Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Force

Modeling and Force-Position Controller Design of Rehabilitation Robot for Human Arm Movements

Mohammed Y. Hassan; Zeyad A. Karam

Engineering and Technology Journal, 2014, Volume 32, Issue 8, Pages 2079-2095

Physical disabilities such as full or partial loss of function in the shoulder, elbow or wrist is a common impairment in the elderly, and can also be a secondary effect due to strokes, trauma, sports injuries, and occupational injuries. Rehabilitation programs are the main method to promote functional recovery in these subjects.
This work focuses on designing and nonlinear modeling of 3DOF non-wearable rehabilitation robot for rehabilitee the upper limbs in human body. The structure of this robot will eliminate singularity problem by depending on articulated configuration through adding shoulder offset to the robot base. The nonlinear modeling of a rehabilitation robot including kinematic and dynamic models is done for three degrees of freedom, with the effect of friction term in robot actuator.
Three Intelligent Force-Position controllers, PD-like Fuzzy logic controllers are designed for position control and P controllers for force control, for moving the shoulder and elbow joints of the rehabilitation robot at desired trajectories. These controllers were tuned in order to make the robot end effecter tracking the desired medical trajectories in a specific time with minimum overshoot, minimum settling time and minimum steady state error. Each controller is tested by applying different trajectories with the application of external disturbances on the robot body.
A comparison between the proposed intelligent controllers and conventional PD Force-Position controllers shows superior of the intelligent type of controller to make the end effecter follow the desired trajectory compared with the use of conventional controllers.

Effect of Boundary Conditions on Impact Resistance of Concrete Slabs

Eyad K. Sayhood; Nisreen S.Mohammed; Sabah K. Muslih

Engineering and Technology Journal, 2013, Volume 31, Issue 5, Pages 841-860

A theoretical analysis based on the numerical solution of the slab impact integral equation is carried out to determine the impact force and deflection time histories, the strain energy absorbed by the slabs and the maximum bending moment.
Effect of slab boundary conditions on impact response of slab is also discussed. The theoretical results obtained in the present analysis are compared with experimental and theoretical works previously done. A good agreement is found between theoretical and experimental results. This indicates that the impact resistance of relatively large slabs may be predicted by using the theoretical approach based on equation of undamped slab vibration. All the derivations required to predict the effect of boundary conditions are performed for both forced and free vibrations. For the same falling mass and the same applied kinetic energy (height of drop) for all cases, the maximum central deflection and the maximum impact force are affected by the boundary conditions of the slabs