— This paper presents a body model of intermediate level of detail to allow prediction of the knee torque produced by thigh muscles based on EMG signals. This torque prediction is used as input for a torque controller that adapts the level of support offered to an operator by a powered leg orthosis. The level of detail of the body model is chosen in such a way, that all parameters of the model can be calibrated for a specific operator with only a few sensors that are mounted on the exoskeleton.