This paper focuses its attention on the mechanical design of autonomous agricultural robots used for the purpose of harvesting fruits in plantations. The paper analysis the present mechanical designs, identifies the research gaps and proposes a novel design of a fruit plucking robot. A design consisting of a four wheeled mobile base, a manipulator and an end-effector has been proposed. An open-chain rotary-rotary-prismatic (RRP) manipulator attached to the mobile base and having two additional active rotary joints at the end-effector at the free-end has been designed. A hose has been provided to transfer fruits from the tree to the basket. The chassis of the mobile base is equipped with four solid rubber power (motorized) wheels controlled by skid steering method and a detachable basket for collecting fruits. A counterweight mechanism has been designed to provide static stability. The paper addresses the issues present in the current mechanical designs with a brief discussion on the system architecture. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.