Hamersham is experienced in electronic brake and drive pedal control software for off-highway mobile working vehicles.
Safe control of braking and drive pedal functions in mobile off-highway vehicles is an area of software for which Hamersham has been providing state of the art software solutions for 20 years. Hamersham also has expertise in control of electronic braking functions in mobile off-highway vehicles.
Providing a robust software solution to Drive and Brake Pedal Control is always more complex than it seems when comprehensive FMEA on the function is conducted. Pedal signal processing according to EN13849-Pld always requires correct hardware selection. This means a pedal is selected with redundant signal outputs and a pre-certified mean time to failure value (MtF) for the whole assembly. The pedal then has to be connected to a safety certified controller and best practice in mobile electrical design has to be followed. As soon as the pedal is electrically connected to the safety control system then the software work begins:
-Calibration of the pedal signals inside safety software has to be handled in such a way that the integrity of the safety function is preserved. This means consideration has to be given as to how adjustable values are changed, stored and used. Processing this part of the function correctly is mandatory because all pedals need recalibration at manufacture and in the field.
-Detection of signals in the correct calibration zone is the next priority. The software has to check that Calibration Min and Calibration Max Values have not been breached.
-The pedal signals then have to be compared for non-linearity. In other words, the 2 pedal signals will always develop a small output differential error. This means the software has to decide when the pedal signals have become unacceptably non-linear.
-The next layer of software checks needs to deal with plausibility. Plausibility software checks look for things like pedal acceleration being too fast. This means that if the pedal can only be depressed in a maximum time of 100ms, then if the software detects a 20ms activation time, a plausibility problem is flagged.
Effective pedal software functions then work at application level in the machine. An example of this can be considered in relation to brakes. If the brake pedal position is monitored then the software can check for appropriate brake pressures against the brake pedal position. In other words an error can be detected for a brake valve hydraulic spool/pressure fault.
These are all examples of how Hamersham can bring years of application control experience into your project in order to provide safe and robust software functionality.
For more information and free advice please call or email us:
T: + 44 1977 529646
T: + 44 77177 90404