RoboSense LiDAR RS-Bpearl, User Manual

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RS-Bpearl User manual
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6. Vertical Angles and Exact Point Time Calculation
6.1.Channel Number and Vertical Angles
The RS-Bpearl LiDAR comes with a total of 32 laser heads vertically allocated along the vertical
field of view of 90 degrees with non-uniform angular resolution. Each laser head, also called a
laser channel, is installed with a designated vertical angle; Due to errors in actual assembly
processes, users can check the DIFOP data packets for the calibrated vertical angule value of each
laser channels.
6.2.Exact Point Time Calculation
6.2.1. Exact Point Time Calculation in Single Return Mode
In single return mode, each MSOP Packet has 12 data blocks and each data block stores
measurements of 1 firing sequences of 32 lasers, therefore, each MSOP Packet records 12 firing
sequences of 32 lasers. It takes 55.52us to complete one sequence of firing and recharging of the
32 lasers: The time to complete 32 laser shooting 1.28us * 32=40.96us (time interval between 2
laser shooting is 1.28us), plus the time cost for two laser charge, the wait time after each charge
and the reference signal time 2 * 4.00us + 2 * 1.20us + 4.16us=14.56us.
After the first laser charge, the RS-BPearl will complete the shooting from channel 1 to channel 8
and channel 17 to channel 24. Then a second laser charge and complets the shooting from
channel 9 to channel 16 and channel 25 to channel 32.
The laser number(data_index) is defined as laser 1 to 32, and the laser firing sequence
number(sequence_index) is defined as sequence 1 to 12. The time stamp of each MSOP packet is
the time stamp of the first laser shooting (laser point), to calculate the exact time of each laser
shooting(laser point), a time offset(time_offset) needs to be added to the time stamp.
The time offset of channel 1 to channel 8 and channel 17 to channel 24 is calculated as:
Time_offset = 55.52 * (sequence_index - 1) + 2.56 * mod((data_index
–
1) , 16) + 1.28 *
floor((data_index-1) / 16)
The time offset of channel 9 to channel 16 and channel 25 to channel 32 is calculated as:
Time_offset = 55.52 * (sequence_index - 1) + 2.56 * mod((data_index
–
1) , 16) + 1.28 *
floor((data_index-1) / 16) + 5.2
The exact time of each laser point is calculated as:
Exact_point _time = Tim Time_offset
Table 6-1 Time Offset of each Laser Point in the MSOP Packet in the Single Return Mode