According to the docs

Some models may have identity columns. These columns usually are the primary key of the mapped table. Phalcon\Mvc\Model can recognize the identity column omitting it in the generated SQL INSERT, so the database system can generate an auto-generated value for it. Always after creating a record, the identity field will be registered with the value generated in the database system for it.

And further on

Phalcon\Mvc\Model is able to recognize the identity column. Depending on the database system, those columns may be serial columns like in PostgreSQL or auto_increment columns in the case of MySQL.

We can then tell the ORM to skip columns in the initialize() method - https://docs.phalcon.io/en/3.0.2/reference/models-advanced.html#skipping-columns

This would make your model become something like (using skipAttributesOnCreate());

class Robots extends Model
{
    public function initialize()
    {
        // Skips only when inserting
        $this->skipAttributesOnCreate(
            [
                "id",
            ]
        );
    }
}