This paper presents a novel method to perform automatic standing balance in a full mobilization exoskeleton. It exploits the locked ankle and the curved foot sole of the exoskeleton TWIICE. The idea is to use the knees to roll the sole and change the position of the contact point with the floor, which allows to stabilize without an actuated ankle. This controller is biologically inspired, originating from a previous experiment with the passive exoskeleton CAPTUR and healthy subjects. Then, a simulation model was built to test the observed balance strategy. Finally, the controller was implemented on the actual actuated exoskeleton, without a wearer for the time being, to experimentally check the basic operation. The next planned step is to test its actual performance with healthy subjects, then paraplegic patients.