<Dd> M = 6 n − ∑ i = 1 j (6 − f i) = 6 (N − 1 − j) + ∑ i = 1 j f i (\ displaystyle M = 6n - \ sum _ (i = 1) ^ (j) \ (6 - f_ (i)) = 6 (N - 1 - j) + \ sum _ (i = 1) ^ (j) \ f_ (i)) </Dd> <P> Recall that N includes the fixed link . </P> <P> There are two important special cases: (i) a simple open chain, and (ii) a simple closed chain . A single open chain consists of n moving links connected end to end by n joints, with one end connected to a ground link . Thus, in this case N = j + 1 and the mobility of the chain is </P> <Dl> <Dd> M = ∑ i = 1 j f i (\ displaystyle M = \ sum _ (i = 1) ^ (j) \ f_ (i)) </Dd> </Dl>

How to calculate degree of freedom in mechanics