In recent years, following the advances in autonomous driving technology, low-speed autonomous service vehicles such as delivery, patrolling, and road-cleaning vehicles have started to emerge. As a promising future cleaning solution, autonomous cleaning vehicles are expected to address the workforce shortage many countries face in the near future. This paper describes the detailed design of an autonomous research platform for cleaning operations in mixed indoor & outdoor environments. An electric manual vacuum sweeper is retrofitted into an autonomous sweeper equipped with the Drive-by-Wire (DBW) system, computer, sensors, and actuators essential for autonomous driving. A complete autonomous driving software stack is also developed upon this hardware setup to enable the vehicle to navigate itself safely in various challenging operating environments. The system has been extensively tested in different environments on the National University of Singapore (NUS) campus, including private roads, car parks, warehouses, and public plaza areas.