A gravitational torque-compensated 2-DOF planar robotic arm design and its active control

Author(s):  
Yalçın Bulut ◽  
Erdinc Sahin Conkur

Serial robot manipulators have their servo motors with reduction gears on the link joints. When it comes to hyper-redundant robots, this kind of joint actuation mechanism cannot be implemented since this makes hyper-redundant robots too heavy. Instead, cable driven mechanisms are preferred. However, the positioning accuracy is negatively affected by the cables. This paper addresses the positioning accuracy problem of cable driven hyper-redundant robots by employing a 2-DOF robotic arm whose modules are counter-balanced. While the actuators connected to the base actively do most of the work using cables and springs, light and compact actuators connected to the links produce precise motion. The method will result in compact, light and precise hyper-redundant robotic arms. The above-mentioned procedure governed by a control software including a 2D simulator developed is experimentally proved to be a feasible method to compensate the gravitational torque successfully.

Author(s):  
Junren Zhang ◽  
Wofhatwa Solomon Ndou ◽  
Nathan Ng ◽  
Paul Gaston ◽  
Philip M. Simpson ◽  
...  

AbstractThis systematic review and meta-analysis were conducted to compare the accuracy of component positioning, alignment and balancing techniques employed, patient-reported outcomes, and complications of robotic-arm assisted total knee arthroplasty (RATKA) with manual TKA (mTKA) and the associated learning curve. Searches of PubMed, Medline and Google Scholar were performed in October 2020 using PRISMA guidelines. Search terms included “robotic”, “knee” and “arthroplasty”. The criteria for inclusion were published clinical research articles reporting the learning curve for RATKA and those comparing the component position accuracy, alignment and balancing techniques, functional outcomes, or complications with mTKA. There were 198 articles identified, following full text screening, 16 studies satisfied the inclusion criteria and reported the learning curve of rTKA (n=5), component positioning accuracy (n=6), alignment and balancing techniques (n=7), functional outcomes (n=7), or complications (n=5). Two studies reported the learning curve using CUSUM analysis to establish an inflexion point for proficiency which ranged from 7 to 11 cases and there was no learning curve for component positioning accuracy. The meta-analysis showed a significantly lower difference between planned component position and implanted component position, and the spread was narrower for RATKA compared with the mTKA group (Femur coronal: mean 1.31, 95% confidence interval (CI) 1.08–1.55, p<0.00001; Tibia coronal: mean 1.56, 95% CI 1.32–1.81, p<0.00001). Three studies reported using different alignment and balancing techniques between mTKA and RATKA, two studies used the same for both group and two studies did not state the methods used in their RATKA groups. RATKA resulted in better Knee Society Score compared to mTKA in the short-to-mid-term follow up (95%CI [− 1.23,  − 0.51], p=0.004). There was no difference in arthrofibrosis, superficial and deep infection, wound dehiscence, or overall complication rates. RATKA demonstrated improved accuracy of component positioning and patient-reported outcomes. The learning curve of RATKA for operating time was between 7 and 11 cases. Future well-powered studies on RATKAs should report on the knee alignment and balancing techniques utilised to enable better comparisons on which techniques maximise patient outcomes.Level of evidence III.


Author(s):  
Dharshan Y. ◽  
Vivek S. ◽  
Saranya S. ◽  
Aarthi V.R. ◽  
Madhumathi T.

<div><p><em>Robots have become a key technology in various fields. Robotic arms are mostly remote controlled by buttons or panels and sometimes in batch process they are autonomous. The usage of panel boards or control sticks includes a lot of hardwiring and subject to malfunction.  It also induces some stress on the operators. Hence major chemical industries like cosmetic manufacturing, paint manufacturing and Biosynthesis laboratory etc., which deals with hazardous environment due to the chemicals and other bio substances, involve humans for the processing. The aim is to reduce the bulk of wiring in the robotic arms and reduce the effort and number of operators in controlling the robotic arm operations. To implement gestures into the process this would be a major breakthrough. This can also be used as pick &amp; place robot, a cleaning robot in chemical industries where a human does not need to directly involved in the process of cleaning the chemicals and also for coating underground tanks.</em></p></div>


2013 ◽  
Vol 655-657 ◽  
pp. 1057-1060
Author(s):  
Li Jun Zong ◽  
Guang Kuo Wang ◽  
Xin Li ◽  
Lei Wang ◽  
Xiao Min Zhang ◽  
...  

Aerospace robotic arms have important applications in aerospace engineering (capture satellite, develop the technology of extra-vehicle activity (EVA), etc.) This paper first introduces the development and background of the Aerospace Robotic Arm. In later sections, a kinematics model of a Six-DOF manipulator is built based on DenavitHartenberg(D-H) method, then, the paper discusses an inverse kinematics solving method of the manipulator. At last, we show the simulation by integrating the use of SolidWorks, Matlab, and a number of their modules.


2018 ◽  
Vol 38 (5) ◽  
pp. 568-575 ◽  
Author(s):  
Weilin Yang ◽  
Wentao Zhang ◽  
Dezhi Xu ◽  
Wenxu Yan

Purpose Robotic arm control is challenging due to the intrinsic nonlinearity. Proportional-integral-derivative (PID) controllers prevail in many robotic arm applications. However, it is usually nontrivial to tune the parameters in a PID controller. This paper aims to propose a model-based control strategy of robotic arms. Design/methodology/approach A Takagi–Sugeno (T-S) fuzzy model, which is capable of approximating nonlinear systems, is used to describe the dynamics of a robotic arm. Model predictive control (MPC) based on the T-S fuzzy model is considered, which optimizes system performance with respect to a user-defined cost function. Findings The control gains are optimized online according to the real-time system state. Furthermore, the proposed method takes into account the input constraints. Simulations demonstrate the effectiveness of the fuzzy MPC approach. It is shown that asymptotic stability is achieved for the closed-loop control system. Originality/value The T-S fuzzy model is discussed in the modeling of robotic arm dynamics. Fuzzy MPC is used for robotic arm control, which can optimize the transient performance with respect to a user-defined criteria.


