The paper 'Quadrotor trajectory tracking and obstacle avoidance by chaotic grey wolf optimization- based backstepping control with sliding mode extended state observer' has how many authors?
How many authors does 'Quadrotor trajectory tracking and obstacle avoidance by chaotic grey wolf optimization- based backstepping control with sliding mode extended state observer' have?
SELECT ?answer WHERE { <https://dblp.org/rec/journals/tinstmc/WangMCZ20> <https://dblp.org/rdf/schema#numberOfCreators> ?answer }
<https://dblp.org/rec/journals/tinstmc/WangMCZ20>