README.md

---
license: mit
task_categories:
  - robotics
tags:
  - robotics
  - manipulation
  - pick-and-place
  - mujoco
  - simulation
  - embodied-ai
  - pika
size_categories:
  - n<1K
---

# Pika Sim — Pick & Place Dataset

Simulated pick-and-place dataset generated with MuJoCo using the [Agilex Pika](https://github.com/agilexrobotics) gripper model.

## Overview

| | |
|---|---|
| **Episodes** | 500 |
| **Steps per episode** | 149 |
| **Success rate** | 100% |
| **Record frequency** | 20 Hz |
| **Sim timestep** | 1 ms |
| **Simulator** | MuJoCo ≥ 3.0 |

## Task

A parallel-jaw gripper on a 3-DOF Cartesian gantry picks up a cube from a randomized position and places it at a randomized target location on a table. Positions are randomized per episode (seed 42).

## Dataset Structure

```
dataset/
├── episodes/
│   └── episode_NNNN.h5    # 500 HDF5 files
└── videos/
    └── wrist_cam_NNNN.mp4 # 500 wrist camera videos (640×480, 20fps)
```

### HDF5 Schema

Each `episode_NNNN.h5` contains:

```
├── actions/
│   ├── ee_pose          (149, 7) float32   # target xyz + quaternion (wxyz)
│   └── gripper          (149, 1) float32   # 0.0 = open, 1.0 = closed
├── observations/
│   ├── ee_pose          (149, 7) float32   # current xyz + quaternion (wxyz)
│   ├── gripper_width    (149, 1) float32   # meters, 0.0–0.087
│   └── timestamp        (149,)   float64   # seconds since episode start
├── videos/
│   └── wrist_cam        (149,)   int64     # frame indices into wrist_cam_NNNN.mp4
├── env_state            ()       str/JSON  # pick/place positions, cube final pose, error
├── success              ()       bool
└── episode_length       ()       int64
```

### Conventions

| Convention | Value |
|---|---|
| Action frame | World absolute |
| Observation frame | World absolute |
| Quaternion format | wxyz (constant — no rotation DOF) |
| Gripper action | 0 = open, 1 = closed |
| Gripper max width | 0.087 m (87 mm) |
| Success threshold | < 20 mm placement error |

## Loading Example

```python
import h5py
import json

with h5py.File("episodes/episode_0000.h5", "r") as f:
    actions_ee = f["actions/ee_pose"][:]        # (149, 7)
    actions_grip = f["actions/gripper"][:]      # (149, 1)
    obs_ee = f["observations/ee_pose"][:]       # (149, 7)
    obs_width = f["observations/gripper_width"][:]  # (149, 1)
    timestamps = f["observations/timestamp"][:] # (149,)
    success = f["success"][()]                  # bool
    env = json.loads(f["env_state"][()])        # dict
    print(f"Pick: {env['pick_pos']}, Place: {env['place_pos']}, Error: {env['placement_error_mm']:.1f}mm")
```

## Generation

```bash
cd sim/pika_gripper_mujoco_sim
python record_dataset.py --episodes 500 --seed 42
```

Source: [pika_ros](https://github.com/agilexrobotics/pika_ros) (`ros2` branch)