Precise robotic chamferless peg-hole insertion operation without force feedback and remote centre compliance (RCC)

Robots can be widely used in the industrial assembly operation if the task can be performed with high precision, high speed and with low cost. Peg-hole insertion is a fundamental operation whose problems have been the focus of much work. In the passive accommodation solution, remote centre compliance (RCC) is used to perform chamfered peg-hole insertion). The principle exploited involves using RCC as a mechanical map which transfers the translational and angular errors, between the peg and the hole, into corrective motion. The potential advantages of minimized cycle times are offset by the limited precision. This contrasts with techniques exploiting active accommodation which use a force sensor to arrive at the deviation, between the peg and hole axes, to achieve chamferless insertion. A strategy is developed here that uses neither of these additional accessories but instead exploits features of both techniques with defined initial conditions. The immediate advantages of reduced hardware complexity are supplemented by evidence of trials. These were based on a 31.99 mm diameter peg and a hole with a diameter clearance of 0.02 mm. The results showed that the algorithm operated reliably with small clearances and with minimum cycle times. This confirms its potentially wide application in industry where its simplicity can be fully exploited.