Zhe Qiu

Pneumatic actuators are lightweight, compact, and capable of generating compliant motions due to the compressibility of air. Despite their advantages, measurement and control challenges significantly limit their industrial applications. Topically, a simple open-loop position control method is applied to pneumatic cylinders, controlling the piston’s pre-determined moving distances without sensor feedback. External position sensors, which are conventionally used for feedback control, increase system complexity and reduce adaptability, particularly in underwater environments. In this study, we propose a new method to estimate the position of pneumatic cylinders using a flow and a pressure sensor that can be positioned away from the cylinder. This results in a compact, lightweight design and prevents disconnections and contacts between the piston and external sensors. Additionally, the system could be used underwater without concerns about waterproofing external sensors. We evaluate the basic performances of the proposed method by estimating pneumatic cylinder positions with a simple experimental system. The experimental results demonstrated that our method could estimate piston positions with an error of approximately 1mm.

Owing to Japan’s aging society and labor shortages, the food and agricultural industries are facing a significant demand for robotic food handling technologies. Considering the large variety of food products, available robotic end-effectors are limited. Our primary goal is to maximize the applicability of existing end-effectors and efficiently develop novel ones, and therefore, it is necessary to categorize food products and end-effectors from the viewpoint of robotic handling and establish their relationships through an effective evaluation approach. This study proposes a system for evaluating robotic end-effectors to identify appropriate ones and develop new ones. The evaluation system consists of food categorization based on food properties related to robotic handling, categorization of robotic end-effectors based on their grasping principles, a robotic system with visual recognition based on Robot Operating System 2 (ROS 2) to conduct handling tests, a scoring system for performance evaluation, and a visualization approach for presenting the results and comparisons. Based on food categorization, 14 real food items and their corresponding samples were chosen for handling tests. Seven robotic end-effectors, both commercialized and under development, were selected for evaluation. Using the proposed evaluation system, we quantitatively compared the performance of different end-effectors in handling different food items. We also observed differences in the handling of real food items and samples. The overall performance of an end-effector can be visualized and quantitatively evaluated to demonstrate its versatility in handling various food items.

A collision detection approach is proposed to determine a link of a manipulator colliding with an unknown environment without using external sensors. A series of artificial indexes physically representing mechanical powers are introduced to isolate a plausible contact link. The virtual power-based indexes use adaptive scheme to estimate the contact force, which does not require the perfect knowledge of manipulator parameters. The implementation of experimental collision detection tasks using a 2 degree of freedom (DOF) planar manipulator validates the robustness of the proposed approach.