diff --git a/robot_modeling/DQ_SerialManipulator.m b/robot_modeling/DQ_SerialManipulator.m
index 55832c70..c1e69f01 100644
--- a/robot_modeling/DQ_SerialManipulator.m
+++ b/robot_modeling/DQ_SerialManipulator.m
@@ -15,7 +15,7 @@
 %
 % See also DQ_Kinematics.
 
-% (C) Copyright 2011-2022 DQ Robotics Developers
+% (C) Copyright 2011-2023 DQ Robotics Developers
 %
 % This file is part of DQ Robotics.
 %
@@ -51,6 +51,7 @@
         % mainly in the plot function.
         handle
         n_links;
+        joint_types;
     end
 
      methods (Abstract, Access = protected)   
@@ -73,9 +74,50 @@
         % Human-Robot Collaboration' by Bruno Adorno.
         % Usage: w = get_w(ith), where
         %          ith: link number
-        w = get_w(obj,ith) ; 
+        w = get_w(obj,ith) ;   
      end
 
+     methods (Abstract, Static, Access = protected) 
+         % This method returns the supported joint types.
+        st = get_supported_joint_types();
+     end
+
+     methods (Access = protected)  
+         function check_joint_types(obj)
+            %  CHECK_JOINT_TYPES() throws an exception if the joint types
+            %  are different from the supported joints.
+            types = obj.get_joint_types();
+            supported_types = obj.get_supported_joint_types();
+            n = size(types, 2);
+            k = size(supported_types, 2);
+            %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+            %  Create a string containing the valid type of joints.
+            msg = 'Unsupported joint types. Use valid joint types: '; 
+            for i=1:k
+              msg_type = ' DQ_JointType.' + string(supported_types(i));  
+              if i==k
+                  ps = '. ';
+              else
+                  ps = ', ';
+              end
+              msg = msg + msg_type + ps;
+            end
+            %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+            for i=1:n
+                  match = false;
+                  for j=1:k
+                      if types(i) == supported_types(j)
+                          match = true;
+                          break;
+                      end
+                  end
+                  if match == false
+                      error(msg);
+                  end
+            end
+         end
+     end 
+
     methods
         function obj = DQ_SerialManipulator()
             obj.reference_frame = DQ(1); %Default base's pose
@@ -98,6 +140,32 @@ function set_effector(obj,effector)
             % SET_EFFECTOR(effector) sets the pose of the effector         
             obj.effector = DQ(effector);
         end
+
+         function set_joint_types(obj, joint_types)
+            %  SET_JOINT_TYPES(joint_types) sets the joint types.
+            % 'joint_types' is a vector containing the joint types.
+            obj.joint_types = joint_types;
+            obj.check_joint_types();
+        end
+
+        function set_joint_type(obj, joint_type, ith_joint)
+            % SET_JOINT_TYPE(joint_type, ith_joint) sets the joint type of the ith
+            % joint.
+            % 'joint_type' type of joint to be set.
+            % 'ith_joint' ith joint to be set.
+            obj.joint_types(ith_joint) = joint_type;
+            obj.check_joint_types();
+        end
+
+        function ret = get_joint_types(obj)
+            % GET_JOINT_TYPES() returns a vector containing the joint types.
+            ret = obj.joint_types;
+        end
+
+        function ret = get_joint_type(obj, ith_joint) 
+            % GET_JOINT_TYPE(ith_joint) returns the joint type of the ith joint.
+            ret = obj.joint_types(ith_joint);
+        end
         
         function x = fkm(obj,q, ith)
             %   FKM(q) calculates the forward kinematic model and
diff --git a/robot_modeling/DQ_SerialManipulatorDH.m b/robot_modeling/DQ_SerialManipulatorDH.m
index 1c0246f7..06d9a943 100644
--- a/robot_modeling/DQ_SerialManipulatorDH.m
+++ b/robot_modeling/DQ_SerialManipulatorDH.m
@@ -30,7 +30,7 @@
 %       set_effector - Set an arbitrary end-effector rigid transformation with respect to the last frame in the kinematic chain.
 % See also DQ_SerialManipulator.
 
