SPACE EXPLORATION

In the context of work on Space Projects the founder and team have performed three major projects to advance the state-of-the-art in planetary rovers and manipulators to be used to perform Earth-based analog Moon and Mars missions. The projects are:

  • SMA: Small Manipulator Arm for detailed terrain sample fetching and manipulation
  • PMM: Planetary Medium Manipulator for Lunar mission feasibility studies
  • MRPTA: Micro‐Rover Platform with Tooling Arm for Lunar and Mars missions

 SMA

The arm is suitable for assembly and material handling in space and manufacturing operations, robotic-based custom automation, service robots, and research & development. SMA can perform autonomous navigation, indoor and outdoor tasks, be operated in remote control and closed loop modes, operate in EMC environments, and perform precise visual servo-supported applications.

SMA is modular, light weight, has high payload-to-weight ratio with advanced control system including force control, visual servo control, and has open software architecture. SMA has six joints, links, payload interface, electronics (drivers and controller), harness, user interface software, and operator control unit. The main subsystems of SMA are:

  • Manipulator: Five joint modules (four single-joint modules and one double-joint module), one link module, payload interface module, and avionics module. The arm has five rotary and one linear joint. The double-joint module is the wrist; it has increased structural stiffness and reduced mass.
  • Joint Modules: Each joint has motor-side incremental encoder and output-side absolute encoder. The absolute encoder adopts BiSS interface and the signal is processed by the motion controller directly into the avionics box.
  • Link Modules: Made of carbon-fiber reinforced plastic to maximize the stiffness-to-mass ratio, or aluminum to reduce the cost. To protect against Electromagnetic Interference (EMI), the carbon-fiber link is coated with a 50 μ nickel alloy layer. It also provides increased impact protection.
  • Payloads Interface Module: Mounted at the outer end of the wrist to provide power and data connections to up to two payloads simultaneously. It provides two-way Gb Ethernet for command and data transmission and 30 VDC / 10 A power for each payload.

The main features of SMA are:

  • High Payload-to-Weight Ratio: The weight is 18.5 kg and payload capacity 17.5 kg, thus the payload-to-weight ratio is 1:1.1. With all accessories and the electronics box, the weight of the system is 30 kg. In selected parts of the workspace the arm can manipulate payloads >50 kg.
  • High Repeatability and Accuracy at Full Extension: SMA has a reach of 1.3 m when fully extended. The positioning accuracy is better than 0.1 mm for translation and 0.5° for orientation; repeatability is better than 40 μ.
  • State-of-the-Arts Electronics: includes military level power supply for 18 - 36 VDC input, military-level motor drivers, multiple processors - Intel Duo Core and Atom for visual servoing and motion control respectively), Gb Ethernet switch and communication, 26 bit BiSS absolute encoder, CAN communication between joints and motion controller, 6 DOF force/torque sensor, and Gb cameras, all located in the Avionics box or locally in joints.
  • Advanced Control Methods: task space impedance control and visual servo; joint level motion control with adaptive friction compensation and gravitation compensation.
  • Visual Servo: used for accurate positioning in unstructured environments. It provides autonomous operation capability that can control the motion of the manipulator with respect to targeted objects or targeted areas using non-contact sensing. The operator can select a target (from images of the area or other sources), and then specify a desired position and orientation of the end effector with respect to the target. The manipulator system then autonomously moves to that desired location. Targets may not be defined in terms of the manipulator coordinate frame.
  • Open Architecture Software: consists of API, libraries of motion control, friction compensation, gravitation compensation, impedance control and visual servo. Users can create their own code by calling the API functions.
  • Built-in Self-Test (BIST) Equipment: helps monitor, diagnose, and trouble shoot the SMA in real time by testing the power supply, joint motors and motor drivers, CAN bus communication, BiSS encoder, 6 DOF force/torque sensor, Gb Camera, Gb Ethernet switch and communication.
  • Upgrade via FTP: control software and configuration files of SMA can be upgraded through FTP server. This provides not only a fast and easy way to upgrade the control software with up-to-date algorithm, but also help the users run SMA with their own algorithm.
  • Operator Control Unit (OCU): OCU can run on a laptop or tablet with Ethernet connection to provide command and control of the SMA using exclusively the functions available in the SMA’s API to configure, monitor, control, and diagnose the arm.
  • EMC Compliance: designed and built to comply with the MIL-STD-461E for EM compatibility, including the CE101, CE102, CS101, CS114, CS116, RE101, RE102, RS101, and RS103. SMA has ESD protection against contact air discharge of 8 KV and 15 KV.
  • Operating in Harsh Environment: water resistant. All exposed surfaces are covered with anodizing or protective paint. All detector and electronics compartments are protected against water and contaminants. It operates in all types of weather conditions, day and night, and various types of wet and dry surfaces. Operational temperature ranges from -10 to +40°C; humidity can be up to 95% at 25°C; storage temperature ranges from -20 to 40°C.

