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Payam Nikdel

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6 papers

1 author row

ICRA Conference 2023 Conference Paper

DMMGAN: Diverse Multi Motion Prediction of 3D Human Joints using Attention-Based Generative Adversarial Network

Payam Nikdel
Mohammad Mahdavian
Mo Chen 0001

Human body motion prediction is a fundamental part of many human-robot applications. Despite the recent progress in the area, most studies predict human body motion relative to a fixed joint and only limit their model to predict one possible future motion, or both. However, due to the complex nature of human motion, a single prediction cannot adequately reflect the many possible movements one can make. Also, for any robotics application, prediction of the full human body motion including the absolute 3D trajectory - not just a 3D body pose relative to the hip joint - is needed. In this paper, we try to address these two shortcomings by proposing a transformer-based generative model for forecasting multiple diverse human motions. Our model generates $N$ future possible body motions given the human motion history. This is achieved by first predicting the pose of the body relative to the hip joint as was done in prior work. Then, our proposed Hip Prediction Module predicts the trajectory of the hip position relative to a global reference frame for each predicted pose frame, an aspect of human body motion neglected by previous work. To obtain a set of diverse predicted motions, we introduce a similarity loss that penalizes the pairwise sample distance. Our system not only outperforms the state-of-the-art in human motion prediction, but also is able to predict a diverse set of future human body motions, including the hip trajectory.

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ICRA Conference 2023 Conference Paper

STPOTR: Simultaneous Human Trajectory and Pose Prediction Using a Non-Autoregressive Transformer for Robot Follow-Ahead

Mohammad Mahdavian
Payam Nikdel
Mahdi Taherahmadi
Mo Chen 0001

In this paper, we greatly expand the capability of robots to perform the follow-ahead task and variations of this task through development of a neural network model to predict future human motion from an observed human motion history. We propose a non-autoregressive transformer architecture to leverage its parallel nature for easier training and fast, accurate predictions at test time. The proposed architecture divides human motion prediction into two parts: 1) the human trajectory, which is the 3D positions of the hip joint over time, and 2) the human pose which is the 3D positions of all other joints over time with respect to a fixed hip joint. We propose to make the two predictions simultaneously, as the shared representation can improve the model performance. Therefore, the model consists of two sets of encoders and decoders. First, a multi-head attention module applied to encoder outputs improves human trajectory. Second, another multi-head self-attention module applied to encoder outputs concatenated with decoder outputs facilitates the learning of temporal dependencies. Our model is well-suited for robotic applications in terms of test accuracy and speed, and compares favorably with respect to state-of-the-art methods. We demonstrate the real-world applicability of our work via the Robot Follow-Ahead task, a challenging yet practical case study for our proposed model. The human motion predicted by our model enables the robot follow-ahead in scenarios that require taking detailed human motion into account such as sit-to-stand, stand-to-sit. It also enables simple control policies to trivially generalize to many different variations of human following, such as follow-beside. Our code and data are available at the following Github page: https://github.com/mmahdavian/STPOTR

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IROS Conference 2022 Conference Paper

Hierarchical Model-Based Imitation Learning for Planning in Autonomous Driving

Eli Bronstein
Mark Palatucci
Dominik Notz
Brandyn White
Alex Kuefler
Yiren Lu 0001
Supratik Paul
Payam Nikdel

We demonstrate the first large-scale application of model-based generative adversarial imitation learning (MGAIL) to the task of dense urban self-driving. We augment standard MGAIL using a hierarchical model to enable generalization to arbitrary goal routes, and measure performance using a closed-loop evaluation framework with simulated interactive agents. We train policies from expert trajectories collected from real vehicles driving over 100, 000 miles in San Francisco, and demonstrate a steerable policy that can navigate robustly even in a zero-shot setting, generalizing to synthetic scenarios with novel goals that never occurred in real-world driving. We also demonstrate the importance of mixing closed-loop MGAIL losses with open-loop behavior cloning losses, and show our best policy approaches the performance of the expert. We evaluate our imitative model in both average and challenging scenarios, and show how it can serve as a useful prior to plan successful trajectories.

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ICRA Conference 2021 Conference Paper

LBGP: Learning Based Goal Planning for Autonomous Following in Front

Payam Nikdel
Richard Vaughan 0001
Mo Chen 0001

This paper investigates a hybrid solution which combines deep reinforcement learning (RL) and classical trajectory planning for the "following in front" application. Here, an autonomous robot aims to stay ahead of a person as the person freely walks around. Following in front is a challenging problem as the user’s intended trajectory is unknown and needs to be estimated, explicitly or implicitly, by the robot. In addition, the robot needs to find a feasible way to safely navigate ahead of human trajectory. Our deep RL module makes decisions at a high level by implicitly estimates the human trajectory and produces short-term navigational goals to guide the robot. These goals are used by a trajectory planner, which is responsible for low-level execution, to smoothly navigate the robot to the short-term goals, and eventually in front of the user. We employ curriculum learning in the deep RL module to efficiently achieve a high return. Our system outperforms the state-of-the-art in following ahead and is more reliable compared to end-to-end alternatives in both the simulation and real world experiments. In contrast to a pure deep RL approach, we demonstrate zero-shot transfer of the trained policy from simulation to the real world.

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IROS Conference 2020 Conference Paper

Relational Graph Learning for Crowd Navigation

Changan Chen
Sha Hu 0003
Payam Nikdel
Greg Mori
Manolis Savva

We present a relational graph learning approach for robotic crowd navigation using model-based deep reinforcement learning that plans actions by looking into the future. Our approach reasons about the relations between all agents based on their latent features and uses a Graph Convolutional Network to encode higher-order interactions in each agent’s state representation, which is subsequently leveraged for state prediction and value estimation. The ability to predict human motion allows us to perform multi-step lookahead planning, taking into account the temporal evolution of human crowds. We evaluate our approach against a state-of-the-art baseline for crowd navigation and ablations of our model to demonstrate that navigation with our approach is more efficient, results in fewer collisions, and avoids failure cases involving oscillatory and freezing behaviors.

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ICRA Conference 2018 Conference Paper

The Hands-Free Push-Cart: Autonomous Following in Front by Predicting User Trajectory Around Obstacles

Payam Nikdel
Rakesh Shrestha
Richard Vaughan 0001

This paper demonstrates an autonomous mobile robot that follows a walking user while staying ahead of them. Despite several useful applications for autonomous push-carts, this problem has received much less attention than the easier problem of following from behind. In contrast to previous work, we use multi-modal person detection and a human-motion model that considers obstacles to predict the future path of the user. We implement the system with a modular architecture of obstacle mapper, human tracker, human motion model, robot motion planner and robot motion controller. We report on the performance of the robot in real-world experiments. We believe that approaches to this largely overlooked problem could be useful in real industrial, domestic and entertainment applications in the near future.

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