Human machine interfaces (HMIs) are an essential part of any industrial system, enabling processes to be controlled and important information to be accessed (monitoring of different parameters, tracking of assets, etc.). The often uncompromising conditions in which they have to operate means that they need to be robust (showing resilience to shocks and vibrations). In situations where exposure to harsh substances (for example the petrochemical industry) or contamination (food/beverage and pharmaceutical production) could pose problems, there is increasing interest in shifting away from touch-based mechanisms. Optical time-of-flight (ToF) may be used instead, for gesture recognition. Among the scenarios where such gesture recognition is certain to be of value is enabling human staff to communicate with robots/cobots (so they can tell them what task needs to be done).