PMM

The arm is suitable for space, security and defense applications mounted on mobile platforms, and for large size manufacturing operations, robotic-based custom automation, and large service robots. The PMM can be mounted on mobile platforms, be operated in remote control and automatic modes, perform autonomous navigation, operate in EMC Environments, perform indoor and outdoor tasks, and be used for R&D. The main subsystems of PMM are:

  • Manipulator: Eight modules: Turret, Shoulder, Upper Arm, Elbow, Lower Arm, Wrist, Automatic End Effector Exchanger (AEEE), and Avionics. The turret provides azimuth motion, while the shoulder, elbow and wrist each provide pitch and roll. The AEEE interface is used to load autonomously tools and other payloads onto the arm. Each module is integrated with mechanical and electronics components. The modular design provides for quick assembling, re-configuring, troubleshooting, and maintenance. Joint modules are: one single-DOF module (turret), and three two-DOF modules (shoulder, elbow, and wrist). The link modules are the upper arm link module and lower arm link module.
  • Joint Modules: Each joint has a motor-side incremental encoder, an output-side absolute encoder, and a torque sensor. The sensors provide feedback to the motor driver located in the joint module. There is a 1 KHz communication link via EtherCAT to the motion controller located in the avionics box. All communication and power cables pass through the middle of the joints to maximize rotation angles and minimize the chance of twisting or snagging of wires. Locating two DOF in a single module increases the structural stiffness while reducing the mass. The joints are back drivable.

The features of PMM are:

  • Lightweight and High-Stiffness Links: stiffness-to-mass ratio of the two links is maximized using carbon-fiber reinforced plastic (CFRP). To protect against Electromagnetic Interference (EMI) the links are coated in a 50μ nickel alloy layer. This provides an exceptionally stiff, damage-tolerant and lightweight structure. This layer also provides the CFRP with increased impact protection.
  • State-of-the-Arts Electronics: includes military level power supply, multiple processors (Intel Duo Core and Atom for visual servo and motion control respectively), Gb Ethernet Switch and communication, 26 bit BiSS absolute encoder, EtherCAT communication, 6-DOF force/torque sensor, and Gb cameras.
  • Automatic End-effector/Tool Exchanger Module (AEEE): includes the drive mechanism for the tool exchanger, 3 cameras and associated auxiliary lighting, a 6-DOF force and torque sensor, and a standardized mechanical, electrical and communications interface for a range of payload tools. This module can be easily replaced with ordinary end effectors or any custom-made end effector.
  • Internal Cabling: Other than power and communication cables between the arm base and the avionics module, all cabling is internal, thus providing protection from the environment and snagging.
  • Advanced Control Methods: multiple control strategies hierarchically layered including joint control, trajectory control, force control via joint and tip sensing, impedance control, adaptive control and visual servo control. They are integrated into a single module while allowing smooth switching in-between. These have never been incorporated into a single robotic arm before. High performance joint level control is obtained using accurate (± 1 arcsec) output position and torque sensing in addition to the typical motor side encoder. Adaptive friction and gravitation compensation are also included.
  • Task Space Control: provides position and orientation accuracy of ± 2 mm and ± 1 degree, respectively, at the end effector in the Cartesian space. A redundancy resolution algorithm controls the joint configurations such that the arm avoids obstacles and singularities. The task space controller includes an impedance controller that has been developed based on the indirect force control method to regulate the force at contact. This prevents large forces being imparted by and to the arm that may damage the arm, or the structure being contacted.
  • Autonomous Operation: Operator can select a target (from images of the area or other sources), and then specify a desired position and orientation of the end effector with respect to the target. Manipulator system autonomously moves the manipulator to that desired location and pose. Consideration is of targets not defined in terms of the manipulator coordinate frame. Vision-based control is used as the core methodology to achieve this functionality. An autonomous task is performed by executing a script that includes multiple subtasks. This allows complex autonomous tasks to be quickly generated using subtasks that have already been tested.
  • EMC compliance: Military-grade electro-magnetic shielding (optional) which includes power conditioning, connectors, and coatings is embedded. It complies with the MIL-STD-461E for the electromagnetic compatibility, including the CE101, CE102, CS101, CS114, CS116, RE101, RE102, RS101, and RS103. PMM has the ESD protection against the contact discharge of 8KV and 15KV air discharge.
  • Operating in Harsh Environment: Water resistant. All exposed surfaces are covered with anodizing or protective coating. All detector and electronics compartments are protected against water and contaminants. It operates in all types of weather conditions, day and night, and various types of wet and dry surfaces. Operational temperature ranges from -10 to 50 deg.

