This paper presents an agent-based architecture for robotic musical instruments that generate polyphonic rhythmic patterns that continuously evolve and develop in a musically "intelligent" manner. Agent-based software offers a new method for real-time composition that allows for complex interactions between individual voices while requiring very little user interaction or supervision. The system described, Kinetic Engine, is an environment in which individual software agents, emulate drummers improvising within a percussion ensemble. Player agents assume roles and personalities within the ensemble, and communicate with one another to create complex rhythmic interactions. In this project, the ensemble is comprised of a 12-armed musical robot, MahaDeviBot, in which each limb has its own software agent controlling what it performs.