Field Service Security Roles

Hi,

If we talk about the available field security roles, who would be responsible for creating a work order? Is it the dispatcher, field service administrator, inventory purchase? 

I am bit confused regarding the roles actually. In my field service instance the dispatcher isn't able to create a new work order and I get field security error for the same. Will I have to assign a user the Field service administrator role to create a new work order?

Any information regarding the roles setup would be really appreciated.