Spherical Motor * 1 * 2 * 1 * 2
نویسندگان
چکیده
原稿受付 2003年 7月 1日 キーワード:Spherical Motor, Actuator, Multi DOF, Ultrasonic Motor ∗1〒 305–8564 つくば市並木 1–2–1 ∗2〒 223–8522横浜市港北区日吉 3–14–1 ∗1Tsukuba–shi, Ibaraki ∗2Kohoku–ku, Yokohama–shi, Kanagawa 矢野らは,立体的に配置した 3組の巻線に流す正弦波電 流の振幅と位相差を変えることにより回転磁界の回転軸を 三次元空間内の任意の方向に制御できることを示し,ロー タを永久磁石にすれば球面同期モータ,ロータをコイルに すれば球面誘導モータが実現できると提案した [2].これら モータの試作機はロータ支持にジンバル機構を,位置計測 にはジンバル機構に取り付けた 1軸のポテンショメータも しくはエンコーダを用いていた.ジンバル機構は支持箇所 が力の働く場所から遠くなるために軸がふらつく,モータ 本体が大きくなるなどの問題を抱えていた. Sheffield大学のWangらは球面同期モータの支持機構に ベアリング,位置計測にホール素子センサを用いてPI位置 フィードバック制御を行い,可動範囲 ±45 [deg],ピークト ルク0.6 [Nm]を確認した [3]. 誘導モータのロータをコイルにするのは渦電流損を減ら すためであるが,球面モータではコイルを立体的に巻くの が非常に困難で,矢野らの試作機は回転するのがやっとの 状態だった. 武蔵野工科大学の海老原らは中空鉄球に適切な厚さのア ルミを融着すれば渦電流損を減らせることに注目し,融着 するアルミ厚をメカニカルギャップと同一の1 [mm]として 球面誘導モータを試作した(図1).試作した球面モータは Z軸周りに1,000 [rpm],X,Y軸周りに60 [rpm]の高速回 転を行い,回転中の軸の方向決めが可能である [4].
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