Multi-agent path planning for mobile robots with discrete-step locomotion

The \u201cswing-and-dock\u201d (SaD) model for realizing displacements has been invented for and is used by the mobile robotic fixtures developed in the SwarmItFix European project. This form of locomotion can be a valuable capability for material handling agents, and fixturing agents enabling simultaneous handling in a non-linear fashion and increasing manufacturing flexibility. The thesis focuses on the design of SaD path planning algorithms for the motion of the agent

IN VIVO HEPATOPROTECTIVE ACTIVITY OF CASSIA AURICULATA POLYMER NANOSPHERES CONTAINING SILYMARIN

Objective: Hepatoprotective activity of herbal drugs has an importance in the treatment of hepatic disorders, but pharmaceutically engineeredproducts are not evolved properly to cure the liver disorders properly based on the demand and also route, target the appropriate site of action.Methods: In our present work, we have been developed a new formulation that possesses a unique nature and site specificity for targeting the diseasestate. Here, we examined hepatoprotective activity of Cassia auriculata polymer nanospheres containing silymarin against carbon tetrachlorideinducedhepatotoxicity in rats using at 50 mg/kg and 100 mg/kg body weight dose levels, and we have been observed that enzyme activities of serumglutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, alkaline phosphate, total protein, albumin, globulin, total cholesterol, high-density lipoprotein (HDL), glutathione (GSH), and total bilirubin were analyzed.Results: C. auriculata polymer nanospheres and silymarin produced significant (p<0.001) hepatoprotective effect by decreasing the activity of serum enzymes, bilirubin, total cholesterol, and increased levels of HDL, total protein, albumin, globulin, and tissue GSH.Conclusion: From these results, it was concluded that of C. auriculata polymer nanospheres would protect the liver cells from carbon tetrachloridefrom liver diseases.Keywords: Hepatoprotective activity, Silymarin, Cassia auriculata, Nanospheres

coordinated selection and timing of multiple trajectories of discretely mobile robots

Abstract The paper addresses the multi-agent path planning (MPP) of mobile agents with multiple goals taking into consideration the kinematic constraints of each agent. The "Swing and Dock" (SaD) robotic system being discussed uses discrete locomotion, where agents swing around fixed pins and dock with their mounting legs to realize displacement from one point to another. The system was developed as a subsystem for mobile robotic fixture (SwarmItFix). Previous work dealt with MPP for SaD agents using the concept of extended temporal graph with Integer Linear Programming (ILP) based formulations. The approach discretized time into unit steps, whereas in reality, the agents are constrained by velocity limits. Hence, a real-time schedule is required to accurately plan the agent movement in a working scenario. We utilize the concept of simple temporal network and extend our ILP formulations to model the velocity kinematic constraints. The mathematical formulations are implemented and tested using a GUROBI solver. Computational results display the effectiveness of the approach

The SwarmItFix Pilot

Abstract The paper presents the integration and experiments with a pilot cell including a traditional machine tool and an innovative robot-swarm cooperative conformable support for aircraft body panels. The pilot was installed and tested in the premises of the aircraft manufacturer Piaggio Aerospace in Italy. An original approach to the support of the panels is realized: robots with soft heads operate from below the panel; they move upward the panel where manufacturing is performed, removing the sagging under gravity and returning it to its nominal geometry; the spindle of amilling machine performs the machining from above

Miniaturized Flexible Flow Pump Using SMA Actuator

AbstractFluid pumps are one of the major components in engineering domain. The presence of fluid pumps in the medical field has gained momentum and has become an essential factor considering handling of life saving drugs and fluidic transport within the body. The need for a miniaturized flow pump based on size, application and capacity has driven the evolution from robust size pumps to MEMS based pumps. This paper proposes a novel methodology of actuation based on flow generation in a flexible tube by inducing variable pressure difference within the tube by external actuation by Shape Memory Alloy (SMA) wires. The proposed method helps in achieving miniaturization and bidirectional flow of fluid which is not possible in traditional pumps. These miniature pumps find their application where there is need for contactless operation between the working fluid and the pump, to avoid contamination of the working fluid or when the working fluid is aggressive or toxic. A detailed insight of the working principle and the conceptual design is provi ded. Preliminary test results and analytical results are presented

Multi-head path planning of SwarmItFIX Agents: a Markov decision process approach

