Multi-layer metal belt transmission mechanism and surgical mechanical arm

The multi-layer metal belt transmission mechanism comprises a driving wheel, a driven wheel and two metal belts of the same structure, the two ends of each metal belt are fixedly connected with the driving wheel and the driven wheel respectively, and the two metal belts are arranged between the driving wheel and the driven wheel in parallel and wound on the left side and the right side of the driving wheel and the left side and the right side of the driven wheel respectively. The metal belt is at least partially wound on the driving wheel and/or the driven wheel, in an initial state, a tangency point formed between the metal belt and the driving wheel or the driven wheel, a fixed connection point of the end part of the metal belt and the driving wheel or the driven wheel and the axis of the driving wheel or the driven wheel form a wrapping angle alpha, and the protection range of the wrapping angle alpha is 60-240 degrees; the driving wheel selectively drives the driven wheel to rotate synchronously through t