Cricket-based robots

T his article describes the development of an autonomous hybrid microrobot that uses legs for propulsion and support of the rear half of the body and a pair of wheels for support of the front half. McKibben artificial muscles actuate the legs, and compressed air is generated by an onboard power plant. Control is also onboard in the form of a PIC microcontroller, from Microchip Technology Inc., that controls the actuators through four three-way valves that are each made up of a pair of microelectromechanical system (MEMS) devices. The biorobotics group at Case Western Reserve University (CWRU) has been developing biologically inspired robots for the past dozen years. This group includes mechanical and electrical engineers , computer scientists, and biologists from CWRU and biologists from Marshall University. The cooperative work has been insightful for both engineers and biologists; we have gained valuable insight into the biological systems modeled, and the biologists have been able to use the engineering research to help evaluate their findings. We have developed four generations of robots using biological principles [1], [2]. Each new robot has been progressively more capable. Robot I demonstrated the flexibility of a neural network controller. Robot II used legs that were more biologically inspired and, more importantly, its controller incorporated reflexes observed in insects. These improvements enabled it to walk over rough terrain and obstacles. Robot III, still in development, is a pneumatically actuated robot where Robots I and II were actuated with dc motors. Robot III is modeled closely after a cockroach and has, so far, been shown to have exceptional power, robust posture control, and smooth motor motion and promises to be an agile robot. Robot IV is similar to Robot III, but uses braided pneumatic actuators because of their muscle-like properties. With our experience in design and construction of insect-inspired robots, we have min-iaturized what we have learned to make a microrobot based loosely upon cricket locomotion. In this article, we describe the design of an autonomous hybrid microrobot (Fig. 1) that locomotes by walking and, in future work, will also jump. By " hybrid " we mean that it uses both wheels and legs. This robot is capable of carrying a payload of small sensors and becoming dormant to extend its useable lifetime. Its small size allows one person to carry many robots and allows relatively small vehicles to deploy large groups of robots in swarms. Since …