You need to institute comprehensive Performance Management System (PMS) in your company. You cannot look at the few departments in isolation. It is HOD's job to design the targets and not yours. HR is only a process facilitator or process owner of PMS.
In my previous reply for the query that was similar to yours, I have given exhaustive reply. You may click the following link to refer it:
In addition to this, I have uploaded my video on PMS. You may click here to refer it.
In my experience, good HR means a person who contributes to the business and for that to happen you have to a) first understand each and every job - what they do and how they do it and b)how each job contributes to organizational Vision / Mission / profitability drivers / - delivery, revenue, cost, customer service, quality etc. Of course you have to go into the depth of each job.
At the intersection of the job & it's linkage to organizational goals, you will find the KPIs.
Let me know if this helps.