Matched context for obstacle and knock

The page lists matched contexts for obstacle and knock.

Share - obstacle	Share - knock	Phrase
1.36%	15.97%	{obstacle or knock} sensor
5.64%	2.40%	detect {obstacle or knock} [perform operation]
1.61%	2.11%	{obstacle or knock} detector
0.92%	2.58%	{obstacle or knock} detection
2.09%	0.53%	{obstacle or knock} presence
1.19%	0.68%	{obstacle or knock} means
3.44%	0.28%	avoid {obstacle or knock} [perform operation]
0.94%	0.68%	not {obstacle or knock}
2.14%	0.24%	present [chronology] {obstacle or knock}
0.91%	0.61%	sense {obstacle or knock} [perform operation]