Computer Aided Synthesis of Adjustable Robotic Mechanisms

Author(s):  
Thatchai Chuenchom ◽  
Sridhar Kota

Abstract Conventional hard automation such as linkage mechanisms or cam-driven mechanisms provide high speed capability at a low cost (using typically one actuator), but fail to provide the flexibility required in many industrial applications. Manufacturers are increasingly turning to multi-axis robots to fulfill flexibility demands. In many cases, however, the flexibility requirements are limited; i.e. a given pick-and-place unit may be required to perform only a handful of different operations. Therefore, the expensive robots are under-utilized. By incorporating flexibility in conventional linkage-type mechanisms, we are developing adjustable robotic mechanisms (ARMs) to serve as a middle ground between hard automation and overly flexible serial-jointed industrial robots.

2015 ◽  
Vol 27 (3) ◽  
pp. 267-275
Author(s):  
Jumpei Arata ◽  
◽  
Yuji Isogai ◽  
Junya Sumida ◽  
Masamichi Sakaguchi ◽  
...  

<div class=""abs_img""> <img src=""[disp_template_path]/JRM/abst-image/00270003/06.jpg"" width=""340"" />Concept prototype</div> Robotic instruments have recently been widely introduced into industrial automation. As energy supply and demand have become global issues, energy saving in industrial robots has become urgent. In general industrial pick-and-place robots, servomotors periodically repeat acceleration and deceleration, consequently lose much energy in motion. We propose a mechanism using an in-frame parallel spring for the pick-and-place robot. During motion, spring blades deform and store energy, then release it as energy of motion, enabling the mechanism to recycle energy that have been lost in conventional mechanisms. In this paper, a 1 DOF proof-of-concept prototype and preliminary feasibility tests are described. In this study, we applied in-frame parallel springs to a mechanism for pick-and-place robot. The parallel springs are fabricated from spring steel SK85M (Young’s modulus: 210 GPa) with 252 mm long, 50 mm wide and 0.3 mm thick. The results suggest that the prototype can achieve a repeated motion with the range of ±145.7 mm in 2.56 Hz by 1.17 W, greatly reduced from that of the the traditional mechanisms. In addition, it is desired to stop the robot immediately in regular motion if anomalies occurred in industrial applications. The prototype showed that an immediate stop in 0.6 s was feasible by dissipating elastic energy stored in spring blades, confirming the feasibility of our proposed mechanism.


Author(s):  
Tsung-Liang Wu ◽  
Jih-Hsiang Yeh ◽  
Cheng-Chen Yang

The Delta robot system is widely used in high speed (4 cycles/s at 25-200-25 mm) pick-and-place process in production line. Some industrial applications include photo-voltaic (PV), food process, and electronic assembly, and so on. The energy saving and system cost are two critical parameters for designing the next generation of pick-and-place system. To achieve these goals, a light-weight moving structure with sufficient strength to overcome the excited vibration will be one of the solutions. In this paper, an asymmetric arm design is proposed and fabricated to gain the benefit of strength-to-weight. The asymmetric arm is designed by reinforcing a specific direction and is validated the vibration suppression capability both by simulation and experiment. A position controller that is derived from the kinematic model of Delta robot is utilized to manipulate the robot under a forward-backward motion with a polynomial trajectory with 200 mm displacement. The residual vibration, then, was measured after the forward-backward motion to compare the settling performance between symmetric- and asymmetric-arms on the Delta robot system, respectively. The results conclude as following: (1) The asymmetric arms perform slightly worse (0.03 sec more in settling time) than symmetric arm but there is 15% weight reducing comparing to symmetric arm. (2) Both energy saving and system cost reducing would be achieved by utilizing actuators with lower power consumption and fabrication on carbon fiber arms with mass customization.


