A novel control scheme utilizing fractional-order terminal sliding mode control with sliding perturbation observer (FOTSMCSPO) is proposed herein. It was used to solve the trajectory tracking problem on a seven-degree-of-freedom robot manipulator. The fractional-order terminal sliding mode in FOTSMCSPO provides a finite convergence time for reaching the sliding surface. A sliding perturbation observer (SPO) is used to estimate the disturbance from the environment and modeling uncertainties. The new control scheme exhibits high precision, fast convergence and robust performance against lumped uncertainties. These advantages are ensured through the newly designed fractional-order terminal sliding surface and the SPO. The stability is analyzed based on the Lyapunov functions for general and fractional-order systems. An implementation on a real robot manipulator demonstrated the effects and performance of the new control method.

This article proposes a method with a potential field for optimizing the configuration of angular velocity to avoid joint limitations while following the desired orientation of the end effector of a redundant manipulator. In the practical application of inverse kinematics for redundant manipulators, the most important tasks include avoiding collisions and maintaining the workspace. The null space projection method has been used to solve inverse kinematics from redundancy with the additional task of avoiding angle limitations. However, because such tasks vary, they can interfere in maintaining the desired orientation and following the end effector's desired trajectory. Furthermore, because of the use of a pseudoinverse matrix, singular value decomposition is applied to each calculation to avoid singularity; however, this increases the calculation time. To resolve these problems, the proposed method optimizes the error between the desired and actual tasks using the potential field method and angular limitation value function. This renders the proposed method more intuitive for assigning additional tasks to the manipulator while avoiding joint limitations and obstacles in real time. In the simulation, the calculation time using the proposed method is confirmed to be shorter than that of the conventional method. Finally, the proposed approach is verified to be capable of avoiding obstacles and angle limitations when the method is applied to a manipulator with seven degrees of freedom in the experiment.

Localization of objects is one of the most important fundamental technology to realize ubiquitous network technology. To realize localization of objects, we construct an absolute positioning system based on RFID and investigate how localization technique can be enhanced by RFID through experiment to measure the position and moving direction of a mobile robot