To detect strong trends, I would use 2 distinct EMAs (say 20 & 50 for example), and check both are going up (or down), the shorter one above the longer one for uptrend (reverse for downtrend) AND the 2 are somewhat parallel (distance between the 2 at last bar ~ same as 5, 10, 15 & 20 bars ago).
You can remove the last criteria for less strong trends.