Detta examensarbete är utfört hos Swisslog under våren 2013. De hade problem med den manuella styrningen av deras pallstaplingskran för höglager, som upplevdes ryckig och svår att kontrollera vid låga hastigheter. Huvudsyftet var att undersöka varför detta fenomen uppstod och hur det kunde lösas med både hård- och mjukvarumässiga metoder. Utöver detta undersöktes hur produktionskostnaden, för delarna av kranen som rör den manuella styrningen, kunde reduceras. Det upplevda fenomenet är känt som biodynamic feedthrough. Det innebär att konstruktionens acceleration matas genom operatörens kropp och skapar en återkoppling till styrdonet, i detta fall en joystick. Operatörens hand ger en oavsiktlig störsignal som gör systemet instabilt som i sin tur skapar en oscillation som ökar i amplitud och är svår eller omöjlig att stoppa. Den föreslagna lösningen är att digitalt lågpassfiltrera styrsignalen från joysticken. Det dämpar de skarpaste spikarna i signalen och förhindrar systemet att ta in de snabba handrörelser som kranens acceleration har skapat. / This bachelor thesis was written at Swisslog, who had a problem with the manual control of their high-bay pallet stacker crane. The ride was perceived rough and hard to control at lower speeds.    The main purpose was to examine the source of the phenomenon and how to solve the problem with both software and hardware. It was also requested to investigate ways to lower production costs of the parts of the crane related to the manual control.   The experienced phenomenon is known as biodynamic feedthrough. It refers to the acceleration of the structure affects the body of the operator causing a feedback loop to the input, in this case a joystick. The hand of the operator causes an involuntary control input and making the system unstable and causing an oscillation increasing in amplitude over time. This may be hard or impossible to stop.   The proposed solution is a low-pass filter applied at the output of the joystick. This attenuates the sharpest spikes from the joystick control signal and prevents the system from receiving the fast hand movements caused by the acceleration of the crane.

Biodynamic feedthrough occurs in many types of operator controlled machines where the operator is a passenger and the motion of the controlled machine excites motion of the human operator, creating unwanted feedback. It is a significant cause for control performance degradation in backhoes. In this research, the problem of biodynamic feedthrough is investigated in a backhoe control system. For simplification, the system is limited to a single degree of freedom. Several controller based approaches are investigated to reduce cab vibration, while maintaining cylinder tracking performance. These controllers are tested in hardware, with and without the human operator and associated biodynamic feedthrough. The effect of this cab vibration reduction on biodynamic feedthrough is tested in a small set of human subject tests. The results indicate that some vibration reduction and improvement in the operator's control performance can be achieved by adding cab vibration compensation.