Unable configure managed identity while using powershell script to automate pool creation through Azure Pipeline

#### Problem Description
Prerequisite:
Batch Account
Key Vault
User Assigned managed identity to provide Key vault access to Batch account

Once above resources are created, then:
I am trying to automate the pool creation through Azure Pipeline with the help of powershell script. How am I going to assign the above created managed identity to the pool. So that the application running on the pool can access their data from AKV.