rostopic pub -1 /turtle1/cmd_vel geometry_msgs/Twist -- '[2.0, 0. 0, 0.0]' '[0.0, 0.0, 1.8]'
[WARN] [WallTime: 1460875755.397486] Inbound TCP/IP connection failed: <class 'struct.error'>: 'required argument is not a float' when writing 'linear:
x: 2.0
y: 0. 0
z: 0.0
angular:
x: 0.0
y: 0.0
z: 1.8'
[WARN] [WallTime: 1460875755.504806] Inbound TCP/IP connection failed: <class 'struct.error'>: 'required argument is not a float' when writing 'linear:
x: 2.0
y: 0. 0
z: 0.0
angular:
x: 0.0
y: 0.0
z: 1.8'

你输入的时候多了一个空格： 2.0, 0.空格0, 0.0