MRPTA

MRPTA is a small and light-weight mobile robot, consisting of multiple track-wheel configurations for different terrains: small or large wheel, long track with proprietary flippers, short track without flipper, wheeled configurations with wheel flippers. All these configurations can be quickly interchanged in the field by one person. The powerful transmission chain provides excellent mobility with enough speed.

MRPTA is an all-weather all-terrain mobile robot for indoor (buildings, public institutions, airports, homes) and outdoor environments (obstacle-cluttered terrains, ditches, gravel, snow, mud, sand). It can be controlled in tele-operation or autonomous navigation modes; can be used for surveillance and reconnaissance in harsh environments; has wireless communication system and provides a LOS range in excess of 1 Km; operates in harsh environments; has multiple sockets (CAN, Ethernet, and USB) available for payload interfaces; and has a tether-aided tele-operated mode for navigation on very steep slopes (>65°). The modes of operations are (i) Tele-operation; (ii) Autonomous navigation; (iii) Tether-aided tele-operation.

The features of MRPTA are:

  • Platform and Mobility: excellent mobility on different terrains. This capability is obtained from its multiple configurations: wheel or track configuration with proprietary flippers. The flipper can move to front or back to facilitate COG control. This flipper mechanism is much lighter than additional the front and back flippers and can provide full control on COG. The COG control is critical in stair climbing and navigation over tall obstacles, and helpful in surpassing wide ditches. The tracks can be used for mobility over rough terrain, stairs and slope climbing. The wheels are used for ordinary terrain and higher speed. There are larger diameter wheels for MRPTA to achieve higher speed and higher ground clearance.
  • Autonomous Navigation Module: includes a dedicated processor, several sensors (Gyro, inclinometer, IMU, LIDAR), and a Tilt Unit to facilitate the laser scanning of LIDAR. Differential GPS is not necessary for MRPTA’s autonomous navigation, although it is an option. The autonomous navigation module detects and avoids obstacles, generate paths and local maps.
  • Advanced Visual Module: accepts traditional analogue and digital cameras signals, including the IEEE1394, USB, and IP camera. The camera is mounted on a Pan-and-Tilt Unit (PTU) on the Perception Mast to achieve full field vision. Typically, the advanced visual module consists of a stereo camera with IEEE1394 interface, LED lights, a dedicated imaging processing processor, an IEEE1394 interface card, and the PTU. The stereo camera, after processing, can provide 3D visual information, including the distance or depth, visual odometry, and point cloud.
  • State-of-Art Electronics: includes multiple PC104+ processors for motion control, autonomous navigation calculations, stereo image processing, scientific exploration data acquisition; sensors for autonomous navigation, stereo image camera; high performance wireless communication; military standard motor drivers, high quality motors; UPS power supply, and SMA (Shape-Memory Alloy) tether releasing mechanism.
  • Communication System: wireless communication system has been verified in the field for 1+ Km LOS. The wireless communication can transfer two-way data and one-way video between MRPTA and OCU.
  • Open Architecture: includes its Platform Motion Control System (PMCS) such that the users can develop their own navigation modules to control MRPTA. The open architecture is achieved with an open protocol, Ethernet port and TCP/IP protocol, and standard USB ports. Each processor has a VGA monitor port, and a USB port for mouse/keyboard for further development and debugging.