Author(s):  
Zexiao Xie ◽  
Peixin Wu ◽  
Ping Ren

A comparative study on the pick-and-place trajectories for high-speed Delta robots is presented in this paper. The Adept Cycle has been widely accepted as a standardized pick-and-place trajectory for industrial robots. The blending curves and optimization methods to smooth this trajectory are briefly surveyed. Three major types of trajectories: Lamé curves, clothoids and piecewise polynomials, are selected as candidates to be compared. The processes to generate these trajectories are briefly reviewed. The trajectories are firstly compared in term of their computation time. Then, based on a dynamic model and an experimental prototype of the Delta robot, different combinations of the geometric paths and motion profiles are compared in terms of power consumption, terminal state accuracy and residual vibration. The effects of trajectory configurations and parameters on the robot’s dynamic performances are investigated. Through a comprehensive analysis on both simulation and experimental results, a near-optimal pick-and-place trajectory for the Delta robot is identified and validated.


1997 ◽  
Vol 119 (2) ◽  
pp. 232-237 ◽  
Author(s):  
T. Chuenchom ◽  
S. Kota

Conventional hard automation such as linkage mechanisms and cam-driven mechanisms provide high speed capability at a low cost, but fail to provide the flexibility required in many industrial applications. On the other hand, for most manufacturing automation applications in high production industries, expensive multi-axis robots are employed for simple repetitive operations that require only limited flexibility. In order to provide a true middle ground between conventional mechanism-based hard automation and overly flexible anthropomorphic robots, we incorporate flexibility in conventional mechanisms, thereby creating “programmable mechanisms” or Adjustable Robotic Mechanisms (ARMs). This paper introduces the concept of ARMs and presents generalized analytical methods for designing adjustable mechanisms based on synthesis of adjustable dyads. The synthesis methods presented here, which are extensions of the well-known Burmester precision point theory, enable one to design multi-purpose mechanisms for multiple sets of precision points, thereby enabling conventional mechanisms to perform multiple tasks. The analytical synthesis method has been implemented in a computer program that generates all adjustable dyad solutions for given sets of precision points. Two or more adjustable dyads are assembled together to form a programmable linkage mechanism that performs multiple tasks. Synthesis formulations and a design example illustrating the analytical and computer-aided synthesis methods are presented.


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.


2011 ◽  
Vol 225-226 ◽  
pp. 589-592
Author(s):  
Yan Liu ◽  
Ze Gang Ye

The current Synchro-to-Digital conversion (S/DC)with high reliability, high accuracy and widely used in the military field, but it has high cost and low tracking speed, not suitable for high speed and low-cost industrial applications. In this work, the principle of synchro and the harmonics of the synchro output signals are investigated. Multifunction S/DC software design using FFT algorithm and IIR digital filter technology is proposed. It Integrated many functions, such as angle position, harmonics analysis and filter, it also improved measurement accuracy and speed, reduced the cost. The simulation results by Matlab show that the method is feasible.


2021 ◽  
Author(s):  
Juan Sebastian Toquica ◽  
José Maurı́cio Motta

Abstract This paper proposes a methodology for calibration of industrial robots that uses a concept of measurement sub-regions, allowing low-cost solutions and easy implementation to meet the robot accuracy requirements in industrial applications. The solutions to increasing the accuracy of robots today have high-cost implementation, making calibration throughout the workplace in industry a difficult and unlikely task. Thus, reducing the time spent and the measured workspace volume of the robot end-effector are the main benefits of the implementation of the sub-region concept, ensuring sufficient flexibility in the measurement step of robot calibration procedures. The main contribution of this article is the proposal and discussion of a methodology to calibrate robots using several small measurement sub-regions and gathering the measurement data in a way equivalent to the measurements made in large volume regions, making feasible the use of high-precision measurement systems but limited to small volumes, such as vision-based measurement systems. The robot calibration procedures were simulated according to the literature, such that results from simulation are free from errors due to experimental setups as to isolate the benefits of the measurement proposal methodology. In addition, a method to validate the analytical off-line kinematic model of industrial robots is proposed using the nominal model of the robot supplier incorporated into its controller.


