The Keztos (275:4) discusses how to understand the requirement for kavana by chalitzah: Is it the same din of kavanah that is required for all mitzvos based on the rule of mitzvos tzerichos kavanah, or is it a kavanah similar to the da'as required to make a kinyan?
Tosfos (Bechoros 19b) based on the Yerushalmi writes that m'doraysa a ketana can perform chalitza. The Chacham Tzvi (quoted in the Ketzos) argues that since a ketana has no da'as, she would not be able to meet any requirement of kavanah based on mitzvos tzerichos kavanah. The kavanah requirement must be similar to kinyan, in which case so long as a gadol is the counter-party in the transaction, his kavanah for the kinyan fulfills the necessary requirement (da'as acheres makneh).
However, Tosfos elsewhere (Yevamos 104b) writes that the requirement of da'as for chaliztah is satisfied by the fact that the ceremony is performed in the presence of Beis Din -- gadol omeid al gabav is sufficient. The din of omed al gabav usually comes into play when there is a requirement of lishma, e.g. baking matzah. It never comes into play in the context of kinyanim. Apparently the type of kavanah/da'as required for chalitzah does not fall neatly into the kinyan category the Chacham Tzvi places it in.
This topic is discussed b'arichus in the seforim of various roshei yeshivas: R' Chaim, R' Shimon in Sha'arei Yosher, and others. Too much of an arichus for me to write about now.