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(eng): The mechanical chain consisting of 4 links with 3 actuators placed between them is considered in this paper. It will be further referred to as the so-called 4-link. The 4-link can be used to study underactuated walking-like movement resembling walking of a pair of legs with knees and hips without a torso. Underactuated mechanical systems have less actuators than degrees of freedom. When a point of contact with surface is fixed, the above 4-link clearly has 4 degrees of freedom while 3 actuators only. The control of the 4-link model in a way resembling a human walk will be designed here based on the embedding of a simpler two degrees of freedom model with one actuator into the model of 4-link. This simpler model is referred to as the so-called generalized Acrobot. The embedding is performed via imposing two virtual constraints fixing dependence between knees angles and hip angle via suitable selection of a pair of constraining functions.