Convert commands from prismatic joint to revolute for FollowJointTrajectory controller, robot arm gripper

I have a robotic arm ([Cyton Gamma 300](http://robots.mobilerobots.com/wiki/Cyton_Gamma_300_Arm)) with a 2-finger gripper, one joint mimics another (see the picture below). My goal is to control and execute trajectories on the gripper using **MoveIt**.  The gripper-related URDF/`xacro` chunk is as follows (the complete `xacro` description of the robot is [here](https://github.com/selyunin/cyton_gamma_300/blob/master/cyton_gamma_300_description/urdf/cyton_gamma_300.urdf.xacro)): As it can be seen from the description, (i) the joints are defined as **prismatic**, and as it can be seen from the photo, (ii) the gripper of the real robot is controlled by one 'dynamixel' motor, which is **revolute**. For the prismatic joint the displacement is specified in meters, whether for the dynamixel joint the rotation angle is defined in Radians. My goal is to use *MoveIt*, both with Gazebo and the real robot and be able to pick/place objects with the arm, leveraging available MoveIt capabilities. I am able to plan & execute trajectories for the manipulator (i.e. shoulder/wrist/elbow, 7 dynamixel motors in total), and bring the arm to the target position in space. However, I cannot execute a trajectory for the gripper properly, since MoveIt reads URDF description and generates a trajectory w.r.t to limits in the URDF, (i.e. it provides displacements in meters, not angle in Radians). To execute a trajectory in MoveIt I define `FollowJointTrajectory` controller as follows (complete configuration can be found [here](https://github.com/selyunin/cyton_gamma_300/)): controller_manager_ns: controller_manager controller_list: - name: cyton_gamma_300/arm_controller action_ns: follow_joint_trajectory type: FollowJointTrajectory default: true joints: - shoulder_roll_joint - shoulder_pitch_joint - elbow_roll_joint - elbow_pitch_joint - elbow_yaw_joint - wrist_pitch_joint - wrist_roll_joint - name: cyton_gamma_300/gripper_controller action_ns: follow_joint_trajectory type: FollowJointTrajectory default: true joints: - gripper_finger1_joint For instance, If I want to plan the following trajectory (gripper should come from red to yellow):  I get the following on my `/cyton_gamma_300/gripper_controller/follow_joint_trajectory/goal` (which is exactly a displacement): goal: trajectory: header: seq: 0 stamp: secs: 0 nsecs: 0 frame_id: /world joint_names: ['gripper_finger1_joint'] points: - positions: [0.00961187223614116] velocities: [0.0] accelerations: [-0.9530453139061077] effort: [] time_from_start: secs: 0 nsecs: 0 - positions: [0.008] velocities: [-0.042613731475556624] accelerations: [-0.9775129354039888] effort: [] time_from_start: secs: 0 nsecs: 58159883 - positions: [0.007838502345021854] velocities: [-0.058384310708380155] accelerations: [-0.6298771853005602] effort: [] time_from_start: secs: 0 nsecs: 60967905 - #and so on... the rest is omitted for brevity Although the trajectory is fine for Gazebo, and will be executed as expected, for the real robot it is a problem since these command would be interpreted as rotation angle, which is not correct. Question: how to map commands from FollowJointTrajectory to another type (i.e. from prismatic to revolute), and map the results back (i.e. feedback). Is there a standard way of approaching this problem? *P.S. if I've missed smth, the code is available [here](https://github.com/selyunin/cyton_gamma_300/). Thanks in advance!*