S. G. M. Hossain

ModRED: Hardware design and reconfiguration planning for a high dexterity modular self-reconfigurable robot for extra-terrestrial exploration

Abstract This paper presents a homogeneous modular robot system design based on four per-module degrees of freedom (DOF), including a prismatic DOF to increase the versatility of its reconfiguration and locomotion capabilities. The ModRED (Modular Robot for Exploration and Discovery) modules are developed with rotary-plate genderless single sided docking mechanisms (RoGenSiD) that allow chain-type configurations and lead towards hybrid-type configurations. Various locomotion gaits are simulated through the Webots robot simulator and implemented in the real ModRED system. This work also addresses the problem of dynamic reconfiguration in a modular self-reconfigurable robot (MSR). The self-reconfiguration problem is modeled as an instance of the graph-based coalition formation problem. We formulate the problem as a linear program that finds the “best” partition or coalition structure among a set of ModRED modules. The technique is verified experimentally for a variety of settings on an accurately simulated model of the ModRED robot within the Webots robot simulator. Our experimental results show that our technique can find the best partition with a reasonably low computational overhead.

Hardware Design and Testing of ModRED: A Modular Self-Reconfigurable Robot System

Unstructured environments are challenging for conventional robots, and modular self-reconfigurable robots (MSRs) can be deployed to overcome this challenge. The goal of the current work was to develop a flexible, cost effective multi-module robot system capable of self-reconfiguration and achieving various gaits in unstructured environments. This paper discusses the communication aspects of the Modular Robot for Exploration and Discovery (ModRED) robot system from a hardware perspective. To ensure enhanced flexibility and local autonomy as well as better reconfiguration, each robot module is built with four independent degrees of freedom, and a novel docking interface provides interconnection of modules. The prototyping effort is described with emphasis on the implementation of inter-module communication. The electronic hardware layout and control system are described, and the communication system is outlined. Finally, some preliminary testing of the developed prototype is presented.

Design of a Four-DOF Modular Self-Reconfigurable Robot With Novel Gaits

Throughout the modern age, exploration of the unknown has been an attractive pursuit to seekers of knowledge. One of the primary frontiers for exploration today involves planetary and lunar environments. Exploration in these environments can involve many different types of tasks in a broad range of environmental conditions. Modular Self-Reconfigurable Robots (MSRs) would be beneficial for completing these tasks in unstructured environments, while having the ability to complete multiple assigned functions. Since payload is a critical concern, a lighter and more dexterous MSR is preferable. This research focuses on the design of a robot that has these qualities. A chain-type modular robot with four degrees of freedom per module has been designed with the goal of reducing weight and size while increasing range of motion. Forward kinematic transformations were derived to analyze the available workspace provided by the MSR. Radio communication and proximity sensing ability were provided in the individual MSR modules to locate each other. The modules are designed to maneuver independently using their individual navigation capability as well as connect to each other by means of a docking mechanism. Locomotion gaits for such multi-module robot chains are also described.Copyright

Modular robot locomotion based on a distributed fuzzy controller: The combination of modred's basic module motions

We describe a distributed and autonomous technique for dynamic gait adaptation for a chain-type, modular self-reconfigurable robot (MSR) using a fuzzy logic based, closed-loop controller. To maneuver itself, each module of the MSR is provided with a set of basic or fundamental gaits within a gait control table(GCT). A relevant problem in locomotion of a chain-type MSR is how to coordinate the gait of the individual modules with each other so that the desired locomotion of the MSR can be achieved. To address this problem, our proposed controller maps the inputs from the sensors of each module to an appropriate gait for the module determined from the goal and position of the module in the configuration, using a fuzzy technique. An inertial measurement unit (IMU) is used to close the loop between the goal and the module. We have verified the operation of our controller on a simulated 3-D model of an MSR called ModRED within the Webots robot simulator and also implemented it on the physical ModRED MSR. Our results illustrate that our controller can successfully adapt ModREDs locomotion by dynamically combining basic gaits from the individual modules in the configuration, regardless of the number of modules in the configuration and in the presence of noisy sensor inputs.

Effect of robotic manipulation on unidirectional barbed suture integrity: evaluation of tensile strength and sliding force.

