Cobot最新文献

{"title":"Load torque observation and compensation for permanent magnet synchronous motor based on sliding mode observer","authors":"Zenghui Lu, Hongjie Fan, Dong Xu","doi":"10.12688/cobot.17689.1","DOIUrl":"https://doi.org/10.12688/cobot.17689.1","url":null,"abstract":"Background Permanent magnet synchronous motors (PMSM) are widely used in various industries. However, in practical applications, the time-varying nature of load torque may lead to speed fluctuations, negatively impacting the motor's control performance and stability. To mitigate these issues, this paper proposes a load torque observation method for PMSMs based on a sliding mode observer. Methods The sliding mode observer is designed to estimate the load torque and convert it into a current, which is fed back as a feedforward compensation to the q-axis current in the current closed-loop control system. The observer's dynamic performance is optimized using a genetic algorithm to minimize the Integral of Time-weighted Absolute Error (ITAE) between the observer and the actual system state. Experimental tests are conducted on a motor torque testing platform. After stabilizing the motor at 800rpm, a sudden torque of 0.5Nm is applied. Results Compared to the situation without load torque compensation, the motor speed fluctuations are reduced by approximately 60% after adding load torque compensation. Conclusions This enhancement improves the system's speed control performance during torque variations and increases the system's robustness and disturbance rejection capability.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141811712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and optimization of soft colonoscopy robot with variable cross section","authors":"Gang Chen, Weiren Yu, Yutong Wu, Jianxiao Zheng","doi":"10.12688/cobot.17677.1","DOIUrl":"https://doi.org/10.12688/cobot.17677.1","url":null,"abstract":"Background Colonoscopy is the best choice for detecting bowel cancer; its effectiveness and early screening can significantly reduce the incidence rate of bowel cancer. However, the existing colonoscopy procedure is very technically demanding for doctors and painful for patients due to the difficult maneuver of long and slender colonoscope inside human colon. This paper will be focused on designing flexible robots with high dexterity to improve the performance of current colonoscopy. Methods This article optimizes and simulates the shape and layout of the driving cavity of the soft robot, as well as the multi-stage structure. This paper presents a design scheme of the soft robot with variable cross-section. The robot comprises two cross-sections in serial connection, with the outer diameter of the upper section 14mm and the outer diameter of the lower part 16mm. The bending angle and direction of the soft robot can be controlled by adjusting the pressure of the cavity. The soft robot is placed at the end of the traditional colonoscopy, replacing the standard manual operation for guidance during colonoscopy surgery. The relationship between the end position of the actuator and air pressure is calculated by the piecewise constant curvature (PCC) method and verified by subsequent experiments. At the same time, the motion trajectory of the soft robot is further simulated by finite element analysis. Results Experimental verification shows that the bending performance of the newly designed soft robot has significantly improved compared to the old design. Conclusion An improvement was made to address the design shortcomings of traditional actuators, and a new actuator was obtained. The performance of the latest and old actuators was compared through experiments, and it was ultimately known that the new actuator had significantly improved performance compared to the old actuator.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140659262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Robot-assisted homecare for older adults: A user study on needs and challenges","authors":"Zhidong Su, Fei Liang, Weihua Sheng, Alex Bishop","doi":"10.12688/cobot.17644.2","DOIUrl":"https://doi.org/10.12688/cobot.17644.2","url":null,"abstract":"Background As the older adult population increases there is a great need of developing smart healthcare technologies to assist older adults. Robot-based homecare systems are a promising solution to achieving this goal. This study aims to summarize the recent research in homecare robots, understand user needs and identify the future research directions. Methods First, we present an overview of the state-of-the-art in homecare robots, including the design and functions of our previously developed ASCC Companion Robot (ASCCBot). Second, we conducted a user study to understand the stakeholders’ opinions and needs regarding homecare robots. Finally, we proposed the future research directions in this research area in response to the existing problems. Results Our user study shows that most of the interviewees emphasized the importance of medication reminder and fall detection functions. The stakeholders also emphasized the functions to enhance the connection between older adults and their families and friends, as well as the functions to improve the efficiency and productivity of the caregivers. We also identified three major future directions in this research area: human-machine interface, learning and adaptation, and privacy protection. Conclusions The user study discovered some new useful functions that the stakeholders want to have and also validated the developed functions of the ASCCBot. The three major future directions in the homecare robot research area were identified.