Robustness analysis of fractional order PID for an electrical aerial platform

This work was performed to objectively measure and assess the robustness and tracking performance of fractional order of proportional, integral and derivative (FOPID) controller as compared to the conventional PID control. In satellite research and development, the satellite undergoes numerous tests such as thermal, acoustic and vibration tests in the cleanroom environment. However, due to space limitation in the cleanroom and the sensitive components of the satellite, it requires vibration-free, smooth and precise motion when handling the satellite. In addition, measurement interference might occur due to cable routing during procedures or tasks performed by an operator. Unlike the previous work, the robustness analysis of FOPID controller was not systematically conducted. In this paper, the analysis took into account the actuator dynamics, and various tests were considered to measure the robustness of FOPID controller. The designed FOPID controller was implemented on the scissor-type lifting mechanism of motorized adjustable vertical platform (MAVeP) model, and its performance was compared with the traditional PID controller. A comprehensive verification using MATLAB and Solidworks was carried out to generate the model and conduct the analysis. Both controllers were initially tuned using Nichol-Ziegler technique, and the additional FOPID controller parameters was tuned using the Astrom-Hagglund method. From the simulation work, it was found that the FOPID controller’s tracking error was reduced between 10 % - 50 % for the disturbance rejection tests and reference to disturbance ratio (RDR) spectrum was higher as compared to PID. The analysis in this paper was predicted to be the main driver to implement FOPID controller in the complex system in the industry, especially for sensitive material handling and transportation such as satellite

Analysis and practical validation on a multi-linkage scissor platforms drive system for the satellite test facilities

This paper evaluates a modified structural analysis in measuring the reaction forces on the multi-linkage scissor mechanism driven by a ball-screw system. The proposed structural-virtual work (SV) analysis takes into account all reaction forces on the designed linkages to evaluate the accurate sizing of the actuator and as the consequence, the overall machinery development cost will be significantly reduced. The idea is proven in three ways: analytical analysis, simulation analysis, and experimental analysis based on the developed prototype. The simulation study has shown that the estimated torque is successfully reduced by 29% as compared to the conventional approach. The superiority of the proposed analysis is confirmed by 12% error between the simulation and results from the developed prototype. The successful method proposed in this paper can be further used for all multi-linkage systems in the heavy-vehicle industry that require accurate sizing of the actuators

Design of mechanisms with scissor linear joints for swept volume reduction

International audienceThis paper addresses the optimal design of a new parallel robot, the Expteron, in which a networked scissor used as linear joint allows to reduce the swept volume of the kinematics chains. This robot is based on the Tripteron robot where the passive elbows constituted by two bars and three revolute joints are replaced by a set of networked scissors. By changing the architecture of the leg, only one working mode stands for each leg. The design is conducted on the basis of one prescribed cubic Cartesian workspace. The number of loops in the networked scissors are computed to avoid self-interference and to reduce the swept volume. A finite element analysis is made to define a preliminary stiffness model to predict the bending deformation when the mobile platform are subjected to unidirectional forces along the z-axis

MAKASLI BİR PLATFORM İÇİN YÜKSELME SÜRESİ VE HİDROLİK SİLİNDİR KUVVETİNE ETKİ EDEN TASARIM PARAMETRELERİNİN İNCELENMESİ

Makaslı platformlar sahip oldukları basit mekanik yapısı ve üretim kolaylığı sebebiyle endüstride yaygın olarak kullanılmaktadır. Platform için gerek duyulan hidrolik kuvvet ve platformun yükselme süresi, tasarımda önemli faktörler arasında yer almaktadır. Bu çalışmada, platformun uzuv boyu, hidrolik silindirin mafsal konumları ve hidrolik hızı değişken parametreler olarak seçilmiştir. Parametreler için öngörülen farklı değerlerin platformun yükselme süresine ve platformda ihtiyaç duyulan hidrolik kuvvetine etkileri incelenmiştir. Ayrıca, parametre seçimlerinde hidrolik silindirin maksimum strok değeri bir tasarım sınırı olarak dikkate alınmıştır. Hidrolik kuvvet ifadesi hem Virtüel İşler Prensibi (VİP) hem de Virtüel Güçler Prensibi (VGP) ile elde edilerek statik ve dinamik hesaplar arasında oluşan farklar belirlenmiştir. Simülasyonlar sonucunda, farklı tasarım ölçüleri ve hidrolik hızları ile elde edilen sonuçlar karşılaştırılarak yükselme süresini ve hidrolik kuvveti minimize etmek için uygun geometri belirlenmiştir

Scissor lift with real-time self-adjustment ability based on variable gravity compensation mechanism

Most robots involved in vertical movement against gravitation require actuators large enough to support their own weight. To improve the inherent safety of such robots against the large actuators and reduce their energy consumption, numerous gravity compensation mechanisms (GCMs) have been proposed. Our previous study proposed a variable GCM (VGCM) that uses two types of springs and can adjust the compensation force. In this paper, a VGCM-based scissor lift (pantograph lift) that uses three springs and a smaller actuator is proposed. A prototype is designed and fabricated, and the performance of the prototype is evaluated experimentally. The results demonstrate that the developed scissor lift meets the design specifications. In addition, a load estimator is established based on the dynamic model of the scissor lift. A real-time self-adjustment method that automatically changes the compensation force is proposed, and its effectiveness is verified