a Schematic illustration for the self-adjusted, unsupervised output power of emergency braking in a self-driving car. b Schematic illustration for the self-regulation of posture balance in robot motions, e.g., soccer robot. c Self-regulation of the output power density at real-time in response to the acceleration of 1, 2, 3, 4, and 5 G. d The changes in output power density with various acceleration. Error bars indicate standard deviations for three sets of data points. The inset shows the setup for the acceleration-feedback-control.