In this report, some 40 papers related to backlash control have been studied, and their results have been arranged into a systematic structure, where the main categories are linear, passive and active nonlinear controllers. The emphasis of the study is on control strategies suitable for automotive powertrain applications, but the reported results are not limited to this field. The reported results are based on partly different system structures, depending on how the backlash is incorporated in the system. Different backlash models are also used. Therefore, the report contains a section that describes these differences as well.

Backlash is the source of an uncomfortable acceleration phenomenon, which in the automotive industry is called “shunt and shuffle”. Until recently, only simple controllers have been used to reduce the discomfort, and the tuning of these is made quite subjectively. A number of approaches to control of systems with backlash are reported in the literature, but very few are directed towards control of automotive powertrains. This paper evaluates four different controllers for powertrains with backlash, by means of simulation. The results show that active nonlinear controllers have a potential for improved backlash control. However, the robustness of these controllers needs further investigation.