Trajectory tracking controller of a robotized arm with joint constraints, a direct adaptive gain with state limitations approach.

Motion restrictions in robotic devices may introduce complex requirements for any closed-loop control design, mainly when the robot joints must track reference trajectories that force the end-effector to perform planned motions. This study summarizes the comprehensive technical design of an adaptive state feedback controller for multi-link robotic manipulators that consider the effect of position and velocity restrictions on the tracking trajectory control approach. The proposed design is less conservative than other methods because of the explicit inclusion of state restrictions in the control gain dynamics. A logarithm barrier Lyapunov function class supports the design of the adaptive gain for the manipulator. Sufficient conditions based on a Riccati equation simplify the implementation of the adaptive controller with gains depending on the distance between the current state and the restriction sets. Numerical simulations show the advantages of the proposed controller with adaptive gains concerning a similar adaptive controller that does not consider the restrictions and a proportional-integral-derivative form. An implementation for the motion control of a robotic arm is presented to demonstrate the development by implementing the proposed gain, which confirms the suggested improvements enforced by the proposed controller. The performed comparison shows the advantages of the suggested adaptive gain control form, inducing better tracking of reference trajectories and smaller control energy applications.

Lower limb prosthesis: Optimization by lattice and four-bar polycentric knee.

Diabetes has brought several health problems; one of the most common is the amputation of the lower limb, for which the development of low-cost lower limb prostheses has taken on an important role to allow people with these injuries to continue independently with their lives. This paper proposes developing a transfemoral prosthesis for a 47-year-old patient with a weight of 100kg and a height of 1.80m. The approach shows the kinematic model of the four-bar mechanism of the knee, following the Denavith-Hartenberg method, and the calculation of the knee angle curve and the gait with the help of OpenSim. Consequently, it is shown the design of the parts of the prosthesis done in Autodesk Fusion 360 and their optimization by a lattice in Creo software. Finally, the stress simulations in Ansys with the materials previously selected in CES EduPack are presented.