INTERNATIONAL JOURNAL OF ROBOTICS
Year:2015 | Volume:4 | Issue:3|Papers Count:5

Although construction has been known as a highly complex application field for autonomous robotic systems, recent advances in this field offer great hope for using robotic capabilities to develop automated construction. Today, space research agencies seek to build infrastructures without human intervention, and construction companies look to robots with the potential to improve construction quality, efficiency, and safety, not to mention flexibility in architectural design. However, unlike production robots used, for instance, in automotive industries, autonomous robots should be designed with special consideration for challenges such as the complexity of the cluttered and dynamic working space, human-robot interactions and inaccuracy in positioning due to the nature of mobile systems and the lack of affordable and precise self-positioning solutions. This paper briefly reviews state-of-the-art research into automated construction by autonomous mobile robots. We address and classify the relevant studies in terms of applications, materials, and robotic systems. We also identify ongoing challenges and discuss about future robotic requirements for automated construction.

Designing the self-balancing two-wheeled mobile robots and reducing undesired vibrations are of great importance. For this purpose, the majority of researches are focused on application of relatively complex control approaches without improving the robot structure. Therefore, in this paper we introduce a new two-wheeled mobile robot which, despite its relative simple structure, fulfills the required level of self-balancing without applying any certain complex controller. To reach this goal, the robot structure is designed in a way that its center of gravity is located below the wheels' axle level. The attention is more paid to obtaining a self-balancing model in which the robot’s arms and other equipment follow relatively low oscillations when the robot is subjected to a sudden change. After assembling the robot using the Sim-Mechanics toolbox of Matlab, several simulations are arranged to investigate the robot ability in fulfilling the required tasks. Further verifications are carried out by performing various experiments on the real model. Based on the obtained results, an acceptable level of balancing, oscillation reduction, and power supply is observed. To promote the self-balancing two-wheeled mobile manipulator, its platform is modified to climb high obstacles. In order to obtain this aim, some transformations are done in mechanical aspects like wheels, arms and main body without any increase in DOFs. The robot is supposed to follow proposed motion calculated according to stability criteria. The kinematic equations are utilized to find a possible motion. In a dynamic simulation, the robot ability in passing over an obstacle is verified.

This research focuses on proposing an optimal trajectory planning and control method of two link rigid-flexible manipulators (TLRFM) for Dynamic Object Manipulation (DOM) missions. For the first time, achievement of DOM task using a rotating one flexible link robot was taken into account in [20]. The authors do not aim to contribute on either trajectory tracking or vibration control of the End-Effector (EE) of the manipulator; On the contrary, utilizing the powerful tool optimal control accomplishing a point-to-point task for TLRFM is the purpose of the current research. Towards this goal, the pseudospectral method will be developed to meet the optimality conditions subject to system dynamics and boundary conditions. The complicated optimal trajectory planning is formulated as a nonlinear programming problem and solved by SNOPT nonlinear solver. To make robust the response of optimal control against external disturbances as well as model parameter uncertainties, the control partitioning concept is employed.The controlled input is composed of an optimal control-based feedforward part and a PID-based feedback component. The obtained simulation results reveal the usefulness and robustness of the developed composite scheme, in DOM missions.

In this study, a novel variable impedance control for a lower-limb rehabilitation robotic system using voltage control strategy is presented. The majority of existing control approaches are based on control torque strategy, which require the knowledge of robot dynamics as well as dynamic of patients. This requires the controller to overcome complex problems such as uncertainties and nonlinearities involved in the dynamic of the system, robot and patients. On the other hand, how impedance parameters must be selected is a serious question in control system design for rehabilitation robots. To resolve these problems this paper, presents a variable impedance control based on the voltage control strategy. In contrast to the usual current-based (torque mode) the use of motor dynamics lees to a computationally faster and more realistic voltage-base controller. The most important advantage of the proposed control strategy is that the nonlinear dynamic of rehabilitation robot is handled as an external load, hence the control law is free from robot dynamic and the impedance controller is computationally simpler, faster and more robust with negligible tracking error. Moreover, variable impedance parameters based on Interval Type-2 Fuzzy Logic (IT2Fl) is proposed to evaluate impedance parameters. The proposed control is verified by a stability analysis. To illustrate the effectiveness of the control approach, a 1-DOF lower-limb rehabilitation robot is designed. Voltage-based impedance control are simulated through a therapeutic exercise consist of Isometric and Isotonic exercises. Simulation results show that the proposed voltage-based variable impedance control is superior to voltage-based impedance control in therapeutic exercises.

A new type of backbone robot is presented in this paper. The core idea is to use a cross shape mechanism with the principle of functioning of the scissors linkages, known as a pantograph. Although this continuum arm acts quite similar to tendon-driven robot, this manipulator does not include any tendon in its structure. This design does not suffer from the weaknesses of the continuum design such as low payload and coarse positioning accuracy. Kinematic model is developed and the equation of motion for this arm is derived by Lagrange's method. The work envelope and the occupied space investigation are supposed to be established on the comparison between tendon-based model as the common backbone models and our proposed idea. The results show the effectiveness of the backbone design.