Hastighetsmätning av kolvrörelser i pneumatiska cylindrar
The purpose of this thesis was to investigate different methods do measure velocity of pistons in pneumatic cylinders at Bosch Rexroth Teknik AB. Through information of velocity the adjustment of a cylinders damping can be done easier.A future transducer will be used by salesmen, service personnel and customers. This requires a sensor that is easy to apply and use. It is also desirable that the sensor is cheap. A number of possible methods to measure velocity have been presented. In general, the requirements above have been difficult to fulfill.In almost all pneumatic cylinders, magnets are mounted on the piston. Magnetic sensors are then used for proximity sensing to detect its extreme positions. A similar way can be used for velocity sensing. Assume that two magnetic sensors are placed on a fixed distance between each other, along the pistons direction of motion. The time to travel between the sensors is an expression for the velocity of the piston.One way to solve the problem has been chosen and the accuracy of this method has been verified. This has been done under the assumption that the errors due to mounting is neglected and that the direction of sensitivity is idealistic.