Modular Robotics

Purpose – The Printable Modular Robot (PMR) is a highly customizable, modular, snake-like robot platform for research and education. The robot can be assembled and re-assembled on the fly and automatically detects changes in its topology during operation.
Design/methodology/approach – The robot consists of a number of autonomous modules coupled by magnetic interfaces. Each module combines 3D printed mechanical parts with widely available standard electronic components, including a microcontroller and a single servo actuator. The mechanical and electrical connection is provided by a set of magnets which generate the physical force between the modules and at the same time serve as wires for power and communication.
Findings – The PMR is a fully equipped robotic device, well integrated into a simulation framework, capable to execute common locomotion patterns but still very affordable (∼25 $ per module). Furthermore, the design is easy to extend and replicate for other research and education groups.
Originality/value – This paper explores a novel approach of connecting robot modules by utilizing very simple magnetic parts. A second focus lies on the concept of closely integrating simulation and hardware development, blurring the edge between the digital and physical world.

The emergence of nano-electromagnetic communications ba-
sed  on  graphene  nano-antennas  has  opened  new  perspec-
tives for communications between small things, referred as
to  the  internet  of  micro-things  or  even  as  the  internet  of
nano-things.  However, these antennas make use of the Ter-
ahertz band which raises many problems like the absorption
of entire range of the available bandwidth by any molecule.
Meanwhile,  recent advances have been made in the design
and fabrication of micro-robots enabling formation of micro-
robots networks.  Nano-antennas are an interesting way of
communicating between micro-robots. We envision two types
of benets using integrated nano-antennas in micro-robots.
First,  nano-wireless  communications  could  enhance  exist-
ing applications enabling a greater communication distance
in  an  ensemble  and  broadcasting  facilities.  Second,  nano-
wireless communications can create new usage and new ap-
plications.  This article presents a simulation framework for
micro-robots  using  nano-wireless  communications  and  an
application being developed within our simulator.

Self-reconfigurable modular robots have been studied worldwide mainly for autonomous exploration in unstructured environments. In previous studies, robotic modules were designed to be functional only as a part of an assembled structure, and thus the exploration capability was limited. Symbiotic multi-robot organisms have been newly proposed to design robotic modules as large-scale swarms of robots that can physically dock with each other and symbiotically share energy and computational resources within a single “artificial-life-form”. In this paper, a novel robotic module named Scout Robot, which is one of the three robotic platforms designed for the multi-robot organisms, is presented. The Scout robot is an autonomous miniature robot and equipped with many onboard sensors and a locomotion capability. It can move autonomously on rough terrains to explore the surroundings and interact with the other robots. The Scout robot is also equipped with 2 DoFs of actuation and shares the same docking design with the other robotic platforms, and thus can be a part of an assembled organism. In the experiments, the image-guided locomotion of a Scout robot and the multimodal locomotion of assembled robots were demonstrated.

Nanowireless electro-magnetic communication networks in
the  Terahertz  band  have  raised  interest  in  the  networking  community these very last years. However, if detailed studies have been published on
analytical  modelling  of  these  networks,  no  simulation  have  been  run  to
study  in  detail  the  characteristics  of  the  transmission  medium.  We  have
designed Vouivre, a standalone nanowireless simulator, which is interfaced
with  two  micro-robots  simulator  DPRSim  and  VisibleSim.  This  paper
describes briefly Vouivre and presents first metrics of the communication
channel using a communication paradigm called TS-OOK (Time Spread On-Off Keying).