2016 ◽  
Vol 10 (4) ◽  
pp. 503-510 ◽  
Author(s):  
Naoki Saito ◽  
◽  
Toshiyuki Satoh ◽  

This paper describes a joint angle control considering the passive joint stiffness of robotic arms driven by rubberless artificial muscle (RLAM), which is a pneumatic actuator. The contraction mechanism of RLAM is the same as that of the McKibben artificial muscle. Unlike the McKibben artificial muscle, RLAM is constructed using an airbag made of a nonelastic material instead of a rubber tube.The objective of this study is to realize a soft contact movement of robotic arms by applying the passive compliance characteristics of RLAMs. In this study, we derive a mathematical expression for the relationship between the output of an RLAM and the joint stiffness of a robotic arm. In addition, we suggest a control scheme for each RLAM. We confirm the validity of these suggestions experimentally. From the result, we observe a good control performance of the joint angle. A robotic arm moves smoothly according to the force added from outside by setting the passive stiffness of the arm.


Robotica ◽  
2005 ◽  
Vol 23 (1) ◽  
pp. 123-129 ◽  
Author(s):  
John Q. Gan ◽  
Eimei Oyama ◽  
Eric M. Rosales ◽  
Huosheng Hu

For robotic manipulators that are redundant or with high degrees of freedom (dof), an analytical solution to the inverse kinematics is very difficult or impossible. Pioneer 2 robotic arm (P2Arm) is a recently developed and widely used 5-dof manipulator. There is no effective solution to its inverse kinematics to date. This paper presents a first complete analytical solution to the inverse kinematics of the P2Arm, which makes it possible to control the arm to any reachable position in an unstructured environment. The strategies developed in this paper could also be useful for solving the inverse kinematics problem of other types of robotic arms.


Author(s):  
Joshua Laber ◽  
◽  
Ravindra Thamma

In automation, manufacturing companies require high speed and efficiency to remain competitive in the global economy. One of the most popular ways to increase precision, speed, and accuracy is to implement industrial robotic arms. As of 2020, 2.7 million industrial robots are in operation worldwide. A robotic arm is a machine used to automatic repetitive tasks by manipulating tools or parts in the space around it. Businesses use robotic arms for many operations including pick and place, machining, welding, precision soldering, and other tasks. But with all the different types and configurations of robotic arms, the question remains: What arm would best suit the task at hand? This paper examines and compares three commonly available types of robotic arm: 5-DoF, 6-DoF, and SCARA to compare which are most efficient in tracing paths.


2017 ◽  
Vol 20 (K5) ◽  
pp. 13-22
Author(s):  
Thai Hong Nguyen ◽  
Thai Quang Nguyen

The most typical method of tunneling in complicated geographical conditions is still blasthole drilling. To improve the efficiency of the work, Vietnam and several other countries have used drilling devices fitted with self-propelled hydraulic seven-link robotic arms which can also be manually controlled to modernize the drilling and blasting processes and improve the accuracy of the work. The task of controlling the robotic arm to automatically drill the holes exactly as specified in the passport of blasting prepared by geotechnical and underground construction engineers requires a control algorithm for the controller of the robot. The matter will be clearly presented in this article.


2021 ◽  
Author(s):  
Guanglei Wu

This paper presents elastodynamic modeling and analysis for a five-axis lightweight robotic arm. Natural frequencies are derived and visualized within the dexterous workspace to show the overall performances and compare them to the frequencies when the robotics is with payload. The comparison shows that the payload has a relatively small influence to the first- and second-order frequencies. Sensitivity analysis is conducted, and the system's frequency is more sensitive to the second joint stiffness than the others. Moreover, observations from the displacement response analysis reveal that the robotics produces linear elastic displacements of the same level between the loaded and unloaded working modes but larger rotational deflections under the loaded working condition. The main contribution of this work lies in that a systematic approach of elastodynamic analysis for serial robotic manipulators is formulated, where the arm gravity and external load are taken into account to investigate the dynamic behaviors of the robotic arms, i.e., frequencies, sensitivity analysis, and displacement responses, under the loaded mode.


Author(s):  
Akhmad Fahruzi ◽  
Bimo Satyo Agomo ◽  
Yulianto Agung Prabowo

Nowadays robotic arm is widely used in various industries, especially those engaged in manufacturing. Robotic arms are usually used to perform jobs such as picking up and moving goods from their place of origin to the location desired by the operator. In this study, a 3d 4 DOF (Degree of Freedom) robotic arm. The prototype was made to move goods with random coordinates to places or boxes whose coordinates were determined in advance. The robot can know the coordinates of the object to be taken or moved. The arm robot prototype design is completed with a camera connected to a computer, where the camera is installed statically (fixed position) above the robot's work area. The camera functions like image processing to detect the object's position by taking the coordinates of the object. Then the object coordinates will be input into inverse kinematics that will produce an angle in every point of the servo arm so that the position of the end effector on the robot arm can be founded and reach the intended object. From the results of testing and analysis, it was found that the error in the webcam test to detect object coordinates was 2.58%, the error in the servo motion test was 12.68%, and the error in the inverse kinematics test was 7.85% on the x-axis, the error was 6.31% on the y-axis and an error of 12.77% on the z-axis. The reliability of the whole system is 66.66%.


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