Abstract: A complete analytical method to study six-link overconstrained mechanisms by using only four basic equations combined turning technique is presented. Meanwhile, closure conditions can be obtained and I-O equations can be further deduced. By using this method, the closure condition and I-O equations of the Bricard trihedral mechanism can be derived expediently. Also, the closure condition and I-O equations of a known 4R2P overconstrained mechanism are deduced for the first time.

Key words: Existence condition, Overconstraint analysis, Spatial six-link loop