In 11g R2, SYSASM privilege was introduced to perform ASM specific operations. Similarly, backup and recovery tasks specific privilege SYSBACKUP has been introduced in 12c to execute backup and recovery commands in Recovery Manager (RMAN). Therefore, you can create a local user in the database and grant the SYSBACKUP privilege to perform any backup and recovery related tasks in RMAN without being granting the SYSDBA privilege.
$ ./rman target "username/password as SYSBACKUP"