Logging Actuator Data to CSV
This tutorial shows how to log data from a PULSAR HRI actuator to a CSV file for later analysis. It covers how to connect to the actuator, select the feedback items to record, write samples to a CSV file, and stop the session cleanly.
Requirements
Before running the example, make sure:
- the C++ API is built,
- the actuator is connected and reachable,
- the user has permission to access the communication device,
- the output directory is writable.
Include files
The following headers are required for this example:
#include <pcp_api/pcp_api.hpp>
#include <chrono>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <stdexcept>
#include <string>
#include <thread>
#include <unordered_map>
#include <vector>
using namespace pcp_api;
Connect to the adapter and actuator
Most of the setup is shared with the other examples. The code below initializes the adapter and connects to one actuator.
std::string port = PCP_over_USB::get_port();
// std::string port = "COM1";
std::cout << "Connecting to " << port << std::endl;
PCP_over_USB adapter(port);
PulsarActuator actuator(adapter, 0);
if (!actuator.connect()) {
std::cerr << "Could not connect to the actuator "
<< actuator.address()
<< std::endl;
adapter.close();
throw std::runtime_error("Actuator connection failed");
}
std::cout << "Connected to the actuator "
<< actuator.address()
<< " (model: "
<< actuator.model()
<< ", firmware: "
<< actuator.firmware_version()
<< ")"
<< std::endl;
Select the items to log
Choose the feedback items you want to save to the CSV file. In this example, the current in the three motor phases is logged.
std::vector<PulsarActuator::PCP_Items> items_to_log = {
PulsarActuator::PCP_Items::IA,
PulsarActuator::PCP_Items::IB,
PulsarActuator::PCP_Items::IC,
};
Prepare CSV logging
Open the CSV file and write the header. Keep the column order consistent with the order used when writing feedback samples.
std::ofstream csv_file("log.csv");
if (!csv_file.is_open()) {
actuator.disconnect();
adapter.close();
throw std::runtime_error("Could not open log.csv for writing");
}
csv_file << "Timestamp";
for (const auto item : items_to_log) {
csv_file << ',' << item_name(item);
}
csv_file << '\n';
Define the feedback callback
The callback writes one CSV row for each feedback sample.
std::ofstream* csv_output = &csv_file;
auto* selected_items = &items_to_log;
auto actuator_feedback = [csv_output, selected_items](
int /* address */,
const std::unordered_map<PulsarActuator::PCP_Items, float>& feedback)
{
using clock = std::chrono::system_clock;
const auto now = clock::now();
const auto timestamp =
std::chrono::duration<double>(now.time_since_epoch()).count();
(*csv_output) << timestamp;
for (const auto item : *selected_items) {
(*csv_output) << ',' << feedback.at(item);
}
(*csv_output) << '\n';
};
This callback uses the same item order as the CSV header, so the logged columns always stay aligned with the selected feedback items.
Configure the feedback rate
Configure the feedback items and request high-frequency feedback at 1 kHz.
actuator.setFeedbackItems(items_to_log);
actuator.setFeedbackRate(PulsarActuator::Rates::RATE_1KHZ);
Start the actuator and log data
This example runs the actuator in SPEED mode for 3 seconds, stores the feedback in log.csv, and then closes the session cleanly.
actuator.change_mode(PulsarActuator::Mode::SPEED);
actuator.change_setpoint(1.0f); // rad/s
actuator.set_feedback_callback(actuator_feedback);
actuator.start();
std::this_thread::sleep_for(std::chrono::seconds(3));
actuator.disconnect();
std::this_thread::sleep_for(std::chrono::milliseconds(100));
adapter.close();
csv_file.close();
Example output
This code generates a CSV file named log.csv with the logged data. The first column is the timestamp, and the following columns are the actuator values.
| Timestamp | IA | IB | IC |
|---|---|---|---|
| 1642780800.123 | 0.15 | -0.08 | 0.12 |
| 1642780800.124 | 0.16 | -0.09 | 0.13 |
| 1642780800.125 | 0.17 | -0.10 | 0.14 |
Complete example
The following program is a complete example that can be copied into a .cpp file and compiled directly.
#include <pcp_api/pcp_api.hpp>
#include <chrono>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <stdexcept>
#include <string>
#include <thread>
#include <unordered_map>
#include <vector>
using namespace pcp_api;
std::string item_name(PulsarActuator::PCP_Items item)
{
switch (item) {
case PulsarActuator::PCP_Items::IA: return "IA";
case PulsarActuator::PCP_Items::IB: return "IB";
case PulsarActuator::PCP_Items::IC: return "IC";
default: return "UNKNOWN";
}
}
int main()
{
PCP_over_USB* adapter_ptr = nullptr;
PulsarActuator* actuator_ptr = nullptr;
try {
std::string port = PCP_over_USB::get_port();
// std::string port = "COM1";
std::cout << "Connecting to " << port << std::endl;
PCP_over_USB adapter(port);
adapter_ptr = &adapter;
PulsarActuator actuator(adapter, 0);
actuator_ptr = &actuator;
if (!actuator.connect()) {
std::cerr << "Could not connect to the actuator "
<< actuator.address()
<< std::endl;
adapter.close();
return 1;
}
std::cout << "Connected to the actuator "
<< actuator.address()
<< " (model: "
<< actuator.model()
<< ", firmware: "
<< actuator.firmware_version()
<< ")"
<< std::endl;
std::vector<PulsarActuator::PCP_Items> items_to_log = {
PulsarActuator::PCP_Items::IA,
PulsarActuator::PCP_Items::IB,
PulsarActuator::PCP_Items::IC,
};
std::ofstream csv_file("log.csv");
if (!csv_file.is_open()) {
actuator.disconnect();
adapter.close();
std::cerr << "Could not open log.csv for writing" << std::endl;
return 1;
}
csv_file << "Timestamp";
for (const auto item : items_to_log) {
csv_file << ',' << item_name(item);
}
csv_file << '\n';
std::ofstream* csv_output = &csv_file;
auto* selected_items = &items_to_log;
auto actuator_feedback = [csv_output, selected_items](
int /* address */,
const std::unordered_map<PulsarActuator::PCP_Items, float>& feedback)
{
using clock = std::chrono::system_clock;
const auto now = clock::now();
const auto timestamp =
std::chrono::duration<double>(now.time_since_epoch()).count();
(*csv_output) << timestamp;
for (const auto item : *selected_items) {
(*csv_output) << ',' << feedback.at(item);
}
(*csv_output) << '\n';
};
actuator.setFeedbackItems(items_to_log);
actuator.setFeedbackRate(PulsarActuator::Rates::RATE_1KHZ);
actuator.change_mode(PulsarActuator::Mode::SPEED);
actuator.change_setpoint(1.0f); // rad/s
actuator.set_feedback_callback(actuator_feedback);
actuator.start();
std::this_thread::sleep_for(std::chrono::seconds(3));
actuator.disconnect();
std::this_thread::sleep_for(std::chrono::milliseconds(100));
adapter.close();
csv_file.close();
std::cout << "Log saved to: "
<< std::filesystem::absolute("log.csv")
<< std::endl;
}
catch (const std::exception& e) {
if (actuator_ptr != nullptr) {
try {
actuator_ptr->disconnect();
} catch (...) {
}
}
if (adapter_ptr != nullptr) {
try {
adapter_ptr->close();
} catch (...) {
}
}
std::cerr << "Fatal error: " << e.what() << std::endl;
return 1;
}
return 0;
}
Example build command
Adjust the include path, library path, and library names to match your build output.