Blake Beckman

Kinematic control and posture optimization of a redundantly actuated quadruped robot

Although legged locomotion for robots has been studied for many years, the research of autonomous wheellegged robotics is much more recent. Robots of this type, also described as hybrid, can take advantage of the energy efficiency of wheeled locomotion while adapting to more difficult terrain with legged locomotion when necessary. The Micro Hydraulic Toolkit (MHT), developed by engineers at Defence R&D Canada - Suffield, is a good example of such a robot. Investigation into control and optimization techniques for MHT leads to a better understanding of hybrid vehicle control for terrestrial exploration and reconnaissance. Control of hybrid robots has been studied by several researchers during the last decade. The methodology applied in this work uses an inverse kinematics algorithm developed previously for a hybrid robot Hylos, and implements an optimization technique to minimize torques occurring at crucial actuators. As well, some added functionality is incorporated into the control method to implement stepping maneuvers. This paper will present the results obtained via co-simulation using Matlabs Simulink and a high-fidelity model of MHT in LMS Virtual Lab.

Integration of a high degree of freedom robotic manipulator on a large unmanned ground vehicle

The Multi-Agent Tactical Sentry Unmanned Ground Vehicle, developed at Defence R&D Canada - Suffield, has been in service with the Canadian Forces for five years. This tele-operated wheeled vehicle provides a capability for point detection of chemical, biological, radiological, and nuclear agents. Based on user experience, it is obvious that a manipulator capability would greatly enhance the vehicles utility and increase its mobility in urban terrain. This paper details technical components of this development, and describes a number of trials undertaken to perform tasks with a manipulator arm such as picking up objects, opening vehicle and building doors, recording video, and creating 3D models of the environment. The lessons learned from these trials will guide further development of the technology.

Adaptive representation for dynamic environment, vehicle, and mission complexity

In order for an Unmanned Ground Vehicle (UGV) to operate effectively it must be able to perceive its environment in an accurate, robust and effective manner. This is done by creating a world representation which encompasses all the perceptual information necessary for the UGV to understand its surroundings. These perceptual needs are a function of the robots mobility characteristics, the complexity of the environment in which it operates, and the mission with which the UGV has been tasked. Most perceptual systems are designed with predefined vehicle, environmental, and mission complexity in mind. This can lead the robot to fail when it encounters a situation which it was not designed for since its internal representation is insufficient for effective navigation. This paper presents a research framework currently being investigated by Defence R&D Canada (DRDC), which will ultimately relieve robotic vehicles of this problem by allowing the UGV to recognize representational deficiencies, and change its perceptual strategy to alleviate these deficiencies. This will allow the UGV to move in and out of a wide variety of environments, such as outdoor rural to indoor urban, at run time without reprogramming. We present sensor and perception work currently being done and outline our research in this area for the future.

Semi-autonomous UAV/UGV for dismounted urban operations

Dismounted soldiers are clearly at the centre of modern asymmetric conflicts and unmanned systems of the future will play important roles in their support. Moreover, the nature of modern asymmetric conflicts requires dismounted soldiers to operate in urban environments with challenges of communication and limited situational awareness. To improve the situational awareness of dismounted soldiers in complex urban environments, Defence R&D Canada - Suffield (DRDC Suffield) envision Unmanned Air Vehicles (UAV) rotorcraft and Unmanned Ground Vehicles (UGV) cooperating in the battlespace. The capabilities provided to the UAV rotorcraft will include high speed maneuvers through urban terrain, overthe- horizon and loss of communications operations, and/or low altitude over-watch of dismounted units. This information is shared with both the dismounted soldiers and UGV. The man-sized, man-mobile UGV operates in close support to dismounted soldiers to provide a payload carrying capacity. Some of the possible payloads include chemical, biological, radiological and nuclear (CBRN) detection, intelligence, surveillance and reconnaissance (ISR), weapons, supplies, etc.. These unmanned systems are intended to increase situational awareness in urban environments and can be used to call upon nearby forces to react swiftly by providing acquired information to concentrate impact where required.

Two dimensional dynamic stability for reconfigurable robots designed to traverse rough terrain

Robots must be designed with consideration for reconfiguring body pose during operation if they are to address more challenging environments. Researchers have mostly relied on static stability methods to monitor the possibility of rollover in stationary or slow moving vehicles. However, little research in dynamic stability is being conducted for robots capable of reconfiguring their pose to overcome obstacles encountered in challenging terrains. A multi-degree-of-freedom robot with the capability to vary its center of gravity is discussed in this paper. It is designed to improve mobility over rough terrain and is used in this paper as an example to address one aspect of dynamic stability. A complete understanding of the dynamic behaviour of a multiple degree of freedom robot in unstructured terrain is a difficult problem to solve. It is too complex to solve completely and therefore a reduced aspect of the problem is addressed. The robot will only have the ability to vary its center of gravity in the plane parallel to its direction of forward motion. In addition the robot will only move on flat terrain and encounter an immovable linear step feature. The result of the research is that once the center of gravity is specified by selection of robot body pose, and a maximum obstacle considered, platform stability can be ensured with a maximum allowable velocity. In other words, a maximum allowable velocity of the robot is governed by the position of the center of gravity relative to the wheel in contact with the linear step feature. If the robot is traveling below the predetermined maximum velocity then the robot is guaranteed to remain upright.

