ATARO is a bio-inspired arm robot with two degrees of freedom. Five artificial muscle-spring units (MSUs) are used for actuation. The MSUs, each consisting of a pneumatic artificial muscle (PAM) and a spring in series, mimic the characteristics of the human muscle-tendon complex. Five proportional control valves actuate the PAMs. To mimic biological proprioception, a force sensor and a length sensor in each muscle, and an angle sensor in each joint are used. A computer with an I/O board is used to control the arm robot in a real-time hardware-in-the-loop setup. The controller is implemented using Matlab 2016b®/Simulink®. This dataset entails detailed technical specifications and exemplary videos showing different movement patterns derived from bio-inspired control concepts.