Luis E. Ramos-Velasco

Visual Servoing for an Inverted Pendulum Using a Digital Signal Processor

This paper discusses the visual servo control of the inverted pendulum system under fixed-camera configuration. The control goal is to stabilize the system using a vision system equipped with a fixed camera to observe the system and a digital signal processor. It presents a control scheme based on the combination of a linear control and the visual feedback. The paper ends with the presentation of several experimental results

Vision Based Control of an Underactuated System Using a Reduced Observer

We present a simulation and partial experimental results in visual servo control of an underactuated system with a dynamic feedback controller from an uncalibrated camera. We incorporate a richer sensing, such as vision, into traditional feedback control schemes

A self-tuning of a wavelet PID controller

In this paper a self-tuning wavelet PID controller using wavelet networks is presented. The wavelet-based multiresolution PID controller was purpose by [8], the ability of this controller is to provide good rejection to disturbances and smooth control signal. One of its disadvantages is that the tuning gains are in trial or error mode. A wavelet network to identify the system and to tune the gains of the wavelet PID controller is proposed. To validate the proposed control system numerical simulation is performed for a motion control system.

Fuzzy iterative learning control applied in a biological reactor using a reduced number of measures

Iterative learning control applied to a biotechnological process.It was used a sample time of one hour to known the concentrations in the process because there are not on-line sensors.Fuzzy logic improves convergence in the control.A theorem is given to have an idea for the gain that guarantees convergence.Due theoretic results, interpolation is made to satisfy the theorem proposed. There exist some processes difficult to control as the chemical ones, a common problem takes place when the output cannot be measured on-line, and so, closed-loop control cannot be implemented. In this work an iterative learning control type proportional-derivative is analyzed and theoretical results are shown, this control is applied to a biological reactor to degrade phenol by working in discontinuous batch state, as the measures of the substrata concentrations are taken by hand, it was proposed to have a sample time of one hour. To guarantee convergence and to improve the control, cubic splines were used to interpolate the measures. Fuzzy logic was used to compute the control gains used to build the control signal. Simulation results are shown and the control signals are presented through iterations, here it is possible to see that the error is smaller using fuzzy logic to compute the control signal when iterations run.

Suboptimal robust linear Visual Servoing for an underactuated system with delays

This article synthesized suboptimal control for an underactuated system with delays; it also presents a robust stability dependent to delay. Using dynamic programming, an optimal quadratic regulator (LQR) controller is synthesized, which is then applied to a linear matrix inequality, giving delay-dependent sufficient conditions. This delay is analyzed for both time-invariant case and for time-variant case. We presented an application in Visual Servoing for the inverted pendulum.

Model-free adaptive controller for autonomous aerial transportation of suspended loads with unknown characteristics

Due to the highly uncertain and dynamic nature of military conflict and planetary exploration missions, enabling aerial and terrestrial unmanned autonomous systems (UAS) to gracefully adapt to mission and environmental changes is a very challenging task. In particular, the United States Army, Air Force, Navy, and NASA have recently shown interest in the task of load transportation by means of UAS, which rely heavily on the knowledge of both the UAS model and the load dynamics to function. Most of the currently available autopilot systems for UAS were built without suspended load transportation capabilities and are thus not appropriate, for example, to assist soldiers or planetary explorers in the tasks of carrying and deploying supplies, transporting injured people, or warfare. This research provides knowledge to the problem of autonomous suspended load transportation, attending national agencies expectations that UAS will perform in a reliable manner even in the challenging situation when loads of uncertain characteristics are transported and deployed, which heavily modify the UAS dynamic during the execution of the task. This work presents a novel model-free adaptive wavenet PID (AWPID)-based controller for enabling aerial UAS to transport cable suspended loads of unknown characteristics. In order to accomplish this goal, a control design is presented which enables the UAS to perform a trajectory tracking task, based solely on the knowledge of the UAS position. The methodology proposes a novel structure, which identifies inverse error dynamics using a radial basis neural network with daughter Mexican hat wavelets activation function. A real-time load transportation mission consisting of a multi-rotorcraft UAS carrying a cable suspended load of unknown characteristics validates the effectiveness of the trajectory tracking control strategy, showing smooth control signals even when the mathematical model of the aerial UAS and load dynamics are not known.

Kinematics Modeling and Experimental Validation of a CyberForce Haptic Device Based on Passive Control System

This paper shows the experimental validation of the forward and inverse kinematic model (position and velocity), of the CyberForce haptic device (CHD). For trajectory tracking is used a passive control technique in operational coordinates (cartesian workspace) and its experimental results in the joint-space. The contribution in passive haptic guidance, is on virtual maze navigation with purposes of diagnosis and rehabilitation of upper limb, and training only as a proof platform without any patients, to this end, for the motion planning is used a time base generator for tracking in finite time.

CyberForce Haptic Device: Kinematics and Manipulability

The position and differential kinematics, for a haptic device, represent the mathematical model that describes the behavior and evolution of its spatial geometry. Contributions in a Human-Robot Physical Interaction system, are: i) operational cartesian motion planning and verification of performance on tasks of passive haptic guidance, ii) torque / force relationship through the analytical Jacobian matrix with purposes in active haptic exploration, iii) the kinematic manipulability analysis in real-time and re-planning paths. In this paper obtaining the position and differential kinematics as well as simulation and experimental validations, for a CyberForce haptic device in its position kinematics chain.

Kinesthetic Guided with Graphotherapeutic Purposes

This paper presents the design, construction and implementation of a calligraphic platform with biomedical applications. This technological tool could be employed in physiotherapy to recover the loss of calligraphic abilities caused by common psychomotor disorders such as dyslexia and brain stroke. The experimental platform allow to define the motion performance (physical interaction variables), in particular on upper limbs. the patient is guided through the end effector of a haptic device; to this end is used a nonlinear control in closed loop with the human operator, with language symbols as a trajectory tracking. This allows that the user can be a passive human, so the control law designed is based on passivity theory and sliding mode to achieve stability and security in human machine interaction. The haptic system described, is designed to improve the physiotherapeutic tasks by supplying the motion measurement (position/velocity) and its errors. Preliminary tests using this novel system demonstrated a significative influence on regain functions in patients with psychomotor disorders.

Experimental results: Suboptimal robust linear visual servoing with delay for an underactuated system

This article synthesized suboptimal control for an underactuated system with delays; it also presents delay-dependent robust stability. A linear quadratic regulator (LQR) controller is synthesized using dynamic programming, which is applied to a linear matrix inequality, giving delay-dependent sufficient conditions. This delay is analyzed for time-invariant and time-variant case. We presented experimental results of the Visual Servoing for the inverted pendulum.