Musical robots provide artists and musicians with the ability to realise complex new musical ideas in real acoustic space. However, most musical robots are created with open-loop control systems, many of which require time consuming calibration and do not reach the level of reliability of other electronic musical instruments such as synthesizers. This paper outlines the construction of a new robotic musical instrument, the Closed-Loop Robotic Glockenspiel, and discusses the improved robustness, usability and expressive capabilities that closed-loop control systems and embedded musical information retrieval processes can afford robotic musical instruments. The hardware design of the instrument is described along with the firmware of the embedded MIR system. The result is a new desktop robotic musical instrument that is capable of continuous unaided re-calibration, is as simple to use as more traditional hardware electronic sound-sources and provides musicians with new expressive capabilities.