How can I get concrete definitions for the results from physics.named.data

[sumwailiu]

Take the "quadruped" domain as an example. It is known that we can get rough understandings from the quadruped.py that self.named.data.sensordata contains sensor readings as follows:

self.named.data.sensordata
Out[33]: 
FieldIndexer(sensordata):
 0              imu_accel [ 7.2     ]
 1              imu_accel [-2.65    ]
 2              imu_accel [ 22.7    ]
 3               imu_gyro [ 0.448   ]
 4               imu_gyro [ 0.411   ]
 5               imu_gyro [-0.751   ]
 6            velocimeter [-0.206   ]
 7            velocimeter [-0.0947  ]
 8            velocimeter [-0.249   ]
 9   force_toe_front_left [-62.4    ]
10   force_toe_front_left [ 30.4    ]
11   force_toe_front_left [-1.41    ]
12  force_toe_front_right [ 85.1    ]
13  force_toe_front_right [ 20.3    ]
14  force_toe_front_right [-101     ]
15   force_toe_back_right [ 1.19e+03]
16   force_toe_back_right [-291     ]
17   force_toe_back_right [-725     ]
18    force_toe_back_left [ 256     ]
19    force_toe_back_left [-23.1    ]
20    force_toe_back_left [-936     ]
21  torque_toe_front_left [ 0.232   ]
22  torque_toe_front_left [ 0.757   ]
23  torque_toe_front_left [-0.187   ]
24 torque_toe_front_right [-0.256   ]
25 torque_toe_front_right [-1.01    ]
26 torque_toe_front_right [ 0.139   ]
27  torque_toe_back_right [ 2.94    ]
28  torque_toe_back_right [-19.2    ]
29  torque_toe_back_right [ 13      ]
30   torque_toe_back_left [-28.8    ]
31   torque_toe_back_left [ 36.2    ]
32   torque_toe_back_left [-9.05    ]
33         center_of_mass [-0.00071 ]
34         center_of_mass [-0.0362  ]
35         center_of_mass [ 0.82    ]

Although these names provide basic information, I still don't know the concrete meanings for each item. For example, it is hard to infer which imu_accel is for x-axis.