Simulation Container
docker pull bedrockdynamics/substrate-sim:ros2-manipulator
| Port | Protocol | Purpose |
|---|
| 8090 | HTTP | MCP tool server |
| 9090 | gRPC | ros2-bridge (joint state streaming + trajectory relay) |
get_joint_state
Returns the current position and velocity of all 6 joints as a JSON object. No parameters.
move_to_named_target
Moves the arm to a predefined MoveIt2 named configuration.
| Parameter | Type | Description |
|---|
target | string | Named target (e.g. "home", "up", "ready") |
move_to_pose
Plans and executes a motion to a Cartesian pose using MoveIt2.
| Parameter | Type | Description |
|---|
x, y, z | float | Target position in meters (base frame) |
qx, qy, qz, qw | float | Target orientation as quaternion |
stop_arm
Immediately halts all joint motion. Sends zero-velocity commands and cancels any active MoveIt2 trajectory. No parameters.
WASM Channels
The ChannelManifest::ur5() manifest defines 6 velocity command channels and 12 state channels (6 position + 6 velocity), all running at 100Hz.
Command Channels (6)
| Index | Name | Unit | Limits |
|---|
| 0 | shoulder_pan_joint/velocity | rad/s | -pi to pi |
| 1 | shoulder_lift_joint/velocity | rad/s | -pi to pi |
| 2 | elbow_joint/velocity | rad/s | -pi to pi |
| 3 | wrist_1_joint/velocity | rad/s | -pi to pi |
| 4 | wrist_2_joint/velocity | rad/s | -pi to pi |
| 5 | wrist_3_joint/velocity | rad/s | -pi to pi |
max_rate_of_change of 0.5 rad/s per tick (50 rad/s^2 acceleration limit at 100Hz). Each velocity command is paired with its corresponding position state channel for position limit enforcement.
State Channels (12)
| Index | Name | Unit | Type |
|---|
| 0-5 | {joint}/position | rad | Position |
| 6-11 | {joint}/velocity | rad/s | Velocity |
Velocity Integration
The WASM controller writes velocity commands. The gRPC bridge relay converts these into position+velocity trajectory points for the scaled_joint_trajectory_controller in ros2_control. On each tick:
- Read current joint positions from state channels
- Integrate velocity over the tick period to produce a target position
- Send a
JointTrajectory message with both the target position and velocity
This approach gives smooth motion because the controller receives both where to go and how fast to get there.
Example
A WASM controller that rotates the shoulder pan joint:
;; Set channel 0 (shoulder_pan_joint) to 0.2 rad/s
(call $set_command (i32.const 0) (f64.const 0.2))
scaled_joint_trajectory_controller.
Real Hardware
For a physical UR5 (no Docker container):
- Run your robot’s
ros2_control stack (UR driver + MoveIt2) on the robot or a companion computer
- Point roz at your ROS 2 environment — the MCP tools and WASM channels work the same way
- The
scaled_joint_trajectory_controller is the same controller used in simulation
Real hardware support is under active development. The safety guarantees are currently simulation-validated only. Additional validation is required before deploying WASM velocity controllers on physical hardware.
Source Code
