Humanoid robots, unmanned rovers, entertainment pets, drones, and so on are great examples of mobile robots. They can be distinguished from other robots by their ability to move autonomously, with ...

https://journals.sagepub.com/doi/pdf/10.1177/1729881419839596

A review of mobile robots: Concepts, methods, theoretical framework, and applications

The goal of this review is to evaluate the current status of multi-robot systems in the context of search and rescue. This includes an investigation of their current use in the field, what major technical challenge areas currently preclude more widespread use, and which key topics will drive future development and adoption. Work blending machine learning with classical control techniques is driving progress in perception-driven autonomy, decentralized multi-robot coordination, and human–robot interaction, among others. Ad hoc mesh networking has achieved reliability suitable for safety-critical applications and may be a partial solution for communication. New modular and multimodal platforms may overcome mobility limitations without significantly increasing cost. Multi-agent systems are not currently ready for deployment in search and rescue applications; however, progress is being made in a number of critical domains. As the field matures, research should focus on realistic evaluations of constituent technologies, and on confronting the challenges of simulation-to-reality transfer, algorithmic bias in autonomous agents that rely on machine learning, and novelty-versus-reliability incentive mismatch

https://link.springer.com/content/pdf/10.1007/s43154-021-00048-3.pdf

Multi-Agent Systems for Search and Rescue Applications

Industrial robots cannot be reconfigured to optimally fulfill a given task and often have to be caged to guarantee human safety. Consequently, production processes are meticulously planned so that they last for long periods to make automation affordable. However, the ongoing trend toward mass customization and small-scale manufacturing requires purchasing new robots on a regular basis to cope with frequently changing production. Modular robots are a natural answer: Robots composed of standardized modules can be easily reassembled for new tasks, can be quickly repaired by exchanging broken modules, and are cost-effective by mass-producing standard modules usable for a large variety of robot types. Despite these advantages, modular robots have not yet left research laboratories because an expert must reprogram each new robot after assembly, rendering reassembly impractical. This work presents our set of interconnectable modules (IMPROV), which programs and verifies the safety of assembled robots themselves. Experiments show that IMPROV robots retained the same control performance as nonmodular robots, despite their reconfigurability. With respect to human-robot coexistence, our user study shows a reduction of robot idle time by 36% without compromising on safety using our self-verification concept compared with current safety standards. We believe that by using self-programming and self-verification, modular robots can transform current automation practices.

https://robotics.sciencemag.org/content/robotics/4/31/eaaw1924.full-text.pdf

Effortless creation of safe robots from modules through self-programming and self-verification

Not all generate-and-test search algorithms are created equal. Bayesian Optimization (BO) invests a lot of computation time to generate the candidate solution that best balances the predicted value and the uncertainty given all previous data, taking increasingly more time as the number of evaluations performed grows. Evolutionary Algorithms (EA) on the other hand rely on search heuristics that typically do not depend on all previous data and can be done in constant time. Both the BO and EA community typically assess their performance as a function of the number of evaluations. However, this is unfair once we start to compare the efficiency of these classes of algorithms, as the overhead times to generate candidate solutions are significantly different. We suggest to measure the efficiency of generate-and-test search algorithms as the expected gain in the objective value per unit of computation time spent. We observe that the preference of an algorithm to be used can change after a number of function evaluations. We therefore propose a new algorithm, a combination of Bayesian optimization and an Evolutionary Algorithm, BEA for short, that starts with BO, then transfers knowledge to an EA, and subsequently runs the EA. We compare the BEA with BO and the EA. The results show that BEA outperforms both BO and the EA in terms of time efficiency, and ultimately leads to better performance on well-known benchmark objective functions with many local optima. Moreover, we test the three algorithms on nine test cases of robot learning problems and here again we find that BEA outperforms the other algorithms.

Time Efficiency in Optimization with a Bayesian-Evolutionary Algorithm

An underactuated self-reconfigurable robot and the reconfiguration evolution

This article presents a review on trends in modular reconfigurable robots, comparing the evolution of the features of the most significant robots over the years and focusing on the latest designs. These features are reconfiguration, docking, degrees of freedom, locomotion, control, communications, size, and powering. For each feature, some of the most relevant designs are presented and the current trends in the design are discussed.

Current trends in reconfigurable modular robots design

We propose an approach for motor skill learning of highly articulated characters based on the systematic exploration of low-dimensional joint coactivation spaces. Through analyzing human motion, we first show that the dimensionality of many motion tasks is much smaller than the full degrees of freedom (DOFs) of the character. Indeed, joint motion appears organized across DOFs, with multiple joints moving together and working in synchrony. We exploit such redundancy for character control by extracting task-specific joint coactivations from human recorded motion, capturing synchronized patterns of simultaneous joint movements that effectively reduce the control space across DOFs. By learning how to excite such coactivations using deep reinforcement learning, we are able to train humanlike controllers using only a small number of dimensions. We demonstrate our approach on a range of motor tasks and show its flexibility against a variety of reward functions, from minimalistic rewards that simply follow the center-of-mass of a reference trajectory to carefully shaped ones that fully track reference characters. In all cases, by learning a 10-dimensional controller on a full 28 DOF character, we reproduce high-fidelity locomotion even in the presence of sparse reward functions.

Low Dimensional Motor Skill Learning Using Coactivation

By considering locomotion as a set of coordinated oscillations, a method for generating a wide variety of periodic linear gait trajectories is proposed. The shape of the generated trajectory can be defined as a set of features such as symmetry, skewness, signal width, duality and squareness, along with amplitude, offset, phase and frequency parameters. Taking previously proven nonlinear bipedal gait trajectories as reference, a set of linear approximates are modeled, and is tested on a simulated humanoid robot. Then, gait trajectories for producing stable and faster bipedal gait on the same humanoid robot are learned using Genetic Algorithm, through a bottom-up approach.

Gait generation through a feature based linear periodic function

Locomotion in humans and animals is highly coordinated, with many joints moving together. Learning similar coordinated locomotion in articulated virtual characters, in the absence of reference motion data, is a challenging task due to the high number of degrees of freedom and the redundancy that comes with it. In this paper, we present a method for learning locomotion for virtual characters in a low dimensional latent space which defines how different joints move together. We introduce a technique called motor babble, wherein a character interacts with its environment by actuating its joints through uncoordinated, low-level (motor) excitations, resulting in a corpus of motion data from which a manifold latent space is extracted. Dimensions of the extracted manifold define a wide variety of synergies pertaining to the character and, through reinforcement learning, we train the character to learn locomotion in the latent space by selecting a small set of appropriate latent dimensions, along with learning the corresponding policy.

https://dl.acm.org/doi/pdf/10.1145/3487983.3488291

Avinash Ranganath

Papers

Current trends in reconfigurable modular robots design

Low Dimensional Motor Skill Learning Using Coactivation

Gait generation through a feature based linear periodic function

Motor Babble: Morphology-Driven Coordinated Control of Articulated Characters