Current Issue : October - December Volume : 2018 Issue Number : 4 Articles : 5 Articles
This paper addresses the explicit force regulation problem for robot manipulators in interaction tasks. A new family of explicit\nforce-control schemes is presented, which includes a term driven by a large class of saturated-type hyperbolic functions to handle\nthe force error. Also, an active velocity damping term with the purpose of obtaining energy dissipation on the contact surface is\nincorporated plus compensation for gravity. In order to ensure asymptotic stability of the closed-loop system equilibrium point in\nCartesian space, we propose a strict Lyapunov function. A force sensor placed at the end-effector of the robotmanipulator is used in\norder to feed back themeasure of the force error in the closed-loop, and an experimental comparison of the performanceL2-norm\nbetween 5 explicit force control schemes, which are the classical proportional-derivative (PD), arctangent, and square-root controls\nand twomembers of the proposed control family, on a two-degree-of-freedom, direct-drive robot manipulator, is presented....
This paper addresses the problem of finding robot configurations to grasp assembly parts during a sequence of collaborative\nassembly operations. We formulate the search for such configurations as a constraint satisfaction problem (CSP). Collision\nconstraints in an operation and transfer constraints between operations determine the sets of feasible robot configurations.We\nshow that solving the connected constraint graph with off-the-shelf CSP algorithms can quickly become infeasible even for\na few sequential assembly operations. We present an algorithm which, through the assumption of feasible regrasps, divides\nthe CSP into independent smaller problems that can be solved exponentially faster. The algorithm then uses local search\ntechniques to improve this solution by removing a gradually increasing number of regrasps from the plan. The algorithm\nenables the user to stop the planner anytime and use the current best plan if the cost of removing regrasps from the plan\nexceeds the cost of executing those regrasps. We present simulation experiments to compare our algorithm�s performance to\na naive algorithm which directly solves the connected constraint graph. We also present a physical robot system which uses\nthe output of our planner to grasp and bring parts together in assembly configurations....
The older adult population is increasing worldwide, leading to an increased need for care providers. An insufficient number of\nprofessional caregivers will lead to a demand for robot care providers to mitigate this need. Trust is an essential element for older\nadults and robot care providers to work effectively. Trust is context dependent. Therefore, we need to understand what older adults\nwould need to trust robot care providers, in this specific home-care context.This mixed methods study explored what older adults,\nwho currently receive assistance from caregivers, perceive as supporting trust in robot care providers within four common homecare\ntasks: bathing, transferring, medication assistance, and household tasks. Older adults reported three main dimensions that\nsupport trust: professional skills, personal traits, and communication. Each of these had subthemes including those identified in\nprior human-robot trust literature such as ability, reliability, and safety. In addition, new dimensions perceived to impact trust\nemerged such as the robot�s benevolence, the material of the robot, and the companionability of the robot. The results from this\nstudy demonstrate that the older adult-robot care provider context has unique dimensions related to trust that should be considered\nwhen designing robots for home-care tasks....
Inspired by the dynamic gait adopted by gecko, we had put forward GPL (Gecko-inspired mechanism with a Pendular waist and\nLinear legs) model with one passive waist and four active linear legs. To further develop dynamic gait and reduce energy\nconsumption of climbing robot based on the GPL model, the gait design and trajectory planning are addressed in this paper.\nAccording to kinematics and dynamics of GPL, the trot gait and continuity analysis are executed. The effects of structural\nparameters on the supporting forces are analyzed. Moreover, the trajectory of the waist is optimized based on system energy\nconsumption. Finally, a bioinspired robot is developed and the prototype experiment results show that the larger body length\nratio, a certain elasticity of the waist joint, and the optimized trajectory contribute to a decrease in the supporting forces and\nreduction in system energy consumption, especially negative forces on supporting feet. Further, the results in our experiments\npartly explain the reasonability of quadruped reptile�s kinesiology during dynamic gait....
This review aims to compare existing robot-assisted ankle rehabilitation techniques in terms of robot design. Included studies\nmainly consist of selected papers in two published reviews involving a variety of robot-assisted ankle rehabilitation techniques.\nA free search was also made in Google Scholar and Scopus by using keywords ââ?¬Å?ankleâË?â??,ââ?¬Â and ââ?¬Å?robotâË?â??,ââ?¬Â and (ââ?¬Å?rehabilitatâË?â??ââ?¬Â or\nââ?¬Å?treatâË?â??ââ?¬Â). The search is limited to English-language articles published between January 1980 and September 2016. Results show\nthat existing robot-assisted ankle rehabilitation techniques can be classified into wearable exoskeleton and platform-based\ndevices. Platform-based devices are mostly developed for the treatment of a variety of ankle musculoskeletal and neurological\ninjuries, while wearable ones focus more on ankle-related gait training. In terms of robot design, comparative analysis indicates\nthat an ideal ankle rehabilitation robot should have aligned rotation center as the ankle joint, appropriate workspace, and\nactuation torque, no matter how many degrees of freedom (DOFs) it has. Single-DOF ankle robots are mostly developed for\nspecific applications, while multi-DOF devices are more suitable for comprehensive ankle rehabilitation exercises. Other factors\nincluding posture adjustability and sensing functions should also be considered to promote related clinical applications. An\nankle rehabilitation robot with reconfigurability to maximize its functions will be a new research point towards optimal design,\nespecially on parallel mechanisms....
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