SwarmItFIX is a flexible fixturing system designed and developed for sheet metal manufacturing applications. In this work, an artificial intelligence technique developed based on Markov Decision Process (MDP) is implemented for the task of multi-head based fixturing suitable for operations such as drilling, milling etc. The trajectory of the machining tool is split into various line segments for the ease of applying the MDP. The MDP is applied for obtaining the state parameters such as position coordinates and orientation of the intermediate heads of all the segments individually. The state parameters of the corner heads are calculated directly by finding the intersection angles of consecutive segments. In MDP, the evolution of utility values of all states are obtained using value iteration algorithm. For the convergence of the optimal policy of all segments in the contour, the policy iteration algorithm is employed. The execution time of both the algorithms were observed. Finally, the multi-head path planning model has been developed based on the algorithm having least execution time. The model returns the optimal policies for all the segments. Computer simulations are performed, and the results show that the multi-robot heads could be positioned in an effective manner in the given trajectory. Therefore, in near future the developed multi-head path planning model will be tested and implemented into the SwarmItFIX setup at the PMAR laboratory, University of Genoa

Artificial intelligence planners for multi-head path planning of SwarmItFIX agents

Sheet metal manufacturing is finding wide applications in automotive and aerospace industries. Handling of giant sheet materials in manufacturing industries is one of the key problems. Utilization of robots, viz SwarmItFIX, will address this problem and automate the fixturing process, which greatly reduces lead time and thus the production cost. Implementation of intelligence into the robots will further improve efficiency in handling and reduce manufacturing inaccuracies. In this work, two different novel planners are proposed which do path planning for the heads of the SwarmItFIX agents. The environment of the problem is modeled as a Markov Decision Problem. The first planner uses the Value Iteration and Policy Iteration (PI) algorithms individually and the second planner performs the Monte Carlo control reinforcement learning. Finally, when the simulation is done and parameters of the proposed three algorithms along with existing Constraint Satisfaction Problem algorithm are compared with each other. It is observed that the proposed PI algorithm returns the plan much faster than the other algorithms. In the near future, the efficient planning model will be tested and implemented into the SwarmItFIX setup at the PMAR laboratory, University of Genoa, Italy

Polytope-based Continuous Scalar Performance Measure with Analytical Gradient for Effective Robot Manipulation

International audiencePerformance measures are essential to characterize a robot's ability to carry out manipulation tasks. Generally, these measures examine the system's kinematic transformations from configuration to task space, but the Capacity margin, a polytope based kinetostatic index, provides additionally, both an accurate evaluation of the twist and wrench capacities of a robotic manipulator. However, this index is the minimum of a discontinuous scalar function leading to difficulties when computing gradients thereby rendering it unsuitable for online numerical optimization. In this paper, we propose a novel performance index using an approximation of the capacity margin. The proposed index is continuous and differentiable, characteristics that are essential for modelling smooth and predictable system behavior. We demonstrate its effectiveness in inverse kinematics and trajectory optimization application. Moreover, to show its practical use, two opposing robot architectures are chosen: (i) Serial robot-Universal Robot-UR5 (6-dof); Rethink Robotics-Sawyer Robot (7-dof) and (ii) Parallel manipulator-Cable Driven Parallel Robot to validate the results through both simulation and experiments. A visual representation of the performance index is also presented

Orientation planning for multi-agents with discrete-step locomotion and multiple goals

The paper addresses the coordinated path planning of mobile agents with multiple goal positions and orientations in a plane. The targeted multi-robot system uses discrete locomotion ensuring uncertainty-free localization and mapping as well as simple and robust control. It is suitable for material-handling, reconfigurable-fixturing, and mobile-manipulation tasks in a flexible-manufacturing environment. Using its three leg, and matching pin-socket couplings with the base surface, each agent either stands fixed or strides along via \u201cSwing and Dock\u201d (SaD) locomotion. Each mounting pin can serve both as a connecting-locking device and as a pivot of a planar rotation. Previous work offered planning solutions only for the agents\u2019 positions. In reality, the orientation in which the agent arrives at the goal is very important because neither robot workspaces nor work-cell geometries have axial symmetry. Herein, we provide for the required orientational planning by labelling the agent\u2019s legs to keep track of its rotation. Integer Linear Programming (ILP) is used to model the path planning problem in the so augmented configuration space. The mathematical formulations are implemented and tested using a GUROBI solver. Computational results display the effectiveness of the approach