问题：在使用gazebo的项目中会遇到下列报错：
[ERROR] [1486485132.488395779, 0.283000000]: Could not load controller 'seven_dof_arm_joint_controller' because controller type 'position_controllers/JointTrajectoryController' does not exist.
[ERROR] [1486485132.488718126, 0.283000000]: Use 'rosservice call controller_manager/list_controller_types' to get the available types
[INFO] [1486485132.533815, 0.295000]: Started controllers: joint_state_controller
[ERROR] [1486485133.491534, 0.560000]: Failed to load seven_dof_arm_joint_controller
[INFO] [1486485133.494729, 0.560000]: Loading controller: gripper_controller
[ERROR] [1486485133.520919999, 0.566000000]: Could not load controller 'gripper_controller' because controller type 'position_controllers/JointTrajectoryController' does not exist.
[ERROR] [1486485133.521358891, 0.566000000]: Use 'rosservice call controller_manager/list_controller_types' to get the available types
[ERROR] [1486485134.523407, 1.095000]: Failed to load gripper_controller首先请尝试：
$ sudo apt-get install ros-indigo-joint-state-controller : This will install joint_state_controller package
$ sudo apt-get install ros-indigo-effort-controllers : This will install Effort controller
$ sudo apt-get install ros-indigo-position-controllers : This will install position controllers
如若不能解决问题可尝试：sudo apt-get install ros*controller*
后者方法并不推荐，因为这种解决方法并不能让你知道问题究竟是出在哪里，不过黑猫白猫先抓到耗子再说，方法能解决问题就行。
相关阅读：https://blog.csdn.net/cookie909/article/details/79787333