Development of Micro-Force Sensor based on 3-RRR Parallel Mechanism

A new style micro-force sensor based on a 3-RRR parallel micro-motion stage which had been researching recent years was introduced in this paper. The sensor can be used in micro-force and micro-torque detection in precision engineering. The result and experience from 3-RRR micro-motion stage research bring this new idea. In the first place, the branched chain structure in motion stage needs to be simplified and improved to adapt to the requirement of sensor. Secondly, a mechanics model is constructed according to the sense organ structure. The Jacobin Matrix which is the most important matrix on parallel structure is analyzed and deduced. The relationship among key dimension is worked out through isotropy parameters. With the theory analysis, the final structure of sense organ is determined. The elastomeric sensor body was pasted with electrical-resistance strain gauges, after it was manufactured by Wire-EDM. Strain gauges employed Wheatstone bridge and amplifier AD620 to produce measuring data. Experiment has indicated that the new sensor is competent for micro-force detecting in X, Y direction and micro-moment around Z direction with high stability and reliability.