Modelling and Control of an Electro-Mechanically Actuated Pushbelt type Continuously Variable Transmission T.W.G.L. Klaassen, B. Bonsen, K.G.O. van de Meerakker, M. Steinbuch, P.A. Veenhuizen, B.G. Vroemen Eindhoven University of Technology Den Dolech 2, 5600 MB Eindhoven The Netherlands For analysis, control design and testing of an electro-mechanically actuated CVT, a sim- ulation model is built. The model incorporates all major driveline components and the proposed actuation system with servo motor actuation. The clamping forces in the variator are calculated using an explicit formulation of a model based on Coulomb friction. Identifi- cation of the non-linear model using step response analysis shows resonances between 8-12 [Hz] and between 20-30 [Hz], depending on the ratio. Closed loop bandwidths that can be achieved are typically 5 [Hz] for ratio control and 20 [Hz] for slip control. Topics / CVT, Modeling, Control 1 INTRODUCTION Use of a Continuously Variable Transmission (CVT) in a car can lead to lower fuel consumption. Because en- gine revolutions can be chosen independently of vehicle speed, efficient operating points of the internal combus- tion engine can be reached that are unreachable with a manual transmission or a stepped automatic transmis- sion. Unfortunately, because the energy consumption of the CVT itself is higher than that of a manual trans- mission, this efficiency gain is partly lost. The pulleys of a pushbelt or chain type CVT are actu- ated axially to adjust transmission ratio and to apply a belt clamping force. In conventional CVTs this is done using hydraulics. The CVT transmission ratio is depen- dent on the ratio of primary and secondary clamping force, and can be controlled by the pressure in the cylin- ders. Hydraulic losses are however substantial. The oil pump is directly coupled to the crankshaft of the internal com- bustion engine. To realize high shifting speeds at low engine speed, for instance during an emergency stop, a large pump volume is required. However, when the ratio is held constant at higher engine speeds, for in- stance while cruising on the highway, an unnecessarily large oil flow from high pressure to sump leads to large energy losses. By using a double planetary gear system and a screw mechanism at both shafts, as shown in Figure 1, it is possible to actuate the CVT electro-mechanically with two electro motors at the fixed world [9]. By rotating the primary motor M p , a relative rotation between the two sun gears of the planetary sets is realized. This results in a translation of the spindles at both pulleys. At the secondary side, by adjusting the torque deliv- ered by the secondary motor M s , the clamping force in the variator can be set and controlled. This sys- tem has the advantage that the CVT transmission ratio and the clamping force can be set independently. An- other advantage is that only mechanical power is needed when the CVT is shifting or when the clamping force is changed. The energy losses are reduced to a minimum in this way. For simulation, control design and testing, a multi-body model of this system is implemented in ADAMS soft- ware. The body oriented modeling used by ADAMS makes it easier to gain insight in the behavior of the system. This article gives an overview of the complete simulation model and presents results from identifica- tion based on state-space realization techniques. The design of SISO controllers for ratio and slip control is also presented. Finally, simulation results are shown. 2 DRIVELINE MODELLING The complete driveline model consists of an engine in- ertia, a torque converter, the CVT and a vehicle in- ertia. The torque delivered by the engine is obtained from measured engine data, depending on the engine speed and throttle position. A driveline controller cal- culates the throttle position based on the tracking er- ror of the vehicle speed. The torque converter (TC) is modeled using an impeller torque at the engine body and a turbine torque at the primary shaft of the CVT.