The compliance challenge
Most mechanical systems can be mathematically modelled and simulated using various excitation frequencies to identify the response point where resonance occurs .
However , the bandwidth of a system can never exceed the initial anti-resonance point . In fact , the higher the compliance , the lower the frequency of the initial resonance point , that reduces bandwidth accordingly .
When the driven load is directly coupled to the motor to minimise compliance , the mismatch is mitigated , increasing the initial resonance frequency and creating a higher bandwidth system .
Mathematical models show that the ultimate solution for a higher bandwidth and cost-effective system is to increase the mechanical stiffness and reduce total system inertia . Consider a direct drive solution where the load is directly coupled to the motor with near zero compliance ; in cases like this , precisely controlling the system with high bandwidth can be achieved with inertia mismatches as high as 30:1 .
As direct drive solutions are not suited to all applications , compliant links will inevitably be introduced . However , advanced analytical tools , such as the bode plot , can readily identify the compliant elements that reduce system performance .
Motion engineering
Applications often characterised by a high inertia mismatch can include printing and labelling , as well as various robot designs .
Although inertia mismatch is no longer the main challenge , resolving the imbalance requires careful specification across a range of aspects , from motor sizing , through to tuning and analytics of the control algorithms , and mechanical architecture .
Assistance in specifying a system is particularly useful for machines with an inherent inertia mismatch .
With comprehensive application sizing and best practices in designing a stiff mechanism , this can achieve a high-performance motion system capable of higher bandwidths , improved move and settle times , and robust dynamic control .
For more information , please visit www . inmoco . co . uk
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