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139605569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine vision-based automatic focusing method for robot laser welding system","authors":"Xiaoxu Qiao, Kai Li, Yi Luo, Xiaodong Wang","doi":"10.12688/cobot.17682.1","DOIUrl":"https://doi.org/10.12688/cobot.17682.1","url":null,"abstract":"Background Defocus distance is a critical parameter in laser welding, especially when encountering changes in the contour of the welding surface. This paper proposed an automated focusing method to address the challenging issue of accurately adjusting the defocus distance. Methods The proposed method involves several steps. Firstly, a clarity evaluation function based on the Kirsch operator is employed to calculate real-time image clarity of the welding surface captured by the machine vision system. Next, an improved Canny edge detection algorithm is applied to identify the edge contours of the welding surface, from which their central points are extracted. Finally, automatic focusing is achieved by employing a variable step-size hill-climbing algorithm to search for the focal plane. Results To verify the applicability of the automatic focusing method proposed for welding the solder ring, a robot laser welding system was designed and constructed. Experimental results show that the positioning error of the robot after automatic focusing is within ±0.4 mm. The average time required for a single automatic focusing process is 16.27 s. These results demonstrated the successful accomplishment of automatic adjustment and control of the focal length. Conclusions The machine vision-based automatic focusing method proposed in this paper enhances the consistency of the robot’s position after automatic focusing in robot laser welding systems. It elevates the level of automation in the welding process and provides an efficient solution for accurately adjusting the welding focal distance during the laser welding process.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139446776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A dynamic obstacle avoidance method for collaborative robots based on trajectory optimization","authors":"Weizong Ge, Hongyu Chen, Hongtao Ma, Liuhe Li, Ming Bai, Xilun Ding, Kun Xu","doi":"10.12688/cobot.17673.1","DOIUrl":"https://doi.org/10.12688/cobot.17673.1","url":null,"abstract":"Background Collision detection is crucial in the design of robot planning algorithms. Efficient distance sensors can provide high-resolution environmental collision information to the robot's planning algorithm. However, this also leads to the robot obstacle avoidance performance being limited by the performance of the sensors. Therefore, it becomes a challenge to achieve efficient obstacle avoidance with low-resolution environmental information. Methods First, we use a self-developed capacitive array non-contact distance sensing flexible surface for sensing the proximity of colliding objects. Second, we designed an optimization-based dynamic obstacle avoidance planning algorithm, using only the minimum separation distance and penetration direction as obstacle avoidance information, and referring to the idea of stochastic gradient descent, using real-time collision avoidance information to do single-step optimization adjustment. Results We conducted the dynamic obstacle avoidance test experiment by connecting the electronic skin to the semi-physical prototype and the full physical prototype. The experiments show that efficient dynamic obstacle avoidance can be realized under the maximum effective range of only 5~7cm, and it has strong flexibility to avoid different shapes of dynamic obstacles in a non-contact manner, and finally arrive at the target position. Conclusions In this paper, an online obstacle avoidance planning algorithm designed based on an optimization method that is not limited to the shape of obstacles is proposed, and the effectiveness of the algorithm is verified by physical experiments in combination with a self-developed flexible distance sensing surface. It is of great significance for the safe operation of human-robot interaction in collaborative robots.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139003013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on desktop object grasping based on ellipse fitting","authors":"Shaolin Zhang, Yueguang Ge, Wenkai Chang, Haitao Wang, Shuo Wang","doi":"10.12688/cobot.17497.2","DOIUrl":"https://doi.org/10.12688/cobot.17497.2","url":null,"abstract":"<ns4:p>The grasping operation task in service scenes faces several problems including too many kinds of objects and a large amount of training data. This paper focuses on the grasping strategy and pose detection in desktop object grasping tasks. A grasping strategy is given based on the combination of desktop normal vector detection, object category detection, and grasping pose detection. The grasping pose is calculated by ellipse fitting on the depth map. An optimal function is designed to evaluate the possibility of the object sliding along the ellipse axis and the stability of the grasping height. The most reliable grasping pose is selected. Finally, experiments were carried out with a six-degree-of-freedom manipulator, and the proposed grasping method achieved effective grasping of desktop objects without prior knowledge of the object.</ns4:p>","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135246597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative study on real-time pose estimation of vision-based unmanned underwater vehicles","authors":"Ming Li, Ke Yang, Jiangying Qin, Jiageng Zhong, Zipeng Jiang, Qin Su","doi":"10.12688/cobot.17642.2","DOIUrl":"https://doi.org/10.12688/cobot.17642.2","url":null,"abstract":"<ns3:p><ns3:bold>Background: </ns3:bold>Navigation and localization are key to the successful execution of autonomous unmanned underwater vehicles (UUVs) in marine environmental monitoring, underwater 3D mapping, and ocean resource surveys. The estimation of the position and the orientation of autonomous UUVs are a long-standing challenging and fundamental problem. As one of the underwater sensors, camera has always been the focus of attention due to its advantages of low cost and rich content information in low visibility waters, especially in the fields of visual perception of the underwater environment, target recognition and tracking. At present, the visual real-time pose estimation technology that can be used for UUVs is mainly divided into geometry-based visual positioning algorithms and deep learning-based visual positioning algorithms.</ns3:p><ns3:p> <ns3:bold>Methods: </ns3:bold>In order to compare the performance of different positioning algorithms and strategies, this paper uses C++ and python, takes the ORB-SLAM3 algorithm and DF-VO algorithm as representatives to conduct a comparative experiment and analysis.