396 research outputs found
A light weight arm designed with modular joints
No full textThe conventional industrial manipulator has some drawbacks such as low payload-weight ratio, bulky structure and high power consumption, which limit their applications in such areas a space, anti-terrorism, service and medical robots. To overcome these shortcomings, a novel lightweight arm was developed based on modular joints, modular connection and light shaft structures. This paper discusses the general requirements for lightweight robots, upon which the new robot was designed. Both mechanics and electronics designs are presented. The development work of a prototype is described. Preliminary tests were conducted to evaluate the performance of the light weight arm. The results demonstrate the good performances of the prototype and validate the feasibility of the new robot system.</p
Compliance Modeling and Error Compensation of a 3-Parallelogram Lightweight Robotic Arm
No full textThis paper presents compliance modeling and error compensation for lightweight robotic arms built with parallelogram linkages, i.e., Π joints. The Cartesian stiffness matrix is derived using the virtual joint method. Based on the developed stiffness model, a method to compensate the compliance error is introduced, being illustrated with a 3-parallelogram robot in the application of pick-and-place operation. The results show that this compensation method can effectively improve the operation accuracy
Singularity analysis of 2R1P spherical parallel mechanisms
No full textThis paper studies the possible configurations and singularities of 3-DOF spherical parallel mechanisms with revolute and prismatic pairs. In particular, the 2R1P spherical parallel mechanisms are studied, for which the kinematic models are established and Jacobian matrices are derived. Three kinds of singularities, namely the boundary, configuration and structure singularities, are identified and analyzed for RRP, PRR and RPR type of spherical parallel mechanisms. The results can be used for further modeling and analysis on workspace and trajectory planning of 3-DOF spherical parallel mechanisms towards the practical application of the kind of mechanisms.</p
Design Analysis and Dynamic Modeling of a High-Speed 3T1R Pick-and-Place Parallel Robot
No full textThis paper introduces a four degree-of-freedom parallel robot producing three translation and one rotation (Schönflies motion). This robot can generate a rectangular workspace that is close to the applicable work envelope and suitable for pick-and-place operations. The kinematics of the robot is studied to analyze the workspace and the isocontours of the local dexterity over the representative regular workspace are visualized. The simplified dynamics is modeled and compared with Adams model to show its effectiveness
Design of a Passive Exoskeleton for the Upper Extremity through Co-simulation with a Biomechanical Human Arm Model
No full textAn approach of designing exoskeletons on the basis of simulation of the exoskeleton and a human body model is proposed in this paper. The new approach, addressing the problem of physical human-exoskeleton interactions, models and simulates the mechanics for both the exoskeleton and the human body, which allows designers to analyze and evaluate an exoskeleton for its functioning, effectively. A simulation platform is developed by integrating a biomechanical model of human body and the exoskeleton. With the proposed approach, two types of exoskeletons with gravity compensating capability are designed for assisting patients with neuromuscular injuries. Results of the design analysis and optimization are included
Design and Analysis of a Compliant Shoulder Mechanism for Assistive Exoskeletons
No full textIn this thesis the design and analysis of a passive exoskeleton to assist the elderly and workers for overhead tasks are presented. The scope of the exoskeleton is to compensate for the gravitational forces. The exoskeleton consists of a spherical shoulder mechanism and a passive variable stiffness mechanism. Both mechanisms are described and further ideas are presented. Numerical, analytical and experimental analyses of the variable stiffness mechanism are carried out and compared. Furthermore, topology optimisation is performed to reduce weight. The exoskeleton focuses on assistance in the sagittal plane, but due to the properties of the modules, also motion in different planes is supported. The final design compensates for of the gravitational torque of the arm with the elbow stretched
Neural Network PID Control of a Variable-Stiffness Shoulder Exoskeleton with Load Prediction
No full textDevelopment of a Passive Lower Body Exoskeleton with Novel Compliant Joints for Walking Assistance
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