Manuel Nandayapa

Sinteza bezsenzornog upravljanja silom za fleksibilnog robota korištenjem upravljanja omjerom rezonancija temeljenim na metodi koeficijentnog dijagrama

Generally, the flexible robot system can be modeled as the two-mass system which consists of a motor and load connected by a spring. Thus, its elasticity causes resonance in the system. By using the conventional PID controller, this method cannot perform well in this situation. Much research has proceeded with the aim of reducing vibration. A new effective control method, the resonance ratio control, has been introduced as a new way to guarantee the robustness and suppress the oscillation during task executions for a position and force control. In this paper, three techniques are proposed for improving the performance of resonance ratio control. Firstly, a new multi encoder based disturbance observer (MEDOB) is shown to estimate the disturbance force on the load side. The proposed observer is not necessary to identify the nominal spring coefficient. Secondly, coefficient diagram method (CDM) has been applied to calculate a new gain of the force controller. A new resonance ratio gain has been presented as 2.0. Finally, the MEDOB and load side disturbance observer (LDOB) are employed to identify a spring coefficient of flexible robot system. By using the proposed identification method, it is simple to identify the spring coefficient and easy to implement in the real flexible robot system. The effectiveness of the proposed identification method is verified by simulation and experimental results.

A mobile augmented reality system to support machinery operations in scholar environments

This paper proposes a mobile augmented reality (MAR) system aimed to support students in the use of a milling and lathe machines at a university manufacturing laboratory. The system incorporates 3D models of machinery and tools, text instructions, animations and videos with real processes to enrich the information obtained from the real world. The elements are shown when the user points the camera of a mobile device to specific parts of the machinery, where augmented reality (AR) markers are placed. The main goals of the project were (1) create an AR system that guides inexperienced users in machinery handling and (2) measure the acceptance rate and performance of the system in the school manufacturing laboratory. The guidance is provided by means of virtual information about how to operate the machinery when the trainer is not present. The system was implemented as a mobile app for Android devices and it was tested by 16 students and teachers at the university manufacturing laboratory through a survey. The results of this study revealed that students, laboratory technicians, and teachers had positive opinions and good acceptance about the use of the MAR system in the manufacturing laboratory.

Robust Control of a 3-DOF Helicopter with Input Dead-Zone

This chapter deals with the tracking control problem of a three-degree-of-freedom (3-DOF) helicopter. The system dynamics are given by a mathematical model that considers the existence of a dead-zone phenomenon in the actuators, as well as a first-order dynamic that adds a lag in the system input. This leads to obtain an eighth-order model where the positions are the only available measurements of the system. The control problem is solved using nonlinear \( {\mathcal{H}}_{\infty } \) synthesis of time-varying systems, the dead-zone is compensated using its inverse model, and a reference model is used to deal with the first-order dynamic in the actuators. Numerical results show the effectiveness of the proposed method, which also considers external perturbations and parametric variations.

Applications of Haptic Systems in Virtual Environments: A Brief Review

Haptic systems and virtual environments represent two innovative technologies that have been attractive for the development of applications where the immersion of the user is the main concern. This chapter presents a brief review about applications of haptic systems in virtual environments. Virtual environments will be considered either virtual reality (VR) or augmented reality (AR) by their virtual nature. Even if AR is usually considered an extension of VR, since most of the augmentations of reality are computer graphics, the nature of AR is also virtual and will be taken as a virtual environment. The applications are divided in two main categories, training and assistance. Each category has subsections for the use of haptic systems in virtual environments in education, medicine, and industry. Finally, an alternative category of entertainment is also discussed. Some representative research on each area of application is described to analyze and to discuss which are the trends and challenges related to the applications of haptic systems in virtual environments.

A Methodology for Optimizing the Parameters in a Process of Machining a Workpiece Using Multi-objective Particle Swarm Optimization

In this chapter a methodology based on multi-objective particle swarm optimization algorithm to identify the optimal parameters for machining a workpiece with a milling is presented. The time for machining, the material removal rate, and the feed rate were identified as the objective functions to optimize. In addition, the proposal considered 4 constraints related to cutting tools, rotating speed of the main spindle, cutting depth per passing, and speed interval for advance. Once the objective functions and constraints were determined, two test workpieces with different geometries were designed by an experienced machinist by means of Solidworks® software, and then exported to Mastercam X® in order to generate the G & M codes. The material selected for machining was delrin. In the experimentation stage, the multi-objective particle swarm optimization algorithm proposed was executed 50 times, and the parameters from the 2 and 3 best solutions were used to design 5 new workpieces. From the results obtained it was observed that the methodology proposed can support unexperienced operators in optimizing the parameters for machining. For the first workpiece the machining time was reduced 32.06%, material removal rate was increased 57.38%, and an increment of 14.06% was obtained for the feed rate. Whereas for the second workpiece the values obtained were 42.91, 50.47 and 30.83%, respectively. Multi-objective optimization procedure may be employed for machining parameter optimization of non-simple geometry workpieces.

BLDC motor commutation based on DSP builder for FPGA

Motion Control focus on BLDC motors based on hall effect sensors needs a strategy of voltage commutation between their windings. In this paper an alternative of a BLDC motor commutation based on DSP Builder toolbox is presented. The DSP Builder is a tool to FPGA programming in the Matlab/Simulink environment that reduce the programming complexity. The strategy is based on hall effect sensor signals and a bit of direction to generate the signals that enable the gates of MOSFETs. The strategy of commutation has been verified by simulation and experimentation with a BLDC motor.

Interaction Control Based on Position/Velocity Control by Means of Disturbance Observer

In the typical industrial applications, the object grasping or manipulation is usually implemented on industrial robots. However, the correct object manipulation also implies to avoid damages. On the other hand, interaction is an action which is influenced by other actions between two or more entities. In this paper an alternative method for interaction control, which is a combination of velocity and position controllers based on disturbance observer (DOB) is presented. The proposed control strategy is a velocity control while the gripper is moving without contact with the environment. When an object is reached, the DOB detects the contact force and the control strategy switches to position control, the switching is commanded by a torque threshold compared with the estimated torque. The control strategy is verified by numerical simulation considering an object with predefined stiffness.