Electromechanical Ski Release Binding with Mechanical Backup

Abstract

To better protect skiers against injuries to both the lower leg and the knee, releasable bindings that offer certain performance capabilities over current designs are warranted. Two capabilities that would be of immediate benefit are: (1) maintaining a consistent release level in twist in the presence of combined loads; and (2) releasing the heelpiece based on the anterior/posterior (A/P) bending moment transmitted by the leg. A third capability that may be worthwhile is modulating the release level in twist depending on the degree of contraction in muscles crossing the knee. Thus, the objective of this work was to design a binding that offered these capabilities through electronic control of binding release yet at the same time provided a conventional mechanical backup in the event of electronic failure. To fulfill the objective, a conventional ski binding was modified. Modifications included integrating dynamometers into the toepiece, anti-friction device (AFD), and heelpiece. The toepiece sensor indicates the twisting moment while the AFD and heelpiece sensors indicate the anterior bending moment transmitted by the leg. To gain electronic control of binding release, a solenoid actuated mechanism was added that translated the heelpiece rearward along the ski to decouple the boot from the binding. Otherwise, the binding allowed normal mechanical function. Prototype testing confirmed the ability of the dynamometers to accurately measure desired loads in the presence of extraneous loads and the reliability of the solenoid actuated mechanism in releasing the boot under loads typical of skiing. Thus, this work demonstrated the feasibility of hybrid electromechanical/mechanical releasable bindings. Such a demonstration should encourage the development of designs for commercial use.