Powered wheelchair users want to be active drivers, not just passengers. However, in some situations (varying from person to person), they may require assistance; hence, research is being carried out into the development of 'smart' wheelchairs. Predominantly, this research has been derived from the field of mobile robotics, focussing on creating autonomous systems, which unfortunately tend to treat the human as little more than a precious piece of cargo. Instead, the design should be based around each individual user's abilities and desires, maximising the amount of control they are given. In this paper, we look at how collaborative control techniques can be used to achieve this, offering the user help, as and when it is required. We then evaluate the effects of this collaboration, which is built by predicting user intentions and responding to these predictions with adaptable levels of assistance.