We consider the modular principle for the construction of functional units of mobile robots. The main ideas of this concept and the general structure of the heterogeneous robot are presented. Basic functions of the robot are used to determine the minimum set of functional modules. For one of the simple configurations of the modular robot (the service mobile robot), we develop a motion module that is one of the main modules of the mobile robot. We present the design of this motion module and the result of a mathematical model of its control system. The control system combines the tactical level (for the construction of motion sub-targets and intermediate trajectories) and the execution level. The execution level of control is implemented on the basis of the system of slave control loops. Introduction Normally, the design of robotic systems (RS) is accompanied by information about the purpose of the device. Accordingly, all the constructive and program decisions made during the design focus on the achievement of the specific purpose by the final device. Because of this, when the scope of application of the RS is changed, the designer has to revise in a varying degree the device construct ensuring its full compliance with the given purpose. One of the modern approaches to robotic design (and to machinery in general) is to divide the device structure into individual functional components. Each component is responsible for some part of the robot functionality. This unit or module normally has a simpler structure because it is responsible for a single function only. As one of many components of the robot, the module can be easily replaced by a similar or more advanced module. Then, there is no need to redesign the robot: it will suffice merely to replace it by particular functional units. Therefore, the modular robots can provide higher economic efficiency.

This paper introduces ModGrasp, an open-source virtual and physical rapid-prototyping framework that allows for the design, simulation and control of low-cost sensorised modular hands. By combining the rapid-prototyping approach with the modular concept, different manipulator configurations can be modelled. A real-time one-to-one correspondence between virtual and physical prototypes is established. Different control algorithms can be implemented for the models.
By using a low-cost sensing approach, functions for torque sensing at the joint level, sensitive collision detection and joint compliant control are possible. A 3-D visualization environment provides the user with an intuitive visual feedback.
As a case study, a three-fingered modular manipulator is presented. Related simulations are carried out to validate efficiency and flexibility of the proposed rapid-prototyping framework.

This paper describes the design and
development of a modular soft manipulator for
minimally invasive surgery, which equals the high
dexterity of classic hyper redundant continuum, but
rigid, robots resulting in safer potential interaction
with internal organs. The manipulator relies on the use
of a soft flexible fluidic actuator in each of its modules,
which can be wireless controlled by means of an
embedded fluidic control unit. This actuation unit is
equipped with three miniaturized latching valves, a
wireless microcontroller board, and a specifically
designed fluidic distributor integrated into the elastomeric
material that the module is made of. FEM
simulations and experimental tests verified the reliability
of the distributor in acting as a piping system
inside each module. The mobility of the fully
integrated soft module was evaluated in terms of
static performances and covered workspace. The
module’s dynamic model during one-chamber motion
was estimated from the parameter estimation analysis.
The characterization of the single module behaviour is
intended as first step to ease the future high level
control of the multi-modular architecture.

This paper introduces a new modular approach to robotic grasping that allows for finding a trade off between a simple gripper and more complex human like manipulators. The modular approach to robotic grasping aims to understand human grasping behavior in order to replicate grasping and skilled in-hand movements with an artificial hand using simple, robust, and flexible modules. In this work, the design of modular grasping devices capable of adapting to different requirements and situations is investigated. A novel algorithm that determines effective modular configurations to get efficient grasps of given objects is presented. The resulting modular configurations are able to perform effective grasps that a human would consider "stable". Related simulations were carried out to validate the efficiency of the algorithm. Preliminary results show the versatility of the modular approach in designing grippers.

— A novel compliant robot is proposed for traversing on unstructured terrains. The robot has a set of modules where each module contains a trunk or link and an active wheel-pair, and it is connected to the adjacent module using a passive joint. This type of robots are inherently lightweight and provide high durability due to the absence of actuators at the link joints. However, they have limited climbing ability due to tendency of tipping over while climbing big obstacles. In order to overcome this disadvantage, the use of compliant joints is proposed in this work. Spring stiffness of each compliant joint is estimated by formulating an optimization problem using the static equilibrium equations of the robot. This is one of the key novelties of the proposed work. A design methodology is also proposed for developing an n-module compliant robot for climbing given height on a surface with prescribed coefficient of friction. The efficacy of the proposed formulation is illustrated for climbing big obstacles and traversing uneven terrains using simulation of 3-and 5-module robots. The robot is successfully able to climb maximum heights of 17 cm and 36 cm using 3 and 5 modules, respectively. Mechanical and electrical design of the robot is conceived, and a working prototype of the robot is developed. Simulation results are validated using the prototype.

