The carbon fiber balance arm can be equipped with an encoder to achieve X-Y coordinate control and a photoelectric encoder to precisely locate the target point. Integrated with the AST(Intelligent foolproof and Error-proofing) system, the tightening operation is carried out in sequence according to the preset process flow and the coordinates of the target point. If the force arm does not reach the target position, the screwdriver will automatically lock, achieving the intelligent foolproof and error-proofing function. It improves assembly quality and torque accuracy, and features lightweight, simple structure, high rigidity, strong shock resistance, smoother operation, software linkage, and error-proofing and error-proofing, among many other characteristics.