An Optoelectronic System for Force-Torque Sensing and Feedback Algorithms Processing

The paper presents the structure of a precise parallel tri-axle manipulator with the functionality of progressing-tilting table. The end effector of the device is a platform, for which three coordinates of position are defined. The manipulator has three degrees of freedom: movement perpendicular to the base and rotation in two mutually perpendicular axes contained in the surface parallel to the base.The concept of the positioning mechanism is based on parallel tripod kinematics where the end effector – the platform – is seated on three active limbs – actuators. The use of parallel kinematics allowed modular construction of the positioning mechanism. The developed modular functional mechanism with minimal number of elements in kinematic chain ensures high positioning resolution. The concept of application of eccentric mechanism for platform positioning is an original idea in this solution. The compact construction allows applying the manipulator in medical devices that require meeting of the hygienic conditions in the medical test and research laboratories. The possibility of the utilisation of the precise manipulator covers wide areas of science and technology where precise positioning of the object is required, e.g. sample positioning for microscopes, scanning systems.

Lessons learned from the STS-120/ISS 10A robotics operations

In this study, we utilized digital twin technology in combination with genetic algorithms to optimize human–robot cooperation in a miniature light bulb assembly production line. First, the digital twin was used to find the robot’s motion trajectory; a digital replica of the assembly system and human was created by combining sensors that track the position and activity characteristics of the human in the workspace, which helped to prevent human–robot conflicts. Then, a multi-adaptive genetic algorithm was applied to calculate optimal ergonomics and create a worker’s movement schedule. To ensure continuous operation and no shortage of materials, the worker must observe and move to the input conveyor and material pallets to supply materials to the system. It aimed to provide more input materials for the assembly line while allowing the worker’s task to take place in parallel with the robotic assembly operation. The algorithm was designed to reduce the number of moves required to obtain materials and to ensure that the robot always had enough materials to assemble along the defined trajectory, thus, saving labor and optimizing the manufacturing process. The combination of a digital twin and multi-adaptive genetic algorithm optimized the robot’s movement path and the number of movements performed by the human operator in parallel.

This paper deals with the development of a special 3+1 Degrees of Freedom (DOFs) end effector used to control the standard laparoscopic instrumentation’s positioning and actuation during laparoscopic surgery. Nowadays, the robotic system da Vinci is the most used robot in the laparoscopic surgery field. The cost of this robot is very high, which limits its spread in hospitals. Moreover, this robot can use only customized tools, called endoWrist, to perform the laparoscopic surgery. This instruments are, however, very expensive and can be used only for few operations, increasing the required economical efforts. The aim of our research is to create an end effector, supported by a navigator arm, able to manipulate standard laparoscopic instruments in order to reduce the cost of the robotic surgery, while keeping most of the advantages introduced by the other robotic systems. The particular structure of the end effector proposed here makes it possible to create a virtual spherical wrist at the insertion point. This solution allows to have the mobility needed to perform the surgery and to avoid excessive stress to the patient skin. The main disadvantage is represented by the DOFs of the standard laparoscopic tools that are less than in the endoWrists. However, the proposed end effector allows to manipulate standard laparoscopic tools smaller than customized robotic instruments, which is a fundamental feature in neonatal and paediatric surgery.

Bimanual robots have been studied for decades and regulation on internal force of the being held object by two manipulators becomes a research interest in recent years. In this paper, based on impedance model, a method to obtain the optimal target position for bimanual robots to hold an object is proposed. We introduce a cost function combining the errors of the force and the position and manage to minimize its value to gain the optimal coordinates for the robot end effectors (EE). To implement this method, two necessary algorithms are presented, which are the closed-loop inverse kinematics (CLIK) method to work out joint positions from desired EE pose and the generalized-momentum-based external force observer to measure the subjected force acting on the EE so as to properly compensate for the joint torques. To verify the effectiveness, practicality, and adaptivity of the proposed scheme, in the simulation, a bimanual robot system with three degrees of freedom (DOF) in every manipulator was constructed and employed to hold an object, where the results are satisfactory.

In this paper, a learning control algorithm for the motion and force of a direct-drive robot, which has a variable table and six degrees of freedom (d. o. f.), is proposed for a task in constrained work space. The five-d. o. f. relative motion of an end effector attached to the wrist of the robot arm and the internal force between the end effector and the table through an object are achieved by utilizing the redundancy to avoid interference with the object. A hybrid controller for an end effector and a position controller for a robot arm are used. Under the over-constrained conditions, which are imposed by the two tasks stated above, a learning control algorithm using neural networks (NN's)is employed to control an end effector with higher priority than the robot arm. The proposed control algorithm is applied to an experiment on the control of both the position of an end effector and the contact force on the surface of the object while avoiding interference with the object. As a result, it has been shown that the trajectories of robot joints can be generated in real-time computation and a high accuracy of the end effector is obtained after the completion of learning. The effectiveness of the proposed control algorithm is demonstrated by the experiment.

Smart Actuators in Robotics

Analyses are continuing in the Man-Systems Division of NASA Johnson Space Center, on the restructured Space Station Freedom (SSF). Viewing requirements for the SSF indicate that assembly and extravehicular crew operations should be viewed by direct means whenever possible. To analyze the extent to which the Cupola meets this requirement, positions on the port side of Node 2 and the zenith side of Node 1 were evaluated. These analyses utilized the tasks from Mission Build (MB) 6 through 16 to investigate these two Node positions. The analyses conducted were based on a 4-position rating scale (Excellent, Good, Marginal, and Inadequate) which solicited data from both expert crewmembers and specialists in the field of robotic assembly operations. To remedy the potential direct viewing problems identified through this investigation, it was recommended that additional camera ports be placed along the truss and on the modules to provide indirect orthogonal viewing for berthing operations and pressurized module attachment. It was also recommended that additional Node positions be investigated to determine the optimal location for the Cupola based on crew considerations, direct viewing requirements, lighting issues, and operational tasking issues.

