Performance evaluation of parallel link mechanism type machine tool

2019 ◽  
Vol 2019.56 (0) ◽  
pp. C043
Author(s):  
Masato UEKI ◽  
Yoshitaka MORIMOTO ◽  
Akio HAYASHI
Author(s):  
Akio Hayashi ◽  
Masato Ueki ◽  
Keisuke Nagao ◽  
Hiroto Tanaka ◽  
Yoshitaka Morimoto ◽  
...  

Abstract Robot type machine tools with parallel link mechanism are characterized by the performance to change tool posture and machine wider range than conventional machine tools. It is realized by simultaneous multi-axis control of parallel link mechanism. However, there are some problems, it is difficult to identify and adjust alignment error. In addition, the machining performance is unidentified due to the rigidity is different from conventional machine tools. In this research, a geometric model is described and the forward kinematics model is derived based on the geometric model. Then, the machining tests were carried out to evaluate the machining accuracy by measured machined surface and the simulated motion of tool cutting edge based on proposed forward kinematics model.


Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 748
Author(s):  
Qi Liu ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
Yu Qiao ◽  
Qian Cheng ◽  
...  

The drive at the center of gravity (DCG) principle has been adopted in computer numerical control (CNC) machines and industrial robots that require heavy-duty and quick feeds. Using this principle requires accurate corrections of positioning errors. Conventional error compensation methods may cause vibrations and unstable control performances due to the delay between compensation and motor motion. This paper proposes a new method to reduce the positioning errors of the dual-driving gantry-type machine tool (DDGTMT), namely, a typical DCG-principle-based machine tool. An error prediction method is proposed to characterize errors online. An algorithm is proposed to quickly and accurately compensate the errors of the DDGTMT. Experiment results verify that the non-delay error compensation method proposed in this paper can effectively improve the accuracy of the DDGTMT.


2010 ◽  
Vol 45 (5) ◽  
pp. 731-736
Author(s):  
Takumi Yaginuma ◽  
Takasi Takesima ◽  
Etsurou Shimizu ◽  
Masanori Ito ◽  
Junnichiro Tahara

2010 ◽  
Vol 154-155 ◽  
pp. 1085-1090
Author(s):  
Dong Qiang Gao ◽  
Zhen Ya Tian ◽  
Fei Zhang

With the development of the rapid prototyping manufacturing for ceramic parts, it is possible to shorten the manufacturing period of ceramic parts and improve the enterprise’s productivity efficiency. The development situation of the machine tools about rapid prototyping manufacturing for ceramic parts was introduced. A new-style device about rapid prototyping manufacturing for ceramic parts, which is based on the technology of laminated coalition and rapid concrete prototyping for ceramic parts, is designed. The basic constitutions, technical processing and working principle of the paving stock mechanism of the device have also been described. The PLC (programmable logic controller) is applied in the paving stock mechanism for controlling and runs well, which meets the requirements of automatic manufacturing for ceramic parts and improves the efficiency.


2002 ◽  
Vol 26 (3) ◽  
pp. 289-295 ◽  
Author(s):  
Takeshi Morita ◽  
Ryuichi Yoshida ◽  
Yasuhiro Okamoto ◽  
Toshiro Higuchi

2013 ◽  
Vol 25 (6) ◽  
pp. 897-905 ◽  
Author(s):  
Takayuki Onodera ◽  
◽  
Eiji Suzuki ◽  
Ming Ding ◽  
Hiroshi Takemura ◽  
...  

The number of physically disabled people in need of rehabilitation is increasing. Unfortunately, there is a shortage of physical therapists specializing in such rehabilitation. This has increased the demand for rehabilitation assist devices that can lessen the burden of physical therapists. In this study, the authors develop a device that can assist in the rehabilitation of the ankle joint by employing a Stewart-platform (SP)-type parallel-link mechanism. With the SP-type parallel-link mechanism, it is possible to measure and control six degrees-of-freedom (DOFs) of ankle-foot movement during rehabilitation. Because the device enables the measurements of the ankle and foot, it is possible to calculate the instantaneous center of the ankle joint. In previous studies, the authors proposed methods to calculate and control the posture of the ankle and foot by an SP-type parallel-link mechanism and verified their accuracy. In this paper, the authors propose a method for force control using the device and also verify its accuracy. Using this device, the force acting on the ankle-foot can be controlled by six air cylinders. The force produced by a single air cylinder is determined by controlling the pressures in the extension and retraction directions. The accuracy of the force control method is verified for a single air cylinder and for the assist device when all six air cylinders are engaged. Results show that the accuracy of the single air cylinder has a mean square error of 0.24 N or less, while those for force control of the entire device are 4.2 N or less for parallel translation and 3.2 Nm or less for rotation. This demonstrates a satisfactory accuracy. To incorporate rehabilitation assistance by means of stiffness or viscous damping in the future, the authors also propose methods to control the coefficients of stiffness and viscous damping of the air cylinder and verify their accuracy. The mean square errors for the accuracies in controlling the coefficients of stiffness and viscous damping are 3.4 N/m and 1.4 Ns/m, respectively, thus verifying the validity of the proposed methods.


1998 ◽  
Vol 10 (2) ◽  
pp. 147-153
Author(s):  
Yasuhito Oooka ◽  
◽  
Haruhisa Kawasaki ◽  
Nobuhito Takemura

This paper presents an efficient computational algorithm of model-based adaptive control for closed-loop robots. The algorithm is an extension of the computational algorithm for serial-link robots, which was derived by Kawasaki and Bito. The proposed algorithm is implemented to a 6 DOF robot with a parallel-link mechanism using a 32-bit DSP. Experimental results of trajectory control are also shown.


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