Multimodal autonomous agent application

1. Concept Introduction

1.1 What is an "Autonomous Agent"?

In the largemodel project, multimodal autonomous agents represent the most advanced form of intelligence. Rather than simply responding to a user's command, they are capable of autonomously thinking, planning, and continuously invoking multiple tools to achieve a complex goal.

The core of this functionality is the **agent_call** tool or its underlying **ToolChainManager. When a user issues a complex request that cannot be accomplished with a single tool call, the autonomous agent is activated.

1.2 Implementation Principles

The autonomous agent implementation in largemodel follows the industry-leading ReAct (Reason + Act) paradigm. Its core concept is to mimic the human problem-solving process, cycling between "thinking" and "acting."

1. Reason: When the agent receives a complex goal, it first invokes a powerful language model (LLM) to perform "thinking." It asks itself, "To achieve this goal, what should I do first? Which tool should I use?" The output of the LLM isn't a final answer, but rather an action plan.
2. Act: Based on the LLM's deliberation, the agent performs the corresponding action—calling the ToolsManager to run the specified tool (e.g., visual_positioning).
3. Observe: The agent obtains the result of the previous action ("observation"), for example, {"result": "The cup was found at [120, 300, 180, 360]"}.
4. Rethink: The agent submits this observation, along with the original goal, to the LLM for a second round of "reflection." It asks itself, "I've found the location of the cup. What should I do next to learn its color?" The LLM might generate a new action plan, such as {"thought": "I need to analyze the image of the area where the cup is located to determine its color", "action": "seewhat", "args": {"crop_area": ​​[120, 300, 180, 360]}}.

This think -> act -> observe cycle continues until the initial goal is achieved, at which point the agent generates and outputs the final answer.

2. Code Analysis

Key Code

1. Agent Core Workflow (largemodel/utils/ai_agent.py)

The _execute_agent_workflow function is the agent's main execution loop, defining the core "plan -> execute" process.

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# From largemodel/utils/ai_agent.py
​
class AIAgent:
    # ...
​
    def _execute_agent_workflow(self, task_description: str) -> Dict[str, Any]:
        """
        Executes the agent workflow: Plan -> Execute. / 执行Agent工作流：规划 -> 执行。
        """
        try:
            # Step 1: Mission Planning
            self.node.get_logger().info("AI Agent starting task planning phase")
            plan_result = self._plan_task(task_description)
            
            # ... (Return early if planning fails)
​
            self.task_steps = plan_result["steps"]
​
            # Step 2: Follow all steps in order
            execution_results = []
            tool_outputs = [] 
​
            for i, step in enumerate(self.task_steps):
                # 2.1. Processing data references in parameters before execution
                processed_parameters = self._process_step_parameters(step.get("parameters", {}), tool_outputs)
                step["parameters"] = processed_parameters
​
                # 2.2. Executing a single step
                step_result = self._execute_step(step, tool_outputs)
                execution_results.append(step_result)
​
                # 2.3. If the step succeeds, save its output for reference in subsequent steps
                if step_result.get("success") and step_result.get("tool_output"):
                    tool_outputs.append(step_result["tool_output"])
                else:
                    # If any step fails, abort the entire task
                    return { "success": False, "message": f"Task terminated because step '{step['description']}' failed." }
            
            # ... Summarize and return the final result
            summary = self._summarize_execution(task_description, execution_results)
            return { "success": True, "message": summary, "results": execution_results }
​
        # ... (Exception handling)

2. Mission planning and LLM interaction (largemodel/utils/ai_agent.py)

The core of the _plan_task function is to build a sophisticated prompt and use the reasoning ability of the large model to generate a structured execution plan.

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# From largemodel/utils/ai_agent.py
​
class AIAgent:
    # ...
    def _plan_task(self, task_description: str) -> Dict[str, Any]:
        """
        Uses the large model for task planning and decomposition. / 使用大模型进行任务规划和分解。
        """
        # Dynamically generate a list of available tools and their descriptions
        tool_descriptions = []
        for name, adapter in self.tools_manager.tool_chain_manager.tools.items():
            # ... (Get tool description from adapter.input_schema)
            tool_descriptions.append(f"- {name}({params}): {description}")
        available_tools_str = "\\n".join(tool_descriptions)
​
        # Build a highly structured plan
        planning_prompt = f"""
As a professional task planning Agent, please break down the user's task into a series of specific, executable JSON steps.
​
**# Available Tools:**
{available_tools_str}
​
**# Core Rules:**
1.  **Data Passing**: When a subsequent step needs to use the output of a previous step, you **must** use the `{{{{steps.N.outputs.KEY}}}}` format for referencing.
    - `N` is the step ID (starting from 1).
    - `KEY` is the specific field name in the output data of the previous step.
    - `outputs` can be followed by `data` (for primary data) or `metadata.sub_key` (for metadata).
2.  **JSON Format**: You must strictly return a JSON object. Do not include any Markdown wrappers (like ```json```).
3.  **Tool Selection**: Strictly select the most appropriate tool based on its description.
​
**#  User Task:**
{task_description}
"""
        
        # Calling large models for planning
        messages_to_use = [{"role": "user", "content": planning_prompt}]
        # Note that the general text reasoning interface is called here
        result = self.node.model_client.infer_with_text("", message=messages_to_use)
        
        # ... (Parse the JSON response and return a list of steps)

3. Parameter processing and data flow implementation (largemodel/utils/ai_agent.py)

The _process_step_parameters function is responsible for parsing placeholders and implementing data flow between steps.

