1. M. Sato Y. Hirota H. Kawarada 1991 Space Interface Device for Artificial Reality -SPIDAR- The Transactions of The Institute of Electronics. Information and Communication Engineers Vol. J74-D-2 No.7 pp. 887--894 M. Sato Y. Hirota H. Kawarada 1991 Space Interface Device for Artificial Reality -SPIDAR- The Transactions of The Institute of Electronics. Information and Communication Engineers Vol. J74-D-2 No.7 pp. 887--894