Real-Time Manipulation of a Hybrid Serial-and-Parallel-Driven Redundant Industrial Manipulator

The real-time implementation of path planning, trajectory generation, and servo control for manipulation of the prototype UPSarm are presented in this paper. The prototype UPSarm, which is primarily designed for studying the feasibility of loading packages inside a trailer, is a ten degree-of-freedom hybrid serial-and-parallel-driven redundant robot manipulator. The direct, forward, inverse, and indirect kinematic solutions of the UPSarm using three coordinate spaces: actuator space, effective joint space, and world Cartesian coordinate space are derived for real-time path planning, trajectory generation, and control. The manipulation of the UPSarm is based upon a general-purpose path planner and trajectory generator. Provided with appropriate kinematics modules and sufficient computational power, this path planner and trajectory generator can be used for real-time motion control of any degree-of-freedom hybrid serial-and-parallel-driven electromechanical devices. A VMEbus-based distributed computing system has been implemented for real-time motion control of the UPSarm. A PID-based feedforward servo control scheme is used in our servo controller. The motion examples of the UPSarm programmed in our robot language will show the practical manipulation of hybrid serial-and-parallel-driven redundant kinematic chains.

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Real-time motion control of a multi-degree-of-freedom variable reluctance spherical motor

Proceedings of IEEE International Conference on Robotics and Automation ◽

10.1109/robot.1996.506596 ◽

2002 ◽

Cited By ~ 10

Author(s):

Zhi Zhou ◽

Kok-Meng Lee

Keyword(s):

Real Time ◽

Motion Control ◽

Degree Of Freedom ◽

Spherical Motor ◽

Variable Reluctance ◽

Time Motion

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Real - Time Trajectory and Velocity Planning for Autonomous Vehicles

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.e2880.0610521 ◽

2021 ◽

Vol 10 (5) ◽

pp. 439-448

Author(s):

Hrishikesh Dey ◽

Rithika Ranadive ◽

Abhishek Chaudhari

Keyword(s):

Path Planning ◽

Velocity Profile ◽

Real Time ◽

Autonomous Vehicle ◽

Optimal Path ◽

Autonomous Driving ◽

Navigation Algorithm ◽

Velocity Planning ◽

Planning Algorithm ◽

Path Planner

Path planning algorithm integrated with a velocity profile generation-based navigation system is one of the most important aspects of an autonomous driving system. In this paper, a real-time path planning solution to obtain a feasible and collision-free trajectory is proposed for navigating an autonomous car on a virtual highway. This is achieved by designing the navigation algorithm to incorporate a path planner for finding the optimal path, and a velocity planning algorithm for ensuring a safe and comfortable motion along the obtained path. The navigation algorithm was validated on the Unity 3D Highway-Simulated Environment for practical driving while maintaining velocity and acceleration constraints. The autonomous vehicle drives at the maximum specified velocity until interrupted by vehicular traffic, whereas then, the path planner, based on the various constraints provided by the simulator using µWebSockets, decides to either decelerate the vehicle or shift to a more secure lane. Subsequently, a splinebased trajectory generation for this path results in continuous and smooth trajectories. The velocity planner employs an analytical method based on trapezoidal velocity profile to generate velocities for the vehicle traveling along the precomputed path. To provide smooth control, an s-like trapezoidal profile is considered that uses a cubic spline for generating velocities for the ramp-up and ramp-down portions of the curve. The acceleration and velocity constraints, which are derived from road limitations and physical systems, are explicitly considered. Depending upon these constraints and higher module requirements (e.g., maintaining velocity, and stopping), an appropriate segment of the velocity profile is deployed. The motion profiles for all the use-cases are generated and verified graphically.

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Real-Time Trajectory Generation and Reachability Determination in Autorotative Flare

Journal of the American Helicopter Society ◽

10.4050/jahs.65.032008 ◽

2020 ◽

Vol 65 (3) ◽

pp. 1-17

Author(s):

Brian F. Eberle ◽

Jonathan D. Rogers

Keyword(s):

Real Time ◽

Trajectory Generation ◽

Contact Theory ◽

Simulation Environment ◽

Order Model ◽

Landing Point ◽

Overall Performance ◽

Simulation Results ◽

Six Degree Of Freedom ◽

Trajectory Generator

Autorotation maneuvers inherently offer little margin for error in execution and induce high pilot workload, particularly as the aircraft nears the ground in an autorotative flare. Control augmentation systems may potentially reduce pilot workload while simultaneously improving the likelihood of a successful landing by offering the pilot appropriate cues. This paper presents an initial investigation of a real-time trajectory generation scheme for autorotative flare based on time-to-contact theory. The algorithm exhibits deterministic runtime performance and provides a speed trajectory that can be tracked by a pilot or inner-loop controller to bring the vehicle to a desired landing point at the time of touchdown. A low-order model of the helicopter dynamics in autorotation is used to evaluate dynamic feasibility of the generated trajectories. By generating and evaluating trajectories to an array of candidate landing points, the set of reachable landing points in front of the aircraft is determined. Simulation results are presented in which the trajectory generator is coupled with a previously derived autorotation controller. Example cases and trade studies are conducted in a six degree-of-freedom simulation environment to demonstrate overall performance as well as robustness of the algorithm to variations in target landing point, helicopter gross weight, and winds. The robustness of the reachability determination portion of the algorithm is likewise evaluated through trade studies examining off-nominal flare entry conditions and the effects of winds.

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