6-DOF Robotic Arm Control System

Project Overview

This project delivers a full control stack for a 6-DOF industrial robotic arm, with a focus on trajectory quality, predictable timing, and reliable operation in production-like tasks.

Responsibilities

• Designed the software architecture for planning, control, and execution layers
• Implemented inverse kinematics and singularity handling in C++
• Integrated trajectory generation with velocity and acceleration constraints
• Built interfaces for teach-and-repeat and operation monitoring

Technical Implementation

Control Architecture

• ROS nodes separated by function: planning, state estimation, controller, and hardware interface
• Clear message contracts for deterministic command flow
• Runtime parameter tuning for key controller gains

Kinematics and Planning

• Forward and inverse kinematics for target pose solving
• Joint limit checks and path feasibility validation
• Time-parameterized trajectory output for smooth interpolation

Safety and Reliability

• Emergency stop software path with immediate command halt
• Command timeout watchdog to avoid stale command execution
• Joint-level soft limits and fault-state transitions

Challenges and Solutions

Challenge: Singular configurations created unstable motions

Solution:

• Added weighted cost terms in IK selection
• Introduced fallback strategy that selects nearest valid joint state
• Applied smoothing around high-condition-number regions

Challenge: Small jitter during low-speed Cartesian motion

Solution:

• Increased interpolation density for short segments
• Added low-pass filtering on velocity command generation
• Calibrated controller update timing against actual hardware loop rate

Results

• Improved endpoint repeatability under constrained motion tasks
• Reduced stop-and-go artifacts in multi-waypoint trajectories
• Enabled stable demos for pick-and-place and precision alignment scenarios

Next Iteration

• Add model-based feedforward terms for higher-speed motion
• Integrate online path replanning for dynamic obstacle handling
• Extend diagnostics dashboard with per-joint quality indicators