Enable force mode compatibility with various move types (#230)

This should make force mode work with various of move types. 
With this commit, the joint positions used for checks and interpolations
is now done without force mode modifications.

When the robot is in an offset situation, where the robot isn't at the position that
is currently used for motion commands, this will use the non-offset position to
check whether a new motion is within the reachable limits of the robot.

Author: urrsk

resources/external_control.urscript

@@ -68,8 +68,8 @@ JOINT_IGNORE_SPEED = 20.0
 global violation_popup_counter = 0
 global cmd_servo_state = SERVO_UNINITIALIZED
 global cmd_servo_qd = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
-global cmd_servo_q = get_actual_joint_positions()
-global cmd_servo_q_last = get_actual_joint_positions()
+global cmd_servo_q = get_joint_positions()
+global cmd_servo_q_last = cmd_servo_q
 global cmd_twist = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
 global extrapolate_count = 0
 global extrapolate_max_count = 0
@@ -158,7 +158,7 @@ end
 thread servoThread():
   textmsg("ExternalControl: Starting servo thread")
   state = SERVO_IDLE
-  local q_last = get_target_joint_positions()
+  local q_last = get_joint_positions()
   while control_mode == MODE_SERVOJ:
     enter_critical
     q = cmd_servo_q
@@ -221,13 +221,13 @@ def cubicSplineRun(end_q, end_qd, time, is_last_point=False, is_first_point=Fals
   local str = str_cat(end_q, str_cat(end_qd, time))
   textmsg("Cubic spline arg: ", str)
 
-  local start_q = get_target_joint_positions()
+  local start_q = get_joint_positions()
   # Zero time means infinite velocity to reach the target and is therefore impossible
   if time <= 0.0:
     if is_first_point and time == 0.0:
       # If users specify the current joint position with time 0 that may be fine, in that case just
       # ignore that point
-      local distance = norm(end_q - get_target_joint_positions())
+      local distance = norm(end_q - start_q)
       if distance < 0.01:
         local splineTimerTraveled = 0.0
         # USED_IN_TEST_SPLINE_INTERPOLATION write_output_float_register(1, splineTimerTraveled)
@@ -263,13 +263,13 @@ def quinticSplineRun(end_q, end_qd, end_qdd, time, is_last_point=False, is_first
   local str = str_cat(end_q, str_cat(end_qd, str_cat(end_qdd, time)))
   textmsg("Quintic spline arg: ", str)
 
-  local start_q = get_target_joint_positions()
+  local start_q = get_joint_positions()
   # Zero time means infinite velocity to reach the target and is therefore impossible
   if time <= 0.0:
     if is_first_point and time == 0.0:
       # If users specify the current joint position with time 0 that may be fine, in that case just
       # ignore that point
-      local distance = norm(end_q - get_target_joint_positions())
+      local distance = norm(end_q - start_q)
       if distance < 0.01:
         return False
       end
@@ -553,7 +553,7 @@ end
 thread servoThreadP():
   textmsg("Starting pose servo thread")
   state = SERVO_IDLE
-  local q_last = get_target_joint_positions()
+  local q_last = get_joint_positions()
   while control_mode == MODE_POSE:
     enter_critical
     q = cmd_servo_q