Feasible Arm Configurations and its Application for Human-Like Motion Control of S-R-S-Redundant Manipulators with Multiple Constraints

This paper presents a general framework for human-like motion control of 7-DOF S-R-S-redundant manipulators. The new framework simultaneously accomplishes five objectives: Cartesian trajectory tracking, obstacle avoidance, joint limit avoidance, human-like movement, and a feasibility evaluation of the Cartesian trajectory.We exhaustively compute all feasible arm configurations. This allows for quick evaluations of the feasibility of the Cartesian trajectories. They are applied to inverse kinematics of the redundant manipulator to improve the capability to handle multiple constraints, and enable the manipulator to imitate human movements. The efficiency of the proposed framework is demonstrated by kinematic experiments with a humanoid robot.

Emulation of pilot control behavior across a Stewart platform simulator

This paper presents a model-based controller consisting of a feedback linearization scheme and a state-dependent proportional derivative (PD) controller adapted to a parallel flight simulator Stewart mechanism. This parallel robot is considered to emulate motions of highly maneuverable aircrafts, which require well-trained pilots. The simulations are based upon a reduced-model prototype built in order to verify kinematic design aspects and control laws. Indeterminacies in the mass distribution of the system will generally affect model-based controllers, necessitating compensation or the employment of robust control methods. Through introducing the pilot's sensorial feedback of acceleration, the pilot's behavior in giving commands is emulated via an optimization process, which tunes the controller coefficients accordingly. Stability of the designed control system is guaranteed via the Lyapunov approach. To further explore the system through perilous flight scenarios, three pre-designed maneuvers are selected as test cases. It is expected that closed-loop control tasks in which a pilot tracks a target, while at the same time the controller rejects disturbances and adapts itself to the pilot's progressive skills, are ameliorated through this arrangement. Numerical results show that the proposed method is found robust in the training process in conditions of parameters indeterminacy.

Obstacle Avoidance Path Planning of Planar Redundant Manipulators Using Workspace Density

This paper presents a new approach to generate the workspace of planar redundant manipulators based on the workspace density of a single link. The workspace density of planar serial redundant manipulators can be computed efficiently by using the concept of the Fourier transform for the group of rigid-body motions of the plane and the convolution theorem. For manipulators using discrete actuation, it is important to study not only the shape of the workspace, but also the density of reachable poses in the workspace. In this paper, we focus on using the workspace density to calculate collision-free paths in complex environments with multiple obstacles in the workspace of the manipulator. This paper presents the algorithm and demonstrates it effectiveness using simulation results.

Configuration comparison among kinematically optimized continuum manipulators for robotic surgeries through a single access port

Many recent developments of surgical robots focus on less invasive paradigms, such as laparoscopic SPA (Single Port Access) surgery, NOTES (Natural Orifice Translumenal Endoscopic Surgery), laryngoscopic MIS (Minimally Invasive Surgery), etc. A configuration similarity shared by these surgical robots is that two or more manipulators are inserted through one access port (a laparoscope, an endoscope, or a laryngoscope) for surgical interventions. However, upon designing such a surgical robot, the structure of the inserted manipulators has not been thoroughly explored based on evaluation of their performances. This paper presents a comparison for kinematic performances among three different continuum manipulators. They all could be applied in the aforementioned surgical robots. The structural parameters of these continuum manipulators are firstly optimized to assure a more fair and consistent comparison. This study is conducted in a dimensionless manner and provides scalable results for a wide spectrum of continuum manipulator designs as long as their segments have a constant curvature. The results could serve as a design reference for future developments of surgical robots which use one access port and continuum mechanisms.