Interaction Mode Control for the Machine Tool Table with Three Linear Servo Motors

Abstract

The linear motor driving mechanism has been adopted as a positioning mechanism of machine tools to realize high speed and precise positioning because of friction-free and no backlash. However, when two or more linear motors are used, minute differences between the thrust forces of each motor causes the generation of micro vibration and the change of velocity of each linear motor generated by yawing around the center of gravity. This study proposes interaction-mode-control method for the machine tool table driven by three linear motors to control the three modes defined as the position of the center of gravity, bending and yawing independently. The interaction-mode-control method is a new technique for applying interaction modes defined according to the workspace to the real control system through modal conversion. From the results of simulation and experiments, it is confirmed that the three modes are controlled independently and, therefore, bending and yawing can be suppressed using interaction-mode-control. Moreover, to combine the interaction-mode-control method with disturbance observer and feedforward control, this control system has high robustness and precise positioning can be realized.

Novel Compact Linear Switched Reluctance Motor with a Thin Shape and a Simple and Easily Replaceable Mover

“…Electromagnetic linear motors have less vibration elements and smaller inertia effects than driving units with power transmission elements, which are typically used in linear drive mechanisms. Their features are suitable for high-speed machines [1,2] and precision systems [3][4][5]. The use of linear motors increases every year [6].…”

Tandem control method of two axes with different reduction ratios (Comparison of three methods to equalize the transmission torque for a load)

“…方法として NC 工作機械の送り制御(松原，2011)を対象に，姿勢と平面運動の同時制御 (Shinno et al, 2004)，複 Akihiro MAEKAWA *1 and Takuya IMAEDA *2 数個のリニアモータ用いて弾性変形を補正する速度差積分法(曽我部他，2007) ，重心位置，振動モードなどを制 御する仮想モータ制御 (Umezawa et al, 2008)が紹介されている．また，モデルベースト制御による機械系振動抑制 (伊藤，賀勢，1998) (Ito, 2013) (Ito, 2014) ，非干渉化制御による位置決め制御(中島他，2003) ，相対速度フィ ードバックによる減衰の改善(松原他，2003) ，構造振動を考慮した制御系設計による振動抑制(松原他，2000) ， ２自由度制御による機台の振動抑制 (本田他， 2004) ， マスタースレーブ方式による協調駆動 (Hur and Nam, 2000) (越智，佐伯，2006) (内田他，2011) ，学習制御を用いた位置決め制御(中村他，2011) ，２台の位置制御器及び 速度制御器を用いてモータ間の相対位置を保ち負荷を駆動する方法 (Robertz et al, 2010) 2 The block diagram of the common torque method. In this method, the position signal and the rate signal from the motor 1 feedback to obtain the torque reference value of the motor 2, and the red part makes the transmission torque TM1 and TM2 of the each motor equal.…”