  • Multiple Payloads: can be mounted including scientific instruments and single and multiple tooling arms.
  • Tether-Aided Mode: platform can be attached to a tether for operating up/down on a steep slope (>65°). The feeding speed is controlled by a winch mechanism via the OCU. The OCU controls the winch mechanism and MRPTA simultaneously. When MRPTA reaches the target location it can be commanded through the OCU to release the tether for further operation.
  • Perception Mast: can be attached in the front of chassis. Stereo camera and its PTU, the LIDAR and its TU, and other autonomous navigation sensors are mounted on it. The mast provides good view for the stereo camera and the LIDAR.
  • Operator Control Unit: With installation of dedicated OCU software, any laptop with Ethernet connection, 17” monitor, two USB ports and 100G hard drive space can be used as the OCU for MRPTA. All the communications with MRPTA are through the Ethernet. Video, sensor readings, MRPTA’s attitude, system health, odometry and motion speed, flipper position, payload status, local map generated by the autonomous navigation subsystem, winch and tether status, etc. can be displayed on the 17” monitor.  From the OCU, the operator can select the control mode (tele-operation or autonomous navigation), set the configuration (track or wheel, large wheel or small wheel, with or without flipper), and send commands to MRPTA. A wireless Logitech joystick can be used by the operator.
  • Operations: water resistant. All exposed surfaces are covered with anodizing or protective paint. All detector and electronics compartments are protected against water and contaminants. Operates in all types of weather conditions, day and night, on wet and dry surfaces. Operational temperature from –20 to +400C; humidity can be up to 95% at 250C; storage temperature ranges from -20 to 500 These specifications were verified in environmental chambers.
  • Mobility: configuration can be exchanged in-field to one of the following: (i) Long track with flipper; (ii) Short track without flipper; (iii) Small wheel; (iv) Small wheel with flipper; and (v) Large wheel.
  • Communication: (i) 2-way Data & Audio, 1-way Video; (ii) Wireless: 3280 ft (1000 m) line of sight; 1312 ft (400 m) urban; 164 ft (50 m) indoors; and (iii) Fiber Optical Cable: Length 650+ ft (200 m) and 1312 ft (400m) optional
  • Payloads: (i) Single Tooling Arm: 1 scoop with 5cm (2.0”) stroke, with ultrasonic distance and sample detection sensing, max weight of sample: 200 gram; (ii) Multiple Tooling Arm: 3 scoops with 10cm (4.0”) stroke, with ultrasonic distance and scoop angle and sample sensing, max weight of sample: 200gram/each scoop; (iii) LIF Scientific instrument: 543-1047nm Laser Induced Fluorescence Spectrometer; (iv) XRF Scientific instrument: X-ray fluorescence Analyzer with one DOF linear motion; (v) High accuracy differential GPS receiver; and (vi) Winch: max tether length: 30m, max tether release speed: 0.1m/s, tether tension, tether angle sensors equipped.
  • Operator Control Station: (i) Laptop running on Linux OS with all information display (Vehicle attitude, Vehicle odometry, Vehicle health status & self-diagnosing, Local Map, Video stream, Scoop Status (scoop angle, sample in, etc.), Scientific Instrument status), Winch Status; (ii) Joystick: Logitech Rumble Pad 2; (iii) Interface Port: Ethernet; (iv) Sensor: Differential GPS base receiver; (v) Portable and enclosed in a weatherproof enclosure; and (vi) Operates 8 hrs with 12 VDC or 110/220 VAC.
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