DSpace Collection:
https://hdl.handle.net/10356/79125
2024-03-28T22:29:09ZReal-time avoidance strategy of dynamic obstacles via half model-free detection and tracking with 2D lidar for mobile robots
https://hdl.handle.net/10356/162467
Title: Real-time avoidance strategy of dynamic obstacles via half model-free detection and tracking with 2D lidar for mobile robots
Authors: Dong, Huixu; Weng, Ching-Yen; Guo, Chuangqiang; Yu, Haoyong; Chen, I-Ming
Abstract: Avoidance is a necessary capability for a mobile robot to perform tasks, such as delivering objects in household or industrial scenarios. The existing avoidance strategy based on timed elastic band local planner and cost-map provided by robotics operating system cannot realize the excellent performance when a robot and an obstacle both move. In this article, we present a real-time, simple, and reliable approach to detecting and tracking obstacles via a two-dimensional lidar in dynamic scenarios where the mobile robot and the obstacle are moving. Obstacles are represented by a set of points against their outlines and the information of obstacles is initialized and updated via the raw laser measurement. First, the obstacle is detected by three main steps: preprocessing, segmentation, and merging, classification of consequent measurements. Second, we use a hierarchical method to realize data associations for figuring out the corresponding matches among obstacles with the consecutive time. Last, after doing the data association, we need to estimate the motion of the dynamic obstacle for being tracked by the Kalman filter. Extensive experiments performed in the simulation and practical scenarios indicate that the proposed method enables a mobile robot to perform dynamic avoidances efficiently [Real-time Avoidance Strategy of Dynamic Obstacles via Half Model-free Detection and Tracking (T-MECH)].2021-01-01T00:00:00ZHuman–robot co-manipulation during surface tooling: a general framework based on impedance control, haptic rendering and discrete geometry
https://hdl.handle.net/10356/159676
Title: Human–robot co-manipulation during surface tooling: a general framework based on impedance control, haptic rendering and discrete geometry
Authors: Kana, Sreekanth; Tee, Keng-Peng; Campolo, Domenico
Abstract: Despite the advancements in machine learning and artificial intelligence, there are many tooling tasks with cognitive aspects that are rather challenging for robots to handle in full autonomy, thus still requiring a certain degree of interaction with a human operator. In this paper, we propose a theoretical framework for both planning and execution of robot-surface contact tasks whereby interaction with a human operator can be accommodated to a variable degree. The starting point is the geometry of surface, which we assume known and available in a discretized format, e.g. through scanning technologies. To allow for realtime computation, rather than interacting with thousands of vertices, the robot only interacts with a single proxy, i.e. a massless virtual object constrained to ‘live on’ the surface and subject to first order viscous dynamics. The proxy and an impedance-controlled robot are then connected through tuneable and possibly viscoelastic coupling, i.e. (virtual) springs and dampers. On the one hand, the proxy slides along discrete geodesics of the surface in response to both viscoelastic coupling with the robot and to a possible external force (a virtual force which can be used to induce autonomous behaviours). On the other hand, the robot is free to move in 3D in reaction to the same viscoelastic coupling as well as to a possible external force, which includes an actual force exerted by a human operator. The proposed approach is multi-objective in the sense that different operational (autonomous/collaborative) and interactive (for contact/non-contact tasks) modalities can be realized by simply modulating the viscoelastic coupling as well as virtual and physical external forces. We believe that our proposed framework might lead to a more intuitive interfacing to robot programming, as opposed to standard coding. To this end, we also present numerical and experimental studies demonstrating path planning as well as autonomous and collaborative interaction for contact tasks with a free-form surface.2021-01-01T00:00:00ZA voice activated bi-articular exosuit for upper limb assistance during lifting tasks
https://hdl.handle.net/10356/159638
Title: A voice activated bi-articular exosuit for upper limb assistance during lifting tasks
Authors: Kim, Yongtae G.; Little, Kieran; Noronha, Bernardo; Xiloyannis, Michele; Masia, Lorenzo; Accoto, Dino
Abstract: Humans are favoured to conventional robotics for some tasks in industry due to their increased dexterity and fine motor skills, however, performance of these tasks can result in injury to the user at a cost to both the user and the employer. In this paper we describe a lightweight, upper-limb exosuit intended to assist the user during lifting tasks (up to 10kg) and while operating power tools, which are common activities for industrial workers. The exosuit assists elbow and shoulder flexion for both arms and allows for passive movements in the transverse plane. To achieve the design criteria an underactuated mechanism has been developed, where a single motor is used to assist two degrees of freedom per arm. In the intended application, the hands are generally busy and cannot be used to provide inputs to the robot, therefore, a voice-activated control has been developed that allows the user to give voice commands to operate the exosuit. Experiments were performed on 5 healthy subjects to assess the change in Muscular Activation (MA), inferred through Electromyography (EMG) signals, during three tasks: i) lifting and releasing a load; ii) holding a position and iii) manipulating a tool. The results showed that the exosuit is capable of reducing EMG activity (between 24.6% and 64.6%) and the recognition rate (94.8%) of the voice recognition module was evaluated.2020-01-01T00:00:00ZA microfabricated dual slip-pressure sensor with compliant polymer-liquid metal nanocomposite for robotic manipulation
https://hdl.handle.net/10356/156983
Title: A microfabricated dual slip-pressure sensor with compliant polymer-liquid metal nanocomposite for robotic manipulation
Authors: Accoto, Dino; Donadio, Alessandro; Yang, Sibo; Ankit; Mathews, Nripan
Abstract: Conventional grippers fall behind their human counterparts as they do not have integrated sensing capabilities. Piezoresistive and capacitive sensors are popular choices because of their design and sensitivity, but they cannot measure pressure and slip simultaneously. It is imperative to measure slip and pressure concurrently. We demonstrate a dual slip-pressure sensor based on a thermal approach. The sensor comprises two concentric microfabricated heaters maintained at constant temperature. An elastic dome, with embedded liquid metal droplets, is placed on top of concentric heaters. Heat transfer between sensor and the object in contact occurs through the elastic dome. This heat transfer causes changes in the power absorbed by the sensor to maintain its temperature and allows for measurement of pressure while identifying slip events. Liquid metal droplets contribute to enhanced thermal conductivity (0.37 W/m-K) and reduced specific heat (0.86 kJ/kg-K) of the polymer without compromising on mechanical properties (Young's modulus-0.5 MPa). For pressure monitoring, sensor measures change in power ratio against increase in applied force, demonstrating a highly linear performance, with a high sensitivity of 0.0356 N-1 (pressure only) and 0.0189 N-1 (slip with simultaneous pressure applied). The sensor discriminates between different contact types with a 96% accuracy. Response time of the sensor (60-75 ms) matches the measured response time in human skin. The sensor does not get affected by mechanical vibrations paving way for easy integration with robotic manipulators and prosthetics.2021-01-01T00:00:00Z