BACKGROUND AND PURPOSE One of the more challenging portions of robot-assisted radical prostatectomy (RARP) is the urethrovesical anastomosis. Because of this, a unidirectional absorbable barbed suture (V-Loc(™)) has been used to complete the anastomosis with better efficiency and less tension. The effect of robotic needle driver manipulation on barbed suture is unknown. Therefore, the aim of this study is to determine whether robotic manipulation decreases the tensile strength and peak sliding force of V-Loc barbed suture. MATERIALS AND METHODS Fifty-six V-Loc sutures were compared with 56 Maxon sutures. All sutures were 3-0 caliber. Half of the sutures in each group were manipulated with a da Vinci(®) robot large needle driver five times over a 5 cm length of suture. The other half was not manipulated. Breaking force was determined by placing sutures in a Bose ElectroForce load testing device. For sliding force testing, 28 V-Loc sutures were manipulated in the same fashion and compared with 28 nonmanipulated V-Loc sutures. Peak force needed to make the suture slip backward in porcine small intestine was determined to be the sliding force. Scanning electron microscopy of the barbs before and after robotic manipulation was also performed. RESULTS The mean difference in breaking forces for manipulated vs nonmanipulated Maxon sutures was 4.52 N (P=0.004). The mean difference in breaking forces for manipulated vs nonmanipulated V-Loc sutures was 1.30 N (P=0.046). The manipulated V-Loc group demonstrated a lower peak sliding force compared with the nonmanipulated group (0.76 vs 0.88 N, P=0.199). Electron microscopy revealed minor structural damage to the barbs and suture. CONCLUSION Tensile strength and peak sliding force of V-Loc suture is decreased by robotic manipulation. This is likely because of structural damage to the suture and barbs. This structural damage, however, is likely not clinically significant.

Silicone catheters may be superior to latex catheters in difficult urethral catheterization after urethral dilation.

BACKGROUND AND PURPOSE Urethral dilation in the setting of difficult urethral catheterization is sometimes necessary to avoid suprapubic catheterization. Anecdotally, we have observed that less dilation is needed when advancing a silicone catheter over a Glidewire compared with a latex catheter of the same size. Our aim was to quantify the difference in the resistance to buckling between silicone and latex catheters. MATERIALS AND METHODS A BOSE Electroforce load testing device was used to test 12F and 16F silicone and latex catheters under tensile and compressive forces. This information was used to characterize the buckling (kinking) behavior of the catheters. RESULTS Silicone catheters showed more than 50% greater resistance to kinking when compared with regular latex or coude latex catheters. CONCLUSIONS In the setting of the difficult urethral catheterization, silicone catheters should be used after urethral dilation, advanced through a Glidewire, because they offer more resistance to buckling and might necessitate less dilation than conventional latex catheters.

RoGenSiD: A rotary plate genderless single-sided docking mechanism for modular self-reconfigurable robots

Docking mechanisms are an integral part of modular self-reconfigurable robot (MSR) systems, allowing multiple robot modules to attach to each other. An MSR should be equipped with robust and efficient docking interfaces to ensure enhanced autonomy and self-reconfiguration ability. Genderless docking is a necessary criterion to maintain homogeneity of the robot modules. This also enables self-healing of a modular robot system in the case of a failed module. The mechanism needs to be compact and lightweight and at the same time have sufficient strength to transfer loads from other connected modules. RoGenSiD is a rotary-plate genderless single sided docking mechanism that was designed to perform robustly and efficiently considering its application in unstructured terrains. The design methodology followed design for manufacture (DFM) and design for assembly (DFA) guidelines as well as considerations for minimal space and weight. As a result, this docking mechanism is applicable for multi-faceted docking in lattice-type, chain-type, or hybrid MSR systems. Bench-top testing validated the system performance.Copyright

A novel vending machine for supplying root canal tools during surgery

A root canal surgery involves the successive use of several tools one after another. Typically dozens of tools are laid out for possible use, and the process of tool selection is done manually. This is a rather inefficient process and uses up a large area on the mobile cart or cabinet of the dental chair due to the large number of tools. In this article, a novel ‘tool vending machine’ is introduced which will be capable of solving those problems and at the same time move a step closer to robot-assisted dental surgery. The tool vending machine was designed considering the needs of the dentists and also from the perspective of the entire product life cycle. For these reasons the design process was implemented using a rigorous analysis of effective manufacturing processes and product quality. To show the feasibility of using such a machine in improving work efficiency during operations, a study of the associated motion patterns and the required time increments were demonstrated.