Brake by wire control with pedal feedback and brake boost

"By wire" technology merged into multiple vehicular subsystems, including gear changing, drive, and braking systems. The brake by wire system is developed to overcome the problems associated with the integration of mechanical and hydraulic systems in novel vehicular systems. Even though brake by wire systems has potential advantages, the conventional brake systems' tactile sensation will be removed if migrated to the electrical by wire control scheme. This paper proposes a novel control mechanism that provides amplification of force, scaling of position replication, and a virtual spring-damper based pedal retraction which provides bilateral brake force feedback to the driver's pedal similar to the hydraulic brake system. The proposed system performance was simulated and tested using a bilateral teleoperation system with disturbance observers (DOB) and reaction force observers (RFOB). The proposed system provides pedal force amplification and brake force feedback to the driver's pedal using RFOBs. The virtual spring retracts the brake pedal, similar to a mechanical pedal retraction system. The system simulation and experimental results provide evidence of the proposed system's force amplification, position scaling, and pedal reaction capabilities.

Observer based dynamic control model for bilaterally controlled MU-lapa robot: Surgical tool force limiting

During laparoscopic surgeries, primary surgical tool insertion is the demanding and strenuous task. As the surgeon is unaware of the type of the tissue and associated parameters to conduct the insertion, therefore, to ease the procedure, the movement of the surgical tool needs to be controlled. It’s the operational capabilities that are to be manipulated to perform a smooth surgery even from a distant location. In this study, a robot system is being introduced for laparoscopic primary surgical tool insertion. It will incorporate a novel observer based dynamic control along with robot assisted bilateral control. Moreover, a virtual spring damper force lock system is introduced through which the slave system will notify the master regarding the target achieved and excessive force. The validation of the proposed control system is experimented with bilaterally controlled MU-LapaRobot. The experiment is comprising 3 cases of bilateral control criteria which are non-contact motion, contact motion, and limit force locking. The results defined the same value for contact and non-contact motion by 0.3N. The results depicted a force error of 3.6% and a position error of 5.8% which validated the proposed algorithm.

Robotic Swarm Self-Organisation Control

This article proposes a new swarm control method using distributed proportional-derivative (PD) control for self-organisation of swarm of nonholonomic robots. Kinematics control with distributed proportional-derivative (DPD) controller enables generation of desired robot trajectory achieving collective behaviour of a robotic swarm such as aggregation and pattern formation. Proposed method is a generalisation of virtual spring-damper control used in swarm self-organisation. The article includes the control algorithm synthesis using the Lyapunov control theory and numeric simulations results.

Control of a nonanthropomorphic exoskeleton for multi-joint assistance by contact force generation

In this article, a novel controller for a nonanthropomorphic exoskeleton robot was designed to reduce joint torque of its operator using the contact force between them. Since the joints of the nonanthropomorphic exoskeletons are not directly connected to those of the operator due to the difference between their kinematic structure, joint assistance is performed by transmitting the contact force on their coupling parts instead of transmitting the joint torque of the nonanthropomorphic exoskeleton directly into the human joint. Most of the previous studies have focused on reducing the measured contact force by moving the coupling parts or commanding the robot joint torque. On the contrary, the proposed method focuses on reducing the human joint torque, which is estimated by formulating inverse dynamics, by obtaining possible contact force solutions. The commanding torque of the nonanthropomorphic exoskeleton was calculated by inverse dynamics based on the model information. To verify the control performance of the proposed method, we have developed a simulation environment for a lower-limb nonanthropomorphic exoskeleton. When the coupling part was implemented to be rigid for an ideal case, the joint torque of the human model to perform the same motion was successfully reduced by the given torque reduction ratio. For a more realistic condition, a nonrigid coupling was also implemented as a virtual spring-damper system, and its effect on the control performance was demonstrated in the simulation.