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# From largemodel/utils/ai_agent.py
​
class AIAgent:
    # ...
    def _process_step_parameters(self, parameters: Dict[str, Any], previous_outputs: List[Any]) -> Dict[str, Any]:
        """
        Parses parameter dictionary, finds and replaces all {{...}} references.
        """
        processed_params = parameters.copy()
        # Regular expression used to match placeholders in the format {{steps.N.outputs.KEY}}
        pattern = re.compile(r"\\{\\{steps\\.(\\d+)\\.outputs\\.(.+?)\\}\\}")
​
        for key, value in processed_params.items():
            if isinstance(value, str) and pattern.search(value):
                # Use re.sub and a replacement function to process all found placeholders. 
                # The replacement function will look up and return the value from the previous_outputs list.
                processed_params[key] = pattern.sub(replacer_function, value)
        
        return processed_params

Code Analysis

The AI ​​Agent is the "brain" of the system, translating high-level, sometimes ambiguous, tasks posed by the user into a precise, ordered series of tool calls. Its implementation is independent of any specific model platform and built on a general, extensible architecture.

1. Dynamic Task Planning: The Agent's core capability lies in the _plan_task function. Rather than relying on hard-coded logic, it dynamically generates task plans by interacting with a larger model.

• Self-Awareness and Prompt Construction: At the beginning of planning, the Agent first examines all available tools and their descriptions. It then packages this tool information, the user's task, and strict rules (such as data transfer format) into a highly structured planning_prompt.
• Model as Planner: This prompt is fed into a general text-based model. The model reasoned based on the provided context and returned a multi-step action plan in JSON format. This design is highly scalable: as tools are added or modified in the system, the Agent's planning capabilities are automatically updated without requiring code modifications.

2. Toolchain and Data Flow: Real-world tasks often require the collaboration of multiple tools. For example, "take a picture and describe" requires the output (image path) of the "take a picture" tool to be used as the input of the "describe" tool. The AI ​​Agent elegantly implements this through the _process_step_parameters function.

• Data Reference Placeholders: During the planning phase, large models embed special placeholders, such as {{steps.1.outputs.data}}, in parameter values ​​where data needs to be passed.
• Real-Time Parameter Replacement: In the _execute_agent_workflow main loop, _process_step_parameters is called before each step. It uses regular expressions to scan all parameters of the current step. Upon discovering a placeholder, it finds the corresponding data from the output list of the previous step and replaces it in real time. This mechanism is key to automating complex tasks.

3. Supervised Execution and Fault Tolerance: _execute_agent_workflow constitutes the Agent's main execution loop. It strictly follows the planned sequence of steps, executing each action sequentially and ensuring data is correctly passed between them.

• Atomic Steps: Each step is treated as an independent "atomic operation." If any step fails, the entire task chain immediately aborts and reports an error. This ensures system stability and predictability, preventing continued execution in an erroneous state.

In summary, the general implementation of the AI ​​Agent demonstrates an advanced software architecture: rather than solving a problem directly, it builds a framework that enables an external, general-purpose reasoning engine (a large model) to solve the problem. Through two core mechanisms, dynamic programming and data flow management, the Agent orchestrates a series of independent tools into complex workflows capable of completing advanced tasks.

3. Practical Operations

3.1 Configuring the Offline Large Model

3.1.1 Configuring the LLM Platform (yahboom.yaml)

This file determines which large model platform the model_service node loads as its primary language model.

1. Open the file in the terminal:

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   vim ~/yahboom_ws/src/largemodel/config/yahboom.yaml
   

2. Modify/confirm llm_platform:

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   model_service:                          #模型服务器节点参数 Model server node parameters
     ros__parameters:
       language: 'en'                      #大模型接口语言 Large Model Interface Language
       useolinetts: False                   #文字模式下此项无效，可忽略 This item is invalid in text mode and can be ignored
   ​
       # 大模型配置 Large model configuration
       llm_platform: 'ollama'              # 关键: 确保这里是 'ollama' Key: Make sure it's 'ollama'
       regional_setting : "international" 
   

3.1.2 Configuration model interface (large_model_interface.yaml)

This file defines which visual model to use when the platform is selected as ollama.

1. Open the file in a terminal.

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vim ~/yahboom_ws/src/largemodel/config/large_model_interface.yaml

2. Find the configuration related to ollama

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#.....
## 离线大模型 (Offline Large Language Models)
# Ollama Configuration
ollama_host: "http://localhost:11434"  # Ollama server address
ollama_model: "llava"            # Key: Change this to the multimodal model you downloaded, such as "llava"
#.....

Note: Please ensure that the model specified in the configuration parameters (e.g., llava) can handle multimodal input.

3.2 Starting and Testing the Functionality (Text Input Mode)

Note: Due to performance limitations, the performance of the Jetson Orin Nano 4GB is limited. To experience this feature, please refer to the "Online Large Model (Text Interaction)" section.

1. Start the largemodel main program (text mode): Open a terminal and run the following command:

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   ros2 launch largemodel largemodel_control.launch.py text_chat_mode:=true
   

2. Send text command

   Multimodal table scanning application

   Voice interaction hardware connection (ReadMe)