diff --git a/actuators-sensors/index.org b/actuators-sensors/index.org
index 1194171..31f1f17 100644
--- a/actuators-sensors/index.org
+++ b/actuators-sensors/index.org
@@ -81,6 +81,14 @@ https://www.bksv.com/en/products/shakers-and-exciters/LDS-shaker-systems/permane
 cite:yedamale03_brush_dc_bldc_motor_fundam
 https://www.electricaltechnology.org/2016/05/bldc-brushless-dc-motor-construction-working-principle.html
 
+* Measurement System / Acquisition System
+** Modal Analysis
+https://dewesoft.com/applications/structural-dynamics/modal-analysis
+Polytec 3D Scanning Laser Vibrometer https://www.polytec.com/us/vibrometry/products/full-field-vibrometers/psv-500-scanning-vibrometer/
+
+* Control System
+Dspace, Speedgoat
+
 * Positioning Stages
 ** Hexapods
 - https://www.alioindustries.com/
@@ -253,3 +261,5 @@ Its bode plot is shown on figure [[fig:L4C_bode_plot]].
 | Frequency Range (±5 %) | 0.7 to 450 Hz       |
 | resonant frequency     | > 2500 hz           |
 | broadband resolution   | 0.00004 $m/s^2$ rms |
+** Modal analysis
+http://www.oros.com/3900-oros-modal-2.htm