[xs_sdk] Added backward compatibility for cobots (#29)

* [sdk_sim] Added backward compatibility for cobot

* [sdk_sim] Added conversion for rack_n_pinion

* [sdk_sim] fixed suggested changes

* [sdk_sim] Updated error to fatal

interbotix_ros_xseries/interbotix_xs_sdk/scripts/xs_sdk_sim

@@ -94,10 +94,17 @@ class InterbotixRobotXS(object):
 
         # populate self.gripper_map
         for gpr, items in grippers.items():
-            self.gripper_map[gpr] = {"horn_radius" : items["horn_radius"],
-                                     "arm_length" : items["arm_length"],
-                                     "left_finger" : items["left_finger"],
-                                     "right_finger" : items["right_finger"]}
+            self.gripper_map[gpr] = {
+                'type': items.get("type", "swing_arm"),
+                'horn_radius': items.get("horn_radius", 0.014),
+                'pitch_radius': items.get("pitch_radius", 0.0127),
+                'arm_length': items.get("arm_length", 0.024),
+                'left_finger': items.get("left_finger", "left_finger"),
+                'right_finger': items.get("right_finger", "right_finger"),
+                'calibrate': items.get("calibrate", False)
+            }
+            if (self.gripper_map[gpr]["type"] != "swing_arm" and  self.gripper_map[gpr]["type"] != "rack_and_pinion"):
+                rospy.logfatal("Invalid Gripper Type: '%s' . Options are: 'swing_arm', 'rack_and_pinion'", self.gripper_map[gpr]["type"])
 
         # populate self.sleep_map, self.gripper_order, and self.js_index_map
         # also, initialize self.joint_states
@@ -217,23 +224,30 @@ class InterbotixRobotXS(object):
     ### @param linear_position - desired distance [m] between the two gripper fingers
     ### @return result - angular position [rad] that achieves the desired linear distance
     def robot_convert_linear_position_to_radian(self, name, linear_position):
-        half_dist = linear_position / 2.0
-        arm_length = self.gripper_map[name]["arm_length"]
-        horn_radius = self.gripper_map[name]["horn_radius"]
-        result = math.pi/2.0 - math.acos((horn_radius**2 + half_dist**2 - arm_length**2) / (2 * horn_radius * half_dist))
-        return result
+        if (self.gripper_map[name]["type"] == "swing_arm"):
+            half_dist = linear_position / 2.0
+            arm_length = self.gripper_map[name]["arm_length"]
+            horn_radius = self.gripper_map[name]["horn_radius"]
+            result = math.pi/2.0 - math.acos((horn_radius**2 + half_dist**2 - arm_length**2) / (2 * horn_radius * half_dist))
+            return result
+        else:
+            return linear_position / 2 * self.gripper_map[name]["pitch_radius"]
 
     ### @brief Converts a specified angular position into the linear distance from one gripper finger to the center of the gripper servo horn
     ### @param name - name of the gripper servo to command
     ### @param angular_position - desired gripper angular position [rad]
     ### @return - linear position [m] from a gripper finger to the center of the gripper servo horn
     def robot_convert_angular_position_to_linear(self, name, angular_position):
-        arm_length = self.gripper_map[name]["arm_length"]
-        horn_radius = self.gripper_map[name]["horn_radius"]
-        a1 = horn_radius * math.sin(angular_position)
-        c = math.sqrt(horn_radius**2 - a1**2)
-        a2 = math.sqrt(arm_length**2 - c**2)
-        return a1 + a2
+        if (self.gripper_map[name]["type"] == "swing_arm"):
+            arm_length = self.gripper_map[name]["arm_length"]
+            horn_radius = self.gripper_map[name]["horn_radius"]
+            a1 = horn_radius * math.sin(angular_position)
+            c = math.sqrt(horn_radius**2 - a1**2)
+            a2 = math.sqrt(arm_length**2 - c**2)
+            return a1 + a2
+        else:
+            return self.gripper_map[name]["pitch_radius"] * angular_position
+
 
     ### @brief ROS Subscriber callback function to command a group of joints
     ### @param msg - JointGroupCommand message dictating the joint group to command along with the actual commands