2020 ◽  
Vol 26 (4) ◽  
pp. 479-495
Author(s):  
Kamil Maliński ◽  
Krzysztof Okarma

Rapid growth of availability of modern electronic and robotic solutions, also for home and amateur use, related to the progress in home automation and popularity of the IoT systems, makes it possible to develop some unique hardware solutions, also by independent researchers and engineers, often with the help of the 3D printing technology. Although in many industrial applications high speed pick and place machines are used for assembling small surface-mount devices (SMD), especially in mass production of electronic parts, there are still some applications, where the traditional through-hole technology used in Printed Circuit Boards (PCB) is utilised, particularly considering some mechanical, thermal or power conditions, preventing the use of the SMD technology. One of the possibilities of supporting such types of production and prototyping, in some cases supported by relatively less sophisticated robotic solutions, may be the application of vision systems, making it possible to classify and recognize some electronics parts with the use of shape analysis of their packages as well as further optical recognition of markings. Another application of such methods may be related to the automatic vision based verification of the assembling quality and correctness of the placement of electronic parts after completing the production. In the paper some experimental results, obtained using various shape descriptors for the classification of electronic packages, are presented. The initial experiments, obtained for a prepared dedicated database of synthetic images, have been verified and confirmed also for some natural images, leading to promising results.


Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4014 ◽  
Author(s):  
Bo Chen ◽  
Juan Abascal ◽  
Manuchehr Soleimani

Electrical resistance tomography (ERT) is an imaging technique to recover the conductivity distribution with boundary measurements via attached electrodes. There are a wide range of applications using ERT for image reconstruction or parameter calculation due to high speed data collection, low cost, and the advantages of being non-invasive and portable. Although ERT is considered a high temporal resolution method, a temporally regularized method can greatly enhance such a temporal resolution compared to frame-by-frame reconstruction. In some of the cases, especially in the industrial applications, dynamic movement of an object is critical. In practice, it is desirable for monitoring and controlling the dynamic process. ERT can determine the spatial conductivity distribution based on previous work, and ERT potentially shows good performance in exploiting temporal information as well. Many ERT algorithms reconstruct images frame by frame, which is not optimal and would assume that the target is static during collection of each data frame, which is inconsistent with the real case. Although spatiotemporal-based algorithms can account for the temporal effect of dynamic movement and can generate better results, there is not that much work aimed at analyzing the performance in the time domain. In this paper, we discuss the performance of a novel spatiotemporal total variation (STTV) algorithm in both the spatial and temporal domain, and Temporal One-Step Tikhonov-based algorithms were also employed for comparison. The experimental results show that the STTV has a faster response time for temporal variation of the moving object. This robust time response can contribute to a much better control process which is the main aim of the new generation of process tomography systems.


2021 ◽  
pp. 1-14
Author(s):  
Jinhao Duan ◽  
Zhufeng Shao ◽  
Zhaokun Zhang ◽  
Fazhong Peng

Abstract Compared with serial robots, parallel robots have the advantages of high stiffness and good dynamics. By replacing the rigid limbs with cables, the cable-driven parallel robot (CDPR) is greatly simplified in structure and lightweight. We designed a high-speed CDPR tensioned by the passive rod and spring, named TBot. The robot can realize the SCARA movement as the classical Delta parallel robot. Comparison analysis of TBot and Delta is carried out to reveal the natures of the CDPRs and rigid parallel robots, identify the key issues, and promote industrial applications. Based on kinematics and dynamics modeling, performances are analyzed with simulation under a typical Adept Motion trajectory. Results illustrate that TBot has advantages of low cost, low inertia, low energy consumption and adjustable workspace and has great application potential. Energy consumption of the TBot is discussed and the trajectory planning is studied with the genetic algorithm to further reduce the energy consumption, considering the influence of the passive spring. Finally, on the basis of 30% less energy consumption for the Adept Motion than Delta, extra 14.3% energy consumption is saved through the trajectory planning of TBot.


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