How many authors finished the paper "An Improved Active Suspension Model for Attitude Control of Electric Vehicles" together?
authors refers to AuthorId; 'An Improved Active Suspension Model for Attitude Control of Electric Vehicles' is the Title of a paper; A paper can have more than one author. Co-authorship can be derived from (paper ID, author ID) pair.
SELECT COUNT(T2.AuthorId) FROM Paper AS T1 INNER JOIN PaperAuthor AS T2 ON T1.Id = T2.PaperId WHERE T1.Title = 'An Improved Active Suspension Model for Attitude Control of Electric Vehicles'