-% (C) Copyright 2020-2022 DQ Robotics Developers
+% (C) Copyright 2020-2023 DQ Robotics Developers
 %
 % This file is part of DQ Robotics.
 %
@@ -71,7 +71,6 @@
 classdef DQ_SerialManipulatorDH < DQ_SerialManipulator
     properties
         theta,d,a,alpha;
-        type
     end
     
     properties (Constant)
@@ -106,7 +105,7 @@
             a = obj.a(ith);
             half_alpha = obj.alpha(ith)/2.0;
             % Add the effect of the joint value
-            if obj.type(ith) == DQ_JointType.REVOLUTE
+            if obj.get_joint_type(ith) == DQ_JointType.REVOLUTE
                 % If joint is revolute
                 half_theta = half_theta + (q/2.0);
             else
@@ -141,7 +140,7 @@
         % Human-Robot Collaboration' by Bruno Adorno.
         % Usage: w = get_w(ith), where
         %          ith: link number    
-            if obj.type(ith) == DQ_JointType.REVOLUTE
+            if obj.get_joint_type(ith) == DQ_JointType.REVOLUTE
                 w = DQ.k;
             else
                 % see Table 1 of "Dynamics of Mobile Manipulators using Dual Quaternion Algebra."
@@ -151,6 +150,13 @@
             end
         end
     end
+
+    methods (Static, Access = protected) 
+         function ret = get_supported_joint_types()
+         % This method returns the supported joint types.
+            ret = [DQ_JointType.REVOLUTE, DQ_JointType.PRISMATIC];
+         end
+    end
     
     methods
         function obj = DQ_SerialManipulatorDH(A, convention)
@@ -189,7 +195,7 @@
             obj.d     = A(2,:);
             obj.a     = A(3,:);
             obj.alpha = A(4,:);
-            obj.type  = A(5,:);
+            obj.set_joint_types(A(5,:));
         end
         
     
diff --git a/robot_modeling/DQ_SerialManipulatorMDH.m b/robot_modeling/DQ_SerialManipulatorMDH.m
index 8f096006..ca276952 100644
--- a/robot_modeling/DQ_SerialManipulatorMDH.m
+++ b/robot_modeling/DQ_SerialManipulatorMDH.m
@@ -30,7 +30,7 @@
 %       set_effector - Set an arbitrary end-effector rigid transformation with respect to the last frame in the kinematic chain.
 % See also DQ_SerialManipulator.
 
-% (C) Copyright 2020-2022 DQ Robotics Developers
+% (C) Copyright 2020-2023 DQ Robotics Developers
 %
 % This file is part of DQ Robotics.
 %
@@ -72,7 +72,6 @@
 classdef DQ_SerialManipulatorMDH < DQ_SerialManipulator
     properties
         theta,d,a,alpha;
-        type
     end
     
     properties (Constant)
@@ -107,7 +106,7 @@
             half_alpha = obj.alpha(ith)/2.0;
             
             % Add the effect of the joint value
-            if obj.type(ith) == DQ_JointType.REVOLUTE
+            if obj.get_joint_type(ith) == DQ_JointType.REVOLUTE
                 % If joint is revolute
                 half_theta = half_theta + (q/2.0);
             else
@@ -142,15 +141,23 @@
         % Usage: w = get_w(ith), where
         %          ith: link number
 
-            if obj.type(ith) == DQ_JointType.REVOLUTE            
+            if obj.get_joint_type(ith) == DQ_JointType.REVOLUTE            
                 w = -DQ.j*sin(obj.alpha(ith))+ DQ.k*cos(obj.alpha(ith))...
                     -DQ.E*obj.a(ith)*(DQ.j*cos(obj.alpha(ith)) + DQ.k*sin(obj.alpha(ith)));
             else % if joint is PRISMATIC          
                 w = DQ.E*(cos(obj.alpha(ith))*DQ.k - sin(obj.alpha(ith))*DQ.j);
             end
-        end
-        
+        end 
     end
+
+    methods (Static, Access = protected) 
+         % This method returns the supported joint types.
+         function ret = get_supported_joint_types()
+        % This method returns the supported joint types.
+            ret = [DQ_JointType.REVOLUTE, DQ_JointType.PRISMATIC];
+         end
+    end
+
     methods
         function obj = DQ_SerialManipulatorMDH(A)
             % These are initialized in the constructor of
@@ -183,7 +190,7 @@
             obj.d     = A(2,:);
             obj.a     = A(3,:);
             obj.alpha = A(4,:);
-            obj.type  = A(5,:);
+            obj.set_joint_types(A(5,:));
         end
         
     end