In Openrave 0.9.0, the function 'GetSensorGeometry' is defined as :
virtual SensorGeometryConstPtr GetSensorGeometry(SensorType type=ST_Invalid) = 0;
The SensorGeometryConstPtr type does not correspond with the actual code, defined as a SensorGeometryPtr, causing a "invalid covariant return type" error. To fix this i changed the definition of the function at forceSensor.h to:
virtual SensorGeometryConstPtr GetSensorGeometry(SensorType type);
PD: Thanks to @jgvictores for the help!