5. Interface Specifications

5.1. Mechanical

Mechanical Specification

A downloadble PDF of this drawing and a simplified CAD model is also available in the table below.

Mechanical Interface Drawing

Mechanical Interface Drawing

Simplified CAD Mode

Simplified CAD Model

5.3. Isolated IO

The MultiSense S7 has opto-isolated inputs and outputs. Currently, the input can be used as a 1:1 frame trigger and the output can generate a pulse-per-second signal (PPS). After generating a PPS pulse, the FPGA sends a PPS timestamp message to the connected client, see PPS Topics for more information.

To correctly interface to these opto-isolated signals, certain external circuity must be connected to the MultiSense S7. The values of the external current-limiting resistors used must change depending on the external voltages supplied or desired. Please read the Opto-Interface Drawing for more details.

Direct connection to external voltage sources WITHOUT the specified current-limiting resistors may permanently damage the opto-isolated inputs and outputs of your MultiSense S7.

Opto-Interface Drawing

Opto-Interface Drawing

Opto-Interface Drawing

5.4. IMU

The accelerometer and magnetometer are mounted in the locations and orientations called out in the CAD drawing below. Their locations correspond with the /multisense/accel, /multisense/mag, and /multisense/gyro frames in the /tf tree.

IMU Locations

"Stereo Origin" corresponds to /multisense/left_camera_optical_frame in the ROS /tf.

IMU Location Drawing

MultiSense S7 IMU Location Drawing

Accelerometer Specification

STMicroelectronics LSM303DLHC, Accelerometer

Gyroscope Specification

STMicroelectronics L3G4200D, Gyroscope

Accelerometer

The accelerometer and magnetometer are combined on a STMicroelectronics LSM303DLHC 3-D linear accelerometer and magnetometer microchip. The measured outputs for the accelerometer and magnetometer are in units of g-force and gauss respectively.

Gyroscope

The gyroscope is a STMicroelectronics L3G4200D three-axis gyroscope. The measured output is in degrees per second.