pipeline, we show that this panoramic representation reduces perceived visual delay and elicits positive user feedback.3

The question of what to imitate is pivotal for imitation learning in robotics. When the robot's tutor is a naive user, it is very difficult for the embodied agent to account for the unpredictability of the tutor's behaviour. Preliminary results from a previous study suggested that the phenomenon of temporal emphasis, i.e., that tutors tend to keep the goal state of the demonstrated task stationary longer than the sub-states, can be used to recognise that task. In the present paper, the previous study is expanded and the existence of the phenomenon is investigated further. An improved experimental setup, using the iCub humanoid robot and naive users, was implemented. Analysis of the data showed that the phenomenon was detected in the majority of the cases, with a strongly significant result. In the few cases that the end state was not the one with the longest time span, it was a borderline second. Then, a very simple algorithm using a single binary criterion was used to show that the phenomenon exists and can be detected easily. That leads to the argument that humans may also be able to detect this phenomenon and use it for recognizing, as learners or emphasizing and teaching as tutors, the end goal, at least for tasks with clear and separate sub-goal sequences. A robot that implements this behavior could be able to perform better both as a tutor and as a learner when interacting with naive users.

Goal extraction in learning by demonstration is a complex problem. A novel approach, inspired by developmental psychology and focused on use in experiments with naive users, is presented in this paper. Participants were presenting a simple task, how to stack three boxes, to the humanoid robot iCub. The stationary states of the task - 1 box, 2 boxes stacked, 3 boxes stacked - were defined and the time span of each state was measured. Analysis of the results showed that there is a significant result that users tend to keep the boxes stationary longer upon completion of the end goal than upon completion of the sub-goals. A simple and straightforward learning algorithm was then used on the demonstration data, using only the time spans of the stationary states. The learning algorithm successfully detected the end goal. These temporal differences, functioning as emphasis, could be used as a complementary mechanism for goal extraction in imitation learning. Furthermore, it is suggested that since a simple, straightforward learning algorithm can use these pauses to recognise the goal state, humans may also be able to use this pause as a complementary mechanism for recognising the goal state of a task.

Music in general and drumming in specific has been used several times in human-robot interaction studies. We present a drumming robotic system based on the iCub humanoid robotic platform using all four limbs to play a full-sized drum set and the exploratory experimental setups used to assess it. The social aspect of the system uses the concept of music as a communicative gesture to transfer information and facilitate the interaction. The first implementation is focused on assessing the imitative capabilities of a robot on a full drum set at different levels of speed and complexity. By treating the rhythmic content as communication, the second implementation allows for improvisation of both the robot and the human in a kind of musical dialogue. While keeping the structure of turn-taking fixed and predefined, the focus of the setup is on the actual content of each turn and how it affects the other participant's communicative exchange. The resulting platform was able to imitate the drumming of the humans within the timing constraints of the rhythm and tempo. The second setup was used to evaluate the improvisation capabilities of the platform and also led to observations about the potential behaviour of the human participant in such an interaction. The robotic drumming system produced can be used for more complex rhythmical interactions between humans and robots. These will facilitate the study of not only the structure of the interaction but also its content.