</ns3:p><ns3:p> <ns3:bold>Results:</ns3:bold> The geometry-based algorithm ORB-SLAM3 is less affected by illumination, performs more stably in different underwater environments, and has a shorter calculation time, but its robustness is poor in complex environments. The visual positioning algorithm DF-VO based on deep learning takes longer time to compute, and the positioning accuracy is more easily affected by illumination, especially in dark conditions. However, its robustness is better in unstructured environments such as large-scale image rotation and dynamic object interference.</ns3:p><ns3:p> <ns3:bold>Conclusions: </ns3:bold>In general, the deep learning-based algorithm is more robust, but multiple deep learning networks make it need more time to compute. The geometry-based method costs less time and is more accurate in low-light and turbid underwater conditions. However, in real underwater situations, these two methods can be connected as binocular vision or methods of multi-sensor combined pose estimation.</ns3:p>","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135215585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quartz crystal based sensor head design and analysis for robot torque sensor application","authors":"Hao Fu, ChinYin Chen, Chongchong Wang, MinChiang Chao, Qiang Zhou, Guilin Yang, Guozhi Wang","doi":"10.12688/cobot.17474.2","DOIUrl":"https://doi.org/10.12688/cobot.17474.2","url":null,"abstract":"<ns3:p><ns3:bold>Background:</ns3:bold> Background: In recent years, with the gradual development of robot human-computer interaction, robots need to meet the precise control of more complex movements. Torque sensors play an important role. The traditional sensor uses metal strain gauge as the sensing element, which makes the sensor slow in response and low in resolution. In view of the shortcomings of strain gauge sensor, a sensor with cut quartz square as the sensing head is proposed.</ns3:p><ns3:p> <ns3:bold>Methods:</ns3:bold> In order to study the quartz square sensitive head, COMSOL56 simulation modeling was first used to obtain the stress ratio relationship between the square quartz chip and the circular quartz chip. The formula for calculating the force frequency coefficient of the circular quartz chip was modified based on the ratio coefficient, and the formula for calculating the force frequency coefficient of the square quartz chip was obtained. The feasibility of the formula was verified through practical experiments; Secondly, theoretical simulation and experimental research were conducted on the buckling limit force of quartz chips, and the calculation formula for the buckling limit force during the installation process of quartz chips was revised, laying the foundation for the theoretical design of quartz sensors; Finally, the designed sensitive head is installed on the elastomer structure for verification; In order to collect frequency signals at a sampling rate of 1000Hz, the frequency signal output by the square quartz sensitive head is mixed, filtered, and amplified to form a 3.3V square wave between peaks. The frequency signal is collected by STM32.</ns3:p><ns3:p> <ns3:bold>Conclusion:</ns3:bold> the test shows that the sensor with square quartz chip as the sensor head has a range of 150Nm, a sensitivity of 350 Hz / Nm, a linearity of 98.14%, a hysteresis of 0.51%, a repeatability of 98.44% and a resolution of 0.02%.</ns3:p>","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135494038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Robot-assisted homecare: A user study on needs and challenges","authors":"Zhidong Su, Fei Liang, W. Sheng, Alex Bishop","doi":"10.12688/cobot.17644.1","DOIUrl":"https://doi.org/10.12688/cobot.17644.1","url":null,"abstract":"Background: As the older adult population increases there is a great need of developing smart healthcare technologies to assist older adults. Robot-based homecare systems are a promising solution to achieving this goal. This study aims to summarize the recent research in homecare robots, understand user needs and identify the future research directions. Methods: First, we present an overview of the state-of-the-art in homecare robots, including the design and functions of our previously developed ASCC Companion Robot (ASCCBot). Second, we conducted a user study to understand the stake- holders’ opinions and needs regarding homecare robots. Finally, we proposed the future research directions in this exciting research area in response to the existing problems. Results: Our user study shows that most of the interviewees emphasized the importance of medication reminder and fall detection functions. The stakeholders also emphasized the functions to enhance the connection between older adults and their families and friends, as well as the functions to improve the efficiency and productivity of the caregivers. We also identified three major future directions in this exciting research area: human-machine interface, learning and adaptation, and privacy protection. Conclusions: The user study discovered some new useful functions that the stakeholders want to have and also validated the developed functions of the ASCCBot. The three major future directions in the homecare robot research area were identified.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45496860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of velocity sensor for robotic fish based on fiber Bragg grating","authors":"Shuhang Xie, Dong Xu, Junjun Dong, Wei Dai","doi":"10.12688/cobot.17618.1","DOIUrl":"https://doi.org/10.12688/cobot.17618.1","url":null,"abstract":"The artificial lateral lines of robotic fish (a kind of underwater unmanned vehicle) have been studied extensively, but mostly based on pressure measurements. Based on fiber Bragg grating, a kind of sensor for artificial lateral line of robotic fish is proposed in this paper. This sensor structure is sensitive to flow velocity. The sensor adopts the target-type structure, and the target is the impacted end of the water flow, so the target arm is deformed. The strain of the target arm is measured by the fiber Bragg grating, so as to reflect the impact of water flow at different flow velocities on the target. The experimental data show that there is an obvious linear relationship between the central wavelength offset and the square of the velocity. Our work demonstrates the feasibility of this sensor structure for velocity measurements.","PeriodicalId":29807,"journal":{"name":"Cobot","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47482282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}