Rigol DS1052D and Open Logic Sniffer

This blog has been moved: http://scholtyssek.org/blog/2014/07/29/rigol-ds1052d-and-open-logic-sniffer/

Today I have tested the logic analyzer of the Rigol DS1052D oscilloscope and I noticed that the LA does not interprete the measured signals. The Rigol DS1052D is a lower priced model, so it is ok that the data is not interpreted by the oscilloscope. But it is possible to export the signals and process them on a PC with the open source tool Open Logic Sniffer. To do so you can export them as a CSV datafile. After an easy converting the data can be read by OLS. The following step describe what you have to do.

STM32F4 controlled omnidirectional mecanum robot with odometry

This blog has been moved: http://scholtyssek.org/blog/2014/07/27/stm32f4-controlled-omnidirectional-mecanum-robot-with-odometry/

In the last months I worked on a new project based on an ARM STM32F4 controller. The goal was to implement a software to control a robot with mecanum wheels (also called swedish wheels). These wheels are very special, because there are rubber rollers arranged at 45 degree on the outer rim that roll passively on the ground. Thus the robot has a further degree of freedom. This means all directions (X, Y, Θ) can be reached by the robot on a plane. Despite the lack of steering axle it has the maximum freedom of movement. X and Y corresponds to the movement in the respective directions, and Θ represents the rotational movement of the robot.

the robot 

In the robot is a Nexus 4WD. It has four Faulhaber motors which are directly equipped with incremental encoders furthermore it also has (ultrasonic) distance sensors and an Arduino controller with suitable motor drivers. The 12 V DC motors are powered by a battery that is connected with a standard Tamiya plug.
Since I have decided to use the STM32F4, I performed some modifications on the robot. In particular, the Arduino controller was replaced by the STM32F4, but this had the consequence that the motor drivers that were permanently installed on the board of Arduino, were also removed from the robot. Therefore, a new engine controller with appropriate drivers (h-bridge) had to be developed so that the motors can be controlled properly.  In addition to the existing sensors and actuators, the robot is equipped with a gyroscope so that the orientation, that is, the rotation movements of the robot, can be measured in the context of odometry.

Figure1 and figure2 are showing the robot with a open chassis. They also show the four Mecanum wheels which are fixed to the shafts of the motors. In addition, you can see - despite the bunch of wires - the hardware components and the battery. Figure2 shows the robot in a top view and figure3 shows the individually hardware highlighted.

Figure1: Nexus 4WD (back view)