This　paper　solves　the　leaderless　consensus　problem　of　multiple　nonholonomic　mobile　robots　over　undirected　graphs　by　a　novel　distributed　event-triggered　controller　where　a　persistently　exciting　signal　is　utilized　to　overcome　the　nonholonomic　constraint.　A　new　triggering　mechanism　containing　two　triggering　conditions　is　developed　with　respect　to　the　cascaded　structure　of　the　closed-loop　system　which　makes　the　leaderless　consensus　problem　tractable　in　the　sense　that　we　no　longer　need　to　find　any　strict　Lyapunov　function　for　the　entire　closed-loop　system.　It　is　proven　in　order　that　the　solution　of　the　closed-loop　system　is　uniformly　globally　bounded,　that　the　full　consensus　subspace　is　uniformly　globally　exponentially　attractive,　and　that　the　Zeno　behavior　shall　never　occur.　A　numerical　example　is　provided　to　validate　the　effectiveness　of　the　proposed　controller.　©　2025　Elsevier　Ltd