Unable to run `example_olfati_saber` with `DRONE_TYPE = "quadcopter"`

[d-marson]

Hello,

When running example_olfati_saber with DRONE_TYPE = "quadcopter", an array size mismatch error is thrown by an inequality operation in compute_vel_olfati_saber on line 252. Some details:

• The value p_swarm.max_a appears to be empty at the time the error is thrown
• The two if statements in this section of the m file, one beginning on line 240 and the other on line 249, appear to check for empty properties. If those properties are empty, the statements execute; however, the statements include attempts to compare the empty properties to values, one of which threw the error I ran into.

For comparison, when running example_olfati_saber with the default DRONE_TYPE = "point_mass", p_swarm.max_a is not empty and contains a scalar previously assigned to it.

Unfortunately, I don't yet know enough about swarm algorithms to propose a specific solution.