This paper presents a novel mechanism to implement caterpillar-like locomotion. First, the caterpillar-like locomotive pattern in nature is investigated and analyzed systematically. From a biological point of view, caterpillar locomotion can be abstracted as a body wave, called half wave. It is simple, but efficient. In this paper, a novel control mechanism, maintaining the half wave property, is integrated into an improved central pattern generator (CPG) model. For the first time, an asymmetric oscillation is employed on the model for gait generation. The movement is proved stable according to a kinematic analysis. Modulation is able to use to change the shape of the half wave during locomotion. A series of simulation shows the feasibility of using asymmetric oscillators for locomotion. Furthermore, the latest results obtained demonstrate that the proposed asymmetric locomotion mechanism is easy to implement while offering a satisfactory motion performance in on-site experiments.

cle represent a first step in our research towards autonomous aggregation and coordination of robots to higher-level, modular robotic organisms that consist of several joined autonomous robotic units. In the end we plan to achieve such aggregation patterns and to control complex shaped robotic organisms by using AHHS controllers, as they are described here.

The HYDRA work provides insight into the exploitation of holistic behavioural and morphological adaptation in the design of new artefacts. The potential of the new design principle has been exemplified through the construction of robotic systems that can change morphology. Two prototype building block systems has been developed, HYDRON for a fluid scenario, and ATRON for a terrestrial scenario. In the HYDRON case, the individual module can perform 3D motion and is able to arrange in clusters of specific formation without the necessity of physical connections. In the ATRON case, the modules are individually simpler, attach through physical connections, and perform 3D motions by collective actions. Control mechanisms identified from cellular biology has been successfully transferred to the physical building blocks.

In this work, the open-source plugin OpenMRH is presented for the Open Robotics Automation Virtual Environment (OpenRAVE), a simulation environment for testing, developing and deploying motion planning algorithms. The proposed plugin allows for a fast and automated generation of different modular hand models OpenMRH combines virtual-prototyping and modular concepts. Each modular model is generated by applying a dynamically generated code, which is consistent with the standard syntax expected by OpenRAVE for the simulated models. In this way, once the desired model is generated, an instance of OpenRAVE can be launched and the model can be visualised. Alternatively, the modular models can be generated from a user-defined input specified via a graphical user interface (GUI). The generated models can be used for testing, developing and deploying grasp or motion planning algorithms. Two case studies are considered to validate the efficiency of the proposed model generator. In the first case study, a modular robotic hand model is generated with OpenMRH by using user-defined input parameters. In the second case study, another hand model is generated with OpenMRH by using algorithmic defined input parameters.

The mechanical design of a novel robotic module for a self-reconfigurable modular robotic system is presented in this paper. The robotic module, named Scout robot, was designed to serve both as a fully sensorized autonomous miniaturized robot for exploration in unstructured environments and as a module of a larger robotic organism. The Scout robot has a quasi-cubic shape of 105 mm × 105 mm × 123.5 mm, and weighs less than 1 kg. It is provided with tracks for 2-D locomotion and with two rotational DoFs for reconfiguration and macrolocomotion when assembled in a modular structure. A laser sensor was incorporated to measure the distance and relative angle to an object, and image-guided locomotion was successfully demonstrated. In addition, five Scout robot prototypes were fabricated, and multimodal locomotion of assembled robots was demonstrated.

The HYDRA work provides insight into the exploitation of holistic behavioural and morphological adaptation in the design of new artefacts. The potential of the new design principle has been exemplified through the construction of robotic systems that can change morphology. Two prototype building block systems has been developed, HYDRON for a fluid scenario, and ATRON for a terrestrial scenario. In the HYDRON case, the individual module can perform 3D motion and is able to arrange in clusters of specific formation without the necessity of physical connections. In the ATRON case, the modules are individually simpler, attach through physical connections, and perform 3D motions by collective actions. Control mechanisms identified from cellular biology has been successfully transferred to the physical building blocks.