An assessment of industrial robots: Capabilities, economics, and impacts

The aim of this paper is to present the design and development of a safe and reliable autonomous cat toy for the purposes of entertaining pet cats when human interaction is not feasible. The proposed Autonomous Feline Entertainment Robot (AFER), an autonomous cat toy, is comprised of a table-mounted base, and a robotic arm with two linkages. The AFER Version 1(vl) has a cat-toy affixed to the end of a linkage as the end effector, while the AFER Version 2 (v2) has a passive joint with a string to which a cat toy end effector is attached. The AFER v1 has 2 Degrees of Freedom (DOF), while the AFER v2 has 3DOF, and both are actuated by servomotors interfaced with an Arduino microcontroller. In order to enable maximum functionality, the AFER is designed with multiple movement patterns or modes for play, as well as the ability to change the specific end effector of the toy. Position control was used for the motion and trajectory planning when developing the movement patterns. The interaction between AFER and two kittens has been evaluated in an experimental scenario, and the results show satisfactory and safe interactions. The AFER can be used as a model for studying effective animal-robot interactions and pet entertainment.

: A configuration of an articulated figure of joints and segments can sometimes be specified as spatial constraints. Constrained parts on the articulated figure are abstracted as end effectors, and the counterparts in the space are abstracted as goals. The goal (constraint) can be as simple as a position, an orientation, a weighted combination of position and orientation, a line, a plane, a direction, and so on, or it could be as complicated as a region in the space. An articulated figure consists of various segments connected together by joints has some degrees of freedom which are subject to joint limits and manual adjustment. This paper presents an efficient algorithm to adjust the joint angles subject to joint limits so that the set of end effectors concurrently attempt to achieve their respective goals. Users specify end effectors and goals: the program computes a final configuration in real time in the sense that actions appear to take no longer than actual physical activities would. If it is impossible to satisfy all the goals owing to the actual constraints, the program should end up with the best possibility according to the user's assignment of importances to each goal. (kr)

Calcul de la matrice Jacobienne nécessaire à la commande coordonnée d'un manipulateur

In the last twenty years genetic algorithms (GAs) were applied in a plethora of fields such as: control, system identification, robotics, planning and scheduling, image processing, and pattern and speech recognition (Back et al., 1997). In robotics the problems of trajectory planning, collision avoidance and manipulator structure design considering a single criteria has been solved using several techniques (Alander, 2003). Most engineering applications require the optimization of several criteria simultaneously. Often the problems are complex, include discrete and continuous variables and there is no prior knowledge about the search space. These kind of problems are very more complex, since they consider multiple design criteria simultaneously within the optimization procedure. This is known as a multi-criteria (or multiobjective) optimization, that has been addressed successfully through GAs (Deb, 2001). The overall aim of multi-criteria evolutionary algorithms is to achieve a set of non-dominated optimal solutions known as Pareto front. At the end of the optimization procedure, instead of a single optimal (or near optimal) solution, the decision maker can select a solution from the Pareto front. Some of the key issues in multi-criteria GAs are: i) the number of objectives, ii) to obtain a Pareto front as wide as possible and iii) to achieve a Pareto front uniformly spread. Indeed, multi-objective techniques using GAs have been increasing in relevance as a research area. In 1989, Goldberg suggested the use of a GA to solve multi-objective problems and since then other researchers have been developing new methods, such as the multi-objective genetic algorithm (MOGA) (Fonseca & Fleming, 1995), the non-dominated sorted genetic algorithm (NSGA) (Deb, 2001), and the niched Pareto genetic algorithm (NPGA) (Horn et al., 1994), among several other variants (Coello, 1998). In this work the trajectory planning problem considers: i) robots with 2 and 3 degrees of freedom (dof ), ii) the inclusion of obstacles in the workspace and iii) up to five criteria that are used to qualify the evolving trajectory, namely the: joint traveling distance, joint velocity, end effector / Cartesian distance, end effector / Cartesian velocity and energy involved. These criteria are used to minimize the joint 27

This paper presents a generalised framework of an image based visual servoing of an articulated arm which has to be deployed inside a simulated Tokamak vessel environment. First wall tiles of the vessel idealised as rectangular grids on a surface are inspected and an attempt is made to replace the damaged tiles with a tile-screwing gripper mechanism. The mechanism of gripper provides compactness and high torque capacity in gripping with pitch and roll as degrees of freedom. The gripper is considered as a class of unknown nonlinear discrete-time system. The gripper mechanism is implemented for unscrewing a square headed screw on the first wall tiles of the vessel. Various stages of tile handling task are explained in detail with theoretical modeling. The vision sensing methodology of the proposed arm is explained. The arm has a camera located at the wrist (end effector) and the control action has to be taken in place at joint level. The kinematics of the manipulator, vision system employed are explained. The preliminary results are illustrated. The camera attached to the end effector and the captured image processing for prediction of type of fault and the gripper tactile sensing issues as well the faulty tile removal are explained.

The authors present the mechanical design of a robotic end-effector which has six degrees of freedom and was built to study autonomous robotic assembly in space. The end-effector's design is based on the mechanism of the Stewart platform. The end-effector consists mainly of two platforms coupled by six linear actuators driven by DC motors. Position feedback is achieved by six linear displacement transducers (LDTs) mounted along the actuators to measure their length variations. Computations are performed to select proper DC motors, ballscrews, LDTs, and platform parameters so that a set of design specifications, including resolution of platform, accuracy, speed, and lifting capability, is satisfied.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>