Perception and mobility research at Defence R&D Canada for UGVs in complex terrain

The Autonomous Intelligent Systems Section at Defence R&D Canada - Suffield envisions autonomous systems contributing to decisive operations in the urban battle space. In this vision, teams of unmanned ground, air, and marine vehicles, and unattended ground sensors will gather and coordinate information, formulate plans, and complete tasks. The mobility requirement for ground-based mobile systems operating in urban settings must increase significantly if robotic technology is to augment human efforts in military relevant roles and environments. In order to achieve its objective, the Autonomous Intelligent Systems Section is pursuing research that explores the use of intelligent mobility algorithms designed to improve robot mobility. Intelligent mobility uses sensing and perception, control, and learning algorithms to extract measured variables from the world, control vehicle dynamics, and learn by experience. These algorithms seek to exploit available world representations of the environment and the inherent dexterity of the robot to allow the vehicle to interact with its surroundings and produce locomotion in complex terrain. However, a disconnect exists between the current state-of-the-art in perception systems and the information required for novel platforms to interact with their environment to improve mobility in complex terrain. The primary focus of the paper is to present the research tools, topics, and plans to address this gap in perception and control research. This research will create effective intelligence to improve the mobility of ground-based mobile systems operating in urban settings to assist the Canadian Forces in their future urban operations.

Novel mobility platforms utilizing intelligent algorithms

The mobility requirement for Unmanned Ground Vehicles (UGVs) is expected to increase significantly as the number of conflicts shift from open terrain operations to the increased complexity of urban settings. In preparation for this role Defence R&D Canada-Suffield is exploring novel mobility platforms utilizing intelligent mobility algorithms that will each contribute to improved UGV mobility. The design of a mobility platform significantly influences its ability to maneuver in the world. Highly configurable and mobile platforms are typically best suited for unstructured terrain. Intelligent mobility algorithms seek to exploit the inherent dexterity of the platform and available world representation of the environment to allow the vehicle to engage extremely irregular and cluttered environments. As a result, the capabilities of vehicles designed with novel platforms utilizing intelligent mobility algorithms will outperform larger vehicles without these capabilities. However, there exist many challenges in the development of UGV systems to satisfy the increased mobility requirement for future military operations. This paper discusses a research methodology proposed to overcome these challenges, which primarily involves the definition and development of novel mobility platforms for intelligent mobility research. It addresses intelligent mobility algorithms and the incorporation of world representation and perception research in the creation of necessary synergistic systems. In addition, it presents an overview of the novel mobility platforms and research activities at Defence R&D Canada-Suffield aimed at advancing UGV mobility capabilities in difficult and relevant military environments.

Posture Reconfiguration and Navigation Maneuvers on a Wheel-Legged Hydraulic Robot

Wheel-legged hybrid robots are known to be extremely capable in negotiating different types of terrain as they combine the efficiency of conventional wheeled platforms and the rough terrain capabilities of legged platforms. The Micro-Hydraulic Toolkit (MHT), developed by Defense Research and Development Canada at the Suffield Research Centre, is one such quadruped hybrid robot.MHT’s relatively small size, mobility, actuation and locomotion types fill a gap in military unmanned ground vehicles (UGVs). Previously, a velocity-level closed loop inverse kinematics controller had been developed and tested in simulation on a detailed physics-based model of the MHT in LMS Virtual.LabMotion. The controller was employed to generate a variety of posture reconfiguration maneuvers, such as achieving minimum ormaximum chassis height at specific wheel separations. In this paper, the aforementioned inverse kinematics controller was adapted to function on the physical MHT. Several test maneuvers, including chassis height and pitch reconfiguration and uneven terrain navigation maneuvers, were implemented on the MHT and the robot’s performance was evaluated.

Control algorithms for stable range-of-motion behaviours of a multi degree-of-freedom robot

The requirement for increased mobility of unmanned ground vehicles (UGVs) operating in urban settings must be addressed if robotic technology is to augment human efforts in military relevant roles and environments. In preparation for this role, Defence R&D Canada - Suffield is exploring novel mobility platforms that use intelligent mobility algorithms to improve robot mobility in unknown highly complex terrain. Robotic platforms often appear conceptually simple. Despite this appearance, the demands on these systems remain extremely ambitious while retaining the need for control systems to handle the many actuator degrees-of-freedom and numerous sensor inputs. Linear control techniques applied to a nonlinear multi degree-of-freedom vehicles are effective in controlling system behaviours in limited conditions. However, in unrestricted conditions, the nonlinear nature of the control problem and impracticality of model-based control of such a complex system have required the investigation of alternative control methods. This paper discusses linear control techniques applied to a multi degree-of-freedom robot in simulation and alternative nonlinear techniques.

Implementation of a leader-follower controller for a skid-steering wheel-legged robot

In this paper, we present a leader-follower controller for the Micro-Hydraulic Toolkit (MHT), a skid-steering wheel-legged robot designed by Defence Research and Development Canada - Suffield Research Centre. The objective of the controller is to maneuver the MHT towards a desired position with respect to a designated leader. Using the range and bearing of the leader from the robot, the leader-follower controller computes the desired wheel velocities of the MHT to achieve leader-follower formation control. In addition to performing wheeled locomotion to follow the leader, the MHT is capable of using its legs to reconfigure its posture. Thus, moving beyond standard implementations, the leader-follower control strategy presented in this paper is combined with a velocity-based inverse kinematics controller developed in previous work to control the posture of the MHT during leader-follower maneuvers. The results of the leader-follower scenarios implemented in simulation and on the physical MHT demonstrate the robots ability to execute leader-follower formation control and posture control simultaneously, adding to the versatility of the vehicle to negotiate uneven terrains.