The ideal constraint force of 1-order nonholonomic constraint

Analyzed the restricted condition with 1-order nonholonomic constraint,the form of 1-order nonholonomic ideal constraint force in the space of C~q is given,and the geometric significance in the velocity space is clarified.It's proved that Appell-Chetaev condition is sufficient and necessary condition to realizing 1-order nonholonomic ideal constraint.