How can I optimize 7 variables using GA?

I am solving an optimization problem for a double loop 5bar mechanism.

My objective function is a cost function that has to be minimized.

I have to optimize at least 6 variables (lengths and angles of the link) such that the cost function is minimum.

How do I optimize the variables and get their values or get a pareto front to find suitable values?

[Abdolkarim Mohammadi]

You should use the multi-objective genetic algorithm, gamultiobj().