IBM Advanced Studies

IBM BPM how to call IBM RPA bot 

RPA version is 23

As there arent much details in your question, i will give you a general answer. 
Here is a code snippet that will help you call IBM RPA bot ( assuming you have necessary libraries set up in your java project ) :

import com.ibm.bpm.integration.runtime.service.ExecutionException;
import com.ibm.bpm.integration.runtime.service.IntegrationService;
import com.ibm.bpm.integration.runtime.service.ServiceFactory;

// ...

// Instantiate the IntegrationService
IntegrationService integrationService = ServiceFactory.getIntegrationService();

try {
    // Prepare the input parameters for the RPA bot
    String botInputParameter1 = "Value1";
    int botInputParameter2 = 123;

    // Invoke the RPA bot using the IntegrationService
    integrationService.invoke("RpaBotServiceName", "RpaBotOperationName", 
        botInputParameter1, botInputParameter2);

    // Handle the response or outputs generated by the RPA bot
    // You can access the response using integrationService.getResponse() method

    // ...
} catch (ExecutionException e) {
    // Handle any exceptions that occurred during the invocation
    e.printStackTrace();
}

Hope this helps you get an idea where to solve your issue.