diff --git a/+acrobot/acrobot_torque_in.m b/+acrobot/acrobot_torque_in.m
new file mode 100644
index 0000000..4e34158
--- /dev/null
+++ b/+acrobot/acrobot_torque_in.m
@@ -0,0 +1,30 @@
+classdef acrobot_torque_in < matlab.System
+
+    % Public, tunable properties
+    properties
+
+    end
+
+    properties(DiscreteState)
+
+    end
+
+    % Pre-computed constants
+    properties(Access = private)
+
+    end
+
+    methods(Access = protected)
+        function setupImpl(obj)
+            % Perform one-time calculations, such as computing constants
+        end
+
+        function tau = stepImpl(obj, pwm, tau_in)
+            tau = 0; % Translate pwm to tau using resistance
+        end
+
+        function resetImpl(obj)
+            % Initialize / reset discrete-state properties
+        end
+    end
+end
diff --git a/+acrobot/acrobot_torque_out.m b/+acrobot/acrobot_torque_out.m
new file mode 100644
index 0000000..14be269
--- /dev/null
+++ b/+acrobot/acrobot_torque_out.m
@@ -0,0 +1,30 @@
+classdef acrobot_torque_out < matlab.System
+
+    % Public, tunable properties
+    properties
+
+    end
+
+    properties(DiscreteState)
+
+    end
+
+    % Pre-computed constants
+    properties(Access = private)
+
+    end
+
+    methods(Access = protected)
+        function setupImpl(obj)
+            % Perform one-time calculations, such as computing constants
+        end
+
+        function pwm_ratio = stepImpl(obj, tau, tau_in)
+            pwm_ratio = 1; % Between 1 and 0, where 1 is maximum speed, 0 is mininum speed
+        end
+
+        function resetImpl(obj)
+            % Initialize / reset discrete-state properties
+        end
+    end
+end
diff --git a/acrobot_sim.slx b/acrobot_sim.slx
index 564a041..b7f3294 100644
Binary files a/acrobot_sim.slx and b/acrobot_sim.slx differ