Tune drivetrain.

Add force knob, efficiency, IMU

Change-Id: I4fd12665490d4e535d5890c2edf8ae611938333d
diff --git a/frc971/control_loops/drivetrain/ssdrivetrain.h b/frc971/control_loops/drivetrain/ssdrivetrain.h
index db255d7..9a9c0d8 100644
--- a/frc971/control_loops/drivetrain/ssdrivetrain.h
+++ b/frc971/control_loops/drivetrain/ssdrivetrain.h
@@ -19,7 +19,7 @@
 class DrivetrainMotorsSS {
  public:
   DrivetrainMotorsSS(const DrivetrainConfig &dt_config,
-                     StateFeedbackLoop<7, 2, 3> *kf,
+                     StateFeedbackLoop<7, 2, 4> *kf,
                      double *integrated_kf_heading);
 
   void SetGoal(const ::frc971::control_loops::DrivetrainQueue::Goal &goal);
@@ -43,7 +43,7 @@
   void ScaleCapU(Eigen::Matrix<double, 2, 1> *U);
 
   const DrivetrainConfig dt_config_;
-  StateFeedbackLoop<7, 2, 3> *kf_;
+  StateFeedbackLoop<7, 2, 4> *kf_;
   Eigen::Matrix<double, 7, 1> unprofiled_goal_;
 
   double last_gyro_to_wheel_offset_ = 0;